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

12/2/16

Another Beautiful, Long Lasting Autumn Makes it Two for Two! Colder Blast Set for Next Week!


Temperatures Autumn 2016

No, it wasn't your imagination - the recent fall was again very nice and one of the warmest across Southeast Lower Michigan. On the whole, Temperatures averaged in the mid 50s this past fall when taking the highs and lows into account across all of Southeast Lower Michigan. Normally, autumns do tend to lean toward the nicer side for weather in these parts - but not this nice nor long lasting! On average; temperatures average around the 50 degree mark in a normal fall but this fall was anything but normal. Temperatures averaged close to 4 1/2 degrees above normal departure /55.4 +4.6/ for all of Southeast Lower Michigan this past fall. This was warm enough to put the region in the top five warmest falls on record at all three cities; Detroit, Flint and Saginaw! That's pretty impressive when you consider this is looking back around a century or more.

And what's more; note I said "again" in the first line. What's even more extraordinary is that this is the second fall in a row that was this nice and warm. Last fall in 2015; temperatures across Southeast Lower Michigan averaged even a bit warmer at 55.9 as opposed to this fall's 55.4! Both Flint and Saginaw averaged slightly warmer last fall while Detroit had its warmer autumn this fall.

Bringing it home; the last time a fall was this warm or warmer was just last fall; a rare feat in itself as there have never been two falls in a row that were this warm over the region. In fact, it's very rare to find any two falls in a row that made even the top 20 warmest listing, let alone top five. There were only two other "back-back" falls at Flint; 1946 /9th/ & 1947 /11th/ and Saginaw with 1930 /19th/ and 1931 /1st/. Detroit had no other back-back warmest falls in the top 20.

Looking at the particular temperature ranking statistics from the last two falls and top 20 warmest


Detroit Area* Flint Bishop** Saginaw Area***
Coldest Warmest Coldest Warmest Coldest Warmest
Temp Year Temp Year Temp Year Temp Year Temp Year Temp Year
 1   46.8 1880   58.4 193146.8 1993  56.5 1931  45.5 1917  57.3 1931
2 46.9 1875 57.6 1881 46.9 1976 55.9 2015 46.2 1972 55.3 2015
3 47.6 1976 57.3 1963 47.0 1981 54.7 1934 46.4 1925 55.0 2016
4 48.0 1876 56.9 2016 47.0 1980 54.2 2016 46.5 1943 54.0 1971
5 48.1 1917 56.6 2015 47.4 1967 53.71971 46.8 1981  53.8 1927
6 48.8 1967  55.8   1946  47.6   1995 53.5  1938 46.8 1976 53.7 1963
7 48.8 1887 55.8 1927 47.8 1997 53.5 1963 46.8 1951 53.2 1998
8 49.1 1980 55.6 2005 47.8 1925 53.5 1927 47.2 1993 52.8 2005
9 49.2 1972 55.5 1961 47.9 1966 53.1 1946 47.2 1980 52.6 2007
10 49.2 1896 55.3 2007 47.9 1943 52.9 2007 47.3 1926 52.6 1920
11 49.4 1907 55.3 1953 48.0 1972 52.9 1947 47.7 1977 52.5 1961
12 49.5 1925 55.3 1941 48.0 1951 52.8 2005 47.8 1992 52.3 1994
13 49.5 1888 55.2 1900 48.1 1996 52.8 1998 48.0 1995 52.2 1975
14 49.7 1974 55.1 1998 48.2 1937 52.7 1975 48.0 1988 52.2 2011
15 49.7 1937 55.1 2011 48.3 1957 52.7 1973 48.1 1952 52.2 1973
16 49.8 1981 55.1 1994 48.5 2006 52.4 1983 48.2 1989 52.2 1946
17 49.9 1895 54.8 1922 48.5 1959 52.4 1961 48.2 1986 52.1 1941
18 50.0 1889 54.8 1920 48.7 1952 52.4 2011 48.2 1959 52.1 1970
19 50.1 1996 54.6 2004 48.8 1992 52.4 1941 48.3 1991 52.1 1930
20 50.1 1943 54.6 1882 48.8 1962 52.3 1953 48.4 1967 52.0 1934
* Detroit Area temperature records date back to November 1874.
** Flint Bishop temperature records date back to January 1921.
*** Saginaw Area temperature records date back to January 1912.

Rainfall Autumn 2016

Rainfall averaged above normal /11.36", +2.78"/ around the Detroit area but that was exclusively due to a wet September with over six inches of rain. Near normal rain was registered at Flint /9.68", +0.71"/ and below average in the Saginaw Valley /7.45",-1.71'/. This coming after a rather dry summer with a pick up in rainfall later in the summer into the early fall.

Looking ahead for the first half of December 

The first several days of December look to be about average with a plunge into colder, below normal temperatures the middle of next week /6-7th/. This will be the coldest air of the season being quite abrupt and noticeable considering the past fall. Look for temperatures to average near to slightly above normal through Tuesday with the decidedly colder weather, thereafter. Average highs for the first week of December are in the upper 30s to lower 40s with lows in the mid 20s across all Southeast Lower Michigan..

After the Polar front moves through by Wednesday; highs will drop off in the upper 20s to lower 30s with lows into the teens to lower 20s much of the remainder of the week. Best chances for precipitation will be snow or rain/snow on Sunday-Sunday night and rain to snow showers Tuesday into Wednesday. Those traveling near and downwind of the Great Lakes should keep abreast for  Lake effect snow forecasts mid-week on, next week.

 

 Making weather fun while we all learn, 

Bill Deedler - SEMI_WeatherHistorian

 


11/20/16

Will La Nina Really Be An Important Factor This Winter? Winter 2016-17 Outlook


Local Data Suggests

TemperaturesNormal to Above


Expect temperatures during the 2016-2017 winter to be more variable than usual with conflicting data in research. This will be due to a variable upper wind jet stream. I look for both a split flow and phasing of jets as much over the Central and Western US as in the East. Guidance and Analogues suggest the heart of the winter /Jan-Feb/ seeing the most of the action (though that doesn't mean there won't be any, other times) but winters tended to start somewhat later than average (see more in Analogues). This will be guided by the anticipated weak La Nina to Neutral state interacting with the North Atlantic and subset Arctic Oscillation /NAO, AO/. Just as important this winter will be the Pacific Decadal Oscillation /PDO/ and associated Eastern Pacific Oscillation /EPO/.

In the final analysis, I look for the Southeast Lower Michigan winter to average around normal to above normal.  Temperature departures should average from -1.0F to + 2.0F.

Actually, expanding on this “normal” idea, it is interesting to note that the 100 year winter mean temperature for Detroit is approximately 26.7 degrees with a one standard deviation spread of 3.5 degrees either side of that 26.7. Statistically speaking, based on this data the temperatures could average as low 23.2 degrees or as high as 30.2 and still be considered within a “normal” range of the 100 year mean. The 30 year mean at Detroit has risen appreciably over earlier averages, mainly due to the local urban heat island. That winter average /1981-2010/ now rests at 27.9, a full degree /1.2/ above the old 100 year.

This outlook hinges mainly on the endurance of the Pacific jet and its extensive eastward push and its interaction with the polar and Arctic jets. Normally during La Nina, the more dominant jet is the polar and/or Arctic jet leading to colder than normal temperatures. However, I feel this winter will see more interaction with the Pacific jet stream jet, a lay-over of sorts, if you will, from El Nino and the warm PDO (discussed at length, below). These variables, combined at times with the Polar Vortex over central and western Canada, supports this variable forecast. I see this hindering the dominance of below normal temperatures this winter. More on the jet structures in the storm track section.

Snowfall and Rainfall Normal to Above depending on location 

Because of the temperature variability and associated storm tracks observed in many of the analogue winters, snowfall in those winters ranged widely from above normal to below. This would be expected since the variance of temperatures hint at the variability of the upper atmospheric patterns and storm tracks. Therefore, pinpointing the perceived prevailing storm tracks this winter will make a significant difference in regard to seasonal snowfall. 

Using the expected dominant storm tracks for the upcoming winter, it is likely much of the region will experience normal to above normal precipitation with above normal snowfall /5.0"+/ around Detroit's northern and western suburbs north into the Flint and Saginaw Valley; to around normal /within 5.0"/ over the far Southeast corner of Lower Michigan (south of Detroit). Mixed precipitation events seem to be a higher than normal risk.

Broad Scale Discussion 

 

An interesting and another challenging winter is ahead with three main climate and weather drivers, a generally weak La Nina to Neutral conditions, the illusive NAO and PDO, working together to bring Southeast Lower Michigan a fairly interesting winter. 

1 - La Nina 

The difference between the current developing La Nina to the last La Nina is the strength and timing. The last La Nina was very strong compared to the current developing La Nina's strength.


                                              Current Developing La Nina as early November




                                             
                              Past La Nina stage as of November 2010
                                       


The strength of the previous La Nina 2010-11 is quite evident by the below normal SST's dipping to -2.0C as opposed this winter's expected ~ -.7C  to -1.1C                                              


                                                        October 2016 Average SST's







Multivariate ENSO Index 1950 - early 2016 shows up to the strong El Nino of the past year and note the strong La Nina during the Winter of 2010-11.






The Southern Oscillation Index /SOI/ below shows well the recent negative corresponding values in conjunction to our recent strong El Nino. Remember; an above normal SST is reflective of a negative SOI.




Latest Modeling Projections of the expected weak La Nina to Neutral conditions







Corresponding Analogue Years by SOI values (positive = La Nina)  

 (only numerical values for the first two analogues available)



        SOI 1878-79
1878  4    -8.2  1
1878  5     2.5  4
1878  6    -3.2  5
1878  7    14.8  4
1878  8    12.4  2
1878  9    17.5  2
1878  10   11.7  2
1878  11   14.4  2
1878  12   16.6  2
1879  1    12.1  2
1879  2    14.1  2
1879  3    10.8  2
1879  4    10.9  2
 
   
 SOI 1889-90 
1889  4    -0.8  4
1889  5    -1.2  5
1889  6    18.4  4
1889  7     1.4  3
1889  8     2.1  5
1889  9    11.1  4
1889  10    4.7  2
1889  11   22.0  4
1889  12   20.7  2
1890  1    20.3  2
1890  2    10.6  2
1890  3    11.8  2
1890  4     5.7  2
 
Available SOI Graphs below from analogues years reflect Neutral to Moderate
La Ninas after strong El Ninos. 








Latest SOI data through October shows a Neutral to weak La Nina state


 

2-Pacific Decadal Oscillation /PDO/ and associated subset EPO

The Pacific Decadal Oscillation remains in the recently switched warm phase, changing over a year ago. A warm phase of the PDO is represented on the left of the following example and compare it to the current state.


                             Warm Phase of the PDO                    Cool Phase of the PDO


Current Warm Phase of the PDO and weak La Nina show well in this recent SST scan on November 6th, 2016. Generally warm phases coincide with El Nino's or Neutral states and rarely La Nina states. It does happen and we have two winters in the current analogues when such an occurrence happened like the present time (and their subsequent winters were our coldest). Studies propose that when the PDO and ENSO are out of phase; which is a somewhat a rare event, that they may cancel out their known effects. Keep this in mind when looking at the Analogues. 


"The Pacific Decadal Oscillation (PDO) is a pattern of Pacific climate variability similar to ENSO in character, but which varies over a much longer time scale. The PDO can remain in the same phase for 20 to 30 years, while ENSO cycles typically only last 6 to 18 months. The PDO, like ENSO, consists of a warm and cool phase which alters upper level atmospheric winds. Shifts in the PDO phase can have significant implications for global climate, affecting Pacific and Atlantic hurricane activity, droughts and flooding around the Pacific basin, the productivity of marine ecosystems, and global land temperature patterns. Experts also believe the PDO can intensify or diminish the impacts of ENSO according to its phase. If both ENSO and the PDO are in the same phase, it is believed that El NiƱo/La Nina impacts may be magnified. Conversely, if ENSO and the PDO are out of phase, it has been proposed that they may offset one another, preventing "true" ENSO impacts from occurring".



"Odd-ball" Pacific SST Analogue Winters

There were only two winters in this winter's outlook research that contained a warm state PDO while the La Nina developed and prevailed; the Winter of 1878-79 and 1983-84. The 1878-79 La Nina winter was fairly weak while the 1983-84 La Nina winter was a bit more developed. Curiously, those two winters were our coldest in this season's analogues.





3-North Atlantic/Arctic Oscillation /NAO & AO/


One of the most important players for winter's outcome and ingredients in this winter’s weather is the trend of the North Atlantic Oscillation/Arctic Oscillation (NAO/AO). This is the biggest challenge to the forecast and potentially has the biggest bust potential. While trends with La Ninas and El Ninos are relatively stable, the NAO is highly elusive and trends are seen only a week or two in advance. Generally, colder winters in the study occurred with a predominately negative NAO. Below is a graph of the NAO in its positive and negative phases with arrows denoting the analogue years in in this winter's study.





Projections of this winter's NAO/AO are variable. One scientist who bases NAO/AO trend expectations and subsequent winter temperatures, Judah Cohen , strongly bases the winter temperature projection on early snowfall across Eurasia along with sea ice coverage in the early Autumn. His research has shown that these variables affect the NAO/AO development and positioning.. At this time with higher than normal snowfall coverage in that area and weaker ice formation in the Arctic this fall, projections are for a colder winter for almost all of the eastern U.S (excepting New England). Mr. Cohen has a nice update here every week or so on current and expected trends.



4-Solar cycle 

Solar cycle actual effects on short term weather and longer term climate variability remain a controversial subject. I've read several articles which support or are against their shorter term winter relevancy. Some theorize that both natural solar cycles and man's influence affect our climate. I am in favor of the solar cycle being somewhat relevant and sometimes giving the present winter cycle a "little kick" in regard to hemispheric wind flow patterns and resulting temperatures.  Studies out of Europe for example, do in fact make the connection to wintertime effects.


"The Euro–Atlantic sector seems to be a region with a par-
    ticularly strong solar influence on the troposphere. In fact,
                               significant positive correlations between solar activity and
    surface temperature in Europe have been reported in several
                                papers (e.g. Tung and Camp, 2008; Lean and Rind, 2008;
                                Lockwood et al., 2010; Woollings et al., 2010), although
                                 long records tend to give very weak signals (van Olden-
     borgh et al., 2013). We found a weak but significant change
     in the mean late winter circulation over Europe, which re-
     sults in detectable impacts on the near-surface climate. Fig-
     ure 9 suggests that during solar minima more cold air is ad-
     vected from the Arctic, thus resulting in a slightly increased
                                probability of colder winters for large parts of the conti-
     nent. Sirocko et al. (2012) recently reached the same con-
                                clusion after analysing 140 yr in 20CR, although their re-
                                sults are strongly dependent on their selection criteria for
       the solar minimum composite (van Oldenborgh et al., 2013),
                                   which includes only one winter for each solar cycle".


Comparing solar cycles of the past analogue winters to the present as a possible influence only and not a major contributor. While the solar cycle was in various modes, the tendency is for these La Nina's to Neutral winters to occur during the mid to lower part of the cycle or during an overall, weaker cycle (like the one we have entered, below).




The closest previous solar cycles (strength and positioning) during the analogue winters to this upcoming winter occurred in; the winter's of 1897-98, 1973-74, 2007-08 (averaged normal temperatures). Besides those winters, the winters that also occurred during the decline but near or at the lull of the solar cycle (like next winter, 2017-18 for example) are; 1878-79, 1889-90, 1964-65 and 2010-11. Therefore, we have seven (out of 11) analogue winters in the study that were near this winter's expected solar cycle positioning. The winter of 1998-99 was near the same positioning but was during the incline.


Here we see the latest solar cycle amplitude compared to the previous cycles back to the mid 1970s.


Winter 2016-17 Analogues

(click on table to enlarge)


Analogue Research and Results

As stated above, the analogue years were quite variable but with a tendency toward below normal temperatures. Remember, looking at Detroit alone, you run into the influenced heat island normals, which then would tend to skew the averages below normal slightly, since they are warmer (than the 100 year) - get it? Anyway, all three cities suggest a normal winter when the variances are averaged. Looking at the individual winters, there still remains a preference for a below normal winter. Winter's were most active mid to late winter, with the highest snowfalls mid winter. Looking at December's alone; suggests that the winters (notable snows) started generally mid to late month, somewhat later than average. Back to the entire winter; the second preference was for a normal winter and the least was for an above normal. This certainly fits La Nina winters but we are not dealing with just a La Nina winter. The analogues represent quite a range Neutral to moderate La Ninas and still I was only able to find 11 that match the past strong El Nino melding into a Neutral to moderate La Nina by the next winter season.

Even with the dominant normal to below normal winters; there were a decent showing of above normal winters, enough to pull the averages back to near normal. As mentioned above, the coldest winters were found when the rare warm PDO existed above the cool La Nina, as in this present year. Studies have found this tends to dampen the effects of the La Nina.



The split in the temperature pattern (above normal Southeast to below North) is well displayed during the analogue years




In addition with the conflicting and variable types of air masses in the same location, note heavier precipitation in the battle zone below.





 

Winter 2016-17 Upper Wind Anomalies & Projected Storm Tracks


Compare the typical jet structure of the La Nina below with the analogue years depicted jet and anomalies in the following section:

 


 

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.



The mean (an average) upper wind flow for the analogue years is shown below but nevertheless, still intimates weak troughing from the Aleutian Low south-southeast to the Desert Southwest. This suggests the phasing of the upper low impulses dropping southeast from Alaska and western Canada and thus, giving  "birth" to a more pronounced western US trough at times. Again, this extended troughing from western Canada and into the US is displayed nicely by the analogue composite anomaly map, above. 

 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.




What do the models have to say about the winter? Mild to warm everywhere if you look as of November 2016




 

For December

NMME                                                                                               IMME








Prob fcst
PAC calib. prob fcst
NCEP_CFSv2
CMC1_CanCM3
CMC2_CanCM4
            GFDL_FLOR 
 
GFDL_CM2.1
NCAR_CCSM4
NASA_GEOS5
NCAR_CESM IMME













 




Forecasted precipitation trends for the winter generally follow the analogue years trend



NMME


Prob fcst
PAC calib. prob fcst
NCEP_CFSv2
CMC1_CanCM3
CMC2_CanCM4
GFDL_FLOR

GFDL_CM2.1
NCAR_CCSM4
NASA_GEOS5
NCAR_CESM



IMME
 

I'll be back at times when notable storms and/or temperature changes are expected to affect the region along with other historic storm information for the winter!

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