Winter 2014-2015 Medium-Term Discussion

[The_Global_Warmer]

This is nuts.

 

 

[brooklynwx99]

This is nuts.

 

 

 

This looks more like a Dec/Jan temperature map than a November map. 

[donsutherland1]

I posted this discussion in the Mid Atlantic thread but could fit here just as easy.

http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/11/06/d-c-to-be-dealt-a-dose-of-winter-in-about-a-week-and-it-may-stick-around/

The stratsophere is interesting. Adria Lang wrote this about it.

There has been much discussion of the forecasted recurvature of Nuri and the re-intensification of Nuri as an extratropical cyclone. There are, as highlighted by many on this list, implications of this extratropical transition process on North American weather and it is linked to the downstream propagation of wave energy along the tropopause waveguide. Something that most of you probably are not looking at are impacts of this Nuri-induced wave activity on the stratospheric polar vortex.

In the recent (0600 UTC 5 Nov) GFS forecast, the wave train associated with Nuri is responsible for two notably large ridge building events, one in the N. Pacific and one linked to an explosive cyclogenesis event in the N. Atlantic. These ridges pinch the Arctic cold pool, creating an amplified wavenumber 2 pattern in the troposphere by forecast day 7 and the return of a lobe of the 'polar vortex' to the US.

The amplified tropospheric wavenumber-2 pattern in the forecast is associated with the amplification of the stratospheric wavenumber-2 pattern. By forecast day 15 (shown below), this wave amplification leads to a stratospheric warming event and the initial splitting of the stratospheric polar vortex. Of course this is a 15 day forecast during a lower predictability period, but for what its worth, in the extended range we are generally talking about planetary scale features. If this forecast holds true, it would be (to my knowledge) the earliest vortex splitting event on record (most occur in Jan-Feb).

If the stratospheric vortex splitting event were to occur as forecast, it would also have substantial implications on the evolution of the vortex for the rest of the winter season. The last time we had a weak stratospheric vortex near this magnitude this early in the winter season was Nov 1996 (linked to the re-intensification of TC-Dale as an extratropical cyclone and a vortex displacement event). By late December 1996 the stratospheric portion of the vortex recovered and by March 1997 we had the coldest Arctic stratosphere observed in the satellite era (associated with low Arctic ozone and cold European temperatures).

This could be an interesting winter!

Andrea

Thanks for posting this commentary, Wes. It is fascinating and it will be interesting to see if the stratospheric polar vortex splitting event takes place and then how things evolve afterward.

[wildweatherman179]

I posted this discussion in the Mid Atlantic thread but could fit here just as easy.

http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/11/06/d-c-to-be-dealt-a-dose-of-winter-in-about-a-week-and-it-may-stick-around/

The stratsophere is interesting. Adria Lang wrote this about it.

There has been much discussion of the forecasted recurvature of Nuri and the re-intensification of Nuri as an extratropical cyclone. There are, as highlighted by many on this list, implications of this extratropical transition process on North American weather and it is linked to the downstream propagation of wave energy along the tropopause waveguide. Something that most of you probably are not looking at are impacts of this Nuri-induced wave activity on the stratospheric polar vortex.

In the recent (0600 UTC 5 Nov) GFS forecast, the wave train associated with Nuri is responsible for two notably large ridge building events, one in the N. Pacific and one linked to an explosive cyclogenesis event in the N. Atlantic. These ridges pinch the Arctic cold pool, creating an amplified wavenumber 2 pattern in the troposphere by forecast day 7 and the return of a lobe of the 'polar vortex' to the US.

The amplified tropospheric wavenumber-2 pattern in the forecast is associated with the amplification of the stratospheric wavenumber-2 pattern. By forecast day 15 (shown below), this wave amplification leads to a stratospheric warming event and the initial splitting of the stratospheric polar vortex. Of course this is a 15 day forecast during a lower predictability period, but for what its worth, in the extended range we are generally talking about planetary scale features. If this forecast holds true, it would be (to my knowledge) the earliest vortex splitting event on record (most occur in Jan-Feb).

If the stratospheric vortex splitting event were to occur as forecast, it would also have substantial implications on the evolution of the vortex for the rest of the winter season. The last time we had a weak stratospheric vortex near this magnitude this early in the winter season was Nov 1996 (linked to the re-intensification of TC-Dale as an extratropical cyclone and a vortex displacement event). By late December 1996 the stratospheric portion of the vortex recovered and by March 1997 we had the coldest Arctic stratosphere observed in the satellite era (associated with low Arctic ozone and cold European temperatures).

This could be an interesting winter!

Andrea

This is a very interesting thought. However it bears importance to keep in mind, as someone mentioned, the background state does not match closely at all. Also, there are years where similar events have occurred and led to some of the coldest winters the Central/Eastern US has ever experienced. Off the top of my head I can think of 1977 and, if the descriptions I have read are correct, the autumn of 1917 saw very similar events lead to a very incredible, snowy and cold winter for 1917-18 for the entire eastern US east of the Rockies. A counterpoint was worth mentioning so I did. Not saying either will happen. This could be a somewhat historic year to follow and I'm going to enjoy it immensely.

[Spartman]

This looks more like a Dec/Jan temperature map than a November map. 

November cancel. Early winter for many on its way.

[Iceagewhereartthou]

This looks more like a Dec/Jan temperature map than a November map.

Unfortunately the southeast ridge is present and the cold has trouble making it to the lee of the mountains there. Would like to see it centered a click to the east, but over the past few years, central US seems to have most of the fun.

[donsutherland1]

Several quick thoughts...

 

1. The kind of cold forecast on the ensembles and operational global guidance fits what one would expect from the forecast teleconnections (1950-2013).

 

 

The coming cold is a high confidence idea and some areas could see readings 1.5 to perhaps 3.0 standard deviations below normal. Given the expanse of the cold anomalies, it would not surprise me if such cities as Philadelphia and New York saw their first snow flakes by 11/20.

 

2. Despite the warmth it has persistently shown across North America, the CFSv2 continues to appear to offer an unlikely scenario. FWIW, one of the more common analog cases showing up based on the mid- and late-October teleconnections and forecast teleconnections going forward is 2000. It should be noted that the most recent CFSv2 forecast for December shows a large area of cold anomalies across northern Canada. Hence, this run might offer the first hint that the CFSv2 could begin to evolve toward a colder December scenario.

[Absolute Humidity]

Several quick thoughts...

 

1. The kind of cold forecast on the ensembles and operational global guidance fits what one would expect from the forecast teleconnections (1950-2013).

 

 

The coming cold is a high confidence idea and some areas could see readings 1.5 to perhaps 3.0 standard deviations below normal. Given the expanse of the cold anomalies, it would not surprise me if such cities as Philadelphia and New York saw their first snow flakes by 11/20.

 

2. Despite the warmth it has persistently shown across North America, the CFSv2 continues to appear to offer an unlikely scenario. FWIW, one of the more common analog cases showing up based on the mid- and late-October teleconnections and forecast teleconnections going forward is 2000. It should be noted that the most recent CFSv2 forecast for December shows a large area of cold anomalies across northern Canada. Hence, this run might offer the first hint that the CFSv2 could begin to evolve toward a colder December scenario.

Thanks Don, great ananysis. Interesting note Dec 2000 which had a warm start then rather quickly transitioned to a cold and snowy 2nd half at least for the North East.

[jdrenken]

I posted this discussion in the Mid Atlantic thread but could fit here just as easy.

http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/11/06/d-c-to-be-dealt-a-dose-of-winter-in-about-a-week-and-it-may-stick-around/

The stratsophere is interesting. Adria Lang wrote this about it.

There has been much discussion of the forecasted recurvature of Nuri and the re-intensification of Nuri as an extratropical cyclone. There are, as highlighted by many on this list, implications of this extratropical transition process on North American weather and it is linked to the downstream propagation of wave energy along the tropopause waveguide. Something that most of you probably are not looking at are impacts of this Nuri-induced wave activity on the stratospheric polar vortex.

In the recent (0600 UTC 5 Nov) GFS forecast, the wave train associated with Nuri is responsible for two notably large ridge building events, one in the N. Pacific and one linked to an explosive cyclogenesis event in the N. Atlantic. These ridges pinch the Arctic cold pool, creating an amplified wavenumber 2 pattern in the troposphere by forecast day 7 and the return of a lobe of the 'polar vortex' to the US.

The amplified tropospheric wavenumber-2 pattern in the forecast is associated with the amplification of the stratospheric wavenumber-2 pattern. By forecast day 15 (shown below), this wave amplification leads to a stratospheric warming event and the initial splitting of the stratospheric polar vortex. Of course this is a 15 day forecast during a lower predictability period, but for what its worth, in the extended range we are generally talking about planetary scale features. If this forecast holds true, it would be (to my knowledge) the earliest vortex splitting event on record (most occur in Jan-Feb).

If the stratospheric vortex splitting event were to occur as forecast, it would also have substantial implications on the evolution of the vortex for the rest of the winter season. The last time we had a weak stratospheric vortex near this magnitude this early in the winter season was Nov 1996 (linked to the re-intensification of TC-Dale as an extratropical cyclone and a vortex displacement event). By late December 1996 the stratospheric portion of the vortex recovered and by March 1997 we had the coldest Arctic stratosphere observed in the satellite era (associated with low Arctic ozone and cold European temperatures).

This could be an interesting winter!

Andrea

 

 

 

Were Andrea's comments created on the 6th?

 

EDIT:  Found it buried in a forwarded email to me.

[blizzardof96]

I don't think it would make our winter mild overall, but I'm sure we'll have a couple warmer periods; but even a lot of our great winters have that. But I wouldn't compare this winter to 1996-1997 as our entire background state is different. ENSO, PDO, SAI/SCE, solar state, and even the QBO was already starting to rise toward neutral/positive by late winter at 30 mb.

Although a true CW this year with a 10mb/60N U wind reversal will be difficult an increase in wave 1 does look very likely if the progged H5 pattern keeps up(Strong Aleutian low with WAF into Alaska). My money is on a Dec SSW.

 

For those curious heres Jan-March in all CW years with a -QBO:

 

-QBO CW years with ONI between +0.5 to +1.5 in the DJF trimonthly period:

 

March in those years has a very warm stratosphere as secondary SSW's in mid to late winter were common(e.g march '59, Jan '77 and March '80):

500mb pattern

[DaculaWeather]

Temps Wednesday morning in Wyoming and Montana

 

[Hoosier]

December 2000 was epic cold/snow in the Midwest.  Many places had their 1st or 2nd coldest December on record IIRC.

[Chicago WX]

December 2000 was epic cold/snow in the Midwest.  Many places had their 1st or 2nd coldest December on record IIRC.

 

A few of them did indeed. Lots of top 5's below:

 

Chicago: 16.0˚  (2nd coldest)

Cleveland: 22.3˚ (4th coldest)

Columbus: 23.3˚ (4th coldest)

Detroit: 19.2˚ (3rd coldest)

Des Moines: 11.6˚ (2nd coldest)

Duluth: 4.4˚ (tied for 5th coldest)

Grand Rapids: 19.0˚ (2nd coldest)

Green Bay: 11.4˚ (tied for 5th coldest)

Indianapolis: 19.7˚ (3rd coldest)

Kansas City: 19.0˚ (2nd coldest)

La Crosse: 8.6˚ (3rd coldest)

Louisville: 25.0˚ (coldest on record)

Madison: 11.2˚ (3rd coldest)

Marquette: 12.1˚ (5th coldest)

Minneapolis: 7.6˚ (4th coldest)

Moline: 13.1˚ (coldest on record)

St. Louis: 21.6˚ (2nd coldest)

South Bend: 17.1˚ (coldest on record)

Springfield IL: 17.3˚ (2nd coldest)

Springfield MO: 23.3˚ (2nd coldest)

[stadiumwave]

Unfortunately the southeast ridge is present and the cold has trouble making it to the lee of the mountains there. Would like to see it centered a click to the east, but over the past few years, central US seems to have most of the fun.

However...for storm track purposes I wouldn't want to be in the heart of the cold. Closer to the baroclinic zone is ideal.

[Harry]

December 2000 was epic cold/snow in the Midwest.  Many places had their 1st or 2nd coldest December on record IIRC.

 

Not sure about the cold rank but for snow it is the record holder ( for any month ) with 52.5" for the month.. Nov 2000 was also the snowiest November as well with 21.5". Very epic stretch that fizzled after the New Year.. Only another 16" or so would fall the rest of the season.. Finished with about 90" on the season..

[JBG]

Not sure about the cold rank but for snow it is the record holder ( for any month ) with 52.5" for the month.. Nov 2000 was also the snowiest November as well with 21.5". Very epic stretch that fizzled after the New Year.. Only another 16" or so would fall the rest of the season.. Finished with about 90" on the season..

By contrast, KNYC's fired up with the December 30, 2000 storm and the snowy cast continued through around March 8 or 9. In fact, right after the March 3 "storm that never happened" we had a nice surprise storm that Friday, at least in Westchester.

[donsutherland1]

In terms of the coming extreme nature of the pattern (not necessarily extreme conditions), below are the forecast 500 mb anomalies on the GFS ensembles (for 11/15 12z):

 

 

The above average height anomalies centered in the vicinity of the Yukon and Northwest Territories reaches 5 standard deviations above normal. In response, it probably isn't too surprising that all of southern Canada and most of the CONUS are forecast to be covered by colder than normal conditions.

[usedtobe]

Were Andrea's comments created on the 6th?

 

EDIT:  Found it buried in a forwarded email to me.

SOunds about right for when I saw the comment. It was forwarded to me by Jason (I think).

[Weathergun]

0z Euro Ensemble Mean has another artic blast coming into the CONUS by day 10:

 

 

[Isotherm]

Below are maps I utilized in my winter forecast last year, illustrating the importance of November.

 

November 500mb pattern prior to bad / warm ensuing winters:

 

 

 

November 500mb pattern prior to good / colder ensuing winters:

 

 

 

 

Note the tendency for higher heights in the EPO, AO, and NAO regions.

[donsutherland1]

Morning thoughts:

 

1. The 120-hour GFS ensemble mean 500 mb anomalies continue to show a 5 standard deviation or greater above normal height anomaly centered over part of the Yukon and Northwest Territories. Even as the CDC forecast for the EPO remains stuck at 11/7 0z, the above height anomalies suggests that the EPO could dive to between 2-3 standard deviations below normal in coming days. 3 standard deviation anomalies persist through 192 hours on the GFS ensembles.

 

2. The AO currently stands at -0.857. The GFS ensembles indicate that it will likely fall to -3 and -2. 

 

All said, a persistently cold pattern should unfold across southern Canada and the CONUS.

[The_Global_Warmer]

Absolutely absurd.  If we manage to get even a weak blanket of 1-4" snow cover from the Missouri valley back to Canada during this period when this blast arrives it could get down right nasty.

 

 

Record lows in STL not only vary between 5-15F next week because they are snow cover dependent they are all from the 1800s to 1950.

 

Even with the modern UHI those teens record could be smashed if we get snow cover.

 

 

[Srain]

Very impressive Day 8+ analogs. Certainly some very memorable years across the Plains.

[andyhb]

Very impressive Day 8+ analogs. Certainly some very memorable years across the Plains.

610analog.off-6.gif

 

Couple of interesting years there about a week in advance of November severe weather events that have been in the top five across the most of the analog suite there for the past several days.

[donsutherland1]

Extreme November Pattern Now Unfolding...

 

As had been indicated on the guidance since near the beginning of the month, an extreme pattern is now developing for November. In response to the record-breaking extratropical system that developed from Supertyphoon Nuri's remnants in the North Pacific Ocean, height anomalies that are forecast to peak at 5.5 standard deviations above normal over a portion of the Yukon and Northwest Territory are now evolving.

 

In response, colder air has been moving steadily southward into the CONUS. In the midst of this cold air, a weak system will likely develop off the northern Mid-Atlantic Coast and bring some showers or a period of rain ending as snow showers even to coastal portions of northern New Jersey, southeastern New York State, and Connecticut. Some areas could pick up a slushy coating.

 

However, the height of the anomalous cold will move into the Plains States early next week (readings up to 3.5 standard deviations below normal) and then across the Southeast (readings up to 5.5 standard deviations below normal) according to the latest run of the GFS ensembles.

 

Afterward, particularly during the week of Thanksgiving, the pattern should become less amplified. Blocking is forecast to temporarily ease of disappear. However, if past similar pattern evolutions are representative, blocking could redevelop toward the end of November or early December.

 

Perhaps as a first indication that the CFSv2 is beginning to pick up on the risk of blocking, that long-range model has begun to show an expansive area of cool anomalies for December for the first time. As previously noted in this thread by numerous posters, its earlier runs depicting warm anomalies across virtually all of North America appeared suspect given the likelihood of the onset of a generally blocky winter (OPI, SAI, historic outcomes following a very blocky October).

 

[MillvilleWx]

Extreme November Pattern Now Unfolding...

 

As had been indicated on the guidance since near the beginning of the month, an extreme pattern is now developing for November. In response to the record-breaking extratropical system that developed from Supertyphoon Nuri's remnants in the North Pacific Ocean, height anomalies that are forecast to peak at 5.5 standard deviations above normal over a portion of the Yukon and Northwest Territory are now evolving.

 

In response, colder air has been moving steadily southward into the CONUS. In the midst of this cold air, a weak system will likely develop off the northern Mid-Atlantic Coast and bring some showers or a period of rain ending as snow showers even to coastal portions of northern New Jersey, southeastern New York State, and Connecticut. Some areas could pick up a slushy coating.

 

However, the height of the anomalous cold will move into the Plains States early next week (readings up to 3.5 standard deviations below normal) and then across the Southeast (readings up to 5.5 standard deviations below normal) according to the latest run of the GFS ensembles.

 

Afterward, particularly during the week of Thanksgiving, the pattern should become less amplified. Blocking is forecast to temporarily ease of disappear. However, if past similar pattern evolutions are representative, blocking could redevelop toward the end of November or early December.

 

Perhaps as a first indication that the CFSv2 is beginning to pick up on the risk of blocking, that long-range model has begun to show an expansive area of cool anomalies for December for the first time. As previously noted in this thread by numerous posters, its earlier runs depicting warm anomalies across virtually all of North America appeared suspect given the likelihood of the onset of a generally blocky winter (OPI, SAI, historic outcomes following a very blocky October).

 

 

Great write up Don as always. It looks like the next 2 weeks will be an appetizer before the main course heading into the winter. This might not be the recipe for a white Thanksgiving, but the future beyond that into December looks formidable with a possible blocky pattern developing into early December. The southern stream looks to remain active throughout the period with no end in sight. The ramifications of which could be prove to be huge for snow lovers and forecasters alike down the road. Thanks

[donsutherland1]

For some perspective on the extremes so far, Casper, WY had a low temperature of -26° yesterday and -27° today. The records for 11/12 and 11/13 were both -11° from 1986. The previous earliest the temperature fell to -26° or below there was December 5, 1972 when the temperature fell to -27°.

[donsutherland1]

Great write up Don as always. It looks like the next 2 weeks will be an appetizer before the main course heading into the winter. This might not be the recipe for a white Thanksgiving, but the future beyond that into December looks formidable with a possible blocky pattern developing into early December. The southern stream looks to remain active throughout the period with no end in sight. The ramifications of which could be prove to be huge for snow lovers and forecasters alike down the road. Thanks

I agree. I suspect it will be an exciting winter for the Mid-Atlantic (at least for those who like cold and snow). I'm looking forward to it.

[Srain]

Couple of interesting years there about a week in advance of November severe weather events that have been in the top five across the most of the analog suite there for the past several days.

It is very possible as a temporary zonal flow becomes established that we could see a rather potent storm across the Plains extending E near the Thanksgiving timeframe. The GFS and the ensemble mean have hinted that such a scenario may be possible.

[N. OF PIKE]

For some perspective on the extremes so far, Casper, WY had a low temperature of -26° yesterday and -27° today. The records for 11/12 and 11/13 were both -11° from 1986. The previous earliest the temperature fell to -26° or below there was December 5, 1972 when the temperature fell to -27°.

Breaking a record low by 15 degrees is amazing.