With The First Week of a New Year Comes a Change in the Weather

The first official month of the Winter 2024-25 season brought a notable change in the prevailing unseasonably warm fall weather. For the most part; the month of December contained equal amounts of below normal temperatures and above until the end; when a quick mild spell boosted the monthly average to above normal at 33.3/+2.0. All in all; December was a fairly "snowless"  month with below average snowfall at 3.6" /normal  8.9"/ through the 31st but with above normal precipitation with 3.27". Thus far; only half our normal amount of snow has fallen this winter with 5.4" /Norm -10.8"/

The outlook for January 2025 keeps the declining temperature trend in vogue for now with a predominantly colder than normal January in store for the early - mid month period. Latest indications are a gradual stratospheric warming trend (not official SSW) far aloft over Siberia toward the North Pole will help elongate the Polar Vortex (and some of the brutal cold at the surface) and push it south (blue/purple) into the mid latitudes, including North America with some moderation. Coldest air at the surface would concentrate over the eastern two-thirds of the nation and deep into the south!

 

Projected 500 MB upper air pattern for all of January shows the elongated trough over eastern Canada into the eastern U.S.

 

With the ridging/upper high pressure building over the eastern Pacific and western U.S at times and blocking in Greenland, this will enable the delivery of Polar/Arctic air south into the U.S.

Low pressure will move along the Polar front early in the new week but at this time it appears much of the snow will stay south in the Ohio Valley. Models have had a terrible time with this system varying from a snowstorm for the southern Great Lakes to nothing, keeping it south. The dynamics and upper air pattern won't be sampled better until Friday. Any significant changes will be blogged.

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

 

The Whitest of Christmases and Other Christmases Past and Chances for a White Christmas - 2024

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 Christmas morning /7AM/, but not necessarily have to fall on Christmas. 

Mom Nature and weather models have been extremely fickle with weather day to day and week to week this holiday season. Frequently, changes in model projections and actual evolving weather many times have not coincided. Thus, the later than average White Christmas post.

At this time /Tuesday/ December 24th 2024; chances of a white Christmas across all of Southeast Lower Michigan pretty well; depends greatly where you are located. Most areas across extreme Southeast Lower Michigan (across much of Metro Detroit south to the Ohio Border) will not have a white Christmas per se' with a trace or nothing. Further west and northwest across Ann Arbor, Milford, Howell around an inch or so - therefore definitely location. Further north over Flint into the Saginaw Valley across into the Thumb Region Mainly around I-69 and north-northeast a white Christmas should hold into Christmas. Temperatures however will be close to normal with highs in the lower to mid 30s.

Christmas of 2023 was a total waste as far as white Christmas with unseasonably mild weather with temperatures in the 50s!

 

Christmas 2022; a cold blast accompanied by several inches of snow fell a few days before and on Christmas across Southeast Lower Michigan making for a white Christmas but with brutally cold wind chills well below zero.

  

On Christmas /2021/ we ended up with no white Christmas. Christmas 2020; we lucked out with generally an inch or two of snow falling over the region on Christmas Eve into Christmas morning. A nice picture-perfect light snow cover.

 

Christmas /2019/ no white Christmas was to be had - and also back in 2018; around Metro Detroit there was no white Christmas. In fact; temperatures pushed up into the 40s and 50s in the few days following Christmas. Further north from the Flint area into the Saginaw Valley and Thumb Region however; a inch or two remained on the ground for a white Christmas across that region.

Over the years, extreme Southeast Lower Michigan has averaged just under 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.

Four years ago /2017/; an unexpected white Christmas was had in spades as low pressure system overachieved; developing robustly over the southern Great Lake/northern Ohio Valley. The system developed into a notable little snowstorm falling mainly on Christmas Eve over the southeast area as seen in this map, bringing snow for a picturesque, classic Christmas scene. The only negative - and a notable one - was the lousy driving conditions Christmas Eve into early Christmas Day but with improving conditions later for Christmas dinnertime.

For more on the system from the NWS; see here.

In 2016; even with mild weather with temperatures in the 30s; Southeast Lower Michigan was able to hold on to a white Christmas as the snow (generally 2-5") slowly melted. In fact; the day after Christmas, warm air surged into the region and pushed temperatures into mainly the 50s and took care of any remaining snow! Back in December /2015/; it was a mild and snowless Christmas with a high temperatures near 50. Of course, the year before, /2014/ contained 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.

More Previous Christmases back to 2004:

In 2013;  even 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 19^th (with another, lesser intense snow falling on the doorstep of Christmas, 23^rd -24^th). 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 15^th. 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 23^rd, 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 124 (including 1900) Christmases in Detroit, 58 (or 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. However; the past 30 year normals /1991-2020/ the shorter time-frame indicates the chance of a white Christmas at Detroit has dropped to just 35%; whereas around Flint the past 30 year norm puts it at basically a 50/50 chance (or exactly 51%). In the Saginaw region; the probability of a white Christmas has dropped to 46%.

Way back on 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 2025!  I plan on continuing my blog occasionally 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

Another Milder Winter In Store For Southeast Lower Michigan? - Is This Becoming a Habit - or Is It? Winter 2024-25 Outlook

 Part I

Current ENSO Conditions and Representative Winter Outlook & Analogues

Well, this Autumn over Southeast Lower Michigan has been what is generally expected over the region when a La Nina /ENSO/ is in the works. Dominating mild weather and more on the drier side when compared to an average fall. The only problem is; officially there was strictly no La Nina. Prevailing Neutral SST conditions slowly ebbing toward La Nina conditions are now what holds sway in the central Pacific. This is evidenced by the changing water temperatures in the official 3-month ENSO readings since the late spring into summer. Latest reading for the last ASO period in the chart below (not placed) continues a Neutral reading at -0.2; so ENSO continues to crawl  toward a weak La Nina.

Year	DJF	JFM	FMA	MAM	AMJ	MJJ	JJA	JAS	ASO	SON	OND	NDJ
2020	0.5	0.5	0.4	0.2	-0.1	-0.3	-0.4	-0.6	-0.9	-1.2	-1.3	-1.2
2021	-1.0	-0.9	-0.8	-0.7	-0.5	-0.4	-0.4	-0.5	-0.7	-0.8	-1.0	-1.0
2022	-1.0	-0.9	-1.0	-1.1	-1.0	-0.9	-0.8	-0.9	-1.0	-1.0	-0.9	-0.8
2023	-0.7	-0.4	-0.1	0.2	0.5	0.8	1.1	1.3	1.6	1.8	1.9	2.0
2024	1.8	1.5	1.1	0.7	0.4	0.2	0.0	-0.1

Current ENSO SST as of Nov 2024

Perusing over Maps 1 & 2 below; it does look like the developing La Nina is still somewhat in the works by the looks of the early and again, mid November data in the Pacific (in and around the equator /0' lat/). What remains to be seen is how well La Nina evolves (these particulars never seem easy, lately). Modeling SST forecasts ahead of the ENSO events (with the American CFS-v2 model anyway) have been too aggressive in ENSO development the seasons/months ahead. All latest expectations have now cut back on the below normal departures of the water temperatures /SST/. 

Before I go any further I must say (and I may regret it); I really don't see La Nina being much of an influencer this winter anyway and think it's probably too hyped. It's having a hard time taking off as it is and there are some negatives against it. If that's a decent assumption and bears out; the weather and systems should act more like Neutral ENSO conditions for the most part. 

Going with that regime; Southeast Michigan's winter season should be more influenced by the PDO (moderate - strongly negative), MJO, the NAO/AO (varying from positive - negative and also; where the oscillation is based), subsequent PNA and lesser extent, the AMO. I'll explore the PDO and others in the analogues more below but in keeping in the vein; continental air masses should be more of player this winter - which should only add to the volatility. 

 Note the Analogue Sea Surface Temperatures Map -1 below as of Nov 1st

         Now, the recent changes in Map -2 below as of Nov 24th

This time; the forming weak La Nina has backed-off slightly (weakened) while the negative PDO continues to form. 

 Current Oceans SST Anomalies 

 

 

3.4 SST Model Guidance

 

 

As mentioned above; what had been forecast by the model(s) was anywhere from a moderate or even strong La Nina this winter months ago; now has the water temperatures just slightly below normal and barely scratching the surface of La Nina territory. Therefore in keeping with the latest forecast; I adjusted my analogue category for winters under past Neutral - Weak La Ninas with similar timings and strengths but still; some with various local & hemispheric patterns beforehand. 

 

 Why the PDO (and EPO) are More Important This Winter

The Pacific Decadal Oscillation /PDO-/ has been trending this autumn to more negative with time. Why is this important - a picture (s) is worth a thousand words (below). How this plays out along with their frequency will be a main driver for the winter. If a positive /PDO+/ jet stream continues to intervene notably, the variance of temperatures will be apparent. Being the Pacific Ocean has influenced our weather this fall into winter we've seen both sides of this dominance (PDO+/PDO-) and not as much from the NAO/AO influence yet.

 

 

 

 

Note the numerical change in the PDO+ to PDO- in the last decade or so. The last few months are not in, in the bottom right.

The blue/negative numbers indicate a negative /PDO-/ has become more dominant the last few years. Also, the yellow/positive /PDO+/ from 2014-18 show the influx of the mainly positive state.

The graph /below/ of the PDO reflect those numerical numbers all the way back to the mid 1800s.

 

 

Current cold Phase of the PDO and weak La Nina show well in this recent SST scan on November 1st, 2024. 

 

 

 

 

Generally cold phases coincide with La Nina's or Neutral states and rarely El Nino states. It does happen and studies propose that when the PDO and ENSO are in phase, such as this Fall they tend to enhance the effects. When out of phase; which is a somewhat a rare event, that they may cancel out their known effects.

 

 

How Warm We've Been!

Again; here at Detroit and much of SE Michigan, we sit with a November average temperature that has blown away any warmest Nov in the past century (and then some) by averaging nearly 50 degrees (ave 49.6/+6.9 thru 22nd *Updated 11/26 @ 48.7/+ +6.7) Take note; the warmest Nov on record in Detroit being 47.8 in 1931! Of course; even with the colder snap that is taking shape for the last quarter of the month, we should still average near/at the top 20. By far however; the most shocking stat is how many warm Novembers and winters there have been since the '90s (or basically, the new norms period 1991-2020). At Detroit alone; nearly half of the Novembers (nine) are in the top 20 and another one is due at the end of this one)! Therefore; about half of the top 20 warmest Novs and winters at Detroit occurred the last 31 years /1994-2024/ including both 1994 & 2024. One more stat; add all those recent /9/ top warmest Novs since 1994 (excluding '24) and the ave is 45.9 (or near 7/8th place at 46)!

                                                        

Top 20 Coldest/Warmest Novembers in Southeast Lower Michigan
Rank	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	29.8	1880	47.8	1931	31.3	1951	47.3	1975	29.8	1951	47.1	1931
2	33.5	1976	47.6	2001	32.0	1995	46.6	2001	31.6	1995	45.9	1975
3	34.2	1996	46.9	1902	32.6	1996	46.4	2020	32.5	1959	45.6	2015
4	34.5	1875	46.8	1975	33.0	1959	46.2	1931	33.3	2019	45.4	2016
5	34.6	1951	46.7	2016	33.3	2018	46.0	2015	33.3	1976	45.3	2001
6	34.9	1894	46.6	2011	33.3	1976	44.6	2016	33.6	1933	44.6	2020
7	35.2	1967	46.0	2015	34.5	1936	44.4	1934	33.9	1996	43.2	2009
8	35.4	1936	46.0	1963	34.5	1933	43.8	1938	33.9	1955	43.1	2011
9	35.5	1995	45.7	2020	34.6	2019	43.7	2011	34.0	2018	43.0	1963
10	35.5	1911	45.7	1948	34.8	1967	43.3	1963	34.2	1989	42.4	1999
11	35.7	1910	45.5	1994	34.8	1955	43.2	1948	34.2	1967	42.4	1948
12	35.7	1892	45.3	2009	35.0	1947	42.8	1999	34.2	1950	42.2	1934
13	35.8	2019	45.2	1999	35.1	1929	42.5	2003	34.3	1947	41.8	1994
14	35.8	2014	44.9	1964	35.2	1950	42.5	1994	34.4	1986	41.8	1938
15	36.0	1933	44.9	1909	35.2	1921	42.4	2009	34.6	2014	41.6	1990
16	36.4	1903	44.5	1953	35.3	2014	42.4	1990	34.7	1949	41.6	1964
17	36.4	1901	44.3	2003	35.4	1986	42.2	1924	35.1	1943	41.6	1913
18	36.6	1959	44.3	1883	35.5	1997	41.8	1998	35.1	1925	41.5	1953
19	36.6	1891	44.2	1990	35.6	1943	41.8	1953	35.2	1926	41.4	1930
20	36.7	1950	43.9	1946	35.8	1949	41.6	1987	35.2	1919	41.3	1998
* Detroit Area temperature records date back to January 1874. ** Flint Bishop temperature records date back to January 1921. *** Saginaw Area temperature records date back to January 1912.

 

Back to the Winter 2024-25 Outlook and Analogues   

My original nine winter analogues in chart (or table) below averaged slightly above the temperature normals of 1991-2020 for the 2024-25 winter. I look for the temperatures and weather to be more variable & possibly bordering on extreme at rarer times as Polar/Arctic jets vie for dominance over the obstinate Pacific Subtropical Jet. The latter should attach intermittently with warmer, moisture laden air from the Gulf of Mexico. A progressive but still; occasionally blocky upper wind jet / air stream will only add to the winter's variability. I look for both; a split flow but occasionally phasing of jets as much over the Central and Western US as in the East. This is the main problem for the winter outlook; how often the Polar/Arctic jets engulf the Great Lakes.

 

That being said; latest model extended guidance into early winter matches well with my dominant early winter analogues suggesting winter's cold will come down in spurts beginning late fall into early winter. While most analogue November's averaged normal-above (like this Nov and annotated with a/n/b next to analogue season on chart); Decembers had the best chance to average below normal or at least a notable period of cold (a far cry from recent Decembers). 

 

Arctic cold that charged up in the Polar Regions during the analogue falls  -our 2024 warm Neutral autumn not withstanding -  found it's way down into the Lakes Region with the majority of December's averaging below normal. In the past; out of the nine Winter Analogues; seven Decembers contained below normal temps, one on the low side of normal and one above. This doesn't mean there won't be notable mild periods and thus, the issue comes up; will the periods of colder weather be able to offset periods of milder weather during the winter. Obviously; this has been a major problem in many of our recent winters. Basically; when we did get the cold; it didn't last. 

The air masses 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/ which looks to be negative for the period. The overall Pacific Jet should continue to be active; a sort of a "layover" of sorts from the long dominant El Nino from mid 2023 to mid 2024. In addition; upper air ridging will have to be watched setting up west of Alaska to Alaska, the question arrives how often and long and thus, influential. This will be discussed in Part Two of my Outlook.

 

   ANALOGUE WINTERS FOR 2024-25 

Note; the two analogues /2001-02 & 2022-23/ at the bottom of the chart below are NOT strictly included in this winter's analogues. They were La Ninas at the end of an extended La Nina cycle (weakening not developing). In addition; they also contain a few developing or developed stronger solar flares like this fall into winter - and peaking solar cycle into 2025.

 

 

 ANALOGUE WINTER CHART FOR 2024-25

		L
A	DETROIT	T	E	M	P	S		P	C	P	N
N	SEASON	DEC	JAN	FEB	WNT AVE	WINTER	NAO/P/SC	SEASON	DEC-FEB	WINTER	QBO
A	1942-43-n	25.6	21.7	28.0	25.1	1	N/P- SC--	1942-43	7.19	1	*
L	1952-53-a	34.1	30.6	32.2	32.3	1	N/P SC--	1952-53	4.66	1	E-
O	1964-65-a	30.4	25.5	26.6	27.5	1	N&N-P- SC--	1964-65	8.42	1	E-
G	1966-67-n	28.7	29.3	23.8	27.3	2	N/P  SC+	1966-67	8.15	2	W
U	1970-71-n	29.0	20.7	27.4	25.7	2	N-/P- SC++	1970-71	5.32	2	E+/-
E	1983-84-n	20.8	18.0	33.3	24.0	3	N+/P+ SC-	1983-84	5.87	2	E
S	1995-96-b	25.6	24.3	26.0	25.3	4	N&N-/P  SC--	1995-96	4.46	3	E-
	2005-06-a	25.8	35.2	29.8	30.3	2	N&N-P  SC-	2005-06	8.47	3	E+/-
N	2016-17-a/	29.1	32.1	38.0	33.1	3	N+/P SC-	2016-17	6.89	3	W
E	BELOW: NOT INCLUDED:	IN ANAL STATS
U	2001-02-a	35.9	32.7	32.9	33.8	1	N+/SC++	2001-02	7.50		W-/+
T	2022-23-a	32.8	33.5	34.0	33.4	2	N+/SC+	2022-23	8.38		W-
R
A	Ave	28.9	27.6	30.2	28.8			Ave	6.85		QBO
L	NORM 30Y	31.2	25.7	28.0	28.3	150yr	26.9	Norm	6.56		W
	Dep	-2.3	1.9	2.2	0.5			Dep	0.29
I					-1.2
	DETROIT	S	N	O	W	F	A	L	L		Oct
W	SEASON	OCT	NOV	DEC	JAN	FEB	MAR	APR	SEA TOT	SEASON	Sib snow
E	1942-43	T	4.4	9.2	18.4	2.7	2.9	6.8	44.4	1	*
A	1952-53	T	T	4.3	9.4	0.7	1.0	1.2	16.6	1	*
K	1964-65	T	2.6	8.4	7.1	15.8	12.9	2.4	49.2	2	*
	1966-67	0.0	11.8	14.9	5.4	11.0	5.8	1.7	50.6	1	B
L	1970-71	0.0	1.7	9.8	8.7	5.9	8.7	0.6	35.4	2	B
A	1983-84	0.0	3.5	19.9	9.9	8.7	9.7	0.1	51.8	2	A
	1995-96	0.0	1.3	4.5	6.3	3.6	11.8	0.1	27.6	3	B
N	2005-06	0.0	4.3	19.8	5.0	3.8	3.4	T	36.3	4	A
I	2016-17	0.0	0.1	16.8	11.8	2.2	6.9	0.1	37.9	5	B
N
A	2001-02	T	0.0	4.9	15.0	6.7	7.1	T	33.7		B
S	2022-23	T	2.5	5.0	11.7	2.0	15.8	0.1/T	37.1		%
I	Ave	T	3.3	10.7	9.9	6.0	7.8	1.2	38.9		%
	30y Norm	T	1.9	8.9	14.0	12.5	6.2	1.5	45.0
2	Dep	0.0	1.0	1.8	-4.1	-6.8	1.6	-0.3	-6.1		Sib Snow
0						7			45	ther	*  N/A
2	Color	Temps	Degrees		Rain	Inches		Snow	Inches
4	Legend:	Below	1.0>		Below	1.00>		Below	<5.0	n
~		Normal	0.0-1.0		Normal	0.00-1.00		Normal	>-5.0<5.0
2		Above	1.0>		Above	1.00>		Above	>5.0
5

Some additional category explanations in the analogue chart for the entire winter

NAO: /N/ - The predominant phase of the North Atlantic Oscillation    N- (negative), N (neutral) or N+ (positive)

PDO: /P/   The predominant phase of the Pacific Decadal Oscillation   P- (negative), P(neutral) or P+ (positive)

SC :  Position of the solar cycle during that winter. 

Breaking it down
SC-- (opposite lowest sunspot cycle compared to the present, thus least similar) 

SC+ (sunspots moderate-high but waning and not approaching or at the highs/maximums like 2024-25.

Finally, SC++ where solar sunspot cycle was very close to the high cycle of 2024-25 and/or is at near the same incline; thus the best comparison and likeness to the upcoming winter.
          
QBO - W=West wind prevailed that winter or E=East wind prevailed. 

Trends: -/- (weak and weakening trend), -/+ (weak but strengthening), no sign  (steady trend, no change) + moderate and strengthening +/- strong but weakening. 

The closest analogues with QBO likeness years are the two with westerly and no change in trend; 1966-67 & 2016-17. Next is 2001-02, not officially an analogue.
         
Sib snow - Siberian snow cover in October and rate of change. All previous analogues winters had mixed snow covers compared to this past October's/early November. Notations: A= above, B=below, % = equal to. 

A bit more on the 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".

 

Local Data Suggests

Temperatures: Normal to Above (-0.5 - +2.0)

Again; Our nine winter analogues in chart (or table) below averaged slightly above the temperature normals of 1991-2020 for the 2024-25 winter. I look for the temperatures and weather to be more variable & possibly bordering on extreme at times as Polar/Arctic jets via for dominance over the obstinate Pacific Subtropical Jet. 

Latest extended guidance matches well with my dominant early winter analogues suggesting the winter cold (below normal temps) will come in spurts beginning as early as late fall-early winter. While most November's averaged normal-above (like this Nov and noted with a/n/b next to analogue season); Decembers had the best chance to average below normal or at least contain a notable period of cold (a far cry from recent Decembers). In the past and present; Arctic cold that charged up in the Polar Region during the our notably mid-late warm Neutral (or weak La Nina) autumn; found it's way down into the Lakes Region with the majority of December's averaging below normal. Out of the nine Winter Analogues; seven Decembers contained below normal temps, one normal and one above. The issue comes up is when and where the notable cold manifested itself from late Nov into early Jan in early winter.

 

Check out this temperature analogue map for Decembers only

 

 

 

 

 

 

 

 

 

 

 

Winter 2024-25  Composite Maps

Despite my temperature table (or chart) above, averaging slightly above normal temperatures for the entire analogue winters; specific composite maps below; averaged the nine analogue winters slightly below normal temperatures. This is unusual but can happen when local analogues are near normal (in this case Detroit is just a 1/2 degree above normal). Looking at some of the warmer months, especially February I can see why locally the averages would be warmer than a national map. 

 

The analogue map is useful at this time since it shows where the cold blasts are intermittently likely this December and winter as a whole - from the Northern Plains, Upper Midwest into the Western Great Lakes and Ohio Valley. Local data doesn't show a continuation of cold nor warmth thus it's beneficial for areas likely to experience the Polar Express at times when revved up.  This of course relates back to the larger cyclical patterns discussed above.  

On the Precipitation side of things: Averaging around normal

The past chosen analogues paint a wet picture for the Pacific Northwest south into central California and eastward into the North and Central Rockies. 

Broadly; normal to above normal precipitation was found over a large area of the North & Central Plains into the Great Lakes/Northern Ohio Valley; then east to the East Coast. This also does indicates relatively active Great Lakes Lake Effect season along with the typical lee of the lakes snow squalls and snow showers. Of course; this will largely depend on the developing upper wind pattern and cyclical oscillations mentioned above. 

Like above discussion - Again; I really don't see La Nina being much of influencer this winter and think it's too hyped. It's been having a hard time taking off and there are some negatives against it. If that is a good assumption; the weather and systems should be more influenced by the PDO /negative/; NAO/AO, subsequent PNA and lesser extent, the AMO. Therefore; continental air masses should be more of player this winter - which will only add to the volatility.

Precipitation and Snowfall for Southeast Michigan:

Quite variable but generally averaging around normal with Lake Effect (Lakes Michigan and Huron -and certainly over the eastern Great Lakes) being more of a player than in many recent winters. Storms tracks will be determined by the above discussioned patterns. There were a few winters where the tracks held across SE Michigan and mixed precipitation was plentiful along with storms. 

In December in Part II; I'll take a look at model projections for the winter period along with observing prevailing jets and associated storm tracks forming. In addition; any shorter term weather related events.

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