2/22/17

Deep Low Pressure System and Attending Strong Upper Air Dynamics Pushing Through The Region Friday Night

   . . .SEVERE WEATHER UPDATE - 2/24/17 AT 12 NOON FRIDAY . . .
 ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
    SOUTHERN LOWER MI...EASTERN IN...WESTERN AND CENTRAL OH...AND
    NORTHERN KY...  
 ...SUMMARY...
    Severe thunderstorms are forecast to affect areas from Lower
    Michigan southward to Tennessee, mainly this afternoon through
    tonight.  The primary threat appears to be damaging wind, but some
    hail and a few tornadoes will also be possible. 
 ...Southern Lower MI/Northern IN...
    Only minor changes have been made to the ongoing forecast.  Water
    vapor loops show a large upper trough over the Central Plains, while
    a deep surface low tracks northeastward across northern IL.  The
    initial severe concern will be ahead of the surface low and into the
    vicinity of the warm front lifting northward into MI.  Relatively
    strong heating and low level moisture advection will result in
    MLCAPE values around 1000 J/kg along and south of the boundary.  12z
    model solutions are consistent in developing scattered thunderstorms
    along this corridor this afternoon and early evening.  Forecast
    soundings suggest a favorable vertical shear profile for discrete
    supercells capable of large hail and damaging winds.  This portion
    of the outlook area holds the greatest concern for supercell
    tornadoes later today.

Previous 2/22/17 Write-Up and Update....

A strong spring-like system will be surging through the Great Lakes and Upper Ohio Valley Friday into Saturday. The unseasonably warm, spring-like temperatures that have affected Southeast Lower Michigan for the past several days will be rudely pushed east of the later Friday night and Saturday.

Ahead of the front; this clash of the spring-like and winter air masses will also bring the potential for strong damaging winds as showers and thunderstorms barrel through the area Friday afternoon into early Saturday morning. This storm system, more typical of a classic late March or April storm system, will also bring the risk of a rather unusual event of severe weather for February.

The set-up Friday night based on Latest NAM, 00Z - 022317

The deep low will occlude and move through Lower Michigan Friday afternoon into the first half of Friday night. Heavy to very heavy showers and scattered thunderstorms can be expected to charge ahead of the cold front and along the warm front. Very strong gusty winds will accompany the activity with gusts in excess of 50 mph are likely in the worst of the storms.























All severe weather parameters (and some not shown) paint the best instability, bulk shear, lapse rates and unusual (for February), surface based CAPE over Southern and Southeast Lower Michigan. The nose of an 80knot Bulk Shear coming into the Southern Great Lakes, certainly draws attention to the potential of realized damaging winds any heavy shower or storm could bring down. At the very least, the idea of a "thunder-less" line of heavy showers with potential severe winds would also be a threat with this system.

A potential for short-fused severe weather event is in the wings from Friday evening into the first half of the night till about 2am EST Saturday morning at this early juncture. Strong low pressure system and attending warm and cold fronts will be barrelling across Southern Lower Michigan at that time.

 
                                                From the Storm Prediction Center



...Southern Great Lakes and Ohio Valley...
Low-level moisture is forecast to slowly increase on strong
southerly flow with boundary-layer dewpoints forecast to range 52-58 degrees F. Although cloud cover will retard strong surface heating, cooling mid-level temperatures to around -19 degrees C will contribute to weak buoyancy (ranging from 250-1000 J/kg MUCAPE) within the northward expanding warm sector during the day. As strong forcing for ascent (DCVA) approaches and overspreads the western parts of the area, a band of thunderstorms will likely develop and intensify. Strong effective shear around 50 kt will act to organize updrafts and strengthening 700-mb flow to the 55-60 kt range will contribute to cold pool's organization and upscale growth. Downward momentum transport via damaging winds are the predominant severe risk. However, some forecast soundings show relatively moist low levels with strong 0-1 km shear in excess of 25-30 kt. A tornado risk may develop with the maturing squall line and/or pre-frontal supercell(s) that eventually merges with the line. A gradual weakening in buoyancy by the early to mid evening into the overnight will likely lead to a lessening in the damaging-wind risk as storms rapidly move east and northeastward after dark.


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




2/20/17

Roller-coaster Pattern of the Winter About to Get Revved Up Again

It's been a slow winter for potential storm discussions but as we turn the calendar from February into March, our various models have been in overdrive trying to peg potential storms from the last weekend of February into the first two weeks of March.

All indications are the "ole' sling-shot pattern" (a strong jet stream that digs south from western Canada into the southern California and/or Rockies & Plains before loading and shooting northeast somewhere in the Midwest/Lakes) will be a major player in the roller-coaster pattern prevalent so much this winter.



 More to follow....

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


2/6/17

Digging Further into January's Weather Records Bring's More Rareness and Oddities - January 2017 Update

There's no doubt about it; besides the more typical climate statistics for the month of January ("warmest, wettest, etc etc), January 2017 had more to offer than the usual headlines.

True, January 2017 was the 12th warmest January on record at Detroit and Flint, while being the 15th warmest at Saginaw. Abundant rainfall of 3.13" made January the 6th wettest in Flint and while both Detroit and Saginaw had above normal rains, the top 20 list was not breached. Snowfalls were near to slightly below normal in most regions.

Elaborating on the oddities mentioned in the my article on January recently (below); January 2017 was also a stand-out month for any January (and other months) with cloud cover, lack of sunshine, dense fog and thunderstorms. Digging back over my records for Detroit, show that January 2017 was indeed lacking in sunshine due to the cloud cover. The sunshine normals or historical data is available up through June 1995. The sunshine switch was then removed from DTW and placed in at DTX. However, due to frequent errors in readings after the move, it was later terminated and dismantled. Past sunshine minutes, percentages and normals were last printed in the 1995 DTW Annual LCD. Again, this was after the NWS moved out of  DTW and DTW became a Contract Station.

January's cloud cover, sunrise to sunset /sr - ss/ is on the monthly F6 below and totaled 8.8 or rounded off  to 9, out of a possible 10. January 2017 had 26 cloudy or mostly cloudy days, 3 partly cloudy days and just 2 clear or mostly clear days. This compares to the averages or normals for January sky conditions/as follows: the 125 year ave /1871-1995/ amount of cloudy days in January sunrise - sunset /sr-ss/ averages to 20,  there are 7 partly cloudy days and 4 for clear. The 105 year average /1891-1995/ of possible sunshine in Detroit for January stands at about 36% while the 110 year average /1886-1995/ cloud cover for January is around 7.5 tenths.

Therefore yes January was a gloomy month - but a record? 


PRELIMINARY LOCAL CLIMATOLOGICAL DATA (WS FORM: F-6)

                                          STATION:   DETROIT MI
                                          MONTH:     JANUARY
                                          YEAR:      2017
                                          LATITUDE:   42 13 N
                                          LONGITUDE:  83 20 W

  TEMPERATURE IN F:       :PCPN:    SNOW:  WIND      :SUNSHINE: SKY/WX :PK WND
================================================================================
1   2   3   4   5  6A  6B    7    8   9   10  11  12  13   14  15   16   17  18
                                     12Z  AVG MX 2MIN
DY MAX MIN AVG DEP HDD CDD  WTR  SNW DPTH SPD SPD DIR MIN PSBL S-S WX    SPD DR
================================================================================

 1  41  23  32   6  33   0 0.00  0.0    0  5.9 14 210   M    M   2 18     17 190
 2  43  27  35   9  30   0 0.08  0.0    0  6.4 12  90   M    M   9 18     17  90
 3  45  38  42  16  23   0 0.36  0.0    0  8.1 18 290   M    M  10 12     24 280
 4  38  19  29   3  36   0 0.01  0.2    0 19.3 24 280   M    M  10        46 280
 5  20  12  16 -10  49   0 0.03  0.7    T 12.2 21 250   M    M   9 8      24 270
 6  17   8  13 -13  52   0    T    T    T  9.1 16 240   M    M   8 18     29 270
 7  17   5  11 -15  54   0 0.02  0.7    T 11.2 21 310   M    M   7 89     28 310
 8  18   8  13 -13  52   0 0.00  0.0    1 10.0 17 290   M    M   5        23 280
 9  31  16  24  -2  41   0    T    T    1 12.4 21 210   M    M  10        25 220
10  49  27  38  12  27   0 0.53  3.0    3 20.2 41 250   M    M  10 1246   53 260
11  57  29  43  17  22   0 0.13  0.0    0 13.9 33 250   M    M   9 138    42 240
12  58  29  44  19  21   0 0.40  0.0    0 11.4 29 230   M    M  10 13     42 220
13  29  20  25   0  40   0 0.00  0.0    0  8.1 17 280   M    M  10        23 280
14  33  23  28   3  37   0 0.00  0.0    0  4.4 10  80   M    M   8        13  90
15  34  18  26   1  39   0 0.00  0.0    0  3.9  9 200   M    M   3 18     12 220
16  36  19  28   3  37   0 0.15  0.0    0  3.3 13 100   M    M   9 168    16 100
17  48  33  41  16  24   0 0.42  0.0    0  8.6 18 250   M    M   9 1236   23 240
18  43  35  39  14  26   0    T  0.0    0 11.0 18 220   M    M  10 1      24 210
19  38  33  36  11  29   0 0.00  0.0    0  7.8 17 240   M    M  10 18     21 240
20  42  33  38  13  27   0 0.16  0.0    0  5.7 13  60   M    M  10 12     16  60
21  59  40  50  25  15   0    T  0.0    0  3.2 10 170   M    M   7 128    13 180
22  49  40  45  20  20   0 0.00  0.0    0  3.9  9  80   M    M  10 12     11  60
23  46  41  44  19  21   0 0.11  0.0    0  7.3 13  60   M    M  10 12     16  50
24  42  39  41  16  24   0 0.04  0.0    0  7.2 17 310   M    M  10 12     22 300
25  48  36  42  17  23   0 0.01  0.0    0 10.1 29 230   M    M  10 18     35 220
26  42  35  39  14  26   0    T    T    0 16.1 26 230   M    M  10 4      32 250
27  35  28  32   7  33   0 0.01  0.1    0 14.7 24 260   M    M  10 46     32 240
28  31  28  30   4  35   0 0.02  0.5    T 13.8 20 230   M    M  10 189    25 240
29  30  25  28   2  37   0 0.05  2.0    1  7.2 15 300   M    M  10 18     19 310
30  27  18  23  -3  42   0 0.06  1.4    2  7.0 14 190   M    M   9 1      19 240
31  36  26  31   5  34   0 0.24  3.2    6  9.1 17 270   M    M  10 18     32 280
================================================================================
SM 1182  811      1009   0  2.83    11.8 292.5          M      274
================================================================================
AV 38.1 26.2                               9.4 FASTST   M    M   9    MAX(MPH)
                                 MISC ---->  # 41 250               # 53  260
================================================================================
NOTES:
# LAST OF SEVERAL OCCURRENCES

COLUMN 17 PEAK WIND IN M.P.H.

PRELIMINARY LOCAL CLIMATOLOGICAL DATA (WS FORM: F-6) , PAGE 2

                                          STATION:  DETROIT MI
                                          MONTH:    JANUARY
                                          YEAR:     2017
                                          LATITUDE:   42 13 N
                                          LONGITUDE:  83 20 W

[TEMPERATURE DATA]      [PRECIPITATION DATA]       SYMBOLS USED IN COLUMN 16

AVERAGE MONTHLY: 32.1   TOTAL FOR MONTH:   2.83    1 = FOG OR MIST
DPTR FM NORMAL:   6.5   DPTR FM NORMAL:    0.87    2 = FOG REDUCING VISIBILITY
HIGHEST:    59 ON 21    GRTST 24HR  0.57 ON 16-17      TO 1/4 MILE OR LESS
LOWEST:      5 ON  7                               3 = THUNDER
                        SNOW, ICE PELLETS, HAIL    4 = ICE PELLETS
                        TOTAL MONTH:  11.8 INCHES  5 = HAIL
                        GRTST 24HR   3.2 ON   M    6 = FREEZING RAIN OR DRIZZLE
                        GRTST DEPTH:   6 ON 31     7 = DUSTSTORM OR SANDSTORM:
                                                       VSBY 1/2 MILE OR LESS
                                                   8 = SMOKE OR HAZE
[NO. OF DAYS WITH]      [WEATHER - DAYS WITH]      9 = BLOWING SNOW
                                                   X = TORNADO
MAX 32 OR BELOW:   9    0.01 INCH OR MORE:  19
MAX 90 OR ABOVE:   0    0.10 INCH OR MORE:   9
MIN 32 OR BELOW:  20    0.50 INCH OR MORE:   1
MIN  0 OR BELOW:   0    1.00 INCH OR MORE:   0

[HDD (BASE 65) ]
TOTAL THIS MO.  1009    CLEAR  (SCALE 0-3)   2
DPTR FM NORMAL  -214    PTCLDY (SCALE 4-7)   3
TOTAL FM JUL 1  2987    CLOUDY (SCALE 8-10) 26
DPTR FM NORMAL  -533

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

CLOUD COVER & SUNSHINE

RECORD NUMBER OF CLOUDY DAYS /AVERAGE FOR MONTH/ AT DETROIT FOR *JANUARY AND **ALL TIME

      MONTH  &   YEAR          NUMBER
 *    JANUARY      1960            9.3
1-**NOVEMBER 1985              9.3
   **JANUARY     1960              9.3
   **DECEMBER 1929               9.3
2-**NOVEMBER 1992               9.2
9-   JANUARY      2017             8.8
      (JANUARY      1932            8.6)



RECORD FOR LEAST AMOUNT OF SUNSHINE AT DEROIT FOR *JANUARY AND *ALL TIME
      MONTH & YEAR          NUMBER
*     JANUARY    1932            14%
1-**DECEMBER 1929              7%
2-**NOVEMBER 1985            13%
?   JANUARY     2017            N/A


November 1985, January 1960 and  December 1929 all tie for the cloudiest month ever in Detroit.  January 2017 doesn't even come close to the cloudiest month nor cloudiest January with 8.8 cloud cover /9th place/.

Looking at the previous sunrise-sunset cloud cover records and least sunshine records above, we can basically be assured that January 2017 would not have placed for the least sunniest month (December 1929 has that honor). How about the least sunniest January?  

January 2017 is a just a contender for the least sunniest January by the following reasoning...

Obviously, it's difficult to say how much sunshine Detroit had in January 2017 since it wasn't recorded locally and doesn't always correlate or is the inverse of cloud cover. Case in point from above: Lowest sunshine on record for January is 14% in 1932 but this occurred with less cloud cover at 8.6 as opposed to the 16% of sunshine in January 1960 with a higher amount of cloud cover at a record 9.3! If one was only to go by a direct correlation by cloud cover and subsequent lack of sunshine alone; then there is a higher chance, January 2017 contained less sunshine than January 1932.  However it isn't always that simple...

Here's where being an older-timer weather observer has its merits, so try to follow along...

It really has to do more to do with the type of clouds and their thickness observed during the day/month and resulting opaqueness.  In the "old days" of the NWS, observations of cloud cover was recorded in both total coverage and opaqueness of the total; say for example 10/10 of cirrostratus (usually a high but partially thin cloud cover) and its opaqueness, might be 10/5. Therefore the observation read something like; 200-OVC (or in the teletype days when I started, it was 200-O with a cross in the middle - sent out and read on teletype but not displayed on a weather map). The symbol (-) was read as thin, when the opaqueness of a cloud cover was half or less. Basically meaning; one could discern the blue sky above (or stars/moon at night). With the advent of ASOS, the thinner parts of all types of cloud cover was lost in the observation. This is where the human element of a weather observation was better to discern the actually cloud cover and its thickness. Clouds above 12,000ft are not officially observed on ASOS therefore some mid clouds and all high clouds are lost - and certainly their opaqueness! This was/is crap to most pre-ASOS days weather observers and many other weather aficionados. Wtih ASOS, sometimes the higher clouds are still augmented  (edited)  into the ASOS where human observers are co-located with ASOS.

Ok, back to the subject at hand...

The absolute dreariest month for sunshine happened after the stock market crash of 1929 when December 1929 had only 7% of the possible (well below anything other month).  I guess mom nature got in on the mood around metro Detroit and the country. Keep in mind, the month of December 1929 has the least amount of possible sunshine during any given December and month. Therefore; December 1929 with just 7% of the possible was indeed, the gloomiest month. Another interesting tidbit for December 1929; however was its Christmas was one of the whitest in Detroit's history with 11 1/2" of snow on the ground.
 
And talk about down right depressing:

It should be noted that November and December 1972 have the record for the gloomiest period /60 days/ in what I could find in both cloud cover and subsequent sunshine (or lack there-of).

    MONTH  &   YEAR          NUMBER  
NOVEMBER      1972                 9.1
DECEMBER      1972                 9.0

    MONTH  &   YEAR         SUNSHINE (%)    

 NOVEMBER      1972               13%
 DECEMBER      1972               13%

So, you see this past January wasn't so bad. There were other times during the 1970s in the winter I recall cloudy, dreary months around here and stats back me up; November 1977 /9.1/ December 1974 /8.7/ and actually it didn't end there in the monthly stats. The whole year of 1972 had 7.1 cloud cover for the cloudiest year on record at Detroit with 1984 a close second at 7.0. More 1970's show up here for cloudier years too, 1970 and 1973 at 6.9, 1974 at 6.8. Actually it sort of follows; being that some of the years in the 1970s, tended to be a bit more stormy in both winter and severe weather seasons...there'd also be more cloud cover. And, that leads me to thunderstorms in January...

RECORD NUMBER OF THUNDERSTORM DAYS FOR JANUARY

YEAR          NUMBER
2017                    3
1909                    3
1907                    2

Thunderstorm days in January while not unheard-of are fairly rare with an average since 1871 of just about .2 (or well less than one day in January). Therefore you can reason, that January thunderstorms days are few and far between.
RECORD NUMBER OF DENSE FOG DAYS DETROIT FOR *JANUARY AND **ALLTIME
DENSE FOG RECORDS


    MONTH & YEAR          MOST DENSE FOG DAYS

 * JUNE          1973                9
**JANUARY  1907                 8
   JANUARY  2017                 8 /TIED WITH 1907 & THUS SUPERSEDES/


There were 8 days total during the month of January (20-24th, 5 dense fog days in a row) which was also very rare. Occurrences of dense fog in January is 2 days on average. January 2017 totaled just one day less the the all time record for dense fog days which belongs to June of 1973. However; January tied for first place for the month of January with 8 days which was also observed in January 1907. Just for an extreme comparison; there were only 6 days in all of 2015 that dense fog was recorded at DTW. The annual average for the year is about 17 days for dense fog.

Previous Preliminary January write-up through January 22nd... 

"Strange January to Get back on Track Later This Week"

It's been an odd and very variable January this year. The first several days started out mild, then a cold blast commencing on the 5th reminded Southeast Lower Michigan inhabitants what month it really was with temperatures well below normal - but that didn't last long did it? We turned the corner by the 9th and again, it was off to the races to warmth with high temperatures basically in the 50s for three days before a slight 4-day cool down took hold through the 16th. Since then; readings have continually averaged above or well above normal through the 21st /yesterday/. In fact; Detroit's high on the 21st of 59 reached the peak reading thus far for the month, making that the third upper 50-degree temperature this month! Not to be a record however as that honor belongs to Jan 21st of 1906 with 65! If we're going to speak of records, Flint's high temperature of 54 on the 21st came within one degree of its 55 degree record in 1954.

In the midst of January's wild roller-coaster ride of frequent up and down temperature swings; came just as many resulting weather phenomena - some typically seen and some not during January. Snow and cold of course, ranks on the side of normalcy in January; whereas balmy spring-like temperatures interspersed through the month, thunderstorms and many dense fog days do not. Oh sure they happen in January; and if at any time, usually during our cyclical January thaw which comes regularly enough to nudge up temperature records in past data during mid to late month for several days. However, there's certainly been more than a weeks duration of thawing weather this January with several notable upward temperature swings during the month. So much so, that even with the bitter cold experienced earlier in the month, readings are averaging 4 - 5 degrees above normal and enough so; that we are beginning to enter the top 20 warmest January's list at all three stations in the bottom (upper teens to 20). Three thunderstorm days have ranked up this month thus far at Detroit, an unusual amount being its the dead of the winter. Dense fog days have just eclipsed (6/5-as of the 22nd) the number of snow days thus far in January with nearly a week total in days where visibilities at Detroit Metro Arpt dropped down to a 1/4 mile or less. Last night (21st-22nd) being the foggiest I've seen it in quite awhile around metro Detroit. Dense fog advisories have been carried/existed since Saturday evening /21st/ (now Sun eve night, 22nd).

The snow machine sputtered the first ten days of the month but then died completely after the tenth. What had been a relatively snowy winter thus far into early January went bye-bye since, with 4.6" recorded the first ten days at Detroit. Flint did a bit better with 5.7" and Saginaw topped it with 7.4" To be fair; all three climate stations still are above normal for the snow season of 2016-17 by about 2-4" - but don't look for much of any addition this week as temperatures hold basically above normal with mainly rain expected until about Friday. The better chances for any addition of light snow will be across the northern portions of Southeast Michigan but then, rain is expected to mix with the snow, which should cut down any appreciable accumulations. Actually more rain than snow days have been observed this month with all of Southeast Lower Michigan having a wet January thus far. Detroit is nearly an inch above normal (a decent departure for January); Flint is nearly an inch and a half above while Saginaw rests at about three quarters above average".


Note; Due to the lack of records for some weather items in Detroit's LCD since 1995, some records were estimated using very long term records which were then, updated.

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




1/30/17

Clipper System Sailing Toward the Southern Great Lakes Tonight 1/30/17

Update 1/31/17
Late January's clipper system deposited snow across much of the region with highest amounts where depicted on forecast map. Generally 2 - 4" with some isolated 4'+ did fall in the the highest totals.

see:  http://www.weather.gov/dtx/170131winteradvisory
-----------------------------------------------------------------------------------------------------


Latest 12Z models are now in excellent agreement with clipper type system moving quickly southeast from the Upper Midwest into the Southern Lakes Monday night into Tuesday Midday. All indications are snow will overspread Southeast Lower Michigan from the northwest to southeast Monday evening and continue through Tuesday morning. Look for the bulk of the snow to fall during the early morning hours of Tuesday and into the rush hour of Tuesday. Some rain mixed with snow could clip the southeast corner  (near/below yellow dashed line) as warmer area clips that area Tuesday. The snow should rapidly diminish and push southeast out of the area during the Tuesday forenoon hours into early afternoon.

Snowfall amounts remain unchanged from earlier thinking below; mainly 1 - 3" with a strip of 2 - 4", isolated 4"+, across the area between I-96/696 to the north to I-94 and extreme Southeast Lower Michigan to the south - or area just north of the base of the weak triple point/occlusion.



Next up, we'll investigate the pattern change discussed last week and it's likely influence on the first half of February.

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




++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
*Previous Short Term Discussion on Clipper System
https://www.facebook.com/weatherhistorianSEMI7415chats/

1/29/17
Clipper System to Add to Snowfalls of Past Day Snow showers; but Where?

There seems to be a divided camp on a clipper low pressure system taking aim on the Lakes Region late Monday night into Tuesday night. The 12Z GFS, 12z Euro and 12Z Canadian all bring a decent clipper system southeast from the upper Midwest into southern Lower Michigan by the forenoon hours of Tuesday. The NAM continues to insist of marching the clipper through central Michigan and thus, maximum snowfalls a displaced further north from SE Michigan to Central and East Central Lower Michigan.

Better sampling of a short wave moving through northwest US/southwest Canada today is beginning to bring a consensus of most of the models with the NAM the outlier.

At this juncture; look for generally 1-3" of snow to fall across Southeast Lower Michigan Late Monday into Tuesday afternoon. I also look for a strip of 2" - possibly 4" within the lighter snowfall region. I will fine tune as better data becomes available to the models.

Below are the snowfall projections of the GFS and NAM along with the tracks of the GFS, Euro & NAM as of Tuesday forenoon hours.

1/22/17

Strange January to Get back on Track Later This Week

It's been an odd and very variable January this year. The first several days started out mild, then a cold blast commencing on the 5th reminded Southeast Lower Michigan inhabitants what month it really was with temperatures well below normal - but that didn't last long did it? We turned the corner by the 9th and again, it was off to the races to warmth with high temperatures basically in the 50s for three days before a slight 4-day cool down took hold through the 16th. Since then; readings have continually averaged above or well above normal through the 21st /yesterday/. In fact; Detroit's high on the 21st of 59 reached the peak reading thus far for the month, making that the third upper 50-degree temperature this month! Not to be a record however as that honor belongs to Jan 21st of 1906 with 65! If we're going to speak of records, Flint's high temperature of 54 on the 21st came within one degree of its 55 degree record in 1954.

In the midst of January's wild roller-coaster ride of frequent up and down temperature swings; came just as many resulting weather phenomena - some typically seen and some not during January. Snow and cold of course, ranks on the side of normalcy in January; whereas balmy spring-like temperatures interspersed through the month, thunderstorms and many dense fog days do not. Oh sure they happen in January; and if at any time, usually during our cyclical January thaw which comes regularly enough to nudge up temperature records in past data during mid to late month for several days. However, there's certainly been more than a weeks duration of thawing weather this January with several notable upward temperature swings during the month. So much so, that even with the bitter cold experienced earlier in the month, readings are averaging 4 - 5 degrees above normal and enough so; that we are beginning to enter the top 20 warmest January's list at all three stations in the bottom (upper teens to 20). Three thunderstorm days have ranked up this month thus far at Detroit, an unusual amount being its the dead of the winter. Dense fog days have just eclipsed (6/5-as of the 22nd) the number of snow days thus far in January with nearly a week total in days where visibilities at Detroit Metro Arpt dropped down to a 1/4 mile or less. Last night (21st-22nd) being the foggiest I've seen it in quite awhile around metro Detroit. Dense fog advisories have been carried/existed since Saturday evening /21st/ (now Sun eve night, 22nd).

The snow machine sputtered the first ten days of the month but then died completely after the tenth. What had been a relatively snowy winter thus far into early January went bye-bye since, with 4.6" recorded the first ten days at Detroit. Flint did a bit better with 5.7" and Saginaw topped it with 7.4" To be fair; all three climate stations still are above normal for the snow season of 2016-17 by about 2-4" - but don't look for much of any addition this week as temperatures hold basically above normal with mainly rain expected until about Friday. The better chances for any addition of light snow will be across the northern portions of Southeast Michigan but then, rain is expected to mix with the snow, which should cut down any appreciable accumulations. Actually more rain than snow days have been observed this month with all of Southeast Lower Michigan having a wet January thus far. Detroit is nearly an inch above normal (a decent departure for January); Flint is nearly an inch and a half above while Saginaw rests at about three quarters above average.


Climate thus far in January at Detroit



There are changes in the offing....

While the week should basically continue mild for January; a gradual cool-down is expected to commence after Tuesday as a storm center pushes through the southern Great Lakes on its way into Canada. It will bring more rain to the region to add to the already above normal totals measured this month. cooler temperatures will push slowly into the area during mid-week with a colder air mass arriving for the last weekend of January!

Note the prevailing upper wind patterns projected for the up coming week at different runs; it's interesting to see the GFS model attempt to forecast these changes while amplifying and/or phasing the main upper weather features discussed in the Winter Outlook back in November.

1-Strong southwest trough approaches Tues Eve (forecast date 1/20 18z). 



2-Jet from southwest moves off over New England and opens the door to northwest jet and Polar trough spilling colder,  Polar/Arctic air south from Canada (forecast date 1/20. 18z) 



3-A full-lat trough has now evolved over North America bringing cold air to much country east of the Rockies by the first day of February (forecast date 1/20. 18z) 


4-Way out in "la la land" our GFS develops this huge block over North America with high over Alaska and deep Polar Vortex over Eastern Canada while both are under-cut by a mid Pacific jet (again, forecast date 1/20. 18z).

The above projections fit very well into the competing prevailing upper air patterns that were discussed in the Winter Outlook. The model has a handle on our pattern this winter but data input causes variances in troughs, short waves, where to phase, where to not - and thus a variety of "ideas" and forecasts evolve.

1- Later on the 01/21/ 00z run, a huge trough has also evolved in "la la land", this time ridging is a bit further east, less of a block shows up now while the Pacific undercut is weaker.

2-Then the next morning's run (01/21/ 12z)  decides to shunt the energy in two places back out over SW Canada and another piece, though much weaker toward the eastern US. keep in mind this is all in a 24 hour forecast period the 20th-21st. 

What's the point? Models regularly dance around with the jet (500 MB) and surface solutions days out? Yes of course they do, the point is.. the prevailing patterns that have evolved this winter, much of what showed up in the prevailing analogue winters are "competing" (if you will) in model-land for evolution in time. Given the upper air patterns dominating this winter and also prevailed in our set of analogues!



 From the Winter Outlook...
 
"The upper wind anomaly pattern from all analogue winters shows a marked difference in jet preferences and placing upper Lows and ridging when compared to a typical La Nina pattern. While the semi-permanent eastern Canadian Low is represented by the lobe of negative anomalies south of Hudson & James Bays; the most predominate departures in the upper wind anomalies materialized over western Canada and the Northwestern US. It's almost like the typical La Nina upper wind trough pattern shifts back west at times and creates the negative departures over that region. Referring to the typical La Nina map (above), the ridging is dominant on the West Coast of Canada and to a lesser extent, the US which would negate the coldest of winters".

 Resulting Storm Tracks This Winter

"Main upper air feature positions along with generated storm tracks by my analysis per analogue data is on the map below. The upper lows and troughs are depicted in black; while the resulting storm tracks are in red. As you can see, the generated storm tracks to our southwest are mainly Kansas and Texas Panhandle Lows which have a tendency to track near or over Southeast Lower Michigan. If the impulse generated is far enough south, some Arkansas or even Louisiana lows are possible but they are not expected to be a main player this winter. East Coast storms should be more the result of Ohio Valley and mid Atlantic phasing".

It will be awhile yet before the current model forecast evolves and I fully expect it to "dance around" with solutions. WHAT evolves will be interesting. Will we go into a full-lat trough and block after like the first run suggested, will the pattern start there with the evolving deep trough but then dive more energy to the Canadian territories and ultimately to the US West/Southwest again. 

In any event, it looks as though the roller-coaster will be revving up again and where it ultimately settles for this period is questionable in model-land. However; we do have the trends this winter and history in analogues to suggest the ultimate outcome - again.

Next up; will see what GFS forecast pattern becomes more dominant with time (later in the week) and ultimately should win out.

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


 



12/20/16

The Whitest of Christmases and Other Christmases Past - Christmas 2016

The Whitest of Christmases and Other Christmases Past 
 
By: William R Deedler; Southeast Michigan Weather Historian
Date: 2PM Tuesday Dec 20th, 2016
 

Frequently during the Christmas Season, meteorologists are asked; Are we going to have white Christmas?  Generally, it is agreed among meteorologists that in order to "officially" have a white Christmas, an average of an inch of snow must cover the ground, but not necessarily have to fall on Christmas. 

At this time /20th/, though warmer temperatures, some melting and rain are possible; it is still likely a white Christmas will be enjoyed. This is likely given the existing heavy snow cover and just an inch of snow is necessary to meet the requirement Christmas morning. Still, at this time the weather looks suitable for holiday travel across Southeast Lower Michigan with the milder weather and possibly just some light rain.

Over the years, extreme Southeast Lower Michigan has averaged about a 50 percent chance for a white Christmas.  Some years it's already on the ground, some years not, some years it melts while other years it falls on the day. However, theoretically, you could actually have nothing on the ground Christmas morning and have a snowstorm dump a foot on the region during the day and still have NO official white Christmas under the standing morning rule. It works the other way too; you could have a several inches on the ground at 7am 12/25 but warmer air and/or rain melts it away by afternoon or evening and still officially have a white Christmas.

Last year's December /2015/ was a mild and snowless Christmas with a high temperatures near 50. Of course, last December was our record breaking warm El Nino December, therefore the hopes for a white Christmas were low anyway. Back on Christmas 2014, the chances for a white Christmas were very similar to 2015 with record setting low amounts of snow for the month (in the top 5 snowless). Officially on 12/25/14 at 7am; no snow was on the ground with a trace of light rain on the date. Only a TRACE of snow had fallen up to that day in December /0.1 for the entire month/.  Most areas over the remainder of Southeast Lower Michigan had a few tenths of snow Christmas eve or Christmas but with less than the amount needed and mild temperatures rising into the upper 30s to around 40...none of the area saw a white Christmas. 

Previous recent Christmases:

In 2013even with all the snowfall throughout last winter, officially on 12/25/13 at 7am Detroit Metro Airport had only a TRACE of snow on the ground. Most areas into the remainder of Southeast Lower Michigan had some residual snow and ice on the ground for a white Christmas. Back in 2012, enough snow did fall at Detroit Metro Arpt (an inch of fresh snow Christmas Eve) to make it an official white Christmas was on the ground as of 7AM. The necessary inch or more was also on the ground at both Flint and Saginaw. Ironically the day after Christmas, the best snowstorm of the winter season hit the region...a day late and several inches short for Christmas. A year earlier in 2011, it was a relatively mild Christmas with temperatures in the 40s and no snow on the ground; so no white Christmas. However back in 2010; residents across Southeast Lower Michigan did enjoy a white Christmas with generally 1” to 6” of snow across as temperatures hovered in the 20s. Then further back in 2009, much of the Detroit area south did not have a white Christmas but points north across Flint, Saginaw and the thumb region generally had a 1” to 3” snow cover. Back in 2008, we saw a “sloppy, melting white” Christmas. That white Christmas involved the melting of a heavy snow cover from past snows that accumulated throughout December. The best of the snowstorms came before Christmas on the 19th (with another, lesser intense snow falling on the doorstep of Christmas, 23rd -24th). After, however, the heavy snow cover melted in earnest as milder air overspread the region Christmas Eve right through the 26th. Christmas of 2007, saw temperatures rise into the mid 40s to mid 50s a couple of days prior to Christmas and that, combined with light rain, pretty much took care of any hopes for a white Christmas as then, like the later Christmas of 2008, the  previous heavy snow cover melted (but this time in its entirety before Christmas). Some scattered light snow did return, skirting the landscape on Christmas Eve but most areas around Southeast Lower Michigan still only had a trace of snow for Christmas. At White Lake and Saginaw, however, the official inch of snow to make it a white Christmas was barely attained in 2007.

Going back further to the Christmas of 2006; it was also mild and therefore, there was no white Christmas. In 2005, we just barely squeaked out a white Christmas (at Detroit Metro Airport, anyway) as a mild spell moved in just before Christmas along with rain, melting the snow down from 4” to 1” by Christmas morning. Originally, there had been 8” of snow on the ground on the 15th. The last really scenic (no slop)  with fresh white snow for Christmas occurred in 2004. A snowstorm brought heavy snow (ranging from 8”at Detroit to around 4” in Saginaw and Flint) on the 23rd, which left the region with a nice white cover for Christmas. It was also a cold Christmas also with highs only in the teens and overnight lows below zero. 




Looking over historical weather records of Christmases past since 1900, a wide range of weather conditions were found. While most people would like to believe that Christmas in the Detroit area should be snowy-white and picturesque, more often than not, they're not. Over the past 116 (including 1900) Christmases in Detroit, 54 (47%) have been what would be called "white" with an inch or better of snow on the ground. Keep in mind however, these records are for Detroit; farther north in Flint, the chance of a white Christmas jumps to 56 percent, while in Saginaw and the Thumb region it rises to 61 percent.

Based on the Detroit records, the Santa award for the "whitest" (most snow on the ground) and also the second snowiest Christmas (snow falling on Christmas) goes to the Christmas of 1951! Just over a foot /13 inches/ of snow was recorded on ground late Christmas day with 6.2 inches of the snow falling on Christmas. Temperatures held well below freezing (HI-26/LOW-18), so what snow did fall, remained. A close second to the "whitest" Christmas, occurred the Christmas after the big stock market crash in 1929. Eleven and a half inches of snow was measured December 25th, 1929 at Detroit but only three tenths /.3/ fell on Christmas. Recently, the Christmas of 2000 was very white indeed, but as to how much of a white Christmas (snow depths) is where the confusion came in. Let me elaborate, officially at Detroit Metro Airport, just six inches of snow was recorded on the ground at 7AM Christmas Day. However, just about anywhere west/north and in the city of Detroit itself, amounts were considerably higher with generally 8 to at least 15 inches. At the National Weather Service in White Lake, 15 inches was observed on the ground Christmas 2000 morning. No additional snow fell on Christmas Day (nor was anymore really wanted with the surplus already at hand). In any event, for Detroit and surrounding communities, the six inches at Detroit Metro Airport is the official snow depth used for the area.

The snowiest Christmas (most snow falling on Christmas), occurred in 1915 when 6.4 inches fell with a snow depth of seven inches on the ground. The timing of this snowfall was impeccable for Christmas with it actually starting Christmas Eve around sunset. Then, it continued to snow through the night into Christmas day. Actually, even more than the 6.4 inches fell from the entire storm with an additional 1.6 inches falling on Christmas Eve. This gave a snowstorm total of eight inches.  A little light rain did mix with the snow during the forenoon hours of Christmas but with a high temperature of only 33, it did little to mar the "Christmas card" scene. Speaking of "Christmas card" scenes, another heavy wet snowfall blanketed the area just after the turn of the century early on Christmas in 1901. The scene is described in the historical weather books as follows:


    "Night of the 24 - 25 cloudy; moist snow continued,
     heaviest between hours of 1:30 and 4:30 am, ended
     at 6 am. amount of precipitation .62 inches. The
     street cars ran all night to keep the tracks open.
     the snow adhered to trees etc, and made a very
     beautiful scene. Depth of snow on ground at 8 am,
     5.5 inches".


 This "Norman Rockwell Christmas scene" was further enhanced by a heavy coating of frost deposited on the buildings and windows Christmas Eve due to the moisture-laden air. But just like memories of some Christmases past, this majestic Christmas scene quickly faded (melted) during the day as temperatures climbed to 41 degrees, leaving just slush , slop and water. During the Christmases of 2002 and 2003, the weather was similar to both of the white Christmases mentioned above /1901 & 1915/. Here again in 2003, snow started falling Christmas Eve and lasted into at least part of, if not all of Christmas Day. On Christmas Day 2003, snowfalls ranged from at least an inch in the far southeast corner of Lower Michigan to as much as six inches across Detroit's northern suburbs, extending northward across Flint and Saginaw. On Christmas Day of 2002, total snowfall at Detroit Metro Airport was measured at 6.4” inches for both days (Christmas Eve and Christmas) with 3.4” of it falling on Christmas Day, itself. Across all of Southeast Lower Michigan snowfalls generally ranged from four to seven inches. A picture perfect Christmas was created both years with the freshly fallen snow. Like the Christmas snowstorms of 1901 and 1915, the snow Christmas 2002 was also somewhat heavy and wet with high temperatures in the lower 30s and lows only in the mid 20s.

Probably one of the slushiest and sloppiest Christmas Days happened in 1973. What started out as a white Christmas with a heavy 7 inch snow cover, quickly melted to a meager 2” slush mess by nightfall. To add insult to injury, it rained nearly a half an inch during the day.The wettest Christmas on record occurred in 1945 when 1.16 inches of rain fell. The rain actually began Christmas Eve as a light freezing rain and continued freezing until nearly dawn on Christmas, when the temperature pushed above freezing. Until the ice melted, a few tenths of an inch of ice coated everything by Christmas dawn. Needless to say, walking and driving early the Christmas of 1945 was treacherous but Santa was in and out of town in a flash!

Without a doubt, and still in the memories of long term inhabitants of Southeast Lower Michigan, is the warmest Christmas on record, the Christmas of 1982. It was as though the whole area was shipped to Florida for the holiday! The official record high at Detroit was 64 degrees, while Flint did one degree better at 65! These readings are about normal for Tallahassee, Florida! Scenes of shirt sleeved people with shorts running or riding bikes, instead of visions of sugar plums, made the Christmas of 1982 to some Michigan Christmas traditionalist, very hard to take.  This spring-like day was complete with scattered showers and, of all things, thunderstorms! Ironically, the bitterest cold Christmas came just a year later in 1983! Maybe a payback from Mother Nature for the warm weather we were treated to, the Christmas past? The temperature plummeted Christmas eve to a record low of -9 at Detroit and was accompanied by a stiff west wind averaging 25 to 30 mph, creating life threatening wind chills at times of near 40 below zero! Santa certainly brought the North Pole with him the Christmas of 1983, when he made his rounds very early that morning. In addition to the record low Christmas eve, another record low /-10/ was established during the very early morning hours of Christmas.

These Christmases past discussed are more the extreme than the norm across extreme Southeast Lower Michigan. But they do show the variable weather that can occur at Christmas (or any other time for that matter). The "normal" (or average) highs in extreme Southeast Lower Michigan Christmas Day are in the lower 30s, while lows average in the upper teens.

And now, I'd like to wish all who read this a very Merry Christmas and/or Holiday Season and the best in 2017! I plan on continuing my blog for the new year if the fates allow and look forward in reaching out to more people (and hear their comments and ideas) across the globe.

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

12/16/16

...Another Storm Takes Aim on Southeast Lower Michigan For Friday Night Into Saturday...

...Another Storm Takes Aim on Southeast Lower Michigan For Friday Night Into Saturday...Includes Epilogue...

/Issued 12/15/16 - 3PM/ for any updates see:
https://www.facebook.com/weatherhistorianSEMI7415chats/ /

(Now includes write-up on storm and snow totals)
 -12/17/16

As mentioned in my last post; we have another storm to contend with for this upcoming weekend /16th-18th/. This time the best snows will focus more north while mixed precipitation falls south.

Low pressure will approach Southeast Lower Michigan late Friday into Saturday morning, crossing the area around sunset.. As the storm approaches, snow will overspread the area from west to east overnight Friday-Saturday as warm air with moisture is pushed into the cold, Arctic air in place. As warmer pushes north Saturday; look for the snow to become mixed with then change to light freezing rain then rain/drizzle far south. Snow will continue north, see particulars below...


South Portion /Generally south of a line from Lansing - Flint - Port Huron or south of I-69/...
Snowfalls at this time look to be in the 3 - 5" range in the south of I-69 before changing over to a period of sleet and freezing rain then light rain and drizzle as temperatures rise into the lower to mid 30s. Light amounts of freezing rain are expected ( less than 1/10") before the changeover.


North Portion /Lansing - Flint - Port Huron and points north through the Saginaw Valley and Thumb Region or I-69 and north/...
This area will see mainly snow with generally 4 - 6" expected. A period of mixed precipitation is possible along the southern areas of the snowfield. Light amounts of freezing rain are expected (at or below 1/10") in the southern areas. Temperature will rise then hold steady around 30 to the lower 30s.
_________________________________________________

At this time, the GFS looks most reasonable and maps below...
1ST Map for Saturday /12-18/ sunrise...
Shows the low approaching from the St Louis area on it's way into Northern Indiana.

2ND Map for Saturday midday /12-18/...
Shows the storm moving from Northern Indiana into Southeast Lower Michigan. At This time; the track should take her right across the Southeast corner of Lower Michigan near Detroit.

Much colder air will flood into the area once again overnight Saturday into Sunday.










...Another Storm Takes Aim on Southeast Lower Michigan For Friday Night Into Saturday...

Sat 12/17...Epilogue

Storm was well behaved and actually was an inch or so light on the totals, but who's complaining? Actually, a general 2-4" prediction would have sufficed. Models were off on the track which affected the end result forecast of warmer temperatures and freezing drizzle/rain going to rain south. The last runs or two did start a southward shift a bit, with last nights GFS more notable.

Snowfall Map - courtesy of the NWS DTX....

 Making weather fun while we all learn, 

Merry Christmas, Happy Holiday's & Happy New Year

Bill Deedler - SEMI_WeatherHistorian


12/12/16

Snowstorm Dec 11-12th , 2016 Over Southeast Lower Michigan

For shorter term forecasts see:  https://www.facebook.com/weatherhistorianSEMI7415chats/
along with write-ups here

Snowstorm Dec 11-12th, 2016

Epilogue;

While models diverged some early mid-stream they came together for the heavier scenario of snowfall which I forecasted early on the 10th. I updated by just an inch on amounts on the plus side 12/11 and very happy with the results. This storm was odd in the sense that generally these type of long duration, weak low situations may deposit 4-6" of light snow. It definitely was an over-achiever for it's dynamics and surface features but shows you what you can get with moisture rich atmosphere, good forcing (old school, overrunning) and multiple pva's. The system actually had two warm advection pva's; one early in the game along the waa and one later with low and warm front...which gave her the added boost to achieve.

- Bill Deedler

NWS Storm Report Dec 11-12th, 2016
http://www.weather.gov/dtx/WinterStormDecember11-12


Reported Snowfalls over Southeast Lower Michigan


NWS Storm Report Dec 11-12th, 2016
http://www.weather.gov/dtx/WinterStormDecember11-12
Reported Snowfalls over Southeast Lower Michigan


 


Making weather fun while we all learn, 

Bill Deedler - SEMI_WeatherHistorian