12/26/15

Update 12/27/15 - Look for a New Battle of Air Masses and Jets to Commence at the Week's Open to Top off an Exceptionally Warm December!

 Update - 12/2715 

Freezing Rain and Strong Easterly Winds to Cause Problems in Areas with the Longest Periods of Freezing Rain Monday Afternoon into Early Night

Very little change to original analysis: 
If anything I am even more definite on the freezing rain and associated problems along with the strong gusty easterly winds which will accompany the battle of the systems mentioned below. Look for mixed precipitation to over spread Southeast Lower Michigan from south to north during the afternoon on Monday. Most of the freezing precipitation from this system should be in the form of sleet then freezing rain as a thicker warm wedge of air surges north quickly on the southern jet over the colder, relatively drier Polar air. Freezing rain will become rain during the evening into night from south to north with time.

Strong high pressure in excess of 1040+ MB will but-up against the deep but slowly weakening low pressure over the middle Mississippi and cause a decent period of freezing rain. Most of the region, especially away from the Southeast corner has the biggest risk of ice build-ups up to around .2" with some "hold-out freezing or below temperature areas" from Detroit suburbs northward of around .2" - to as much as .4 - .5" of ice possible. This along with strong easterly winds of 20 to 30 mph with gusts to near 40 will bring the risk of icy roads and falling weaker tree limbs and power outages where conditions hold on the longest before the changeover. Temperatures hovering from upper 20s to lower 30s early in the event will gradually rise into the lower to mid 30s by evening.


Original Post 12/26/15

Earlier in the month, I sent out a blog about how the second half of the month would see a resurgence of the battle of the two distinct air masses that would dominate our winter weather. I stated it would not all be about El Nino this winter and from time to time, an impressive battle would brew between the Pacific energized El Nino jet stream and the Polar/Arctic jet stream. All indications are a new battle will commence in style early this upcoming week but first; lets look at this exceptional December...

Thus far this December has held true to form for an El Nino December with unseasonably warm weather, so much so, it should be at the top of the warmest Decembers on record at all three sites; Detroit, Flint and Saginaw! Even though cooler weather is expected this upcoming week; it shouldn't be enough to knock Detroit's standing out of first place while both Flint and Saginaw are more than safe.

In our analogue section for this winter; December had the best chance at being above normal and notably so - but admittedly, not ranking in first place. In the December analogues, there were three distinct very mild Decembers; 1877 - 38.1, 1940 - 35.6 and 1982 - 37.3. Overall; early in the game, the Winter of 1940-41 seemed to be the best analogue fit for the entire winter but with the two very strong El Nino's of 1982-83 and 1997-98 contending for very close seconds. In winter of '97-98, which arguably has had a very good showing for similar Pacific "goings-on" this past summer into early winter, its December locally though was not all warm as this years - nor the other three mentioned. December of '97 had an average temperature of just 32.2 (didn't even make the top 20 warmest Decembers). The exceptional warmth occurred later in that Winter of '97-98.

Top 20 Coldest/Warmest Decembers 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 17.8 1876 42.2 2015 16.1 1989 42.42015 16.2 1989 40.62015
2 18.0 1989 40.6 1881 16.6 2000 37.2 1982 17.2 2000 35.3 1923
3 19.2 2000 39.3 1889 17.4 1976 36.8 1923 18.8 1983 34.5 1982

The second half of December has not all been tranquil and nice as our former air mass battle that occurred last week; brought an outbreak of severe weather over the Midwest and South - and a very rare tornado in Southeast Lower Michigan near the border of Canton and Plymouth. Never had a tornado been reported in Michigan during the month of December - a very rare bird indeed! This severe weather outbreak across the country was preceded by record warmth over the Midwest and East. Detroit broke an very old record high from 1893 /56/ with a 58 on the 23rd...while Flint topped the 60 mark with a 61 for both the 23rd/24th. Its previous records occurred in 1982 (an analogue) with 55 and 56 respectively. Other warm records occurred during the month and can be found here.

Now on to our new battle...

This time around an intense low pressure center over Texas expected to produce a news worthy blizzard over portions of eastern New Mexico and western Texas (see map) overnight into Sunday.

Dawn Sunday 12/2715



The deep low will track north northeast aided by a strong jet streak over the south which came aboard from the Pacific. Note the 135K jet feeding into the storm at 250 MB at that time.



As the low approaches, the cold dome of high pressure will glide across Southern Canada. Timing of these systems, along with cold air in place after being advected in Sunday by the high pressure will determine what sort of mess  (snow, sleet and freezing rain) will be on the docket for Monday and Monday evening. in addition; ground temperatures are unusually warm for late December which only complicates matters. At this time, the risk of mixed precipitation will be the greatest at the onset of the approach of the low later Monday.

The surge of moisture remains robust even with the cold, dry air and subsidence advected in by the 1040+ high pressure - a fairly impressive strength. And thus, our battle commences locally between the deep low moving north northeast toward
western Illinois/eastern Iowa and large Polar high to our northeast in Canada. this will also create strong easterly winds across the region. One thing noted at this time is the remarkable agreement with various models on positioning and affects of the aforementioned systems.

It's interesting and passing to note, a few days ago this storm was progged to move more northeast into the Ohio Valley, which would have put Southeast Lower Michigan in heavy snow and/or a possible ice storm. That solution remains more transitory at this time as the air masses and jets have become bettered sampled. That is not to say Southeast Lower Michigan is out of the woods for mixed precipitation and possible icing, just not extent that was telegraphed a few days ago. This system appears to have enough wind at its sail to surge far enough northward to drag milder air back over the region.

At this time; the best chance for mixed precipitation runs from Monday afternoon into mid evening; the map below /Mon, early eve/ shows the classic mixed precipitation of snow, sleet and freezing rain set up when the clash of air masses takes hold over a the region. Picture warm, moist air being pushed northward aloft while colder, around freezing or below air remains trapped below near the ground. If a stand-off develops, an extended period of mixed precipitation, including destructive freezing rain as it accumulates on surfaces. The warm air is expected to win the battle and therefore, an extended period of freezing rain is not anticipated. However, the situation will be watched as new guidance and actual events unfold.



 
In any event, look for a mix of precipitation to move into the region later Monday into Monday evening with icing to affect mainly "exposed in the air items" as opposed to warmer ground surface areas, including roadways. Temperatures should hover in the lower to mid 30s for a time until the low pressure and jet streak has enough "umph" to push aside the cold residual affects of the high pressure. Any mixed precipitation accumulation is expected to be limited and transitory over extreme Southeast Lower Michigan with a slower change over time as one moves into Detroit's northern suburbs and points north and northeast toward Saginaw and the Thumb. At this time I look for ice to accumulate any where from a trace over the extreme southern regions to up around a 1/4" possible further north before any changeover to rain.

Various model solutions for Mon eve:











 Any important updates will be forthcoming for this holiday period.

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



12/19/15

Ghost of Christmases Past; The Whitest of Christmases and Other Christmases Past - 2015 version

The Whitest of Christmases and Other Christmases Past 
 
By: William R Deedler; Southeast Michigan Weather Historian
Date: 4PM Saturday Dec 19th, 2015
 

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 /19th/, at this time it is highly unlikely for a white Christmas across Southeast Lower Michigan even though temperatures should drop some for Christmas after a cold front pushes through, reading should still be above normal into the 40s with no or little precipitation. In fact, at this time the weather looks very conducive for holiday travel across Southeast Lower Michigan with tranquil weather.

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.  Now officially there must be an inch of snow on the ground Christmas MORNING at 7am. That is how the official "white Christmases" have been tallied in the past. So 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 rule. It works the other way too; you could have a several inches on the ground at 7am 12/25 but warmer air and/or rain melts it away by afternoon or evening and still officially have a white Christmas.

Last year's December /2014/ and Christmas time was very similar to this year's with record setting low amounts of snow for the month (in the top 5 snowless) and the chances for a white Christmas last year, also being almost non-existent. Even with the normal snowfall throughout last winter, officially on 12/25/14 at 7am; Detroit Metro Airport only a TRACE of snow that fell for the month with nothing on Christmas nor on the ground at Detroit Metro Airport. Most areas into the remainder of Southeast Lower Michigan had a few tenths Christmas eve or Christmas but with less than the amount needed and mild temperatures rising into the upper 30s to around 40...none of the area saw a white Christmas. 

Previous recent Christmases:

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

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




Looking over historical weather records of Christmases past since 1900, a wide range of weather conditions were found. While most people would like to believe that Christmas in the Detroit area should be snowy-white and picturesque, more often than not, they're not. Over the past 115 (including 1900) Christmases in Detroit, 54 (47%) have been what would be called "white" with an inch or better of snow on the ground. Keep in mind however, these records are for Detroit; farther north in Flint, the chance of a white Christmas jumps to 56 percent, while in Saginaw and the Thumb region it rises to 61 percent.

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

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


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


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

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

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

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

And now, I'd like to wish all who read this a very Merry Christmas and/or Holiday Season and the best in 2016! I plan on continuing my blog for the new year if the fates allow and look forward in reaching out to more people (and hear their comments and ideas) across the globe.

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

12/9/15

Will the Battle Reignite?

 Will Second half of December Resemble the Second half of November?

Back in mid November; El Nino energized central Pacific Jet along with the normal dive of the late autumn Polar Jet created a stormy battle across the country as the two patterns competed for dominance. It now appears this will again commence during the second half of December as both air masses and associated jets begin to carve out deeper upper level troughs over the West (were the initial battle will commence) and push northeast in time across the country into the Great Lakes. As time wears on, heights drop across the country and the Polar jet/air mixing with the Pacific Jet becomes more established, basically from the US Southwest to the Northeast. Of course this is a favored storm tracked for storm lovers as the churning of jets and air masses brew storms. This track of storms will bring rain, snow and likely difficult driving conditions depending on each particular storm and available cold, warmth and moisture - and where. Early in the battle anyway, it appears the systems will bring mainly rain to Southeast Lower Michigan but as colder air filters in behind systems, this would set up the region for snow.

As an example of the jet configurations the GFS model 18z 12/09/2015 is projecting, it is easy to see the strong El Nino Pacific enhanced jet gradually becoming mixed with the lowering heights and colder air from the polar region. Note; not only the jet express from the Pacific but also toward the end of the period, the large ridge block developing over Alaska. I would initially take this strong block with a moderate grain of doubt this far out but examining the upper pattern daily for weeks now, suggests at least transitory ridging developing with time toward Christmas in that region as heights lower across the lower 48. One thing that has been trending toward the negative is both the NAO/AO with time which reflects the lower heights..




Check out the loop of the 250MB Jet 18z GFS 12/09/20115 (click on arrow). Of course this will dance around with exact features and storm tracks the next couple of weeks but we are mainly interested in the trend, which shows a definte lowering of heights with time as the NAO/AO appraoch negative territory. How much they move into negative territory will strongly dictate the amount of cold air delivered into the country. Anorther factor I'm watching is the EPO which so far remains positive.



In any event; the second half of December is beginning to look very active and changeable - something holiday travelers will want to watch, especially after mid month.

I'll return with a new blog when specifics become more apparent and affecting the region.

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





11/18/15

*Update - Sunday - 11/22/2015 - Snowstorm Epilogue Over Southeast Lower Michigan

Sunday  - 11/22/2015 - Snowstorm Epilogue

As many years as I've been involved with weather; still occasionally a storm comes along that surprises me or takes me back, reminding me of another. This storm was not only an over-achiever; it had a tricky snowfall forecast placement due to all the things mentioned in the previous posts.

Probably the most surprising item about the storm was the amazing snow depths that focused on the expected heaviest snow area (in the center of Southeast Lower Michigan). In every forecast I observed, I didn't see anyone forecasting 12-16" of snow, even in last forecast period before the storm's arrival- with notably less amounts in the days leading up to the storm. It goes to show you how even with as much meteorological science as we have, the last say will always be Mom Nature! And that my friends; is why I'm still a weather-enthusiast spelled.... N U T.... the unpredictable excitement that still happens.

Observing snowfall rates personally during the storm and seeing video in the worst (or best, depending point of view) snowfall regions with the huge, continuous snowflakes and near zero visibilites for hours as temperatures hovered near freezing. This reminded me somewhat of the first monster I observed many years ago in my infancy with the NWS - see: The Thanksgiving Weekend Snowstorm of December 1st, 1974 in which the 40th anniversary was just reached last year. The storms were different as far as synoptic pattern and max snowfalls but similar as far as personal visual observance, snowfall patterns with its sharp highest snowfall amounts over Southeast Lower Michigan and ironically, also occurring near Thanksgiving (the weekend before rather than the weekend after). Even the storm hour timing was similar; starting near dawn in some areas and lasting into part of the night. The heaviest being the mid-late morning into the early evening

The present day storm only approached max snowfalls in a small area seen back in 1974 (with the core being further north yesterday) since   in 1974, the heart of the heaviest core was further south from Jackson to Detroit with Detroit Metro /DTW/ recording 19.3", which was pretty much the highest over the area (though much of immediate Detroit area saw similar amounts). The '74 storm also contained more wind overall causing more substantial drifting. I worked that storm and to this day, nothing has equaled it for me as far as long continuous large snowflake rates nor snowfall amounts over the Detroit Metro area. Those who remember the 1974 storm and now live up in this recent heaviest snow areas might also have some comparative memories. BTW - The Blizzard of '78 was a much larger, widespread super snowstorm in more ways than the '74 and I also worked and wrote about here, BUT snowfalls were less over the metro Detroit area than in 1974.

Here is a nice summary of November 21st 2015 Snowstorm from the NWS in White Lake, who also keep forecasters on their toes! It was the largest snowfall recorded at the office /DTX/ since the office was built in 1994  

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


=================================================================



Sat - 11/21/15 Update 

Very interesting storm in progress as far as snowfall rates and sharp delineation of visibilites and accumulations. Look for quite a range of intensities over the extreme southeast corner of lower Michigan through the afternoon and early evening - where the sharpest change of snowfall accumulations will occur. This mainly runs from the immediate Detroit area, southeast to the Ohio border (see map). Otherwise; boosted snowfall amounts somewhat in the best snowfall area to account for heavier band of snow projected this afternoon into early evening. Of course, the best snow amounts will be on grassy areas along with some settling/melting. ENJOY!






As discussed below; 

Snowfall positives for highest snowfalls include system's more southern track, upper energy and available moisture. Negatives include atmospheric low level temperatures mainly in the lower to mid 30s through the afternoon, possible period of snow mixed with rain over the extreme southeast corner of Lower Michigan and of course, some melting due to the relatively warm ground.
 


*Fri - 11/20/15 Update

STORM CENTER NOW EXPECTED TO TRACK FURTHER SOUTH, DROPPING THE AREA OF HEAVIEST SNOW SOUTH ALONG WITH IT OVER SOUTHEAST MICHIGAN

Latest guidance from last night continues the trend of dropping the track of the low pressure south into the the northern Ohio Valley. Earlier consensus tracks brought the low to the Michigan/Ohio border. Better sampling of the phasing of the two areas of energy spoke about at the onset now suggests the further south track.






With that in mind and looking at the latest surface and upper air data; snowfall projections (+/- an inch) are being updated in accord with latest information.  

 SNOWFALLS




As discussed below; 

Snowfall positives for highest snowfalls include system's more southern track, upper energy and available moisture. Negatives include atmospheric low level temperatures in the lower to mid 30s, possible period of snow mixed with rain mainly at the onset over the extreme southeast corner of Lower Michigan and of course, some melting due to the relatively warm ground.



*Thu - 11/19/15 Update 


No major changes from yesterday as current modeling continues projection of the development and progression of the low pressure responsible for snow potential. At this time, it appears the low will track across extreme Northwest Ohio/extreme Southeast Lower Michigan region. I stated below a snowfalls of a Trace to around 4" across Southeast Lower Michigan for the system and that still is close to my analysis possible higher amounts in the Saginaw Valley. That being said, I can narrow down the particulars:

Pattern:
Snow should begin Friday overnight into Saturday and diminish off to flurries Saturday night. The snow should mix with rain over the far southeast corner of lower Michigan.Temperatures should hover mainly in the 30s through much of the snowfall.


Snowfall Estimate Map (give or take an inch)



Snowfall positives for highest snowfalls include system's track, upper energy and available moisture. Negatives include atmospheric low level temperatures and possible mix with rain.

Look for updates if needed.


_________________________________________________________

Original - 11/18/15

In my Winter Outlook issued last weekend, I discussed the upper wind pattern getting charged up under the Fight Has Just Begun paragraph:

The Fight Has Just Begun!

While El Nino has been strong over the Pacific, its downwind affects for the most part, have yet to be seen much in our neck of the woods. We've had a relatively beautiful, warm fall thus far - somewhat uncharacteristic of strong El Nino's (dependent on El Nino strength and timing) which tend to be cooler, see Autumn Outlook analogues. During the strong El Nino's of 1982-83 and 1997-98 the atmospheric characteristics and downwind affects really didn't peak until the winter period. Thus far, along the central and southern West Coast, the "wave-train" of storms has yet to materialize but if history is any indicator, next month should see things pick up some. Things have begun to change here in November though with some storms tracking further south into the West Coast, deepening on the lee side of the mountains and heading into the Great Lakes. However, this pattern is really not unusual for any late fall period so, nothing too El Nino-like.

At the same time; the Polar/Arctic jet has shown signs of expanding and phasing further south into the sub-tropical jet, typical for November. While the subtropical jet is becoming more active, so is the Polar/Arctic jet. This has created a combative, progressive rolling jet pattern across the country. I look for this pattern to continue into at least into early December as timing is always an issue this far out


This upcoming weekend we have a fine example of discussed phasing of the Polar Jet and the Pacific jet energy over the western portion of the country and trekking east across the Plains, Midwest and Great Lakes/Ohio Valley. This mixed/phased system should brew a low pressure over the Midwest into the Great Lakes. 

Depending on the exact track of the low, along with lower atmosphere/surface temperatures and ground temperatures will determine the exact amounts of snow/rain accumulation. She's not even on the map yet but her "parents" are so let's take a look at this "mating" of weather systems. Realistic snowfalls depending on existing conditions at the time could range from a trace to potentially as much as 4" across portions of Southeast Lower Michigan since this system hasn't even formed yet. Let's give it time to get better sampled and tracked.







 Updates as development and track becomes more apparent.

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


 

11/15/15

A Strong El Nino Winter Always Promises Mild Temperatures and Light Amounts of Snow for Southeast Lower Michigan - or Does It?


Perhaps no other Winter Outlook, its expectations and anticipation has been "trumped" up (pardon the political pun, please) more than this upcoming winter's. Ever since last spring, the expectations of a significant El Nino and how it will affect the Winter of 2015-16 has been the topic of weather prognostication across the country. In ENSO terms, it is a strong El Nino, the likes that will be moving into full boar shortly. It's projected strength (as of early November) is to be on par with the modern "super El Nino's" the likes not seen in 1997-98 and 1982-83.

The Fight Has Just Begun!


While El Nino has been strong over the Pacific, its downwind affects for the most part, have yet to be seen much in our neck of the woods. We've had a relatively beautiful, warm fall thus far - somewhat uncharacteristic of strong El Nino's (dependent on El Nino strength and timing) which tend to be cooler, see Autumn Outlook analogues. During the strong El Nino's of 1982-83 and 1997-98 the atmospheric characteristics and downwind affects really didn't peak until the winter period. Thus far, along the central and southern West Coast, the "wave-train" of storms has yet to materialize but if history is any indicator, next month should see things pick up some. Things have begun to change here in November though with some storms tracking further south into the West Coast, deepening on the lee side of the mountains and heading into the Great Lakes. However, this pattern is really not unusual for any late fall period so, nothing too El Nino-like.

At the same time; the Polar/Arctic jet has shown signs of expanding and phasing further south into the sub-tropical jet, typical for November. While the subtropical jet is becoming more active, so is the Polar/Arctic jet. This has created a combative, progressive rolling jet pattern across the country. I look for this pattern to continue into at least into early December as timing is always an issue this far out. While the Polar Vortex is expected to remain much of the time up in the Arctic; looking at my data and the past few winters, I look for it to be a player at times.

Due to the strong El Nino and considerations given to other hemispheric patterns and oscillation discussed below, My Winter Outlook for Southeast Lower Michigan is as follows:

Temperatures: 

In spite of a classic, strong El Nino in place I don't look for a winter placing as warm as the classic El Nino's of 1982-83 and 1997-98. I do look however, for the winter pattern downwind to behave at times like a Hybrid or Modoki El Nino (discussed below) rather than just the typical classic El Nino. Because of the other hemispheric patterns in place; I would expect more of a "roller-caster" type of temperatures pattern established especially going into the winter, as mentioned above and coming out; directly involving the El Nino, EPO and NAO.

In any event; look for a milder, less cold winter than the past couple with temperatures averaging around 2 to as much as 4 degrees above the established normals. More on the particulars including the analogues below.

Snowfall:

Snowfall should average mainly below normal with pockets of normal across the entire region. Recent patterns along with analogue data suggest less snow than average should be expected across the southern areas of Southeast Lower Michigan with normal to below across the Saginaw valley/Thumb Region. This area and pattern involvement will be watched during the season for variations as the storm tracks materialize.

Generally, Southeast Lower Michigan receives 40" - 50" of snow in a given season with somewhat higher amounts off the snow-belts of Lake Huron, and in the highland areas over the middle region of Southeast Lower Michigan. Again, with hemispheric patterns in place (discussed above and below) and associated contrasting air masses; the risk of rain mixed with snow and ice systems will be higher than average.

Strongest Hemispherical Players (in order of importance)


I - ENSO including Southern Oscillation Index for pre - 1950 years


Strongest analogue years post 1950 are few and far between with 1997-98, 1991-92, 1982-83 and 1972-73 all the best strong El Nino contenders in my opinion. Out of the four, 1997-98 shows the strongest correlation in some ways in the central Pacific and has been compared the most to this years.



The parallels between now and 1997 are the strong El Nino near the equator. However, there are still notable differences; those being the extent of warmer waters just northeast of the El Nino in 2015 and the more pronounced warmth along the Pacific Coast into Alaska. The warmth up near Alaska was a contributing factor the past few winters in the Eastern Pacific that favored a -EPO which encouraged West Coast ridging. This in turn, aided in the dumping of Cold Arctic air south into the country. I believe this will, at least intermittently, be a player from the north (more below under oscillations). How often and how far south Arctic air masses get into the country this season could at least, challenge El Nino's strong mild jet.

In addition; note the extensive warmer than normal waters off the East Coast. This is an interesting addition to the puzzle since that may encourage ridging over the western Atlantic. With warmer waters well up into Alaska on the West coast and warmer than normal waters projected along the East Coast, would that not aid in occasional troughing over the U.S.?  Where, will depend on the strength of El Nino jet in the Pacific along with its most eastern extent which are historically, far and encompassing. Back in the1997-98, El Nino pattern had already been well developed longer than our current 2015 El Nino (as far as the SOI and downwind affects) with its El Nino kicking into gear by late fall and more importantly, it held strongly the entire winter. The Southern Oscillation Index, or SOI, gives an indication of the development and intensity of El Niño or La Niña events in the Pacific Ocean

From NCDC

The winter of 1997-1998 was marked by a record breaking El Nino event and unusual extremes in parts of the country. Overall, the winter (December 1997- February 1998) was the second warmest and seventh wettest since 1895. Severe weather events included flooding in the southeast, an ice storm in the northeast, flooding in California, and tornadoes in Florida. The winter was dominated by an El Niño - influenced weather pattern, with wetter than normal conditions across much of the southern third of the country and warmer than normal conditions across much of the northern two-thirds of the country. 

Prior to the winter of 1997-1998, strong warm-episode (El Niño) conditions had persisted in the tropical Pacific since June 1997. Sea surface temperatures throughout the equatorial east-central Pacific increased to near 29 degrees C during February and March 1998. At the same time, departures from normal were near +4 degrees C along the west coast of South America. During 1997 the National Center for Environmental Prediction (NCEP) statistical and coupled model predictions were consistent in indicating the development and persistence of strong warm-episode conditions.


Comparing the past two Strong El Nino's to 2015

What's is interesting to note from the above and data below; while the monthly ONI anomalous water temperatures are a bit higher earlier this year than in 1997, the SOI index was not as strong until this year until late this summer. In fact, the SOI in 1997 was stronger earlier than 2015 and continued stronger on both an ONI and SOI basis well into the Winter of 1997-98. This comparison of course, is based on projections of El Nino for the upcoming winter, which may turn out more variable than projected. This winter's El Nino is projected to peak the in the November - December time-frame but then, fall rather rapidly after. The above could be said about the later stages of the 1982-83 El Nino, where the ONI topped in the December-January time-frame but the SOI remained very strong well into the Spring of '83.

 
                                                                        ONI
               Jan                                                        Jun                                                                     Dec
1997
-0.5
-0.4
-0.2
0.1
0.6
1.0
1.4
1.7
2.0
2.2
2.3
2.3
1998
2.1
1.8
1.4
1.0
0.5

2015
0.5
0.4
0.5
0.7
0.9
1.0
1.2
1.5
1.7




1982
0
0.1
0.2
0.5
0.6
0.7
0.8
1.0
1.5
1.9
2.1
2.1
1983
2.1
1.8
1.5
1.2

                                                          SOI


*












Back in 1991-92 period, the El Nino's SOI development was much more akin to the 2015 development, though not quite as strong as this year, 1997-98 nor 1982-83. Reviewing the rest of the El Nino's (the ONI's where available and SOI's back into the early 1900s) from my selected analogue years, brought up some interesting finds in regard to strength and timing of that strength. Since the ONI's are not available for earlier strong El Nino's, a comparison of SOI's is beneficial to give a broader view of both the Pacific SST's and pressure patterns. The Southern Oscillation Index, or SOI, gives an indication of the development and intensity of El Niño or La Niña events in the Pacific Ocean. The SOI is calculated using the pressure differences between Tahiti and Darwin.

The best matches for strength and timing of the El Nino's was the aforementioned 1997-98 (the ONI's not SOI's), 1991-92, except it did not contain quite as warm ONI's as the current El Nino and 1940-41 which may turn out the best overall comparison in these two categories. Since the ONI is not available for 1940-41; we will now compare the SOI's. of 2015, 1991-92 and 1940-41. The traces and patterns of the three that are most similar thus far:


       
                                      

Current Data

Late October 2015 Pacific Anomalies



10/25/15 changes
Index Previous Current Temperature change
(2 weeks)
NINO3 +2.3 +2.2 0.1 °C cooler
NINO3.4 +2.1 +2.2 0.1 °C warmer
NINO4 +1.1 +1.3 0.2 °C warmer


IndexAugust September Temperature change
NINO3 +2.0 +2.2 0.2 °C warmer
NINO3.4 +1.9 +2.0 0.1 °C warmer
NINO4 +1.1 +1.1 no change


Projections Winter 2015-16

A classic El Nino is projected by all models /CFSv-2 below/ for the Winter of 2015-16 with a stationary/slight weak drift to the west, late winter and spring with the max anomalies gradually fading under the cooler season. If the shift west occurs somewhat, this would indeed set up a more of a Hybrid affect.





At this time, this classic or traditional El Nino in the Pacific is projected to maximize early in the winter, typical for El Nino. Recently, it has been discovered there are basically two types of El Ninos; the centrally based or Hybrid El Nino (El Nino Modoki) and the easterly based, called Classic or Traditional.

Different Types of El Niño Have Different Effects on Global Temperature

The El Niño–Southern Oscillation is known to influence global surface temperatures, with El Niño conditions leading to warmer temperatures and La Niña conditions leading to colder temperatures. However, a new study in Geophysical Research Letters shows that some types of El Niño do not have this effect, a finding that could explain recent decade-scale slowdowns in global warming.

The authors examine three historical temperature data sets and classify past El Niño events as either traditional or central Pacific (El Nino Modoki). They find that global surface temperatures were anomalously warm during traditional El Niño events but not during the central Pacific El Niño events. They note that in the past few decades, the frequencies of the two types of El Niño events have changed, with the central Pacific type occurring more often than it had in the past, and suggest that this could explain recent decade-scale slowdowns in global warming.




This is what the Japanese Department of Meteorology JAMSTEC has to say about Modoki.
"El Nino Modoki has recently been identified as a coupled ocean-atmosphere phenomenon in the tropical Pacific Ocean and has been shown to be quite different from the canonical El Nino/Southern Oscillation (ENSO) in terms of its spatial and temporal characteristics as well as its teleconnection patterns (Ashok et al. 2007; Weng et al. 2007; Ashok and Yamagata 2009). Traditionally the term “El Nino” was used for the canonical El Nino associated with warming in the eastern tropical Pacific. However, as we realize now, during El Nino Modoki the sea surface temperature (SST) anomaly in eastern Pacific is not affected, but a warm anomaly arises in the central Pacific flanked by cold anomalies on both sides of the basin (Fig. 1). Together with its counterpart La Nina Modoki, when colder central Pacific is flanked by warmer eastern and western Pacific, the new phenomenon is now called as the ENSO Modoki that assumes both warm and cold phases of its behavior. Several studies have shown that the ENSO Modoki has become more prominent in recent times, as compared to ENSO, and thereby changing the teleconnection pattern arising from the tropical Pacific. Moreover, the associated decadal changes in the sea level are shown to affect not only the islands of central Pacific but remote regions off California and southwestern Indian Ocean (Behera and Yamagata 2009)Figure 1: Schematic diagrams of El Nino Modoki and La Nina Modoki the two phases of ENSO Modoki.

The ENSO Modoki has distinct teleconnections and affect many parts of the world. For example, the West Coast of United States of America is wet during El Nino but dry during El Nino Modoki (e.g. Weng et al. 2008). Recent studies show that teleconnections associated with ENSO Modoki influence the rainfall over India and South Africa (Ratnam et al. 2010; Ratnam et al. 2011)."

II - Winter Oscillations 

Hemispheric oscillations remain the most illusive trends or phases to predict more than a week or two. I starting researching and studying about them back in the mid 90s and to this day, there has been no tried and true way of predicting them for more than a few weeks. It certainly would help if we knew for certain the main phase each oscillation will be in along with expected interactions with teleconnection patterns. That isn't to be said there hasn't been advancement in research and studies of the various oscillations, some of which I'll discuss here and how it pertains to this upcoming winter.

NORTH ATLANTIC/ARCTIC OSCILLATION - NAO/AO

Generally, the North Atlantic Oscillation NAO is the most discussed and main key player influencing our weather in the central and eastern U.S. The NAO/AO and its phases can be one of the make or break influences on weekly, monthly and seasonal forecasting. 

The monthly trace on the chart below shows the NAO oscillations for better than the past century. The inclusive Arctic Oscillation/AO is basically a subset of the larger North Atlantic Oscillation.The Arctic Oscillation often shares phase with the North Atlantic Oscillation (NAO), and its phases directly correlate with the phases of the NAO including its implications on weather across the U.S. 





The dominant positive phase of the NAO for the past couple of winters is easily seen here on the DJFM chart below. Remember our severe cold in the second part of the Winter of '14 and '15 was due more in part to occasional strong negative EPO (discussed below) and subsequent southward displacement of the Polar Vortex!



Just recently forecasted, the phase of the NAO/AO for the upcoming 2015-16 winter is anticipated to revert back to more of a negative phase for the winter. The negative phase was also seen more during our past summer, which helped keeping a lid on hot weather.
Note below the strongly negative phase back in our tepid July and short term projection, the second half of November. This short term drop in November should allow colder, Polar air into the region the second half of the month.


 
So, what are the exact projections for this winter thus far? Keep in mind the projected NAO forecast seen below from Kyle MacRitchie, a PHD student who has been working on projecting out the NAO and other Oscillation phases for several years.







In addition, AER scientist Dr Cohen has been on a trail-blaze of sorts by projecting the NAO in part due to Siberian snow cover in October. Author Judah Cohen, Ph.D., works at Atmospheric and Environmental Research (AER), a division of Verisk Analytics. Let's look at his maps as we dig through the snow...




The snow cover this October 2015 was again above normal, though not a much as the past few winters. See his latest discussion and attending snow cover plot for the past several years.

Northern Hemisphere Snow Cover

Seasonal snow cover continues to advance both across Eurasia and North America, though so far snow cover has advanced more rapidly across Eurasia.  Eurasian snow cover is above normal at this time (Figure 10). Eurasian snow cover extent for the month of October was above normal. Also recently the snow cover across Eurasia has advanced more to the south across East Asia.  This has resulted in an even higher value for the snow advance index (SAI) value for October, since only snow cover equatorward of 60°N contributes to SAI values. Above normal Eurasian snow cover extent for the month of October favors a negative winter AO.












Pacific Decadal Oscillation/Eastern Pacific Oscillation - PDO/EPO 

The warm waters extending up and down the West Coast represent a recent warm Pacific Decadal Oscillation PDO phase that commenced in early in 2014; as it went from mostly negative values to a very strong warm phase which continues dominant today. This still may be short lived since the overall 30 - 40 year term phase reversed to general cold phase, just after the last major El Nino in 1998. Back in just 2008; the transition was completed as recent observations of the coastal waters have been among the coolest in the past 109 years.

The warmer waters on the West Coast up into Alaska encouraged strong ridging on the Coast at times during the last two winters. This encouraged a -EPO I mentioned in previous Outlooks (the first back in the moderate El Nino Winter outlook in 2002-03) as a major participant in the cold winter periods then and the past few winters. Thus far, as seen by the El Nino projection maps, the unusually warm waters remain as of late fall. This too will have to be watched and could challenge El Nino's warming affects at times.  Checking back in the ENSO section above, there is a notable difference between the West Coast water temperatures in 1998 as opposed to 2015.   

Quasi-biennial Oscillation - QBC 

The QBC is a tropical stratospheric wind that descends in an easterly then westerly direction over a period of around 28 months. This can have a direct influence on the strength of the polar vortex in itself. The easterly (negative ) phase is though to contribute to a weakening of the stratospheric polar vortex, while a westerly (positive) phase is thought to increase the strength of the stratospheric vortex. However, in reality the exact timing and positioning of the QBO is not precise and the timing of the descending wave is critical throughout the winter. At this time, the QBO is westerly and is this expected continue throughout the winter.

 

Westward phases of the QBO often coincide with more sudden stratospheric warmings, a weaker Atlantic jet stream and cold winters in Northern Europe and eastern USA whereas eastward phases of the QBO often coincide with mild winters in eastern USA and a strong Atlantic jet stream with mild, wet stormy winters in northern Europe (Ebdon 1975).




III -             Strong El Nino Analogues for the Winter of 2015-16



General Take 


The warmth talked about with El Nino is reflected well across the El Nino analogues; so much so that this is the warmest set of winter analogues I believe I've seen. This is also the first time I can recall there were no below normal winters (for our general purposes; a degree or more below normal). That being said; if one digs through the data, actually two types of winters emerge; The warmer with light amounts of snow winters and the mild (near normal to a couple of degrees above), mixed temperatire and precipitation winters with nearer normal snow. This is also the first time I can recall there were no below normal winters (for our general purposes; a degree or more below normal).

Digging Further 


Temperatures

Interestingly, when using the large set of available data /Detroit/, there were five "warm" winters and five "normal" winters. All warm winters averaged 30 degrees or better, while the normal winters averaged within a degree of normal. Our "coldest" winters were all hit with a below normal month, February 1889, January 1897 and February 1942. The two other normal winters 1940-41 and 1972-73, monthly temperatures were more uniform.

On the flip side; the warmest winters had two or three months average above 30 degrees; Winter of 1905-06, 1982-83, 1991-92 and 1997-98 in which all three months averaged above normal. Maybe not surprising; the Winter's of 1982-83 and 1997-98 are the warmest winters at all three cities.

Looking at particular months; December has the best chance to average above normal with January, the second best. This jives well with El Nino peaking in that time period and affecting the downwind jet stream. The month with the best chance for colder weather was late in the season with February (some Marches followed that trend). Again, with El Nino fading by then, it stands to reason and as always timing of the dominant patterns can vary.  

Snowfall/Precipitation

With snowy winters (above normal snowfalls) dominating the past 10 - 15 years, the season snow outlook for snow lovers is rather dreary. In fact, like the warmer temperature dominance this analogue go-around, snowfall averaged on the lightest side of past analogue winter totals seen at Detroit. Snowfall deficit runs from around a foot at Detroit to just a inch or so at Saginaw. This also fits with thinking of the polar jet still affecting the Lakes enough to bring near normal snows in that region.


However, all is not lost snowfall lovers! Two winters contained normal snowfall at Detroit, one normal and two above normal at Flint and finally; two normal and three above normal at Saginaw. Therefore, the most obvious pattern seen in these winters is that the further north one goes in Southeast Michigan, the better chance for more snow. The same can be said for general precipitation across the region. The Winters of 1991-92 and 1972-73 saw the best snows across the entire region with normal to above normal. The Winter of 1940-41 saw the next best "snow showing" the entire region but still well below at Detroit /26.8/ to near 50 at Saginaw /49.7/.The actual snow pattern for this winter will be watched for updates. 

COMPOSITES


The temperature and precipitation composites show the differences from all available analogue winters in the first two maps, the "cooler" El Nino winters in the second two and "warmer" El Nino winter in the last two. Be advised, because of extremes, some scale departure numbers change.
 

All ANALOGUE EL NINO WINTERS 

TEMPERATURES

 



PRECIPITATION



COOLER EL NINO ANALOGUE WINTERS

TEMPERATURES



PRECIPITATION


Note the temperature/precipitation difference pattern during the "cooler" strong El Nino winter's of 1896-97, 1940-41, 1941-42, 1972-73 and 1991-92. I included 1991-92 since it was borderline /near the 30 degree ave/ and higher snow amounts, thus not a typical warm, drier El Nino winter. It clearly shows colder conditions (normal to below from New England west into the Great Lakes) and less warmth over a much larger area, along with near normal precipitation in the Great Lakes.


WARMER ANALOGUE EL NINO WINTERS

TEMPERATURES



PRECIPITATION


 

Two of the warmest El Ninos occurred during the last two strongest El ninos, 1982-83 and 1997-98. Will history repeat itself?


Jet Stream and Storm Tracks

As discussed above in Hemispheric Patterns above; the strongest pattern affecting jet streams and storm tracks this winter is expected to be the very strong El Nino but next in line in my opinion are the NAO/AO and the EPO. All patterns below are a result of Winter Analogue years; 500 MB Heights and dominant jet streams and resulting storm tracks.

 

 

 

Look for updates and notable storm advisories during the upcoming winter!


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