12/15/14

Update-12/20/14>>>Extended Models Intimating Notable Pattern Change Christmas Week - HO HO HO?

Latest Indications Point To a Wet Christmas Eve & Light Snow and Snow Showers For Christmas Day  

A reasonable pattern evolution of the Christmas week storm is unfolding for the Great Lakes and Southeast Lower Michigan. The storm development previously blogged below, remains intact while the Great Lakes tract depicted as one of the possibilities, the most likely winner. 

Jet structure and max winds depict a large negatively tilted trough developing over the region on the 23rd into the 24th, Christmas Eve. At the surface, a deep cyclone will develop along a slow moving - quasi stationary cold front extending from the Gulf States northward into Lower Michigan during the day on Christmas Eve. This deepening storm center will pull substantial moisture and moderate warmth northward into the Great Lakes and Southeast Lower Michigan in the form of rain on the 24th and then light snow and snow showers Christmas Day. With any luck, we'll see enough snow showers on Christmas for a "snow in the air" Christmas but I wouldn't count on an official "white Christmas" this year - at least as things look now. I wish I could be more hopeful for a white Christmas but possibly enough moisture will remain behind the system in the seasonably colder air to generate the inch needed /per GFS/, so will update as the time rolls on closer. Speaking of "White Christmas" look for my annual "Ghost of Christmases Past; The Whitest of Christmases and Other Christmases Past, shortly. 

Surface Maps Particulars

Note the European is faster and further north with the low over Lower Michigan by Christmas Eve 7AM, whereas the GFS brings the center into the region by Christmas Eve 7PM.



 
Then by Christmas morning on Thursday, the Euro has the center of the storm
well up into Canada where as the GFS holds more moisture and energy aloft along with the surface reflection over the Great Lakes and thus, a better chance for light snow and snowshowers.



Look for a further update early this week.
  
Merry Christmas & A Happy and Healthy New Year
_______________________________________________________________________
 
12/15/14 - Initial Post

Meteorologists and Weather Enthusiasts have seen it before, too many times to count in extended model la la land, an overhaul or notable change of the prevailing pattern being suggested a week to 10 days out. This time, the pattern change is rather strongly intimated by the GFS and European model right around Christmas - or at least Christmas week /22nd-28th/. Each day something new and different pops up; a snowstorm for the East Coast, the Midwest or the Ohio Valley and Great Lakes followed by a sharp cold blast in its wake. The only thing for "certain" is that an overall Jet Stream pattern change will evolve sometime the latter part of December and that will likely create a mess for someone (more further below) around the holiday.

Autumn into Early Winter 

No one has to be told it's been a rather tranquil and boring beginning of the meteorological winter /Dec-Feb/ and this coming after a rip-snortin' unusually cold, blustery and busy November (which had its deep cold roots in place by Halloween time). Looking back, the pattern this fall into early winter was well projected by upper air and surface patterns of the past with similar hemispheric traits in the Autumn Outlook.

Fall is cited for its wild swings in temperatures and this fall certainly should be no different as impressive upper lows in Canada dive south and southeast into the U.S. The aggressiveness of this overall, now common-place pattern shows little change in the last year. Both upper air and analogues also do suggest typical to strong cold outbreaks along with some contrasting upper ridging to bring classic Indian Summer weather.

Oscillations of upper and related surface patterns with a preference toward troughing and cooler than normal weather should be balanced out somewhat, leaving us with an average or normal fall with notable sharply contrasting patterns. I look for temperatures to average around normal...or within two degrees of the normal. 

As it turned out; temperatures this past autumn did fall well within the projected spread of the selected analogues and Outlook across Southeast Lower Michigan averaging exactly a degree /-1.0/ below normal at 49.8 /norm 50.8/. September and October averaged near to slightly above normal where as our cold November, averaged well below normal.

This "now suitable, now brutal" kind of weather regime was projected to persist into the winter with strongly oscillating weather patterns resulting in cold, mild, stormy and tranquil kind of winter. I bring this all up because as you know; recently we've had a few weeks of the rather tranquil weather to start off December and the winter thus far - BUT there is a change afoot!

 

Back to the present and future...

Many meteorological indicators are pointing to a colder and stormy pattern with this change, certainly not uncommon and pretty much expected. It's the questions of where (and thus who), what and when that have to be answered.  The NAO and AO both are pointing to radical hemispheric change later in the month while the PNA remains weakly positive (or suggests troughing east of the Rockies). Both the NAO and especially AO are rather extreme with their collapse into negative territory (likelihood of colder weather). There still are variances in the overall decline from positive to negative and thus, problems in forecasting are strongly affected.

 

 

 

It is easy to see as both oscillations advanced into their positive phases beginning in December, the month became more tranquil and progressively milder over Southeast Lower Michigan, the Great Lakes and East. And generally, when there is a notable change like this projected there is a storm-a-brewin for someone and some part of the country. Here's some scenarios spit out by the GFS & European models for Christmas time.

 

Dec 15th 00z GFS, Snowstorm for the Eastern Lakes Christmas Eve 12/24>>>

 

This morning's, Dec 15th 12z GFS run (note the storm is again over the Eastern Lakes but it's now Friday morning 12/26)


 

The Dec 15th 12z Euro has a different view, she puts most of her eggs in a Northwestern Lakes Low Christmas Eve Day with a second forming just west of the Appalachians but as you can see (second map below), it undoubtedly makes headway toward the Northeast Coast just in time for Christmas

 

 

Of course, there is a lot of time between now and Christmas week and thus, numerous scenarios will be created in model la la land. In the meantime, it would be prudent to keep abreast of this change in the weather projections since it is definitely a heavily traveled time.

 

As the time gets closer I'll look at what's the most likely scenario - and where and when.

 

Merry Christmas & A Happy and Healthy New Year

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

12/3/14

40TH Anniversary of Detroit's Highest Snowfall in Modern Times!

This week marks the 40th anniversary of Detroit's biggest snowfall in amounts in modern times; December 1st, 1974 - including surface maps. The biggest snowfall of all time was way back on April 6th, 1886. Back in 2000; I wrote what I called "A Tale of Two Storms" which paralleled the two biggest snowstorms (in amount) to ever hit Metro Detroit. The second storm in the article, I will never forget as I worked it during my first year as a novice with the NWS. To this day, I have yet to see a storm quite like it; as far as the magnitude it snowed and for such a long period of time! Enjoy!  Here are reviews of both storms:

THE TALE OF TWO STORMS
By: William R Deedler, Southeast Michigan Weather Historian

Initially, I had intended to write about Detroit's biggest snowstorm ever recorded (24.5") but while researching the storm (which occurred way back on April 6th, 1886), I was struck by the uncanny similarities between that storm and Detroit's second biggest snowstorm (19.3") which occurred nearly a century later on December 1st, 1974. Besides the obvious similar snowfall amount between the two systems, other significant parallels could also be drawn. In addition,  while I was obviously not around to observe the first huge storm, I did have the opportunity to witness the second first-hand, in my earliest days with the National Weather Service. Unfortunately, weather maps for the1886 storm are unavailable, unlike the 1974 storm (below). With the aid of surface observations and weather journals however, at least an estimate of the surface and upper air data can be made. Perusing through the carefully scrolled weather journals of the late 1800's, one can't help but be amazed and "taken back" by the simplistic, yet stylish way of which they were written. In addition to hourly weather observations and climatic statistics, each day contains usually a short synopsis of the weather experienced for that day. It is the weather logs from late on April 5th - April 7th, 1886 that really commands ones attention and awe.
 
APRIL 1886 -
By early April 1886, some residents of Southeast Lower Michigan had most likely started on spring outdoor activities. High temperatures frequently pushed well into the 50s from mid March on; the last hint of snow fell nearly two weeks before on the 23rd. No doubt the growing season's new green vegetation was well underway.
 
The weather days proceeding the massive and incredible snowstorm hinted little of what was yet to come; however, there were some subtle signs of trouble brewing. The first was a fresh, brisk northeast wind that blew continuously for nearly three days prior to 6th (generally, an easterly wind along with a falling barometer in this region, foretells of foul weather approaching the area). On the 4th into the 5th, observations including temperatures, wind flow and pressure changes indicated an unseasonably cold high pressure system pushing slowly into Southern Canada and the Northern Great Lakes. This persistent and strengthening northeast wind along with an extended period of steady, then slowly falling barometric pressure, during the three-day period (3rd, 4th and 5th), indicates this high was a fairly strong, resilient and a blocking type of high pressure. A second and more foreboding sign of what was to come was indeed a rapidly falling barometric pressure later on the 5th, which foretold of the major storm approaching Southeast Lower Michigan. The surface observations late on the 5th indicated a low pressure and storm center approaching the Southern Great Lakes from the south or southwest (most likely from Illinois, Indiana or Ohio) as the cold high to the north slowly retreated.
 
The afternoon high on the 5th reached only 38 degrees (about 15 degrees below normal) and then held nearly steady into the evening. Increasing high cirrostratus clouds mingled with the sunset but then, quickly lowered to altostratus and nimbostratus as midnight approached. Light snow began to fly just after midnight and remained light until becoming heavy during the predawn hours. Note the following taken from the actual Detroit Weather Log dated April 6th, 1886:
"Snow began at 12:30 AM and fell light until about 4:30 AM when it began to fall heavy and a tremendous fall of snow continued all day, ending at 9:00 PM. The fall at 7:00 AM was 4.6" and at 3:00 PM was 17.1" and at 11:00 PM, 2.4" making the total of 24.1 inches melted from the snow gauge. The rain gauge was soon snowed full and was practically useless. Total fall of the snow on the level was 24.5 inches. The snow was badly drifted by the heavy gale. The drifts in some places were 12 feet high and the snow in the street was from 10" to 40" inches deep. A heavy north gale set in at 1:45 AM and raged in fury all day reaching 40 miles north at 2:15 PM and continued all the remainder of the day. Its force with the snow was appalling. It blew the snow in fine particles against the face, cutting like a knife."
The synopsis continues with a description of numerous street cars that were abandoned, strewn about and laying in all sorts of positions. As one might expect with the snow falling in April, the snow contained a high water content (2.43") and, therefore, it was very heavy and packed down well. Obviously, wading through the snow to get around on foot was extremely difficult - so much so that it became necessary to use crowbars and ice picks just to clean a path on the street. Maneuvering through, or just moving the snow, was such a monumental chore that even several ton railroad cars were "held prisoner in their houses". On the train tracks, freight cars were immobilized and abandoned across all of Southeast Lower Michigan. Temperatures held in the upper 20s to around 30 through the entire snowfall, with over two feet of snow reported on the ground. The strong northeast to north gale sculptured towering drifts of snow up to 12 feet high across the landscape .The howling wind averaged over 30 mph during the 24 hour period. The lowest barometric pressure reading noted was 29.60 inches at 11:00 AM on the 6th. This reading isn't too terribly deep or severe (the lowest pressure ever observed in Detroit was 28.34 inches during the late January blizzard of 1978), but the pressure was taken only five times daily (7:00 AM, 11:00 AM, 3:00 PM, 7:00 PM and 11:00 PM), so it likely fell lower As the center of the low pressure drifted further north into the Great Lakes on the 7th, milder air from the south was drawn into Southeast Lower Michigan. The sky cleared as the wind shifted to the south and the temperature rose to 40 degrees, in spite of the very heavy snow cover. In the days following the storm, temperatures managed to push up well into the 50s and even reached the mid 70s by mid month, after all, this was April, right?
 
This storm stands as Detroit's biggest and severest snowstorm and is well summarized by the following quote in the journal and actually would still stand to this day. . .
"The storm was unprecedented in fierceness, snowfall and blockades in the history of the service and the oldest inhabitants can recall nothing to equal it".
DECEMBER 1974 -
It would be nearly a century later before a very similar storm, a sort of "meteorological clone" would arrive and again leave the region snowbound with the second highest snowfall (19.3" as compared to 24.5") ever recorded in metropolitan Detroit in a single storm. While there were several similarities between the two storms, one obvious difference was their timing in the snow season. Also, it is interesting to note here, that neither storm occurred during what is officially called "winter." While the 1974 storm occurred in late fall at the forefront of the 1974-75 winter season, the April 1886 storm showed up on the doorstep of spring.

Besides the similar heavy snowfall between the storms, there is the likeness of the surface observations taken before and during each storm. As its predecessor, the 1974 storm was proceeded by a few days of persistent northeast winds along with an initially rising barometric pressure, then after, an extended period of steady pressure readings before giving way, slowly at first, to falling pressure. Also, like the 1886 storm, temperatures crept up into the mid to upper 30s on both the 29th and 30th (though these highs were not anywhere near as below normal as in the April 1886 storm). On the 30th, the northeast wind averaged around 19 mph with peak gusts close to 30 mph. The persistent strong northeast wind with just a slow climb in daytime temperature was a result of a large stationary polar ridge axis of high pressure that extended in a horseshoe shape (an Omega High) from the Great Plains, north into the Dakotas, then east across Lake Superior into Quebec, Canada and finally south along the East Coast. The high's strength and position also recalls that of the1886's high pressure mentioned previously.
The development and track of this super snowstorm was complicated and quite a hassle for forecasters that Thanksgiving weekend. The primitive forecast models (when compared to the more sophisticated and better resolution of today's models) had quite a time in predicting the track of the storm and its intensity. Even up to the day of the storm, the forecast models continued to weaken the center of the storm as it moved into Kentucky and Ohio, while intensifying a new storm along the East coast. On Saturday, November 30th, a strong closed-off 500 MB Low advanced into the Mid-Mississippi Valley, while at the same time, at the surface, an inverted trough of low pressure extended from a low over the northern Gulf of Mexico, north northwest to a second low over Missouri. The consensus of the forecast models was to bring the 500 MB and surface low generally east, into the Ohio Valley and weakening both. In the meantime, the Gulf Low was forecast to track north northeast up the East Coast and intensify; thus, becoming the main low and storm center of the entire system. This was the accepted forecast scenario with the data available at the time and could hardly be argued otherwise. Actually, this predicted path and subsequent weakening of the Ohio Valley low as the East Coast storm intensifies or "bombs-out" is what generally happens. The models failed in forecasting the weakening trend of the Ohio Valley system. The 500 MB Low and the surface low not only did not weaken, they actually intensified and became vertically stacked in the atmosphere. Generally, when this happens the system tends to hold on to its intensity longer and slow down in movement, both of which proved detrimental to the computer forecast.
 
Light snow moved into extreme Southeast Lower Michigan during the predawn hours between 5:00 AM and 7:00 AM. Even at the 5:00 AM forecast issuance, it looked as if just one to three inches of snow would blanket extreme Southeast Lower Michigan for this event. However, by sunrise, already up to three inches of snow covered the region and the snow was not getting any lighter. A stiff northeaster' also accompanied this storm, though not as severely as the 1886 storm, averaging 20 to 30 mph with gusts above 30 mph. By sunrise, an area of snow had settled over extreme Southeast Lower Michigan. On radar during the forenoon hours, bands of heavier snow appeared over Northern Ohio and Lake Erie, trekking west-northwest toward Michigan. By now, the forecasters knew the forecast was in trouble and updated the forecast to read "six or more" inches of snow.

The 500 MB Low and associated energy to support the surface system drifted east over Kentucky, while the surface low that was over Missouri drifted east right along with it. A huge conveyor belt of moisture had set up in the atmosphere extending from the Gulf of Mexico and the Western Atlantic, east into the Ohio Valley and Southern Great Lakes. Not only had the storm tapped the usual Gulf moisture; now Atlantic moisture started to be drawn into the mix. After analyzing surface data from the 1886 storm, it is strongly suspected that this too was the case at that time. Huge moisture plumes from both the Atlantic and Gulf of Mexico fed the1974 storm and likely, the1886 storm, with nearly duplicate surface observations before and during the event.

Bands of snow (much of it moderate to heavy) continued to be produced across the Eastern Great Lake States on the "conveyor-belt" through the afternoon, with the heaviest snow falling across extreme Southern Ontario, extreme Southeast Lower Michigan and extreme Northwest Ohio. By mid afternoon, already between six and ten inches of snow was on ground across much of extreme Southeast Lower Michigan, with generally eight to ten inches in the metro Detroit area. Visibilities were frequently near zero and moderate northeast winds blew the heavy, wet snow into at least three to five foot drifts. Another notable item observed during the storm was frequency of large snow flakes. Generally in the majority of snowstorms there may be a period or two of heavy snow with large flakes and a quick accumulation of snow. During this storm however, there were several periods, or waves, of heavy snow with continuous large flakes and very low visibilities, migrating in from the east over the region.



 
The surface low drifted north northeast from Kentucky into West Virginia by Sunday evening on the 1st and gradually matured and occluded. It still remained however, the dominant low (which was not forecasted by the forecast models), while the second low on east coast moved north at the triple point (at the point where the occluded, warm and cold front of the system met) and never really developed. As darkness fell, generally up to a foot and a half of snow smothered the metro Detroit area, with six to twelve inches elsewhere in extreme Southeast Lower Michigan. During the evening the snowfall became lighter and by midnight, 18.4" was officially observed at Detroit Metro Airport. Another nine tenths of an inch fell early on the 2nd, for a grand total of 19.3" (19.2" of it falling in 24 hours) with Flint reporting a snowstorm total of 8.1". As the low drifted northward, milder air filtered into the region and the snow became mixed with, and then changed to drizzle.

Coincidentally, the next day (Monday, December 2nd, 1974), the temperature also warmed to 40 degrees in the afternoon, but the wind remained more northerly rather that shifting to the south (as on April 7th, 1886). This was due to the fact that the center of the low tracked further east of Southeast Lower Michigan into Pennsylvania, rather than into the suspected Great Lakes area in 1886.
 
Some other accounts of the storm:





http://www.annarbor.com/news/top-10-storm-snowfall-totals-for-the-ann-arbor-area/

http://www.theoaklandpress.com/general-news/20130208/10-worst-snowstorms-in-metro-detroit-history

http://www.toledohistorybox.com/2010/12/01/snowstorm-buries-toledo-december-1-1974/


From a reader -

Attn: Bill Deedler re: snowstorm Dec 1, 1974

Sir, I remember that storm well: I was visiting a friend in Kalamazoo. She watched the fledgling Weather Channel early in the morning when she awoke to lightly falling snow. She told me to leave early because the snow would fall first there. Little did I know that the farther east I drove back to Ann Arbor, the snow would get worse and worse. A normal trip of maybe 2 hours turned into 5 hours. It took me an hour to exit I-94 up the State Street exit, at times pushing my car myself. When I finally arrived at my apartment, I got stuck outside. I left it there. Cold, wet, tired, frustrated and alone, I got a phone call from a friend whose parents took him back to U of M early that morning. He walked 3 miles in 18 inches of blowing snow to comfort me. I married that man and am still happily married to him to this day. I will never forget December 1st!!

Sincerely, Judi -  Allen Park, MI
Any other accounts, I can publish in Comments section below.

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

11/16/14

Is It Cold Enough Yet?? Eh, Mom Nature's Just Gettin' Started; Now For Round 2 & 3...

Last week, I warned of the unseasonably cold air projected in our extended guidance to slam the region. "The polar plunge is slated to push into Southeast Lower Michigan by Tuesday night and then, hang around to get reinforcements into the following week (11/16-22)"!

Well hang on because those cold reinforcements are yet to come for Southeast Lower Michigan. They, basically will come down in two cold waves; the first (and the worst) will arrive during Monday, while the second comes down later Wednesday, just to "seal the deal". Gusty winds with bone chilling wind chills down as low as zero or below will accompany snow showers and squalls to complete the 5 week before winter scenario. Looks for temperatures to range from mainly the 20s for highs and teens and even some single figures for lows, during the coldest time in the up coming week. Normals this week; mid to upper 40s for highs and lower 30s for lows. So several days we won't crack the normal lows! In fact, some days this week won't match the normals for the coldest winter days in later January!

Ironically (as mentioned in my last blog, below), we should be engulfed in the throws of the Arctic regime around the same time as the incredible cold wave of 1880!  A welcome moderation, finally should commence this next weekend /22nd-23rd/ and beyond (at least for awhile) so those records for next weekend /22, 23/ look more than safe.

"It will be interesting to see if we can challenge the resilient stretch of record low temperatures for mid November that I wrote about here, previously as SE_Mich Weather Historian (and earlier with the NWS). This record cold stretch occurred /1880/ way back near the dawn /1874/ of official records at Detroit and still hold up till this day! Both the intensity of the cold that we experience and timing may be an issue, we'll see. Something to keep in mind, especially if we have snow on the ground at the time".

DETROIT - NOVEMBER RECORD LOW MAXS AND LOWS IN BLUE
18 48 34 41.0 69/1941 18/1880 55/1954 11/1880 60/1954 14/1880 0.97/1929 18
19 47 33 40.0 68/1985 22/1880 58/1985 9/1880 63/1985 16/1880 1.07/1948 19
20 47 33 40.0 70/1942 23/1895 57/1913 12/1880 60/1931 19/1880 1.02/1988 20
21 46 33 39.0 67/1913 12/1880 56/1931 3/1880 61/1931 8/1880 1.16/2007 21
22 46 32 39.0 69/1913 16/1880 57/2010 0/1880 62/1913 8/1880 2.59/1909 22
23 45 32 38.0 69/1931 21/1880 57/1931 8/1880 63/1931 14/1880 1.24/1891 23

Now while it remains to be seen if we can break any of those archaic records at Detroit from 1880. Flint and Saginaw may be another story, as their records don't include the brutal cold of 1880 for November and little, if any heat island affects those sites. Still, they both have some decent standings in the cold record department this week and several may be a tough "ice-cube" to crack....

FLINT - NOVEMBER RECORD LOW MAXS AND LOWS IN BLUE
18 46 30 38.0 68/1975 25/1989 52/1971 11/1959 59/1971 19/1989 1.03/2003 18
19 45 30 38.0 70/1953 28/1927 58/1985 13/1986 63/1985 22/1927 1.20/1921 19
20 45 30 37.0 68/1953 25/1969 56/1942 14/1969 61/1934 20/1969 1.40/1942 20
21 44 29 37.0 66/1931 24/1964 55/1934 7/1969 60/1934 17/1969 0.65/2007 21
22 44 29 36.0 65/1934 23/1929 57/2010 9/1929 61/1934 16/1929 1.02/1992 22
23 43 29 36.0 68/1931 25/1956 54/2003 10/1956 60/2003 18/1956 0.61/1983 23

SAGINAW - NOVEMBER RECORD LOW MAXS AND LOWS IN BLUE
18 45 31 38.0 68/1975 24/1989 52/1971 11/1989 60/1971 0/1998 1.30/2003 18
19 44 30 37.0 72/1953 29/1951 56/1985 11/1914 61/1991 0/1998 1.16/1913 19
20 44 30 37.0 69/1931 25/1914 52/1982 11/1914 58/1931 0/1998 0.85/1942 20
21 43 30 36.0 69/1913 25/1964 55/1934 10/1969 62/1913 0/1998 0.60/1979 21
22 43 29 36.0 66/1913 23/1929 55/2010 11/1929 58/2010 0/1998 1.70/2010 22
23 42 29 36.0 72/1931 25/1917 56/1931 7/1950 64/1931 0/1998 1.06/1983 2

It will largely depend on the cloud cover and snow cover. While this air certainly has the potential for record cold, I would be remiss if I didn't mention the importance of cloud cover, snow cover AND perhaps the most important; the overall moderating affects on the Arctic air mass - the Great Lakes. Still with the right conditions...

Here are the villains in the piece this week....



* Latest Euro's Polar Vortex prog below; 11/18/12z
That's incredible to have such a low height/cold Polar Vortex over the northern Lakes in   MID NOVEMBER! Got to be a record in upper air data if she verifies...

  
Keep you and the pets warm.


Next Up - What's the big travel day Wednesday along with Thanksgiving/Thanksgiving weekend look like?


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

11/9/14

Polar Surge Heading for the Region Impressive for November Standards!

I will say; it's been awhile since I've seen the likes of the upcoming cold projected by our models for November (both in intensity and extent) for several days now. First of all, "some 3 - 4 standard deviations below normal" when speaking of the depth of the trough - from WPC. Then today again from WPC - "Well-advertized cold snap will lead the medium range period next week (week coming up) as strong ridging /500MB standard anomaly nearing +4 - which is VERY rare/. Here, the "Italian" gent (I assume) Mr. Fracasso is referring to the giant "ridge or hill" developing off and over the west coasts of the US and Canada and well into Alaska. This, ridge in turn, will grab and help plunge the polar air that two polar vortex's (one, over Siberia/Russian and the other over eastern Canada) have pinwheeling between them in a very cold conveyor-belt more reminiscent of January! Take a look>>>




And the map above is a week from now (11/9) which brings up the third notable item about this cold wave - it's endurance! The polar plunge is slated to push into Southeast Lower Michigan by Tuesday night (below) and then, hang around to get reinforcements into the following week (11/16-22)!



Two other things come to my mind this early on; One- I'll be damn surprised if we don't place in or near the top 10 coldest Novembers - barring any extreme warm-up the last week. The last time we placed in the top 20 record coldest November's list was back 1997, in the 20th position with 37.1 degrees. A colder and much better placement occurred just the year before in 1996 with a 34.2 - which placed 3rd! Ironically, the year before that /1995/ we again placed in coldest Novembers list, with 35.5 degrees - 9th spot.

Rank Detroit Area* Flint Bishop** Saginaw Area***
Coldest Warmest Coldest Warmest Coldest Warmest
Temp Year Temp Year Temp Year Temp Year Temp Year Temp Year
1 29.8 1880 47.8 1931 31.3 1951 47.3 1975 29.8 1951 47.2 1931
2 33.5 1976 47.6 2001 32.0 1995 46.6 2001 31.6 1995 45.9 1975
3 34.2 1996 46.9 1902 32.6 1996 46.2 1931 32.5 1959 45.5 1902
4 34.5 1875 46.8 1975 33.0 1959 44.4 1934 33.3 1976 45.3 2001
5 34.6 1951 46.6 2011 33.3 1976 43.8 1938 33.6 1933 43.5 1909
6 34.9 1894 46.0 1963 34.3 1936 43.7 2011 33.9 1996 43.2 2009
7 35.2 1967 45.7 1948 34.4 1933 43.3 1963 33.9 1955 43.1 2011
8 35.4 1936 45.5 1994 34.8 1967 43.2 1948 34.2 1989 43.0 1963
9 35.5 1995 45.3 2009 34.8 1955 42.8 1999 34.2 1967 42.4 1999
10 35.5 1911 45.2 1999 35.0 1947 42.5 2003 34.2 1950 42.4 1948


Two - It will be interesting to see if we can challenge the resilient stretch of record low temperatures for mid November that I wrote about here, previously as SE_Mich Weather Historian (and earlier with the NWS). This record cold stretch occurred /1880/ way back near the dawn /1874/ of official records at Detroit and still hold up till this day! Both the intensity of the cold that we experience and timing may be an issue, we'll see. Something to keep in mind, especially if we have snow on the ground at the time. By the way, the last time we had a record low temperature in November is back in 1991 - and we had four during that cold snap.


DETROIT - NOVEMBER RECORD LOW MAXS AND LOWS IN BLUE
18 48 34 41.0 69/1941 18/1880 55/1954 11/1880 60/1954 14/1880 0.97/1929 18
19 47 33 40.0 68/1985 22/1880 58/1985 9/1880 63/1985 16/1880 1.07/1948 19
20 47 33 40.0 70/1942 23/1895 57/1913 12/1880 60/1931 19/1880 1.02/1988 20
21 46 33 39.0 67/1913 12/1880 56/1931 3/1880 61/1931 8/1880 1.16/2007 21
22 46 32 39.0 69/1913 16/1880 57/2010 0/1880 62/1913 8/1880 2.59/1909 22
23 45 32 38.0 69/1931 21/1880 57/1931 8/1880 63/1931 14/1880 1.24/1891 23

Again, if you'd like to read about the November 1880 stretch of record cold, click here.

And if you missed the upcoming winter's outlook, click here.

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

11/8/14

Winter Outlook 2014-15 for Southeast Lower Michigan - Another Cold Winter?


                       Winter 2014-15 Outlook for Southeast Lower Michigan                                                                      William R Deedler; Southeast Michigan Weather Historian

This winter's data presents a mixed picture for the upcoming season as natural forces and oscillations vie for domination. This revelation comes from various data sources past and present. Keeping one eye on recent upper air and surface patterns - and the other on this season's analogue and upper air data leads me to a relatively confident conclusion....

Temperatures: Below Normal /-1.0 to -4.0 degrees of the norm/

Temperatures are more variable in this winter's analogues and guidance as opposed to last winter when nearly all headlined a cold winter. That being said, normal to below normal temperatures dominate this winter again in the analogues and is suggested in other meteorological data presented here and why the below normal temperature range of -1 to -4 degrees. The largest below normal departures this winter are projected to be south and southeast of the Great Lakes. In addition; recent past seasons along with very recent unfolding conditions and the subset of preferred analogues also predict  another colder than average winter. Analogue timing of the coldest parts of the winter varies but majority suggest temperatures most likely to be below normal mid and late winter. Again, like past seasons, timing issues will most likely present themselves this winter. Recent upper wind patterns (along with the consensus of the analogues snowfalls), do suggest an early start to the winter anyway, in November. The data does imply breaks however, along the way unlike last winter.

Snowfall: Normal to Below /+5" to -10" of the norm/

With the expected jet axis and timing this season, I look for closer to normal snowfalls, if not some below normals. Upper air patterns and storm track map below suggests a somewhat busy winter across the eastern half of the country. However, I look for the substantially above normal snowfalls to be south and east of Southeast Lower Michigan. This could change depending on evolution of expected storm tracks and their ensuing placement and updates will be sent.

Analogues suggest snowfalls around normal over metro Detroit and areas north up to around 1-69... and normal to below, north of that region in the Saginaw Valley and Thumb Region - away from the lake effect regions of Lake Huron. Lake effect snows should actually be fairly busy this winter. More discussion on the analogues are below and also will be sent as the winter evolves. 


SOUTHEAST LOWER MICHIGAN WINTER 2014-15 ANALOGUE DATA

                                                    (click on to enlarge)

BROAD SCALE DISCUSSION 
As we move toward the winter of 2014-15; the near normal or neutral sea surface temperatures /SST/ that dominated the past several seasons are expected to drift into a very weak El Nino. Gone is the idea of a stronger El Nino that the model projections intimated earlier in the spring and summer. This idea of a weak El Nino (or even borderline Neutral) after several seasons of Neutral conditions, limited the number of similar hemispheric analogues for this winter to just ten (Detroit).

It is still assumed however, that the weak El Nino will affect the cold season upper and surface wind flow by aiding and abetting the subtropical flow into the country. In addition, another item of importance is the large area of above normal water temperatures seen out in the mid Pacific north of the standard El Nino. I feel this too will also influence the sub-tropical jet, especially the late Autumn into early winter anyway (see Nov map below). By mid to late winter, the warmer waters all around the central Pacific are understandably projected to wane (Feb map). 

The below Pacific water temperatures pattern is now reminiscent of a positive PDO /PDO+/ along with the weak El Nino. Recently, negative PDO conditions have held sway out over this region. Below are the current November water temperatures including the positive PDO with warmer waters surrounding cooler waters in a horse-shoe shape. 

                                                               Positive PDO


Downstream positive PDO /PDO+/ affects on the US are mapped out below. As you we see, this pattern matches well with our analogue set of composite maps this winter of the US temperature and precipitation departures section, further down below.






Unlike last winter, there is expected to be at least some influence from the Pacific via warmer waters. Of course, along with the weak El Nino and positive /PDO+/, will be the usual direct influences of the phases of the North Atlantic/Arctic Oscillation /NAO, AO/ and the Pacific and North American /PNA/ pattern. At this time, the PNA projection is primarily postive which would compliment a colder than average winter (see PNA, NAO and AO projections below). Of a major concern also will be whether or not the northern latitude heights will be inclined to go into blocking patterns...and of course, where (I exhibit this in my main player map)!

North Atlantic Oscillation/Arctic Oscillation - NAO/AO

One of the most important aspects this winter will be the phases of the NAO and subset AO.  Much has been learned about the NAO/AO and its accompanying phases in the past several decades. From the Climate Prediction Center's NAO discussion page:

The NAO exhibits considerable interseasonal and interannual variability, and prolonged periods (several months) of both positive and negative phases of the pattern are common. The wintertime NAO also exhibits significant multi-decadal variability (Hurrell 1995, Chelliah and Bell 2005). For example, the negative phase of the NAO dominated the circulation from the mid-1950's through the 1978/79 winter. During this approximately 24-year interval, there were four prominent periods of at least three years each in which the negative phase was dominant and the positive phase was notably absent. In fact, during the entire period the positive phase was observed in the seasonal mean only three times, and it never appeared in two consecutive years.

An abrupt transition to recurring positive phases of the NAO then occurred during the 1979/80 winter, with the atmosphere remaining locked into this mode through the 1994/95 winter season. During this 15-year interval, a substantial negative phase of the pattern appeared only twice, in the winters of 1984/85 and 1985/ 86. However, November 1995 - February 1996 (NDJF 95/96) was characterized by a return to the strong negative phase of the NAO. Halpert and Bell (1997; their section 3.3) recently documented the conditions accompanying this transition to the negative phase of the NAO.

Many (myself included) believe this winter will be dominated by a more negative phase of the NAO/AO through observations and some various newly discovered indexs.

Here is the experimental NAO/AO forecasts into early this winter I post every year from Kyle Macritchie Ph.D. candidate in Atmospheric Science at the University at Albany. As you can see, his experimental projections, based on the CFSv2 analysis are decidedly negative for both indices into the winter as of early November. Again, the PNA pattern projection is decidedly positive.







October Pattern Index /OPI/

The OPI strongly suggests a negative NAO/AO pattern to dominate this winter, any negative value indicates this and a preliminary value of -2.2 was reached. Click on the /OPI/ above for an explanation and how this is calculated.


High Latitude Eurasia October Snow Cover

The snow cover over Siberia/Eurasia is the second highest on record behind 1976-77 (and we all know what that winter was like). It been theorized that the snow cover over that part of the country in October directly relates to the building cold air masses for the upcoming winter. However, still exactly where it will be delivered is more problematic.

                                               Long Term Snow Cover Analysis

                                      Short Term analysis since 2007 (-2008)
                                
                                                Flow Chart for the Snow Cover


What Upper Air Features to Watch For This Winter




As discussed above, this diagram displays the main players to this winters expected pattern.



Creating the Winter 2014-15 Analogues

These selected analogue winters below followed a similar sequence of events (though timing may vary a bit) that recently were observed over the Pacific during the past several seasons. Neutral conditions prevailed for a considerable time period (generally two to three years) then they were followed by a primarily weak El Nino. Their numbers were smaller than in previous years as this particular type ENSO pattern in sequence is less common.

This year, I also included the ongoing solar cycle chart at the time of the analogues and compared it to the cycle threshold we are presently in. 

More studies have been formulated as to the connection of the solar cycle (max/min) and the 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 easterly and is this expected continue throughout the winter.


A strong polar vortex is more likely to herald a positive /AO+/ with the resultant jet stream track bringing milder conditions to the Great Lakes as the vortex contracts north and the Pacfic onshore flow dominates in its absence (figure on the left).  Whereas, a weaker polar vortex (under a less cold stratosphere) can contribute to a negative /AO-/ with the resultant jet stream track of colder air from the north pole and a more blocked pattern, more typical. Therefore, a warmer stratosphere and subsequent negative /AO-/, leads to a colder winter and higher chances of blocking. This is the pattern much of the early data suggests.


The main influence on the QBO from solar cycles has been studied
with 65 years of data studied. The results for the entire data set fully confirm the early findings and suggest a significant effect of the sunspot cycle /SSC/ on the strength of the stratospheric polar vortex and on the mean meridional circulation.

EPO- or NAO-?

While this is typical it is not always the cause and effect for a cold winter; case in point - last winter's very cold winter. One of the main culprits was the negative Eastern Pacific Oscillation in which, in a negative phase, encourages strong ridging high up into the northern latitudes over Alaska and extreme western Canada and thus, sends a "waterfall" of Arctic air cascading south through Canada and into the US.  While this happened frequently last winter, back in my Winter Outlook of 2002-03, I explained this while analyzing past winters...

"The Eastern Pacific Oscillation (EPO) is the upper wind flow over the Eastern Pacific influenced by the ocean. When in a positive phase, the EPO generally is reflected by dominant stronger zonal flow and/or troughing along the West Coast of the U.S. This combination, in turn, tends to funnel milder Pacific air well inland into the country and thus, limits arctic outbreaks by holding them at bay up in Canada. When the EPO is dominated by a negative phase (as with the NAO), more ridging develops along the West Coast as higher pressure extends from the Gulf of Alaska south along the West Coast of Canada (opposite of the positive phase). This, in turn, encourages a northwesterly flow from Canada into the middle and eastern sections of the US and thus, the delivery of polar or arctic air."



Cooler Northeast Pacific waters are more favorable or encourage troughing and thus a positive /EPO+/, while warmer waters over the same region area more favorable for ridging and a negative /EPO-/


                                                 Winter of 2013-14


The main influence on the QBO from solar cycles has been studied
with 65 years of data studied. The results for the entire data set fully confirm the early findings and suggest a significant effect of the sunspot cycle /SSC/ on the strength of the stratospheric polar vortex and on the mean meridional circulation.  Again below are this winter's analogues...
 

SOUTHEAST LOWER MICHIGAN WINTER 2014-15 ANALOGUE DATA

(CLICK-ON TO ENLARGE)


Note how all the solar sunspot cycle numbers during our analogue winters were in the lower half of the solar cycle. The current solar cycle amplitude this year also duplicates this well with the sunspot numbers mainly below 100 Rt
  (see chart below).



TEMP COMPOSITE MAPS FOR ANALOGUES


                                                    PRECIPITATION COMPOSITE MAPS FOR ANALOGUES


     

               COMPOSITE JET STREAM /500 MB/ MAP OF ANALOGUE YEARS

                                           

Referring back to our main players map and upper air anomaly for continuity below, shows the polar vortex occasionally exudes it influence well to the S-SE

 


 

Next Up; Winter Get's An Early Start!

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

Winter 2013-14 Epilogue

Overall, last years analogues and Outlook held up considerably well...even to the point of having and projecting some of the most brutally cold and snowy winters combined ever experienced in modern times across Southeast Lower Michigan. That being said, while past and present trends back then held the foreboding of a "rough", "hard" or simply "bad" winter as early as November; nothing as extreme as experienced last winter could have been forecast unless one would be so bold (and foolish in every instances except ONE) to use the headline sentence  "Worst Winter Ever to Hit Southeast Lower Michigan Since Records have Been Kept Expected This Winter 2013-14". It's just not done when looking out several MONTHS ahead without being called an alarmist, wish-casting or a plain winter weather nut. One would have had to predict the coldest winter when combined with a record amount of snow since 1880 to succeed totally.


First from LAST winter's season outlook;

Temperatures:

In one of the strongest below normal signals I've seen in the 17 years of Outlooks; you'd think it'd be a slam dunk but not always. Granted most of the time when a temperature trend was even close to this strong, it turned out to be in the right direction.I can't go against a cold signal this strong and dominant nor from what I'm seeing this fall, therefore below normal it is.

In addition; winter analogues and resulting final statistical data strongly suggest a colder than normal winter. I look for the final winter statistical departure to range between -1.0  to -4.0 across Southeast Lower Michigan when compared to the 30 year 1981-2010 normals (also included on analogue charts).  

While the analysis of my winter analogues show mainly below normal (very similar to our recent summer analogues), it is felt the coldest of analogues are too cold and thus, skewing the average down some. However, at the same time, some of the cold outbreaks seen this winter will rival some of the outbreaks seen in recent compared milder winters, leading to a normal to above normal amount of below zero days. 

In hind-cast;  

The analogues, some real time upper wind data, recent autumn trends along with long-term experience pointed to a notably cold winter. My Winter Outlook called for this strongly along with the cold being dominant trend through the winter - but not of the magnitude of what did occur.  Forecasting up to -4.0 for the winter departure many months out, I deducted was a good "live-with" projection at the time... but still risky both ways! I will say, I did make the mistake in thinking the the coldest of analogues were "too cold"- not this time. No way was last winter's cold analogues too cold but still, I would have NOT forecast the worst winter ever in regards to a combination of temperatures and snowfall!

 

Snowfall:

 

As would be somewhat expected in a Neutral ENSO winter, snowfall amount ranges were more extreme in the analogue years with some of the snowiest to snow-less seasons included this season. Overall, however snowfall means in the analogue years tended to hug the lower end of the normal ranges. Southeast Michigan was clearly in the sweet spot for heavy snows in first analogue of 1880-81 (snowiest winter on record) and ironically about 100 years later for #3 snowiest in 1981-82.

On average, snowfall should average near to above normal (or near normal to 12"above of the normal) across the south half of the region and normal to 12” below  across the northern sections. 

 

In hind-cast; 

As mentioned later last winter/spring, 1880-81 and 1981-82 were very good analogues for the Winter of 2013-14. Not only did they contain the highest amounts of snow previously recorded in Detroit but they were in the top ten coldest...a feat hard to come by considering a century plus of records. The Winter of 1880-81 final winter statistics were almost a duplicate of this past winter's /2013-14/ snowfall in Detroit and close to the average temperature. 

In 1880-81 the average temperature at Detroit came in at 21.8 degrees and 93.6" of snow fell, while in 1981-82 the average temperature again came close at 21.9 and 74.0" of snow fell. However, clearly 2013-14 was a worst winter as much of the area around and south of I-69 to the Ohio border received record amounts of snow AND the entire region averaged the 7th coldest winter on record! As a side note, also remember there was a heat island affect at times at Detroit Metro Arpt which makes Detroit's  average temperature that much more impressive! Here again are the impressive stats:

 

                                                Winter 2013-14 Temperature Statistics

Location Winter 2013-14 Coldest Winter Since
2013-14 Ranking All-time Coldest
Detroit 20.9 1977-78
8th 18.8 (1903-04)
Flint 19.0 1978-79 5th 16.7 (1976-77)
Saginaw 18.2 1978-79
T-7th 15.7 (1962-63)

                                 

                                                2013-14 Seasonal Snowfall Stats 

Seasonal Normal Winter 2013-14
(through May 5th)
Record (Year) Seasonal Ranking
Detroit Area 42.5" 94.9"
93.6" (1880-81) 1st
Flint Area 47.4" 83.9"
82.9" (1974-75) 1st
Saginaw 45.5" 59.4"
87.2" (1966-67) 15th

To see a more complete listing of last winter's stats and winter review, go here.

Second, we have the October Pattern Index, or OPI. The above image shows anomalies of the October Pattern Index over the last several days, since the start of October. The OPI, the concept of which was brought about by a group of Italian scientists, says that monitoring of the atmosphere during the month of October can yield great hints at what the coming winter will bring. October is a month well-known for big winter-predictors showing their cards for the coming cold season (i.e. the LRC, and Judah Cohen's Snow Advance Index (SAI)), but it may interest many to know what the OPI may be one the best, if not the best predictor of the upcoming winter season out of the three mentioned above.

The explanation page of the OPI tells of the index's incredible accuracy, around 90%, of being able to predict the December-January-February Arctic Oscillation. In the winter, a negative phase of the Arctic Oscillation (AO) means the polar vortex is weak and is more prone to sending cold outbreaks to the mid-latitudes, while a positive AO indicates a strong polar vortex, hence a warmer winter increases in probability.

The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion. - See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion. - See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The explanation page of the OPI tells of the index's incredible accuracy, around 90%, of being able to predict the December-January-February Arctic Oscillation. In the winter, a negative phase of the Arctic Oscillation (AO) means the polar vortex is weak and is more prone to sending cold outbreaks to the mid-latitudes, while a positive AO indicates a strong polar vortex, hence a warmer winter increases in probability.

The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion.

Lastly, let's go over the Lezak Recurring Cycle.

HPC/WPC
Something I've discussed on here more than a few times is the concept of the Lezak Recurring Cycle, or LRC. The LRC was developed by meteorologist Gary Lezak, and discusses the idea that weather patterns which develop in October leave a 'footprint' of sorts that is repeated in a regular interval, between 40-60 days through the winter and following spring. In other words, the weather patterns that develop in October repeat themselves for the better chunk of the next year.

Since mid-September, we've seen predominantly below-normal temperatures for large swaths of the Central and East US. One of the more impressive atmospheric set-ups came with this very strong upper level low positioned just north of the US/Canada border. Notice how the influence of this low extends all the way to the Gulf Coast, per the contour lines. My worry is that this upper level low will end up being another piece of the polar vortex, like we saw last winter, that might push south and bring intense cold back once or twice through the coming winter. I'm not going to speculate any further, but some sharp Arctic blasts may be in the works for the next few months.
As we dip into a warm period right now, this will likely reflect in the LRC with some warm periods in the coming winter, but I'll go into that further down the road when we know how long this warmth might last.
- See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The explanation page of the OPI tells of the index's incredible accuracy, around 90%, of being able to predict the December-January-February Arctic Oscillation. In the winter, a negative phase of the Arctic Oscillation (AO) means the polar vortex is weak and is more prone to sending cold outbreaks to the mid-latitudes, while a positive AO indicates a strong polar vortex, hence a warmer winter increases in probability.

The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion.

Lastly, let's go over the Lezak Recurring Cycle.

HPC/WPC
Something I've discussed on here more than a few times is the concept of the Lezak Recurring Cycle, or LRC. The LRC was developed by meteorologist Gary Lezak, and discusses the idea that weather patterns which develop in October leave a 'footprint' of sorts that is repeated in a regular interval, between 40-60 days through the winter and following spring. In other words, the weather patterns that develop in October repeat themselves for the better chunk of the next year.

Since mid-September, we've seen predominantly below-normal temperatures for large swaths of the Central and East US. One of the more impressive atmospheric set-ups came with this very strong upper level low positioned just north of the US/Canada border. Notice how the influence of this low extends all the way to the Gulf Coast, per the contour lines. My worry is that this upper level low will end up being another piece of the polar vortex, like we saw last winter, that might push south and bring intense cold back once or twice through the coming winter. I'm not going to speculate any further, but some sharp Arctic blasts may be in the works for the next few months.
As we dip into a warm period right now, this will likely reflect in the LRC with some warm periods in the coming winter, but I'll go into that further down the road when we know how long this warmth might last.
- See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion. - See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion. - See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion. - See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion. - See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The image above shows correlations with the Pacific Decadal Oscillation (PDO) and surface temperatures during a December-January-February period. What this chart is saying, is whenever the PDO is positive, temperatures in the West US will be warm (due to the positive correlation), and temperatures in the East US will be cold (due to the negative correlation). Similarly, when the PDO is negative, temperatures in the West US (East US) will be cold (warm), due to the positive (negative) correlation. So long as the PDO remains positive this winter, the risk of a cold winter would still be maintained for most of the Central and all of the East US. It remains to be seen if the cold waters will keep pushing east and erase the positive PDO completely, but as of right now, this would be a beneficial development for both cold weather fans in the East US, and warm weather fans in the West US.

Interestingly enough, positive PDO winters tend to bring wetter than normal winters to the Northern Plains... - See more at: http://theweathercentre.blogspot.com/#sthash.7JVoR6Xe.dpuf