The Whitest of Christmases and Other Christmases Past and Chances for a White Christmas - 2020

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 /Wednesday/; December 23rd, 2020 chances of a white Christmas across all of Southeast Lower Michigan have improved -slightly- just recently across the region. Up until these past few days, it looked as though another brown, boring looking Christmas would greet Southeast Michiganders. This may still be the case, since the chances this year are still well less than 50%. However; a storm developing upper Midwest will slam a cold front through the area early Christmas Eve day /24th/ bringing abruptly colder weather. Rain is expected ahead of the front but the colder air flooding in behind is expected to change any residual rain over to snow showers Christmas Eve into Christmas Day. Remember; at least an inch of snow is needed on the ground Christmas morning as of 7am est for an official white Christmas. The amount of snow that falls will depend on the residual moisture available that streams up from the south and east on the upper winds - as a wave of low pressure zips up along the front. How far west the system throws back the moisture will determine if we get any system snow. Lake effect snow showers are also possible. Keep your fingers crossed!
Last Christmas /2019/ there was no white Christmas to be had and back in /2018/ again 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 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.

Three 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 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 120 (including 1900) Christmases in Detroit, 56 (or just barely 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 2021!  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



Winter Outlook 2020-21~ Type of La Nina Conditions, Polar Vortex and Busy Northern Pacific

As the global pattern evolved into a La Nina by mid fall; autumn's weather across Southeast Lower Michigan was fairly nice but a bit cooler than average early to mid season but was interrupted by a very notable spell of warm Indian Summer weather the first half of November (more below). The fall season was also wetter than average into early November with much of the surplus coming in September.

As stated; one of the most notable autumn weather events was the well above normal temperatures in November that contrasted greatly to the cold and snowstorm during the first half of November 2019! One check of Detroit's LCD of November of 2020 to the November of 2019 LCD shows in detail, the astonishing contrast. 

Indian Summer weather with a few highs flirting with the upper range of record high temperatures isn't all that unusual around Southeast Lower Michigan, especially during La Nina falls. This autumn's stretch of Indian Summer weather not only flirted with record warmth but created several record high days of its own with three record highs at Detroit and four record highs at both Flint and Saginaw from the 8-11th! The record warmth wasn't confined just to Southeast Lower Michigan but to all of Michigan


                                                    Courtesy of the NWS DTX
                                                  Courtesy of WJRT TV_Channel 12

Glancing back at the first half of the last two Novembers at Detroit; makes some interesting contrasts - and what a difference a year makes!




                                          STATION:   DETROIT MI

                                          MONTH:     NOVEMBER

                                          YEAR:      2019

                                          LATITUDE:   42 13 N

                                          LONGITUDE:  83 20 W




1   2   3   4   5  6A  6B    7    8   9   10  11  12  13   14  15   16   17  18

                                     12Z  AVG MX 2MIN




 1  42  35  39  -8  26   0    T    T    0 12.8 26 280   M    M   9 8      35 280

 2  48  37  43  -4  22   0 0.03    T    0 11.3 30 270   M    M   9 5      39 260

 3  47  33  40  -6  25   0    T    T    0  9.6 16 240   M    M   9        21 250

 4  54  42  48   2  17   0 0.02  0.0    0 13.0 25 220   M    M  10        31 250

 5  48  31  40  -6  25   0 0.00  0.0    0 10.4 22 250   M    M   7        30 250

 6  43  27  35 -10  30   0    T    T    0  5.7 14 310   M    M   8 18     17 310

 7  38  25  32 -13  33   0 0.03  0.2    T 11.5 18 310   M    M   8 1      25 340

 8  39  22  31 -14  34   0 0.00  0.0    0  7.7 15 340   M    M   4        21 290

 9  41  27  34 -10  31   0 0.00  0.0    0 11.0 21 210   M    M   9        27 210

10  47  34  41  -3  24   0 0.03    T    0  7.9 16  10   M    M  10 18     20  10

11  34  23  29 -15  36   0 0.81  8.5    1 11.0 18 330   M    M  10 128    24 330

12  25  13  19 -24  46   0 0.05  0.7    9 10.7 20 310   M    M   6 18     27 300

13  25   7  16 -27  49   0 0.00  0.0    7  8.4 17 190   M    M   8 18     23 180

14  33  24  29 -13  36   0    T  0.1    6 10.3 20 250   M    M  10 18     26 250

15  36  26  31 -11  34   0 0.00  0.0    5  8.6 18 250   M    M   8 18     24 260

16  34  22  28 -14  37   0 0.00  0.0    3  8.4 14  60   M    M   7        19  40

                                          STATION:   DETROIT MI
                                           MONTH:     NOVEMBER
                                          YEAR:      2020
                                          LATITUDE:   42 13 N
                                          LONGITUDE:  83 20 W
1   2   3   4   5  6A  6B    7    8   9   10  11  12  13   14  15   16   17  18
                                     12Z  AVG MX 2MIN
 1  50  33  42  -5  23   0 0.04    T    0 20.3 32 280   M    M   7 18     45 280
 2  48  28  38  -9  27   0 0.00  0.0    0 15.9 26 240   M    M   7        35 310
 3  59  33  46   0  19   0 0.00  0.0    0  9.2 16 220   M    M   2        21 270
 4  72  42  57  11   8   0 0.00  0.0    0 12.1 23 210   M    M   1        30 200
 5  66  52  59  13   6   0 0.00  0.0    0 12.3 18 220   M    M   7        23 220
 6  71  46  59  14   6   0 0.00  0.0    0  9.3 18 230   M    M   4 8      22 230
 7  71  46  59  14   6   0 0.00  0.0    0  7.1 20 210   M    M   4 18     24 240
 8  73  43  58  13   7   0 0.00  0.0    0  2.6 10 140   M    M   1 18     14 170
 9  77  47  62  18   3   0 0.00  0.0    0  5.1 14 200   M    M   4 18     20 180
10  77  57  67  23   0   2 0.21  0.0    0 12.7 29 220   M    M   7 1      36 190
11  65  35  50   6  15   0 0.03  0.0    0 11.7 24 230   M    M   5 1      31 240
12  50  30  40  -3  25   0 0.00  0.0    0  1.9  9 180   M    M   2 18     12 120
13  48  31  40  -3  25   0    T  0.0    0  8.5 22 270   M    M   9 18     29 290
14  47  25  36  -6  29   0 0.08  0.0    0  6.9 17 170   M    M   5 18     26 160
15  54  39  47   5  18   0 0.75    T    0 22.3 45 240   M    M  10 138    61 230
16  46  37  42   0  23   0    T    T    0 14.5 26 270   M    M   8 8      36 270



The most impressive departures and in spite of several record highs this November; would certainly have to go to the cold in the first half of November of 2019. It was twice as cold /-11.0/ as this November was warm /+5.5/ relative to normal. Therefore; the first half of last November averaged 16.5 degrees colder than this November! Add to that; the record snowstorm on the 11-12th with 9.2" and a couple of record lows for good measure (November 12th- 13 & 13th- 7) at Detroit and you've got quite a contrast! Check out here the coldest November on record /1880/ with a severe cold wave for November.


Winter Outlook for the Winter of 2020-21

Local Analogue Research, Hemispheric Data and Computer Modeling suggests:  

Temperatures - Normal to Above (or -1.0 to +2.5 temp departure)

Most analogue winters averaged normal to slightly below with an average sitting at 26.5 (30 year norm @ 27.9 or -1.4 below). Taking into account the more recent La Nina winters (including Modoki La Ninas), computer guidance and recent trends; I look for a normal to above normal temperature winter. This is both for the winter (Dec-Feb) and cold season (Nov-Mar).  


Since my October update on La Nina; latest computer guidance and the patterns of the more recent La Nina analogues present an argument for an overall milder winter but with aggressive cold snaps. In fact; past data in the analogues also argue for a sharply colder than average month (or period) into early spring see analogue section (or intra-month example; mid Jan to mid Feb, depending on timing). With the variability in these type of La Nina's; leaves me with a two-tier temperature forecast - normal to above.


Precipitation - Above

Analogue guidance and computer model guidance from numerous sources overwhelmingly call for a wetter than normal winter.


Snow - Normal to Above

The majority of winters were active as there were three main storm tracks affecting the region.

Snowfall prognostication this season is more problematic than precipitation as a whole since storm tracks affecting the region will be north, over Southeast Lower Michigan and south over the Ohio Valley. This leads to snow, rain, rain to snow, snow to rain depending on the system. The unusually strong mid Pacific jet (for a La Nina) will lead systems to bring in milder Pacific/Gulf of Mexico air and thus; mixed precipitation should be a frequent visitor.

In addition; there is some conflicting data for this winter's La Nina. A winter that on first indication, should have been a more straight forward, moderate to strong La Nina. This year's unfolding La Nina and its hemispheric affects may not turn out a typical La Nina (see below). 

Hemispheric Discussion - ENSO

Recent cooling of water temperatures across the central Pacific have led a rapidly developing La Nina that already is in moderate territory (SST anomaly between -1.0 and -1.4 degrees C). Latest temperature anomalies across the 3.4 ENSO have dropped to between -1.5 to -1.7 now and thus, just dipping into the strong category. It is my thinking that the La Nina has attained its general strength for this cycle, therefore the moderate or strong past La Nina's represent analogues best - with a couple of weaker ones. 

                        Past ENSO La Ninas /blue/ and El Ninos /red/ thru 2006

 Recent ENSO 2000-2018

A caveat now making an appearance is the coldest water departures have drifted to the center of the La Nina (see image below) and thus a La Nina "Modoki" could be in our meteorological midst.


Recent 5KM surface water temps show the colder waters of the La Nina have migrated out into the mid Pacific while the waters over the eastern Pacific, have moderated and warmed a bit (Fig's 1 & 2, click images).

 Fig 1

                                                  Fig 2                                                 


I first introduced this (Modoki) ENSO phenomena back in the El Nino of 2018-19 and it's possible influnce on our winter.  That winter was an "on and off" El Nino influenced winter as far as temperature and snowy/snowless winter pattern during the season and location. Detroit and areas south received much below normal snow but a heavy snow area occurred around the Flint region and areas north into the Saginaw Valley. Those locations received above to well above normal snow. The overall weather pattern across the country was more a-typical for a normal La Nina winter.

A La Nina Modoki (Fig 1) disrupts the typical La Nina atmospheric pattern as the waters remain colder over the center of the Pacific while moderating and warming over the eastern Pacific near South America (Fig 2).  The result is a more complicated pattern across the States with the Pacific Coast receiving more moisture and rain than is normally seen in a La Nina (especially the northern half). In addition; troughing occurs more over the west and center part of the country leading to a stormy and colder pattern in the north; while the eastern half of the country oscillates more between cold and mild - snow and rain.  

Figure 1 shows key differences in sea surface temperature distributions and atmospheric circulations; (a) A conventional La Niña and (b) A La Niña Modoki. The single-cell broad scale Walker circulation splits into two cells during a Modoki event.

Since the late 1970s, conventional ENSO La Niña and El Niño events have become less frequent, while a second “flavor” of ENSO – Modoki – from the Japanese language meaning ‘similar but different’ – has become slightly more prevalent. Both El Niño and La Niña Modoki events can occur independently at times when tropical ocean indices may not achieve thresholds in a classic El Niño or La Niña event.

Japanese research scientists later uncovered the Modoki phenomenon in 2007. Both El Niño and La Niña Modoki events can significantly influence the temperature and precipitation over many parts of the globe. For example, the West Coast of the United States is wet during El Niño but dry during El Niño Modoki.

Types of La Ninas related to placement of colder, below normal waters

Thus far the projection for the La Nina is for the coldest departures to be located  in the center to east Pacific, closer to the seasonal to the mild winters


Latest computer projection consensus has La Nina peaking but still with varying intensities. Our CFSv2 model had continued to strengthen it further down into the stronger category, averaging around -2.0C (black dashed line, second chart) but now has been corrected recently further up to -1.5 to -1.7 (third chart) and current intensity. At one point the model had the La Nina peaking around -2.5C, which would have been a record La Nina, I believe. 


                                                  Model Consensus


   CFSv2 Model Projections

A corrected version of the CFSv2 SST's was put out which projected the La Nina to be less intense and frankly; more believable.


  Running 3-Month Mean ONI values for past ENSOs

                     North Atlantic Oscillation/Arctic Oscillation - NAO/AO

As usual; this should be one of the most important meteorological influences for this winter In the last few years, it's had an on and off again effect on our weather, working with Stratospheric warming and the EPO (more later). Refreshing our memory on this little number shows why the major influence with our weather.


Generally when the NAO/AO index is in the positive phase; more zonal winds dominate as the polar vortex lifts up toward or over it's home, the North Pole region. However; when in a negative phase; the cold vortex or wind flow is more meridional and thus; cold Polar or Arctic air is readily pushed south from the Pole; down into the eastern half of the U.S. (among other Northern Hemisphere areas). Many times ridges of higher pressure develops in conjunction on the North American west coast and/or into Greenland.

Most winters; the phase of the NAO/AO is one of the most important ingredients to the type of winter to be had over the central and eastern part of the country. However, this is also one of the most elusive oscillations to predict for more than a week or two. Last winter the NAO was dominated by a positive phase and that in conjunction with the weak El Nino resulted in a mild winter (Dec-Feb)

Seasonal NAO

Recent winter/cold season NAO index values

Latest NAO projections shows the positive phase during November (yellow highlighted) to fall into neutral and negative with time, thus predicting colder weather within the time-period. Be advised; this is updated daily and doesn't always remain consistent.

Pacific Decadal Oscillation /PDO/ and associated subset EPO

The warm phase of the Pacific Decadal Oscillation is represented on the left side of the following example and the cold phase on the right.

                               Warm Phase of the PDO               Cool Phase of the PDO

Latest SST's (below) seemed to have evolved into a cool phase recently. Note the above or well above normal SST's west of Alaska and south over the mid Pacific. Relatively cooler anomalies have formed further east right along the West Coast.

The warmer SST's further off the West Coast south of Alaska; generally encourages high pressure ridging which may help at times, deliver Polar and Arctic air from the northern Canadian regions into the Lakes. This was especially true during the hard, snowy winter of 2013-14 even when the NAO was not always negative.

Recent Global SST

Eastern Pacific Oscillation

A negative Eastern Pacific Oscillation /-EPO/ is displayed below along with its cold affects it can have downwind on North America. The Winter of 2013-14 was one cold, bitter winter along with exceptionally heavy amounts of snow across Southeast Lower Michigan. The brutal cold delivered to the region on many occasions was either the cause or was aided by a strong -EPO helping to build a strong high pressure ridge on the West Coast which in turn; slammed our region with a deep low pressure trough filled with cross polar air from Siberia and North Pole.

Likewise; a positive Eastern Pacific Oscillation /+EPO/  pattern is displayed below along with its mild affects it can have downwind on North America.

A three-way indices pattern /NAO, AO and EPO/ evolving together can have interesting weather for the eastern half of the country as seen below in the autumn of 2019.


Pacific/North American /PNA/ Pattern

The above oscillations help create the Pacific/North American /PNA/ pattern. A negative /-PNA/ generally reflects a trough over the western portion of the US with ridging and warmer weather in the East. A positive /+PNA/ is reflected by a broadening trough and influx of colder air into the center and subsequently, the eastern portion of the US.




 Solar Cycle Relevance

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.  Numerous recent studies for example, do in fact make the connection to our climate and solar activity including wintertime effects. One of the studies stated the following:

The Euro–Atlantic sector seems to be a region with a particularly 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 Oldenborgh et al., 2013). We found a weak but significant change in the mean late winter circulation over Europe, which results in detectable impacts on the near-surface climate. Figure 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 continent. Sirocko et al. (2012) recently reached the same conclusion after analyzing 140 yr in 20CR, although their results bare 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 is a possible influence only and not a major contributor. While the solar cycle was in various modes, the tendency is for La Nina winters to occur during the lower part of the cycle or during an overall, weaker cycle. This season's La Nina analogues resulted in about two thirds in the lower part of the sunspot cycle.

Longer Term Solar Sunspot Activity since 1850 ( X includes this season's Winter Analogues)

Note the analogues years that are below 100 (1-8) on the solar threshold and particularly the ones below 50 which are near/or at the bottom of the cycles (2-8). Interesting we have so many La Nina analogues (2-8) near the bottom of the solar cycles. Out of the 13 analogues, a little over half /7/ are at the bottom. The second chart shows we are in the beginning phase of the 25th cycle.

This year's solar sunspot cycle; at the bottom/start of the 25th cycle.


Siberia/Eurasia /North America Snow Cover 

One of the studies by Dr. Jonah Cohen uses October snow-cover over Siberia/Eurasia to aid in projecting out the main phase of the NAO and likely corresponding temperature pattern for the winter. Recently, early November is also considered in the comparisons.

The snow-cover over Siberia has actually been less than average until recently (second-third week of Nov?) and now one of the higher of recent years.  While across North America; snow-cover extent had been the largest in recent years from mid October to early November with a drop-off recently.

From recent Dr Jonah Cohen blog:

Northern Hemisphere Snow Cover

Snow cover advanced rapidly over the past week across Eurasia and is currently near decadal highs. Snow cover advance will likely continue to increase especially across East Asia and possibly into Europe the next two weeks. Above normal snow cover extent in October, favors a strengthened Siberian high, cold temperatures across northern Eurasia and a weakened polar vortex/negative AO this upcoming winter followed by cold temperatures across the continents of the NH.

 North American snow cover has stalled and is now near decadal means. The early advance of snow cover across Canada this fall, has likely contributed to an early start of cold temperatures across the Central and Eastern US.



The QBO, or Quasi-Biennial Oscillation, is an oscillation in the wind direction in the stratosphere within about 15 degrees of the equator. Over a roughly two-year period, winds tend to oscillate between westward and eastward, with the switch between west and east winds starting high in the stratosphere and then shifting lower in altitude with time. The QBO is the result of waves propagating vertically in the atmosphere that then interact with the mean flow to slowly change wind speeds and direction. These changes influence the overall global circulation patterns, which in turn influence winter weather patterns across North America. 
The amplitude of the easterly phase is about twice as strong as that of the westerly phase. At the top of the vertical QBO domain, easterlies dominate, while at the bottom, westerlies are more likely to be found. At the 30mb level, with regards to monthly mean zonal winds, the strongest recorded easterly was 29.55 m/s in November 2005 and the strongest recorded westerly was only 15.62 m/s in June 1995 (Wikipedia).

If you notice on my analogues; I included the QBO's for each available winter and compared it to the upcoming winter's QBO phase and trend. The present and expected QBO this winter is for a light to possibly moderate westerly wind.  The set of maps below show the differing influences of the QBO dependent on phase and trend. The QBO is presently in the light westerly (closest being maps in sequence; C then A).
 QBO and WinterTemperatures Trends


Some additional analogue conclusions and category explanations in the analogue chart


AO - The predominant phase of the Arctic Oscillation during that winter. AO- (negative), AOn (neutral) or AO+ (positive).

SC -  position of the solar cycle during that winter. Breaking it down (see solar cycle chart):  

SC-- (opposite high cycle compared to the present, least similar) SC+/- (sunspots 
waning but not near minimum or 2019 low level. Finally, S++ where solar sunspot cycle is at or very close to the low cycle of 2019-20 and/or is at the same positioning 2019-20...the best comparison and likeness. There are several this time at 8, one of the highest likes - meaning the sunspot phase of the sun is very close to 7 other analogues out of the 13.
QBO - W=West wind prevailed that winter or E=East wind prevailed. Trends: -/- (weak and weakening trend), -/+ (weak but strengthening), s (steady trend, no change) +       
moderate and strengthening +/- strong but weakening. Note that the trend now in the fall of 2020 is W-, a light west wind and steady or slowly increasing /W/. This fits with all the analogue winter's that contained a light westerly to possibly moderate westerly QBO. 
Sib snow - Siberian snow cover in October and rate of change. Only one previous analogue winter had below compared to this past October's/early November since the data only goes back to the late 1990s. Notations are this fall compared to analogue fall: WA=Way above, A= above, B=below, % = equal to.

Letter n /next to the analogue winter years at Detroit/ - A warm November preceded these winters in all of Southeast Lower Michigan - like this present November 2020. 

Warmer than normal Novembers preceded several of my later Novembers in my analogues. Five analogues in the last six contained warmer than average Novembers. The best was November of  1975 which may turn out to be the closest to this November's average at 46 (and early indications not a bad analogue either). My set of analogues included mainly moderate to strong La Ninas with some weak in the 13 count this go around. The 1949-51 strong La Nina was not included due to it beginning during the winter of the 49-50 and ending during the early winter of 1950-51. Several are Modoki La Nina's with just as many "classic" La Nina's to give a good representation to both including various intensities but as stated, a decided preference to moderate to strong -as this year's.

A short detour on Detroit's warming if you can stand it:

One of the first things noticed is many of the earlier La Nina winters being a bit colder than the later La Ninas (since the 1980s). Ironically; the last four winters averaged 27.7 degrees; whereas all /13/ the winters averaged 26.5  or -1.2 lower. Therefore; the earlier winters before the 1980s have to be colder on average than 26.5 for all winters since the later four winters warmed the average up some. Sure enough; the first nine winters averaged 26.0 degrees. I only use the winter's since the 1980s for warmer because that is also when the heat island migrated out and around Metro Airport. Ironically (and what this paragraph is leading to) is that part of the 1.7 degree difference in the later four winters reflects the Detroit heat island rise in temperature at Detroit Metro; part is also due to the climate change warming and most likely, those winters were a bit warmer because of the heat island and climate warming.  The 100 year average winter temperature is about 26.7 degrees. Now the latest 30 year average from 1980 - 2010 is 27.9 or about 1.2 degrees warmer than the 100 year. In a year or two, we'll have the 1990-2020; 30 year average - and one guess which way that will trend). Working at Detroit Metro Airport better than half my career and all of my career in Southeast Michigan, I can assuredly say that Detroit's average temperature since the 1980s has been strongly influenced by meso-heat island due to expanding population and infrastructure in Southeast Lower Michigan and the airport itself.

Back to the Winter Outlook:

Temperatures and Snowfall:

Most analogue winters averaged normal to slightly below with an average sitting at 26.5 (30 year norm @ 27.9 or -1.4 below). Taking into account the more recent La Nina winters - Modoki La Nina winters- computer guidance and recent trends; I surmise the average of the winter analogues are on the cooler side and therefore; I look for a normal to above normal temperature winter. This is both for the winter (Dec-Feb) and cold season (Nov-Mar). The analogues contained front-end loaded, mid-loaded or back-end loaded winters regarding temperatures (coldest relative to norms) and snowfall (relative to averages). There were twice as many snowier winters (8/4) as there were snowless (see analogues and legends below). Potential for a major snowstorm or two in the snowy La Nina analogues was slightly greater in every month Dec-Mar with a lean toward late season.

In descending order; back-end loaded (roughly late Jan-Mar) winters were favored in regard to colder temperature and/or heavier snowfall with front-end loaded (roughly mid Nov-to late Jan) second. There were just a hand-full of cold Decembers, Januarys and Februarys which helps gives more credence to a sharply colder month or period mentioned earlier. On the flip-side; chances of mild periods increase with time with February looking the best.

And one more thing; there are enough well below normal (or "snowless") months that showed up in every set of analogues to be concerned about a bust on the snowfall prediction but I'll hang tough with the normal to above - for the time being anyway. 

Analogue Maps
Computer Guidance

The predominant upper flow shows up well in both the analogues and the computer projections. In addition; the temperature and precipitation projections from both are a close match. Note; how the Canadian Upper low settles in and expands with time as the Arctic/Polar jets dig into the northern part of the country. Meanwhile; the Pacific and subtropical jet remains strong bringing in milder air aided by higher pressure ridging from the Pacific into Southeastern US. The two dominant features also show up well in the temperature predictions from both the analogues and computer outlooks.

Annotated analogue maps and storm tracks

Active storm tracks from the north and west (southern Canada, north and central US) and south and east (Mississippi and Ohio Valley, Eastern Lakes and East Coast) will follow the jets. Placement of the jet core and surface air will determine temperatures and types of precipitation   

Placement of storm tracks

Atmospheric storm tracks are very important for climate dynamics. They indicate regions of maximum transient poleward energy transport and zonal momentum transport (Chang et al. 2002) and play an important role in setting the dynamical response of the mid latitudes to global warming through their radiative forcing (Voigt and Shaw 2015). Storm tracks are generally calculated as the standard deviation of atmospheric data that has been filtered in the time domain to isolate synoptic variability (Blackmon 1976). Typical variables used to calculate storm tracks are meridional wind, eddy kinetic energy, or geopotential height at a fixed vertical level. This metric represents the climatology of baroclinic wave activity (i.e., high and low pres-sure systems), but for historical reasons has been termed ‘‘storm track’’ [see Wallace et al. (1988) for more discussion; go here.

Temperature/Precipitation Maps from Analogues then CFSv2 model

A Blend of various Foreign Models is very similar to our CFSv2 for upper air patterns; temperatures and precipitation.

Predominant 500 Heights



Look for winter weather write-ups from time to time here and on Facebook! 

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

Hope you have a Good Thanksgiving