The Whitest of Christmases and Other Christmases Past

The Whitest of Christmases and Other Christmases Past 
 
By: William R Deedler; Southeast Michigan Weather Historian

Date: 12PM Wednesday Dec 20th, 2017
 

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/, warmer temperatures and light rain have really did a number on our heavy snow-cover received just last week. Many areas have fallen to just a trace to a few inches. Moderate temperatures the next few days before the straight-out colder weather due Christmas weekend, will continue to slowly eat away at any remaining snow. A system moving across Friday into Saturday may bring some light rain and snow before the cold surges in and then; some light snow and snow showers may fall Christmas eve or Christmas day.  At stage; the likelihood of a white Christmas is questionable even with just the inch of snow necessary to meet the requirement by Christmas morning. Also; as Christmas approaches, early indications very cold air is slated to engulf Southeast Lower Michigan with temperatures estimated to falling into the teens that day.

*Update -  A weak low pressure will move across the southern Great Lakes and northern Ohio Valley and slowly develop over the eastern Lakes into the Northeast. This system will bring mainly light snow to much of Southeast Lower Michigan Christmas Eve and snow showers on Christmas Day along with colder blustery winds. This will provide a white Christmas to the region with generally 2-4" through Christmas. Merry White Christmas!

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.

Even with mild weather with temperatures in the 30s; Southeast Lower Michigan was able to hold on to a white Christmas even with last year's moderate temperatures 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. 

Previous recent Christmases:

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 117 (including 1900) Christmases in Detroit, 55 (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 2018! 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

Another Day...Another Clipper? However: there are differences this time...Including Update

12/13/17 - 300PM

Epilogue:

The forecast and clipper system behaved very well. In fact; the anticipated strengthening deeper than even the models projected came to pass with the central pressure diving to 992-994 MB. On much of the the 12z guidance 12/12/17, central pressure was deepening to around 996-997 MB. Snowfall forecast overall also went well issued 245 PM. Nit picking; I could have said areas of 8" and isolated higher amounts but I'm happy with the overall forecast outcome.

From original forecast below;

"This system has all the ear-marks of a possible over-achiever in the latest guidance compared to  
the earlier runs. All models are leaning toward a bit of a wetter system considering the classic clipper system. This has me concerned and as we have seen; the past few have been achievers-overachievers. The Great Lakes are wide open which won't hurt and the dynamics /vorticity/ projections were notable and getting even stronger".

"At this point the max amounts of snow may very well be in the 6" to pockets of 8" totals with 3-6" encompassing that area."

Snowfall Map below: Courtesy of the NWS DTX

 Individual amounts and more can be found here

-----------------------------------------------------------------------------------------------------------

12/12/17 - 245PM

More snow will move into Southeast Lower Michigan during the forenoon hours of Wednesday. Generally speaking this system appears to have more "uumph" with it than the last one. Simply meaning; depending you location, the same or better amounts of snow than Monday night's & gusty winds while it's falling. In addition; the band of snow will orientate Northwest-Southeast as it moves into the region before leveling off again west-east like Monday night.

At this point the max amounts of snow may very well be in the 6" to pockets of 8" totals with 3-6" encompassing that area. Points further north-northeast will see the least with this system in the 1-4" range. I see no reason to deviate with the models upping amounts seeing the upstream wave impulse and projected track. This system has all the ear-marks of a possible over-achiever in the latest guidance compared to the earlier runs.

The main models are in remarkable agreement on the general snowfall with a snow to water equivalent averaging 2.0"/.15". I believe that's a bit low as the the environmental air initially is quite cold and dry; a 15/1 to 20/1 (2.0"/.10") doesn't seem too outrageous. Then however, one must account for evaporational cooling initially and moistening/saturating the column of air before the snowfall can accumulate much. All models are leaning toward a bit of a wetter system considering the classic clipper system. This has me concerned and as we have seen; the past few have been achievers-overachievers. The Great Lakes are wide open which won't hurt and the dynamics /vorticity/ projections were notable and getting even stronger.

Since the models are very close with this system and they look reasonable at this time with the track; I've decided to post the snowfall amounts generated by some of the pertinent ones. One caveat in the forecast would be main the track and its deviation from the track forecast. Further north, less snow south, more snow north; further south, less snow most areas except near Ohio border. Also of course; true available moisture and speed at which she tracks.will also affect the outcome.

 GFS                                   CAN      

 

                                      

3K NAM                              NAM                                      










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

Winter 2017-18 Outlook for Southeast Lower Michigan - Some surprises along the way?

While the past several months have had some notable weather; to a large extent the summer into mid autumn was fairly tranquil with just the occasional upset in the pattern. We are beginning to see a busier and more contrasting and subsequently, conflicting pattern rev-up as we head into the latter part of the year. What's been somewhat gratifying yet a bit uneasy for me is how well the present mid fall pattern fits into the upcoming winter pattern I found for this; my 21st Winter Outlook.

Some changes in my Outlook are in store for the beginning of my third decade of season outlook forecasting. They include an even more thorough analogue chart including previously mentioned patterns in the past such as: Arctic Oscillations, Solar and QBO cycles along with Siberian/Eurasia October snow cover (available since 1998) during the previous analogue winters. This in turn is compared to the upcoming Winter of 2017-18's observed or projected patterns. Therefore, much of the information discussed is there for the reader to quickly scan on the chart. I still will provide a brief summary of each indicator but limit the amount of description, while still occasionally connecting the reader to the corresponding website. The overall, Winter Outlook format remains the same as presented in the past. Now on to the Outlook...

Winter Outlook for the Winter of 2017-18 

Occasionally in my past Winter Outlooks, I've eluded to Mom Nature 'tipping her hand' as to what the upcoming winter will bring. This appears to be the case this time as one casts one eye on the recent autumn pattern change and the other eye on this winter's analogues and general upper and surface weather pattern - which actually agree strongly with computer guidance. Of course, sometimes even though the overall general pattern verifies well; the final winter statistics may differ from the forecast - this too I could easily see being the outcome with this winter's projected pattern with the wild fluctuations.

Local Data Suggests 

Temperatures: Normal to Below 

Expect temperatures during the 2017-2018 winter to be quite changeable as opposing air masses vie for dominance under a fluctuating jet stream. This is not only a developing trend seen the past month or two but it's well displayed in the Winter Analogues for 2017-18 and finally; the computer guidance for the upcoming winter. While this is a typical La Nina pattern, my research shows and I believe again this winter the Pacific jet will be more of a key player against the typical La Nina pattern. The basic difference this winter from last winter is all data that I research is intimating a notably colder winter than last winter. This is likely due to a preponderance of polar/arctic air masses.

In the final analysis, I look for the Southeast Lower Michigan winter to average around normal to below normal.  The outlook for temperature departures will be of a wider range than generally forecast; averaging from -3.0F to +1.0F.

Precipitation: Above

Because of the parade of conflicting air masses diving in from the north and west, with temperature variability and associated storms and storm tracks ignited; above normal precipitation is likely for the Winter of 2017-18. This trend is supported by many of the analogue winters, along with model output for the winter and recent autumn trends. With the discussed storm tracks below; mixed precipitation is at a higher risk this winter. I do look for the alternating extended wet and dry periods to persist into the winter from the autumn.

Snowfall: Around Normal to Above 

The especially tricky part of this forecast is how much of the expected precipitation will be snow and/or mixed precipitation? In the analogues: snowfall in the 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. This is similar to last year's La Nina and is strongly suggested in model output. Remember; an above normal precipitation winter does not necessarily mean above normal snow...even with a colder winter! It's been awhile since we've had a cold winter but with below normal snowfall. The state of the atmosphere when the precipitation becomes available is the key and this looks especially relevant this winter. Leaning on the analogues; I look for generally normal, or an average winter's snowfall (+/- 5" of the norm) across much of extreme Southeast Lower Michigan. This is a winter however where below normal snows could certainly occur especially in this area if the storm track rides further north. The better chance for above normal snow expected further west and north away from that region. Therefore; best chance for above normal snow will lie in an arc from the Brighton/Howell area /I-96 area/ east northeast across Flint and Port Huron /I-69/ and points north/northwest into the Saginaw Valley/Thumb Region.

Below Normal snowfall; less than /- 5.0"/ of the winter average snowfall  
Normal snowfall; +/- 5.0" of the winter average snowfall

Above Normal snowfall; better than /+5.0"/ of snow above the average.

Hemispheric Discussion 

In case you haven't surmised by now; the upcoming winter is expected to be, like last winter, a La Nina winter. In addition; this winter's La Nina is likely to be generally similar in strength to last year's; albeit possibly a bit stronger and may reach borderline moderate at -1.5 departure. I also look for this winter's La Nina to have more of an influence on our weather than last winter's; mainly due to the atmosphere's stronger resultant La Nina pattern reaction (not dominant last winter) along with the cool Pacific Decadal Oscillation in place.

 ENSO Regions in the Pacific

 

 

 

Current ENSO SST anomalies as of mid November

 

 

Current ENSO map conditions as of mid November

 

The Oceanic Nino Index /ONI/ 1950 - mid 2017 below; shows all the El Nino's and La Nina's strong and moderate - weak are not depicted except for last winter's.

  ONI

 SOI

The Southern Oscillation Index /SOI/ below shows well the recent negative corresponding values in conjunction with our recent strong El Nino of 2015-16. Remember; an above normal SST is reflective of a negative SOI. This comes into play especially pre-1950 for analogue research.

 

North Atlantic/Arctic Oscillation - NAO/AO 

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; and even parts of the mountainous areas of the west at times. This is one of the most elusive oscillations to predict for more than a week or two out.

SNOW-COVER 

One of the newer studies uses October snow-cover over Siberia/Eurasia to aid in projecting out the main phase and likely corresponding temperature pattern for the winter. In my analogues; I've included this past October's coverage (and looking at the rate of coverage) that has been researched since 1998. In the analogues; you will notice minus signs and a plus sign for this October. Simply put; this October had the most snow-cover over that region for all the analogue years. The analogue years since 1998 are less than this year /-/ and this October is /+/ for the greatest relative to those analogue years. As a matter of fact; this past October 2017 had one of the snowiest overages by the end of October relative to any year since 1998 with only a few non-analogue years that equaled it. This study suggests a more -NAO/-AO likely to prevail this winter and thus; colder temperatures (see map below). The research and up to date discussions can be found here on Dr. Jonah Cohen's pages.

Mr. Cohen has a nice update here every week on current and expected trends.

From his discussion 11/20/17...

"October Eurasian snow cover extent was above normal, Arctic sea ice extent is well below normal and will continue to be below normal for the entire winter.  Also, strong blocking was observed this fall across the high latitudes.  All three factors favor colder temperatures across at least parts of the Northern Hemisphere (NH) mid-latitude continents during the winter months".

  Snow-cover as of Nov 20th 2017

 

Pacific Decadal Oscillation /PDO/ and associated subset EPO

The previous warm phase Pacific Decadal Oscillation recently switched to a cool phase this year. A cool phase of the PDO is represented on the right of the following example and compare it to the current state.

 

                             Warm Phase of the PDO                    Cool Phase of the PDO

The recently evolving cool phase of the PDO and weak La Nina are displayed well in this recent Global SST scan on November 16th, 2017. 

Generally warm phases coincide with El Ninos or Neutral states and rarely La Nina states while cool phases coincide with La Ninas, as in the present state. Studies propose that when the PDO and ENSO are out of phase; which is a somewhat rare event, that they may cancel out their known effects. This isn't expected to happen during the upcoming winter.

"When SSTs are anomalously cool in the interior North Pacific and warm along the Pacific Coast, and when sea level pressures are below average over the North Pacific, the PDO has a positive value. When the climate anomaly patterns are reversed, with warm SST anomalies in the interior and cool SST anomalies along the North American coast, or above average sea level pressures over the North Pacific, the PDO has a negative value" (Courtesy of Mantua, 1999).

Recent PDO values 

YYYYMO VALUE

201612  0.55

201701 0.10

201702 0.04

201703 0.13

201704 0.52

201705 0.29

201706 0.18 

201707 -0.54 *

201708 -0.64

201709 -0.26

201710 -0.60

*The notable change from positive to negative values are shown

"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 up to 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 Niño/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". 

http://jisao.washington.edu/pdo
http://www.john-daly.com/theodor/pdotrend.htm

Last winter, the ENSO (La Nina) and PDO (warm phase) were out of phase and the winter was indeed notably warmer than what is generally seen in a La Nina winter. This was mentioned in last Winter's Outlook and one of the reasons noted that may interfere with the normal LA Nina winter jet and temperature pattern.

SOLAR CYCLE /SC/

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 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 continent.
 Sirocko et al. (2012) recently reached the same con-

 clusion after analyzing 140 yr in 20CR, although their results

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 ones we have entered below on the Sunspot chart - only three winter's at opposite ends of the solar sunspot spectrum were noted in our La Nina analogues.

Recent Sunspot chart since the new millennium

Longer Term Solar Sunspot Activity since 1849 (includes the Winter Analogues)

 THE QBO INFLUENCE

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, while 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 an easterly QBO (recently switching from west since the summer shown below as a negative wind speed) and also increasing in amplitude. The set of maps below show the differing influences of the QBO dependent on phase and trend.The QBO is presently in the negative and trending more negative phase (first map).

Recent Monthly QBO Data for 2017 through October

2017:     14.92   14.78   14.35   13.88    8.01   -3.18  -10.48  -14.42  -15.28  -16.79

  

 

WINTER 2017-18 ANALOGUES - SOUTHEAST MICHIGAN

         

    

                        CLICK ON TO ENLARGE

 Some additional category explanations in the analogue chart from left to right

AO/SC

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 2017 low level. Finally, S++ where solar sunspot cycle is  
          at or very close to the low cycle of 2017 and/or is at the same decline with 2017...the   
          best comparison and likeness.
          
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 2017 is E/+, a moderate east wind and still strengthening. This fits with all the winter's
            that contained a easterly QBO. Those winters were the Winter of 1917-18 (also  
            increasing),  1950-51 (weak and weakening further), 1984-85 (strong but weakening), 

           2000-01  (moderate  easterly and steady) and finally 2011-12 (weak but increasing).  

Sib snow - Siberian snow cover in October and rate of change. All previous analogues winters

                  had less snow cover than this past October's. There have been a few winters not in

                  the analogue list that had roughly equal to and one of two that had more snow cover

                  but a clear majority had less snow cover.

WINTER ANALOGUE SUMMARY 

Temperatures 

One of the first things one notices about this winter's analogues is the wide-ranging temperatures and snowfalls. That is clearly NOT surprising; one look at the dominant atmospheric players for the winter, the subsequent jet streams and storm tracks explains exactly why the variable analogue results, in spades. This winter will not be a clear-cut La Nina influenced; mainly because of the influential strong Pacific jet tempering results at times. This shows up mainly in the variable jet stream/storm tracks, temperature patterns and resulting snowfall amounts. As an example; though on average Decembers averaged below normal, there were still a notable amount above /Detroit; 4 out of 14/ all in the later years since the 1970s. At the same time; if the Decembers were mild, then the Januarys were generally cold or below normal. Looking across the board at the three cities, there were a predominance of normal to below normal winters (also my forecast) with a few above normal. Generally; these winters were early to middle loaded with the preponderance of storms roughly from mid December into mid February with later winter, average to below. However; colder weather tended to hold on into at least early spring...not surprising in these parts. By the way; severe weather buffs should note that the spring looks to be busier than the past several years.

 

Precipitation

Total precipitation and snowfall also widely ranged from below to above. However; a definite trend was seen in normal to above precipitation (matching well with all guidance, La Nina winters on average and recent trends) while a dry winter was least likely. There again though, there were enough drier winters that made a showing not to eliminate that possibility. With the storm tracks created this winter (see below); the risk of mixed precipitation is higher.  In other words: a normal to below normal temperature winter with below normal rain and snow is not out of the question reflecting back in previous analogue years...and it's been a while since we've had a "cold but relatively dry winter". 

 

Snowfall

The snowfall category by itself is quite interesting with a wide amount of snow totals and where those snow amounts fell.  First off; it was close to an even split for below, normal or above normal snowfalls across the Southeast half of our concerned region. This area extends from the Flint to Port Huron area; south to the Ohio border. There were significant below normal snows ranging in the 20s (inches) across Detroit and 20s and 30s into Flint, constituting a good third of the sample. On the higher side of normal; there were just as many above normal snowfalls into the 50s and 60s around the Detroit region and 50s to even a few in the 70s across the Flint region. I'm sure the reader here can see why snowfall for a season can be such a tough call...and where.

 

The only region where snowfall truly showed a trend (above) was across the northern third of Southeast Michigan; the Saginaw Valley and Thumb region. This are had 7 above normal snow winters and 4 normal - there were no below normal. Above snowfalls ranged from around 50" into the 70s. In fact; the average snowfall for the analogue winters at Saginaw was a foot above normal. Where as Detroit and Flint settled in the normal range.

 

Below are the maps from the analogue winters for Temperature departures, 500MB Low placement and subsequent likely storm track placement (Dec-Mar). Note the time period encompasses March also (still a winter month in my book)

 

TEMPERATURES 

 

 500 MB LOW PLACEMENT

STORM TRACK PLACEMENT 

 

 Latest Model Output for the Winter of 2017-18 with a few surprising models.

CFS /American/

TEMP

 PCPN

ECMWF /EUROPEAN/

TEMP

 

PCPN

UKMET /BRITISH/

TEMP

 

PCPN

 

METEO FRANCE 

TEMP

 

PCPN

Look for more write-ups through the winter involving notable weather events, major storms and comparing the Winter Outlook trends and actual weather trends!

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