7/24/14

A Relatively Cool July Will Support a Below Normal Summer Thus Far & Severe Weather 7/27/14

With two-thirds of July complete and in the midst of another refreshing cool summer-time air mass with another significant one in the wings by early next week, July 2014 will undoubtedly average notably below normal across Southeast Lower Michigan. While June averaged above normal across Southeast Lower Michigan, July's potent cool spells will have erased all the above normals at month's end and the region will sit in below normal territory thus far for the summer.

The temperature pattern thus far for the two months has been above normal then below, and how August plays out will clarify the picture. Therefore; when the timing of the temperatures pattern and upper air was similar to this year, how did August fare? In analogue data when July averaged more than one degree below normal; the August analogues averaged normal to below; just like our summer data did.

Latest CFS Model projections for August is a cool one for most of the country. It must be remembered that this 16 member CFS is highly weighted to the recent, last few weeks trend; also cool.







This member of the CFS projects more of a normal Aug in the Great Lakes with the cooler below normal area west of the lakes. Interesting how the computer models agree strongly with our analogues for August set up in the spring, normal to below tempertures.




Finally; looks like CPC is going middle of the road with the models with the below normal encompassing the western Lakes.





Of course, our summer departure data at Detroit will have to be taken with a grain of salt since its normals have been influenced by the urban heat island. When calculating Flint or Saginaw thus far, a lesser below normal departure is seen. Whats most important is the average temperature and where we place at Detroit, Flint and Saginaw relative to an average or normal summer; and a Southeast Lower Michigan summer temperature as a whole. At the end of July, I'll look at the Summer 2014 in statistics and where we place relative to an average summer thus far.

Severe Weather  on 7/27/14

Widespread severe weather accompanied by damaging winds and hail was observed over Southeast Lower Michigan Sunday afternoon and early evening on the 27th. This was well telegraphed by the models mid to late week (see original write-up 7/24) This appears to be our strongest event for the Severe Weather Season of 2014 thus far....

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
930 PM EDT SUN JUL 27 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0221 PM     HAIL             5 NW AUBURN             43.65N 84.15W 
07/27/2014  E2.50 INCH       BAY                MI   PUBLIC          

            RELAYED VIA SHAVE REPORT.

0230 PM     HAIL             3 ENE MIDLAND           43.64N 84.17W 
07/27/2014  M3.00 INCH       MIDLAND            MI   PUBLIC          

            RELAYED VIA SHAVE PROJECT

0230 PM     HAIL             MIDLAND                 43.62N 84.23W 
07/27/2014  M1.75 INCH       MIDLAND            MI   PUBLIC          

            LOTS OF 1.5 INCH HAIL...A FEW TO 1.75 INCHES. RELAYED VIA
            FACEBOOK WITH PICTURES.

0241 PM     HAIL             4 NNW AUBURN            43.65N 84.13W 
07/27/2014  E2.00 INCH       BAY                MI   911 CALL CENTER 

            RELAYED VIA SHAVE PROJECT.

0243 PM     HAIL             1 E WILLARD             43.67N 84.09W 
07/27/2014  E1.75 INCH       BAY                MI   PUBLIC          

            RELAYED BY SHAVE PROJECT

0249 PM     HAIL             3 WNW KAWKAWLIN         43.67N 84.00W 
07/27/2014  E2.00 INCH       BAY                MI   PUBLIC          

            RELAYED VIA SHAVE PROJECT

0250 PM     HAIL             2 W KAWKAWLIN           43.65N 83.99W 
07/27/2014  M2.00 INCH       BAY                MI   PUBLIC          

            RELAYED VIA SHAVE PROJECT

0250 PM     HAIL             4 SSW LINWOOD           43.69N 84.01W 
07/27/2014  E1.00 INCH       BAY                MI   PUBLIC          

            RELAYED VIA SHAVE PROJECT

0256 PM     HAIL             1 ENE KAWKAWLIN         43.66N 83.93W 
07/27/2014  E2.50 INCH       BAY                MI   PUBLIC          

            RELAYED VIA SHAVE PROJECT

0300 PM     HAIL             3 S LINWOOD             43.70N 83.98W 
07/27/2014  E1.50 INCH       BAY                MI   PUBLIC          

            RELAYED VIA SHAVE PROJECT

0300 PM     HAIL             KAWKAWLIN               43.65N 83.95W 
07/27/2014  M1.75 INCH       BAY                MI   PUBLIC          

0300 PM     HAIL             2 NNW KAWKAWLIN         43.68N 83.96W 
07/27/2014  E1.75 INCH       BAY                MI   PUBLIC          

            RELAYED VIA SHAVE PROJECT.

0305 PM     HAIL             1 ESE KAWKAWLIN         43.65N 83.93W 
07/27/2014  E2.00 INCH       BAY                MI   PUBLIC          

            RELAYED VIA SHAVE PROJECT

0310 PM     HAIL             4 N BAY CITY            43.65N 83.87W 
07/27/2014  M1.00 INCH       BAY                MI   TRAINED SPOTTER 

0310 PM     HAIL             3 S PINCONNING          43.81N 83.96W 
07/27/2014  M2.00 INCH       BAY                MI   AMATEUR RADIO   

            RELAYED WITH PICTURES

0310 PM     HAIL             4 NNE BAY CITY          43.65N 83.87W 
07/27/2014  M1.50 INCH       BAY                MI   TRAINED SPOTTER 

            IN BANGOR TWP RIGHT ON SAGINAW BAY

0400 PM     LIGHTNING        1 SSW CASEVILLE         43.93N 83.28W 
07/27/2014                   HURON              MI   911 CALL CENTER 

            BUILDING DAMAGE CAUSED BY LIGHTNING STRIKE. 

0400 PM     LIGHTNING        1 SSW CASEVILLE         43.93N 83.29W 
07/27/2014                   HURON              MI   911 CALL CENTER 

            HOUSE FIRE CAUSED BY LIGHTNING.

0415 PM     HAIL             3 ENE HARTLAND          42.67N 83.69W 
07/27/2014  M1.00 INCH       LIVINGSTON         MI   TRAINED SPOTTER 

0420 PM     MARINE TSTM WIND 8 ESE AU GRES           44.02N 83.54W 
07/27/2014  M59.00 MPH       LHZ421             MI   BUOY            

            MEASURED AT GRAVELLY SHOALS LIGHT

0425 PM     HAIL             6 SW SANFORD            43.61N 84.47W 
07/27/2014  M1.50 INCH       MIDLAND            MI   TRAINED SPOTTER 

            AT M-20 AND 11 MILE

0430 PM     HAIL             3 NNE HIGHLAND          42.68N 83.61W 
07/27/2014  M1.75 INCH       OAKLAND            MI   TRAINED SPOTTER 

            HARVEY LAKE RD AND MILFORD RD

0431 PM     HAIL             HIGHLAND                42.64N 83.62W 
07/27/2014  M1.75 INCH       OAKLAND            MI   TRAINED SPOTTER 

0435 PM     TSTM WND DMG     6 N MILFORD             42.67N 83.62W 
07/27/2014                   OAKLAND            MI   EMERGENCY MNGR  

            AT MOBILE HOME PARK AT MILFORD AND MIDDLE ROADS. 80 
            PERCENT OF MOBILE HOMES DAMAGED WITH BROKEN WINDOWS.

0435 PM     TSTM WND DMG     4 WNW CHELSEA           42.33N 84.10W 
07/27/2014                   WASHTENAW          MI   AMATEUR RADIO   

            TREES AND LARGE LIMBS DOWN BLOCKING THE ROAD. SHERIFF ON 
            THE SCENE.

0435 PM     HAIL             3 SSE ROSE CENTER       42.69N 83.58W 
07/27/2014  E1.25 INCH       OAKLAND            MI   TRAINED SPOTTER 

            AT DUCK LAKE RD AND M-59

0435 PM     TSTM WND DMG     4 S MOUNT FOREST        43.83N 84.11W 
07/27/2014                   BAY                MI   911 CALL CENTER 

            POWER LINES DOWN.

0438 PM     HAIL             5 NNE MILFORD           42.66N 83.56W 
07/27/2014  M1.00 INCH       OAKLAND            MI   TRAINED SPOTTER 

            MEASURED IN WHITE LAKE TWP

0440 PM     HAIL             5 NE MILFORD            42.63N 83.52W 
07/27/2014  M1.75 INCH       OAKLAND            MI   NWS EMPLOYEE    

            MEASURED IN WHITE LAKE TWP

0440 PM     HAIL             4 SE ROSE CENTER        42.69N 83.57W 
07/27/2014  M1.75 INCH       OAKLAND            MI   TRAINED SPOTTER 

0442 PM     HAIL             WHITE LAKE              42.65N 83.50W 
07/27/2014  M1.75 INCH       OAKLAND            MI   TRAINED SPOTTER 

0443 PM     HAIL             5 ENE MILFORD           42.61N 83.51W 
07/27/2014  M1.75 INCH       OAKLAND            MI   AMATEUR RADIO   

            MEASURED AT BOGIE LK AND COOLEY LK ROADS

0445 PM     TSTM WND DMG     4 W ALGONAC             42.63N 82.62W 
07/27/2014                   ST. CLAIR          MI   TRAINED SPOTTER 

            LARGE LIMBS DOWN

0449 PM     TSTM WND GST     WATERFORD               42.66N 83.39W 
07/27/2014  M62.00 MPH       OAKLAND            MI   ASOS            

            MEASURED AT PONTIAC OAKLAND COUNTY INTERNATIONAL AIRPORT 
            /KPTK/

0450 PM     MARINE TSTM WIND 12 NNW BAY PARK         43.81N 83.72W 
07/27/2014  M41.00 MPH       LHZ422             MI   BUOY            

            MEASURED AT SAGINAW BAY LIGHT

0450 PM     HAIL             WATERFORD               42.66N 83.39W 
07/27/2014  M1.00 INCH       OAKLAND            MI   TRAINED SPOTTER 

            MEASURED AT AIRPORT ROAD AND M-59

0500 PM     TSTM WND DMG     2 SW PONTIAC            42.63N 83.32W 
07/27/2014                   OAKLAND            MI   PUBLIC          

            MULTIPLE LIMBS DOWN AT TELEGRAPH AND VOORHIES. RELAYED 
            VIA TWITTER.

0500 PM     TSTM WND DMG     2 N SAGINAW             43.45N 83.94W 
07/27/2014                   SAGINAW            MI   PUBLIC          

            TREE UPROOTED

0500 PM     TSTM WND DMG     4 NW HEMLOCK            43.46N 84.29W 
07/27/2014                   SAGINAW            MI   TRAINED SPOTTER 

            10 INCH DIAMETER BRANCH TOOK DOWN POWERLINE ACROSS FROST 
            ROAD

0500 PM     TSTM WND DMG     6 WSW PONTIAC           42.61N 83.38W 
07/27/2014                   OAKLAND            MI   TRAINED SPOTTER 

            6 INCH LIMB DOWN AT WEST BLOOMFIELD AND CASS LAKE ROAD

0500 PM     TSTM WND DMG     4 W WARREN              42.49N 83.11W 
07/27/2014                   OAKLAND            MI   TRAINED SPOTTER 

            TREE FELL ONTO HOUSE.

0502 PM     TSTM WND DMG     6 SW PONTIAC            42.60N 83.37W 
07/27/2014                   OAKLAND            MI   TRAINED SPOTTER 

            4 INCH DIAMETER BRANCHES DOWN AT CASS LAKE AND ORCHARD 
            LAKE ROADS

0505 PM     TSTM WND GST     CHESANING               43.18N 84.12W 
07/27/2014  E60.00 MPH       SAGINAW            MI   TRAINED SPOTTER 

0505 PM     HAIL             4 SSE PONTIAC           42.60N 83.25W 
07/27/2014  M1.00 INCH       OAKLAND            MI   TRAINED SPOTTER 

            AT SQUARE LAKE AND OPDYKE

0505 PM     TSTM WND DMG     4 SSE PONTIAC           42.60N 83.25W 
07/27/2014                   OAKLAND            MI   TRAINED SPOTTER 

            LARGE LIMBS DOWN ON I-75 SOUTH OF SQUARE LAKE ROAD

0507 PM     TSTM WND DMG     5 NNE CHESANING         43.25N 84.10W 
07/27/2014                   SAGINAW            MI   911 CALL CENTER 

            BARN ROOF TORN OFF, TREES UPROOTED. FERGUS RD IN ST 
            CHARLES

0507 PM     TSTM WND DMG     5 NNE CHESANING         43.25N 84.09W 
07/27/2014                   SAGINAW            MI   TRAINED SPOTTER 

            POWER LINES DOWN FOR ONE HALF MILE AND DAMAGE TO PORCH AT
            BIRCH RUN AND STEWART

0510 PM     TSTM WND GST     BLOOMFIELD HILLS        42.58N 83.25W 
07/27/2014  E70.00 MPH       OAKLAND            MI   TRAINED SPOTTER 

            AT SQUARE LAKE AND WOODWARD

0510 PM     TSTM WND GST     5 SSE PONTIAC           42.58N 83.25W 
07/27/2014  M53.00 MPH       OAKLAND            MI   TRAINED SPOTTER 

            NUMEROUS 1 FOOT LIMBS DOWN NEAR SQUARE LAKE AND OPDYKE

0514 PM     TSTM WND DMG     MADISON HEIGHTS         42.50N 83.10W 
07/27/2014                   OAKLAND            MI   TRAINED SPOTTER 

            LARGE TREE LIMBS DOWN AT 12 MILE AND DEQUINDRE

0515 PM     TSTM WND DMG     2 NW SAGINAW            43.44N 83.98W 
07/27/2014                   SAGINAW            MI   TRAINED SPOTTER 

            15 INCH DIAMETER LIMB DOWN

0515 PM     TSTM WND DMG     4 ENE SOUTHFIELD        42.49N 83.18W 
07/27/2014                   OAKLAND            MI   TRAINED SPOTTER 

            ONE LARGE LIMB DOWN AT STANFORD AND CAMBRIDGE IN BERKLEY

0520 PM     HAIL             NORTH BRANCH            43.23N 83.19W 
07/27/2014  M1.25 INCH       LAPEER             MI   TRAINED SPOTTER 

            FELL FOR 7 MINUTES AT HALF DOLLAR SIZE. ALSO 45 MPH GUST.


0530 PM     TSTM WND GST     3 SE BIRCH RUN          43.22N 83.75W 
07/27/2014  E60.00 MPH       GENESEE            MI   911 CALL CENTER 

0530 PM     TSTM WND DMG     1 N WYANDOTTE           42.23N 83.16W 
07/27/2014                   WAYNE              MI   TRAINED SPOTTER 

            LARGE BRANCH DOWN ON POWERLINES

0530 PM     HAIL             1 ENE WARREN            42.50N 83.01W 
07/27/2014  M1.00 INCH       MACOMB             MI   TRAINED SPOTTER 

            AT MARTIN AND HOOVER

0537 PM     HAIL             SHELBY TOWNSHIP         42.67N 83.03W 
07/27/2014  M1.00 INCH       MACOMB             MI   TRAINED SPOTTER 

            25 MILE AND JEWELL

0540 PM     MARINE TSTM WIND 2 SE ST. CLAIR SHORES   42.47N 82.87W 
07/27/2014  M46.00 MPH       LCZ460             MI   C-MAN STATION   

0546 PM     TSTM WND GST     3 ESE MOUNT CLEMENS     42.58N 82.83W 
07/27/2014  E65.00 MPH       MACOMB             MI   TRAINED SPOTTER 

            TREES SNAPPED AND UPROOTED AT METRO VILLA DR AND NORTH 
            POINTE PKWY IN HARRISON TWP

0546 PM     MARINE TSTM WIND 3 ENE MOUNT CLEMENS     42.61N 82.83W 
07/27/2014  M46.00 MPH       MACOMB             MI   AWOS            

            MEASURED AT SELFRIDGE ANGB /KMTC/

0546 PM     TSTM WND DMG     2 SE MOUNT CLEMENS      42.57N 82.85W 
07/27/2014                   MACOMB             MI   TRAINED SPOTTER 

            LARGE TREE FELL ONTO HOUSE. MULTIPLE LARGE TREE LIMBS 
            ALSO DOWN.

0547 PM     TSTM WND DMG     4 ESE MOUNT CLEMENS     42.59N 82.81W 
07/27/2014                   MACOMB             MI   TRAINED SPOTTER 

            TREE LIMBS GREATER THAN ONE FOOT DIAMETER DOWN NEAR METRO
            BEACH IN HARRISON TWP

0553 PM     TSTM WND DMG     1 NW OTISVILLE          43.18N 83.54W 
07/27/2014                   GENESEE            MI   911 CALL CENTER 

            TREES DOWN UP TO 3 FEET IN DIAMETER ON M-57 BETWEEN IRISH
            RD AND M-15

0553 PM     TSTM WND DMG     2 ESE TECUMSEH          42.00N 83.91W 
07/27/2014                   LENAWEE            MI   TRAINED SPOTTER 

            TREE DOWN AT M50 AND BILLMYER RD

0600 PM     HEAVY RAIN       STERLING HEIGHTS        42.58N 83.03W 
07/27/2014  M1.50 INCH       MACOMB             MI   TRAINED SPOTTER 

            1 HOUR TOTAL AT 18 MILE AND RYAN

0600 PM     TSTM WND DMG     BROWN CITY              43.21N 82.99W 
07/27/2014                   SANILAC            MI   911 CALL CENTER 

            LIMBS DOWN AND POWER OUTAGES

0600 PM     MARINE TSTM WIND 1 SSE PORT SANILAC      43.42N 82.54W 
07/27/2014  M46.00 MPH       SANILAC            MI   BUOY            

0621 PM     HAIL             MANCHESTER              42.15N 84.04W 
07/27/2014  E1.00 INCH       WASHTENAW          MI   TRAINED SPOTTER 

0625 PM     TSTM WND DMG     6 ENE CARLETON          42.08N 83.28W 
07/27/2014                   MONROE             MI   911 CALL CENTER 

            TREES DOWN NEAR TELEGRAPH AND ARMSTRONG

0630 PM     TSTM WND DMG     4 W CHELSEA             42.31N 84.09W 
07/27/2014                   WASHTENAW          MI   TRAINED SPOTTER 

            10 INCH DIAMETER LIMB DOWN

0646 PM     TSTM WND DMG     CHELSEA                 42.31N 84.02W 
07/27/2014                   WASHTENAW          MI   TRAINED SPOTTER 

            3 FOOT DIAMETER TREE DOWN ON A HOUSE AT JEFFERSON AND 
            EAST

0651 PM     TSTM WND GST     3 NE ANN ARBOR          42.31N 83.69W 
07/27/2014  E60.00 MPH       WASHTENAW          MI   TRAINED SPOTTER 

            AT GREEN AND PLYMOUTH

0651 PM     TSTM WND DMG     2 NE ANN ARBOR          42.30N 83.70W 
07/27/2014                   WASHTENAW          MI   TRAINED SPOTTER 

            14 INCH TREE LIMB REPORTED DOWN.

0700 PM     MARINE TSTM WIND 10 SSE STONY POINT      41.82N 83.19W 
07/27/2014  M39.00 MPH       LEZ162             MI   C-MAN STATION   

0704 PM     TSTM WND DMG     4 SSE WHITMORE LAKE     42.38N 83.72W 
07/27/2014                   WASHTENAW          MI   LAW ENFORCEMENT 

            10 TREES DOWN BLOCKING ROAD

0717 PM     TSTM WND DMG     NORTHVILLE              42.44N 83.49W 
07/27/2014                   WAYNE              MI   911 CALL CENTER 

            A COUPLE OF DOWNED TREES

0753 PM     MARINE TSTM WIND GROSSE ILE              42.13N 83.15W 
07/27/2014  M43.00 MPH       WAYNE              MI   AWOS            


7/27/14- Update
No severe weather erupted on Saturday nor Saturday night as the most unstable air remained south over the Ohio Valley. There still is a risk of severe weather on Sunday and a strong cold front pushes southeast across the region by Sunday afternoon.

Original - 7/24/14

On a completely different weather note; the potential for severe weather this weekend (7/26-27) has increased with the last few model outputs and certainly bears monitoring.

All models (GFS, NAM & EURO) strongly intimate the risk of severe weather across the southern Great Lakes and northern Ohio Valley. Impressive instability, strong shear and other dynamics seem to be coming together in this region Saturday into Sunday. It looks as though some area(s) will be clobbered by severe thunderstorms and possibly even a few tornadoes. 

Here in Southeast Michigan we will be on the northern side of this system with the greatest risk of severe weather across northern Illinois into northern Indiana and Ohio. However, this system has the potential to drive the severe weather into the southern tier of Lower Michigan. At this early juncture; the highest risk of severe weather will be Saturday into Saturday Night. Sunday too could bring another round of at least strong to severe storms with the final push of the next cool air mass. If this trend continues; updates will be forthcoming!

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian


7/16/14

NICE AND BRIGHT TO BLACK AS NIGHT; THE JULY 16TH, 1980 DERECHO

Step back in time on the 34th anniversary of one of the most notable derechos ever to clobber Southeast Lower Michigan from Ann Arbor into Metro Detroit; The July 16th 1980 Derecho!
 

NICE AND BRIGHT TO BLACK AS NIGHT!

THE JULY 16TH, 1980, DERECHO

Written by: William R. Deedler, Weather Historian
Originally written:
July 22nd, 2005 
 
The word "derecho" may sound unfamiliar or its use in meteorology relatively recent in nature, but the word actually was brought into meteorological vernacular way back in 1888. Dr. Gustavus Hinrichs, a physics professor at the University of Iowa, was given that credit when he used the word, derecho, in a paper he had published in the American Meteorological Journal in 1888. Dr Hinrichs chose this terminology for thunderstorm induced straight-line winds as an analog to the word tornado. Derecho is a Spanish word which can be defined as "direct" or "straight ahead" while tornado is thought by some, including Dr. Hinrichs, to have been derived from the Spanish word "tornar" which means "to turn". This definition and other derecho facts are taken from the Storm Prediction Center's About Derechos web page, which contains many interesting facts and background studies about derechos.

Even though the term "derecho" dates back well over a century, it has only been relatively recent (since the 1980s) that more investigative studies and research has greatly increased our knowledge about these types of storms. Derechos are associated with a line of showers or thunderstorms that are often "curved" in shape on radar and satellite. These bowed out storms are called "bow echoes". A derecho can be associated with a single bow echo or multiple bow echoes. By definition winds in a derecho must meet the National Weather Service criterion for severe wind gusts (greater than 57 mph) at most points along the derecho path. In the stronger derecho events winds can exceed 100 mph.

Southeast Lower Michigan has had several derechos in the past, but certainly one of the more memorable ones plowed through extreme Southern Michigan during the forenoon hours of Wednesday, July 16th, 1980.

Summer of '80 starts out on a chilly note

The Summer of 1980 actually hadn't been much of a summer as far as warm temperatures and dry weather were concerned. The summer had been unseasonably cool and soggy into early July. June's average temperature was a relatively chilly 63.7 degrees, making it the eighth coolest June on record at Detroit. To add insult to injury, not only had June been cool, it also had been very wet. June's monthly rainfall totaled up to nearly six and a half inches /6.42"/, making it the sixth wettest June on record, which undoubtedly made the month seem even worse.

While the first few weeks of July averaged a bit below normal, some good ole' fashion summer-time heat finally began to bubble up into the region by mid month. Hot and unstable air pushed its way north into the Great Lakes by the 15th as temperatures surged into the lower to mid 90s. Up until that time, only once before had temperatures pushed up into the 90s that summer. The arrival of the hot and humid air mass set off some scattered showers and thunderstorms on the 15th, but really nothing of consequence compared to what would generate to the west overnight.

Birth of a Hybrid Derecho 

 

Surface map from 8 am EDT, July 16th, 1980; click on image to enlarge A low pressure area with attending warm and cold fronts (map-2) pushing through the Upper Midwest was responsible in igniting the derecho at the surface late on the 15th. Thunderstorms developing over extreme Eastern Iowa and Northern Illinois during the very early morning hours of the 16th, intensified and formed into a squall line that pushed through Northern Illinois between 3 AM and 5 AM EDT. The storms were spawned out ahead of the frontal system as it approached northern Illinois, mainly ahead of the triple point juncture and nearly perpendicular to the warm front. At the same time, a potent mid level short wave (map-3) and wind max (approx 60-70 knots) surged east across the Upper Midwest toward the Southern Great Lakes.

Nice and Bright to Black as Night

The derecho surged quickly east across Northern Indiana and Southern Lake Michigan with a measured wind gust of 98 mph at the St. Joseph Coast Guard as it blasted onshore in Southwest Lower Michigan! While the sky was relatively bright at sunrise over Southeast Lower Michigan, a band of foreboding clouds advanced in quickly from the west, covering the celestial dome. As the forceful storms and associated hurricane force winds approached the area, several observers remarked about the horrid dark green color the sky took on as the squall moved overhead. In fact, numerous people over the years have commented about the "dark pea green sky" that accompanied the July 16th 1980 storm. The green color in the sky may have been reflective of the low sun angle at the time (the derecho moved through region between 730 and 930 AM EDT) and abundance of moisture in the low clouds. It got so dark that many street lights were triggered and popped on over portions of the region. Severe thunderstorm warnings were issued over the region though some remarked: "it happened so quickly and early in the day, it caught us off guard".

The hardest hit regions across Southeast Lower Michigan were Washtenaw and Wayne counties, extending mainly from the Ann Arbor area east into southern sections of Detroit (or south of the Ford Road /M-153/ corridor). While the wind officially gusted to 71 mph at Detroit Metro Airport, much higher winds were reported in other areas (see storm report below) in the strongest core of the derecho.

As one person who witnessed the swath of damage across southern portions of Washtenaw and Wayne counties, the following excerpts from storm data relay the incredible outcome of the storm. In the storm data below, the derecho is referred to as a downburst. In addition, the derecho was accompanied by a small tornado as it exited extreme Southeast Lower Michigan. Tornadoes can occur in isolated thunderstorm supercells ahead of the derecho producing squall line or they may be associated with the squall line itself.


STORM DATA
Counties in
SE Mich
Date
7/16/80
Time
830-920AM EDT

Washtenaw
Wayne
Monroe
"Intense downburst developed just west of Ann Arbor. Path of the most intense damage across southern Ann Arbor then eastward through the Downriver suburbs of Detroit. Winds estimated up to 100 mph in Washtenaw county, up to 150 mph in Wayne County. Innumerable buildings, vehicles and trees destroyed in eastern Washtenaw, central and southern Wayne, and northeastern Monroe counties. Several boats were swamped on the Detroit River. Power off in some areas up to ten days."

Downriver CommunitiesDate
7/16/80
Time
910 AM EDT

Allen Park, Lincoln Park, and Ecorse, in Wayne county "Railroad cars blown off track in both directions in Allen Park. Department store roof blown sideways in Lincoln Park. Funnel sighted over Detroit River from Canadian shore. Tornado damage included in, and hardly distinguishable from large area of straight line wind damage. Funnel continued eastward several more miles into Canada".
It's amazing that after reading about the force of the wind and subsequent damage, that only one person - a woman - was reported injured in sort of a freak accident when the wind forced her into a revolving door! Note the following that was taken from "Derecho Hazards in the United States" by Walker S. Asley, Climatology Research Laboratory at the University of Georgia, Athens, Georgia. It gives an interesting account of the July 16th,1980 Derecho storm damage relative to other storm damage.

Fujita and Wakimoto (1981) provided extensive documentation of the 16 July 1980 derecho that produced widespread damage across large areas of Michigan, Illinois, Wisconsin, and Minnesota. They indicated that this storm produced approximately $650 million in damage as it traversed the four-state region. Accounting for inflation (to 2003 dollars), this storm produced an estimated $1.3 billion in damage from strictly straight-line winds. This estimate exceeds many damage tallies from U.S. hurricanes and is larger than the inflation-adjusted damage estimates from all major tornadoes that have affected the U.S. since 1890 (Brooks and Doswell 2001). This single event illustrates that derecho damage can exceed the damage from most hurricanes and tornado events affecting the contiguous U.S.

Graph of wind gusts by month for the U.S.; click on image to enlarge Note the graph to the right which displays monthly damaging wind events in the U.S. July and June are the top months for wind storms. Many of these wind storms occur as derechos over the Great Lakes states (Johns and Hirt, 1987).






More on the Derecho by Dr. Fujita in 1981
http://www.spc.noaa.gov/misc/AbtDerechos/papers/Fujita_1981.pdf

Making weather fun while we all learn,
Bill Deedler - SEMI_WeatherHistorian

7/9/14

Extended Models Continue To Project Outstanding Dynamic System For Mid Summer!

Quick Update 7/13----

From;

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1140 AM EDT SUN JUL 13 2014
 
BIG STORY CONTINUES TO BE THE ANOMALOUS COOLING IN THE CENTRAL
PLAINS AND TOWARD THE EAST... WITH 850 TEMP STND ANOMALIES IN THE
-3 TO -3.5 RANGE YIELDING SFC TEMPS ABOUT 20-30F COOLER THAN
AVERAGE. DAILY RECORD COOL HIGH TEMPS SHOULD BE CHALLENGED IN MANY
LOCATIONS. 
 
Strong dynamics and cold air aloft should produce scattered showers and an isolated thunderstorm
mainly Monday but generally sinking air, limited instability and moisture will keep a cap on anything 
severe. High temperatures at their coldest will be in the 60s; while lows dip into the upper 40s to lower 50s. 
 
Look for more typical summer time temperatures that are closer to normal to return by the weekend.


Quick Update 7/12-----

General consensus of model and numerical guidance remains similar to that of last few days. Best chance for storms, possibly strong to severe, will be late overnight Saturday into Sunday morning. Variably cloudy skies with instability showers and isolated storms, along with gusty winds, can be expected Monday into Wednesday as the cold air aloft and at the surface overspreads Southeast Lower Michigan. Coldest temperatures still appear Tuesday into Wednesday with overnight lows falling into the upper 40s to lower 50s...and highs in the 60s.

Update 7/10----

Latest guidance from both GFS and Euro continue to amplify intense vortex diving out of Canada and into the upper Great Lakes states Sunday night through Wednesday. If anything, the latest GFS is a bit stronger with the system with very impressive wind max jet cores and cold temperatures aloft by summer standards.

As the colder air and front approaches Sunday night into Monday showers and thunderstorms will be likely and, depending on the environment instability, some could be strong to severe but at this early juncture strongest storm potential appear to be w and south of the region but this bears watching since close.

After; a high altitude jet stream core flirting with 140 knots is now projected by the GFS model Tuesday afternoon over the region! This max wind aloft is even notable for winter standards let alone summer. Of course it's early, but winds in excess of 100 knots seem likely anyway over the Great lakes region given the dynamics and strength of the system the past several runs. In addition; upper level heights /500 MB/ are now forecasted to hover near the all time record low for July ~ 558 dm over Southeast Lower Michigan recorded in upper air data.




Fortunately with limited instability in place, showers and isolated storms with moderate squalls would be expected. Winds closer to the ground in the 5 to 10 thousand denoting possible gusts range in the 30 to 50 mph, but again this is still up in the air - pun intended. How much wind is realized and the surface will be largely dependent on; how much sunshine and instability is realized, how much convection will be able to develop along with how much of the stronger winds are able to mix down to the surface.

Here is the surface map Tue Morning; note the "cool season-like" low pressure developing over the eastern Great Lakes on jet core/dynamics aloft. In addition, the large extensive cool high pressure and air mass for mid summer, pushing overnight lows down into the 40s and 50s over a large portion of the interior part of the country.



 Note the single digit 850 MB temps @ 5K FT Tue Eve


The large cool high pressure and air mass for mid summer extends far south to near the gulf states; a feat hard to come by in mid summer. Overnight lows over a huge portion for the country are in the 40s and 50s...more typical of early October weather.

Yes indeed; this Polar Vortex won't give up the ship in the normally warmest time of the summer!



Coldest of air over Southeast Lower Michigan still appears to be from Tuesday into Wednesday with possibly Thursday morning as well. Little change in original thinking as highest temperatures during Tuesday and Wednesday afternoon look to be in the upper 50s to mid 60s across Southeast Lower Michigan, while lowest temperatures in the mid 40s to the lower 50s.

We'll have more time to zero in on this system over the weekend.

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian
 _____________________________________________________________________

Original 7/9/14----

Ironically, just over six months to the date of the first notable visit of the winter polar vortex (this is nothing new of course; happens every year but with varying intensities); she is expected to make a return visit mid summer. What IS impressive on this visit (not unlike her past winter visits) is the depth and position south. At early inspection, the upper low "polar vortex" is expected to average around 3 deviations BELOW average for a summer type upper low over the upper Great Lakes. Along with the fanfare of her arrival will be strong upper winds /jet stream/ and possibly some tough weather in the form of wind storms with such impressive energy at and above ground level. When such cold air (for  summer standards) rudely plows into even temperate summer like temperatures (in this case 70s to lower 80s), something's got to give.

The two questions are when and where the best clash of the notably different atmospheres will be; which will be involving very impressive dynamics and instability levels at the time. It's much too early to give an exact timing but an estimate seems to be in the late Sunday into Monday time frame for it's arrival - and early - mid week when she spins up over southern Canada and northern Great Lakes. Even at this time, if available moisture is in place, it wouldn't take much to pop a gusty storm or shower with such cold conditions aloft along with the impressive strong winds. 






Projections for upper heights and widespread low level cool temperatures are some of the best (lowest) I've seen for mid July. Upper low height projections are sub 550 MB /546 MB/ on the GFS along with 850 MB temperature projections in the single digits. At the coolest (preliminary timing; Tuesday night-Wednesday morning) widespread overnight lows in the 40s to lower 50s are likely across Southeast Lower Michigan with highs around 60 to the mid 60s. If these temperatures are realized, both record low maxs and record low mins may be in jeopardy. Record low max's for mid July are in around 60 to mid 60s across the region, while record lows are in the 40s to near 50.  One glaring exception is a record low max of just 74 degrees in Flint on the 16th, much higher than other record low maxs from the 14th thru the 16th.

Its too early to predict the exact coolness of the air mass due over the area early-mid week during next week but model projections have been pretty well unanimous on this summer cool outbreak - it is coming with the particulars yet to unfold. If you are heading up north this weekend and plan to stay awhile pack for fall-like weather for a few days - LOL- really not a bad idea in Southeast Michigan too.

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian

7/2/14

One Month Into the Summer and Outlook Along With Upper Air/Surface Pattern Playing Out Thus Far

June is in the record's book and widespread calls for a notably cool summer has yet to materialize with June's temperatures averaging slightly above normal. Dominate trends seen in the later spring along with data from the analogues pointed to a normal summer. The second dominate trend in analogues suggested a cooler than normal summer. This is precisely why I went normal to slightly below normal; I didn't expect it to be quite as cool as many were calling for in my research..

Temperatures :

Overall; a comfortable summer is on tap as I look for temperatures to average around normal to slightly below for the summer. That being said I don't anticipate a notably cool summer. I look for temperatures to average between +1.0 degree and -2.0 degrees of the summer norms across Southeast Lower Michigan.


JUNE TEMP STATISTICS

DETROIT       June '14    Norms    Departures
AVG. MAXIMUM     80.1      79.3     +0.8
AVG. MINIMUM     60.9      59.5     +1.4
MEAN             70.5      69.4     +1.1

FLINT
AVG. MAXIMUM     80.0      77.9     +2.1
AVG. MINIMUM     58.2      55.2     +3.0
MEAN             69.1      66.5     +2.6


SAGINAW
AVG. MAXIMUM     79.4      77.9     +1.5
AVG. MINIMUM     59.9      56.5     +3.4
MEAN             69.7      67.2     +2.5

Along with temperatures being on the higher side of normal thus far, the best performing analogues on average, continue to be relative. Two of the best performing analogue summers averaged around normal and one below normal.

Also from the Outlook;

Best Performing Analogues since Autumn '13


Temperatures

Since late fall of 2013, we have had a couple of years which take full marks for past prediction of the past few seasons; 1880-81 and 1981-82. And, maybe not surprising; 1881 contained a normal summer while 1982 had a cool summer (like our two prevalent trends seen). Another year; 1899 joins these analogue ranks as a decent performer during the winter and a good parallel this spring. All three analogues projected a cool spring with the temperature pattern we've seen this spring with time; below normal - normal - above normal. These analogue springs averaged below normal because of a very cold beginning to the season but will a gradual trend change from below to normal to above (Mar; Apr, May). The Summer of 1899 turned out to have a normal summer, therefore we have two normal summers and one below for the recent better performing analogues. 

While June's in the analogues averaged a bit below normal (see below /-.7/) and had the best chance (along with August) of averaging below normal; there was quite a variance of temperatures ranging from 64.2 to 72.4. This is over eight degrees which is fairly impressive for a summer month. Simply put; it was mainly about whether the ridge or trough dominated during the month - or some of both and timing. As stated many times; patterns can't be wrapped up in monthly intervals and one must look at the overall pattern in time. Normal to above normal temperatures began to hold sway in May (as expected in the spring outlook), especially later May which has continued into June but with some notable cool breaks...thus tempering the monthly average. Junes overall temperature performance followed 1963, 1991 and 2002. Now two of these summers averaged above normal and thus...a trend to watch but one month, a trend does not make. However; in the monthly data; July's had the best chance averaging above normal (maybe we're ahead of schedule ;-)). Analogue timing may well be slow and July actually ends up normal or even below since the upper jet in Canada remains strong. In any event, our upper air, precipitation and storm pattern timing has come to fruition thus far.
 
 

 From the Outlook:
  
Stormy Weather?
As mentioned above; the data to me depicts a notable confrontation zone and I believe we have just recently entered it as of late May. Typically, the busiest times for severe weather in these parts is June into July; with mid June to mid July prime-pickens. I've included the severe weather stats for Southeast Lower Michigan since 1980. Looking above at our analogue summers since then are 1982, 1991, 1997 and 2002 and all but 1982 contained normal to above normal (or busy) severe seasons. That's not surprising given the jet stream that's been dominant in Canada this year. Were this upper jet continued to be aggressive, notable wind events, squall lines and possibly a derecho event or two across the country would be the risk. Off the top of my head; both 1991 (derecho) and 1997 (squall line and tornado) contained notable July squall lines and tornado and 2002's severe weather season was overall, busy.

 
As one can easily see, the zone of air mass confrontation between all of these systems is like most summers and extends from the Great Plains, east through the Great Lakes and on to the East Coast.




This upper air pattern has dominated with routinely heat and humidity pushing northeast into the region and cold fronts still routinely surging out of Canada. From the Outlook:

Analogue Upper Wind Data
Past analogue upper wind data paints upper height ridging and oscillations extending from the Rocky Mountains eastward into the Gulf States and points north into the Great Plains to Eastern Great Lakes. In conjunction; an Upper low pressure oscillated over the eastern half of Canada and extended south and oscillated from the western Great Lakes to off the East Coast. This type of pattern would give us overall normal temperatures during the summer with warm to hot spells routinely extinguished by parading Canadian cool air masses. If one or the other prevails more; of course it will be cooler or warmer than expected. Looking at recent past trends along with this analogue data and subsequent pattern suggests to me normal to below normal temperatures.




The upper jet stream across Canada remains amplified along with impressive jet wind maxs at times. This along with frequent moderate to strong instability from the Plains eastward into the Lakes and Ohio Valley/East Coast has ignited storms, severe weather and plentiful rains.

The upper air pattern now affecting the region has brought fresh, cooler Polar air into the Great Lakes once again as the troughs and upper lows settling across eastern Canada remain active. No hot July 4th this year...but beautiful with highs in the 70s.


In the Outlook, I expected best rains to fall over the southern half of Southeast Michigan, closer to the main instability axis during the summer. Here is the rainfall pattern thus far... 


And percent of mean (or normal) rainfall....


As one can see it's been wet and stormy from portions of the Plains, Mississippi Valley, Midwest, southern Great Lakes into the northern Ohio Valley. The southern half of Southeast Michigan has seen the highest rainfalls with up to 150% of the norm. Northern areas range from near normal rain to only 50% of normal. Therefore thus far; the best rains have been across the south.

Of course one month is only a third of the way through the summer and there's a lot of weather to be had between now and September. And many more chances to be wrong, or right.

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian



6/9/14

The Flint-Beecher Tornado; June 8th 1953

One of my earliest researched published articles while at the National Weather Service was about the incredibly destructive EF-5 Flint-Beecher Tornado. This storm occurred 61 years ago with its anniversary on June 8th 1953.

The Flint-Beecher Tornado

Written by: William R. Deedler, Weather Historian
National Weather Service Detroit/Pontiac, MI
First published: June, 1996 
 
One of the most devastating tornadoes to hit Southeast Michigan occurred during the month of June. Known as the "Flint-Beecher Tornado," it plowed an east/west path across the northern part of Flint in what is known as the Beecher District on June 8, 1953. The tornado touched down about 2 miles north of Flushing and from there, created a path of destruction averaging about a half mile wide as it moved across Flint to about 2 miles north of Lapeer. A 23 mile long path of death and destruction was left in its wake with over a hundred lives lost, including as many as 20 families reporting multiple deaths.

The afternoon weather map on June 8, 1953, showed a warm front pushing northeast out of the Ohio Valley into Southern Lower Michigan. At the same time, a cold front was advancing east across Eastern Wisconsin. Temperatures were in the 70s ahead of the warm front, while dew points were in the lower 60s. South of the warm front, temperatures and dew points jumped up about 10 degrees. The most impressive weather feature was the intense energy, spin and shear in the upper levels of the atmosphere, that moved over Michigan during the late afternoon and evening.

By late afternoon, the warm front had progressed northeast to just north of Flint, while the cold front advanced east over Lake Michigan. Temperatures over Southeast Lower Michigan had warmed into the lower 80s as dew points flirted with 70 degrees. The atmosphere was warm and very unstable and the stage was set for possible severe weather. All that was needed was a trigger mechanism and, as though on cue, it did arrive that the evening in the form of the potent cold front.

Strong thunderstorms broke out over Lower Michigan during the late afternoon and evening with some quickly becoming severe as they moved into Southeast Lower Michigan. At dusk, a severe thunderstorm moved into Southeast Lower Michigan, just northwest of Flushing. At approximately 830 pm, a violent tornado was spawned 2 miles north of Flushing. It then tracked east across the north side of Flint to as far east as 2 miles north of Lapeer. A second twister was then generated just northeast of Lapeer and moved across northern St. Clair county until finally dissipating over Southern Lake Huron.
The Flint-Beecher tornado was described in the Flint Journal as an "ugly, dancing black cloud with a ball of fire in it." As the tornado roared through the area, the sound was equated to that of "roaring furnaces and freight trains, only many times louder!" The Journal captured the horror in the aftermath of the tornado in the following: "The injured and dead, some bodies battered beyond recognition, were strewn amidst twisted heaps of wreckage and debris". As darkness descended, extensive power and communication outages also plagued the area.

Like many others, this tornado was not without its remarkable tales. Take for instance the lady who, with her six children in her car, literally put the pedal to metal and drove frantically at 100 mph to outrun the tornado. Luckily, she did without an accident nor a ticket, but this is not advised in tornado safety rules. Or how about the sick woman in bed who saw her roof collapse and then threw her hands over her eyes. The next thing she knew, she was in a field about 100 yards away, still in bed with her purse next to her. Then, there are the stories of a huge 100 year old elm tree pulled out of the ground by its roots, the two-by-four driven deep into a concrete pillar, and what about the man who found his house trailer he had parked in his yard...some eight miles away, near Columbiaville. Stories (and pictures) of defeathered chickens, roses with all petals intact sitting next to a completely leveled house and one of the most astonishing, a letter was "air mailed and delivered" from a couple's home in Flint to 60 miles away to its addressee, their second cousin. All sorts of papers and debris were found across the Thumb region of Lower Michigan and as far as 200 miles away in Southern Ontario.

The loss of life and property in the Flint area was concentrated largely in a residential area along Coldwater Rd. and Kurtz Ave. between Clio Rd. and N. Dort Hwy. The final tally of people killed in this storm reached 116, making it the eighth deadliest tornado in U.S. history and the last single U.S. tornado to kill more than 100 people. There were around 900 injured, many critical, taxing nearby hospitals in emergency care.

At the time of this devastating tornado, there were no short-term tornado warnings like we have today. Had there been a warning, more than likely fewer people would have been killed or injured. The tornado is considered an F5 on the Fujita Scale, the most powerful and potentially the deadliest, with estimated wind speeds of 261 to 318 mph. While tornadoes can potentially develop during any month in Southeast Lower Michigan, the majority occur March into September, with April through June having the highest occurrence.

On June 8th 2003; A 50th Anniversary Commemoration of this terrible tornado was held in Flint.

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian

 





5/31/14

Will The Summer of 2014 Be a Cool One?

               

Summer 2014 Outlook for Southeast Lower Michigan

 

Temperatures :

Overall; a comfortable summer is on tap as I look for temperatures to average around normal to slightly below for the summer. That being said I don't anticipate a notably cool summer. I look for temperatures to average between +1.0 degree and -2.0 degrees of the summer norms across Southeast Lower Michigan (see a more thorough discussion under Analogues).

 

Rainfall:

I look for rainfall to be quite variable as mixed data presents conflicting results but this is not unlike many summers. Taking all data (past and present) into account; rainfall is expected to be around normal over the southern sections of Southeast Lower Michigan and normal to below across the Saginaw Valley and Thumb Region. Rainfall trend data intimates the wetter weather in the early to mid summer with drier conditions later summer (see a more thorough discussion under Analogues).

 

Discussion:

Many are calling for a cooler than normal summer across the Great Lakes; including Southeast Lower Michigan. A common reasoning is the colder than normal Great Lakes water temperatures left over by the horrendously long, cold and stormy winter. As of this writing, ice still remains in scattered sections of Lake Superior on Memorial Weekend. 

                                                                    (Photo courtesy: Melissa Ellis)

The colder than average lake water temperatures surely affect the shore and inland areas near the Great Lakes in the spring, especially when the wind's onshore. The more pertinent questions are; will there be enough of an affect to last into the summer and state-wide temperatures? After all, we do see the opposite effect every fall into at least, early winter across the Great Lakes as their mammoth water heat reservoirs temper the chilly Arctic blasts. So then; will the Lakes temper a bit, summer's heat blasts across the entire region; courtesy of mom nature's air conditioning? While this may occur early in the summer season state-wide and especially near shore areas; history and analogue data suggests a mixed picture otherwise for the balance of the summer. And besides; here in Southeast Lower Michigan warm to hot winds from the south-southwest do not pass over any large Great Lake anyway.

Frigid Water Temperatures of Lake's Huron and Michigan at the close of May




To investigate this assumption further, in addition to the usual analogue data I post for the season; I also included another chart of analogues so to speak, the cold winters and subsequent following summers. Simply put; If a terribly cold winter chilled down the Great Lakes enough to start off the summer season with below normal water temperatures, then what happened in Southeast Lower Michigan that summer?  This is especially true in those summers where the springs were also on the cool-side, as in this year. And the best way to check that out would be to take the top 20 coldest winters and see what kind of summer followed but again; just in Southeast Lower Michigan. By doing this; obviously if Southeast Lower Michigan had one cold, bitter winter, then there's a strong likelihood so did the state...and the Great Lakes. Subsequently; the best correlation to this year would be where temperatures in the spring averaged below normal.

Because more recent normals for Detroit have been "contaminated" by urban sprawl and its heat island, I used a 100 year normal before the pronounced heat island evolved at Detroit Metro Arpt in the mid 1980s. Since most of the colder winters were also during that time; it's a better representation of a true normal for the summers...a hundred year average. As one can see; the old-time 100 year normal is well over a degree cooler than the latest (70.6 as compared with the latest 30 year normal of 71.9).

Cold Winter, Cool Summer Analogue Study 


 Looking at the chart above at the 21 coldest winters and the 20 summers that followed (2014 is yet to be determined); we find a subtle but definite correlation between cold winters and cool summers. There is even a better correlation between a cold winter and cool spring followed by a cool summer. Out of the original 20 coldest winters; eight of the following summers were more than a degree below normal using our legend. Of the remaining twelve summers; nine summers were normal and three were warmer. Therefore; 40% of the summers the temperatures averaged below normal; 45% were normal while just 15% of the summers were above normal. Therefore; relating just this analogue study to this summer; the chances of a normal to below normal summer are an impressive 85%.

Finally; narrowing down this data further by just using the seven cooler springs that followed the cold winter (and again, paralleling the past six months); four were followed by a cool summer and three were followed by a normal summer. None of these cold winter - cool spring periods were followed by a hot summer, or even an above normal /1.0+/ summer. In percentage terms on this data alone then; 57% of the summers were cool and 43% were normal.

Now, on to the typical season analogue study...

What do the Summer Analogues Project?




Remarkably; the typical season analogues chosen for parallel timing of hemispheric climate conditions at the present reflect our previous cold summer, cool summer analogues to a large extent. There is just a slight difference; normal summers have a slight edge over cool summers which is the reverse of the cold winter, cool summer analogues, where cool summers had the edge. The general message is the same however, where a cool to normal summer is preferred by all analogue data presented. In these carefully chosen analogue years; a prolonged period of neutral ENSO's were followed by an ever increasing summer El Nino. The two warm summers of the lot in this analogue study were the more recent summers of 1991 and 2002 with average temperatures of 73.6 and 73.4, respectively. Neither of these warm summers appeared in the previous cold winter, cool summer analogue study .

What are the best performing analogues thus far suggesting for the summer temperatures?

Temperatures

Since late fall of 2013, we have had a couple of years which take full marks for past prediction of the past few seasons; 1880-81 and 1981-82. And, maybe not surprising; 1881 contained a normal summer while 1982 had a cool summer (like our two prevalent trends seen). Another year; 1899 joins these analogue ranks as a decent performer during the winter and a good parallel this spring. All three analogues projected a cool spring with the temperature pattern we've seen this spring with time; below normal - normal - above normal. These analogue springs averaged below normal because of a very cold beginning to the season but will a gradual trend change from below to normal to above (Mar; Apr, May). The Summer of 1899 turned out to have a normal summer, therefore we have two normal summers and one below for the recent better performing analogues. The over all summers were cool to normal with June having the best chance being the coolest month relative to normal with August a close second. July's were the notably warm months  relative to normal.

Rainfall

Rainfall projections for the summer, are really a mixed bag, as it frequently is in the summer with four normal rainfalls, four below and two above with the average skewed on the drier side. A notable trend from many of the summer analogues are wetter conditions early and/or mid summer with drier weather later summer. If high pressure over central Canada and the upper low over eastern Canada exude more force, then a summer on the drier side is likely. This will have to be watched as to where these systems dominate and rainfall patterns evolve.

That being said; it is reasonable when considering all the data and recent trends this spring to keep the prevailing dry/wet oscillations in view. While I look for generally normal rains this summer especially southern regions, I also look for the decidedly typical dry-spell this summer which frequently happens (I researched and wrote about this in 1997 and updated in 2007, while with the NWS). Below are the temperature and precipitation composites for the analogue years in the research. One the left is the data against the 105 year normal; while on the right is the same data against the latest 30 year normal /1981-2010/. In Southeast Lower Michigan; average summer temperatures prevailed against the 105 year normal and normal to below against the 30 year. The rainfall averaged close to normal against the 105 year norm and below against the 30 year.















Analogue Upper Wind Data

Past analogue upper wind data paints upper height ridging and oscillations extending from the Rocky Mountains eastward into the Gulf States and points north into the Great Plains to Eastern Great Lakes. In conjunction; an Upper low pressure oscillated over the eastern half of Canada and extended south and oscillated from the western Great Lakes to off the East Coast. This type of pattern would give us overall normal temperatures during the summer with warm to hot spells routinely extinguished by parading Canadian cool air masses. If one or the other prevails more; of course it will be cooler or warmer than expected. Looking at recent past trends along with this analogue data and subsequent pattern suggests to me normal to below normal temperatures.



The composite upper air anomaly data below shows more clearly what we are up against this summer as far as opposing upper air features. The composite shows where upper air systems were more exaggerated than during a normal summer; thus an anomaly. A blocking upper high pressure system was noted during these summers from central Canada, south into the mid Mississippi Valley. It is the same system I mentioned above that oscillates back and forth but was more dominant up in central Canada in these analogue summers. This system will be responsible for bringing the warm winds from the south when over and east of us and cooler winds from the north when west of the Lakes (blue arrows). Meanwhile; the cold upper low that was so dominant for months /Polar Vortex/ shares the stage with the high pressure as it aligns from eastern Canada south into the eastern U.S. It will be responsible for pushing cooler air southeast or south (in the form of back-door cold fronts) into the Lakes Region (also blue arrows), as it has for months; albeit weaker. Were the upper wind features develop as in the past; sunshine during the summer would average normal to above with the placement of the high.

Another interesting feature is the pronounced upper low feature that showed up over central and southern California; this too will aid in pushing warmer air northeast (red arrows) into the Plains, Mississippi Valley and Midwest behind the upper high pressure. As one can easily see, the zone of air mass confrontation between all of these systems is like most summers and extends from the Great Plains, east through the Great Lakes and on to the East Coast. If the upper high pressure and low pressure heights in Canada play out more to our east, then storms will be more focused to the south and east.



 

Stormy Weather?

As mentioned above; the data to me depicts a notable confrontation zone and I believe we have just recently entered it as of late May. Typically, the busiest times for severe weather in these parts is June into July; with mid June to mid July prime-pickens. I've included the severe weather stats for Southeast Lower Michigan since 1980. Looking above at our analogue summers since then are 1982, 1991, 1997 and 2002 and all but 1982 contained normal to above normal (or busy) severe seasons. That's not surprising given the jet stream that's been dominant in Canada this year. Were this upper jet continued to be aggressive, notable wind events, squall lines and possibly a derecho event or two across the country would be the risk. Off the top of my head; both 1991 (derecho) and 1997 (squall line and tornado) contained notable July squall lines and tornado and 2002's severe weather season was overall, busy.


Annual Totals
Year
Hail
Wind
Tornado
Total

Rpt
Days
Rpt
Days
Rpt
Days
Rpt
Days
1980
58
17
186
32
29
16
116
37
1981
13
7
54
21
5
3
23
22
1982
45
15
117
19
17
9
79
28
1983
86
15
283
30
22
12
130
34
1984
31
12
79
29
20
12
71
39
1985
103
16
158
22
13
9
129
31
1986
72
21
165
36
34
19
140
46
1987
30
16
196
31
16
13
62
38
1988
75
22
198
35
19
10
113
40
1989
32
17
128
30
19
13
70
38
1990
33
16
141
21
23
12
79
27
1991
78
24
320
39
29
10
136
46
1992
66
24
262
32
52
16
170
42
1993
61
22
168
29
8
7
77
37
1994
159
30
239
37
12
8
183
48
1995
76
27
272
41
8
5
92
48
1996
120
35
244
41
14
8
148
56
1997
118
30
330
39
21
5
160
45
1998
270
36
595
39
28
16
326
52
1999
165
28
385
40
15
9
195
45
2000
292
30
381
46
16
9
324
53
2001
198
39
356
53
41
11
280
66
2002
145
39
394
53
22
6
189
62
2003
359
42
559
47
17
12
393
55
2004
326
45
489
45
22
10
370
60
2005
164
32
523
38
3
3
170
48
2006
424
50
404
49
12
9
448
70
AVG
133
26
282
36
20
10
436
45






























Hemispheric Data


As mentioned above; Summer will be accompanied by a progressively ensuing El Nino but I just included this small amount of data below as I expect it will have negligible affects on our weather at home this summer. It will be the fall and especially wintertime that this little baby boy will be more of a player. Check out the CFSv2 models projection into the winter; quite interesting...


And while on the subject of the CFS, lets take a look at its projection for the summer. Really nothing earth-shaking here, though she does intimate the cooling Lakes effect and possibly stalled fronts in the lower Lakes on the rainfall side. I think we are seeing that starting now as of late May.

Temperatures


Rainfall

Interesting how the CVS summer precipitation pattern projection above "mimics" that of the Summer of 1982 (one our best analogues) below. The overall trend is there but the drier areas in the north are displaced further north into Canada in the computer projection closer and just downwind to the upper high pressure block - logical. The heavier precipitation is more to the west in the computer projection (closer to the upper low pressure out west) while the dry Texas and wet Florida are nearly a duplicate. In our region, the wetter areas are over and just to the south of Michigan in the model while in 1982 they were over west-central Michigan into the western Lakes.




Try to get out and enjoy the Summer but if swimming in the Great Lakes; just wait a bit longer for those lake temperatures to warm up! Brrrrr.






Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian