Winter 2013-14 medium range discussion

[donsutherland1]

that's pretty encouraging to say the least don. the way the -EPO is cooperating but the AO/NAO and PNA aren't its going to be a battle to get that ideal setup we need for those nice east coast winter storms. I guess by the end of this month we'll know more as to what to expect for atleast the first half of January. your forecasts/analysis have been pretty accurate as well

It will be interesting to see how things turn out. NYC and Boston have now joined Philly with 8.0" or more snow for December.

[REDMK6GLI]

It will be interesting to see how things turn out. NYC and Boston have now joined Philly with 8.0" or more snow for December.

 

with 95'-96' being thrown around and having you post these charts its gotta be encouraging for us in the megalopolis for the remainder of winter. big wild card still being other indices besides the -EPO we have pretty much holding the winter pattern up thus far this winter

[Absolute Humidity]

Don, that chart is very impressive. I wonder if any of those years featured many winters without a KU event. If the EPO can remain predominantly negative, it seems the region can achieve at least average snowfalls, via warm air advection, frontal waves and clippers. However, without real AO or NAO blocking, a KU event seems unlikely. North Atlantic blocking aside, it seems it might actually be possible if the PNA can rise a little above neutral to allow a well timed system to dig. The current placement of polar vortex could act as a pseudo block. What are your thoughts?

[OSUmetstud]

It's difficult to try to pinpoint storm tracks. Neither ensembles nor analogs provide much insight into such storm tracks.

 

However, December snowfall patterns can offer some insight. With today's clipper system, PHL, NYC, and BOS will very likely reach 8" or more snowfall for December (PHL is already there). Looking westward to Buffalo, such years have seen 50% with 80" or more seasonal snowfall in Buffalo and 50% less than 80" seasonal snowfall.

 

For the winters with less than 70" snowfall: December snowfall: < 20" (4/4 cases)

For the winters with less than 80" snowfall: December snowfall: < 25" (5/6 cases)

For the winters with 80" or more snowfall: December snowfall: 25" or more (5/6 cases)

For the winters with 100" or more snowfall: December snowfall: 25" or more (4/4 cases)

 

December snowfall through 12/16 was 16.6". The cold shot that appears likely after this weekend might produce some meaningful lake effect snows to boost that figure. The GFS shows an even stronger cold shot before the end of December, so there might be another opportunity for lake effect snow. Lighter synoptic snows might coincide with the frontal passages.

Don, unlike most east coast cities, December is BUF's snowiest month with the normal being near 27".  Also, December snowfall has the highest correlation with seasonal snowfall.  

[donsutherland1]

Verification:

 

In Message #190 (11/28/2013) I posted the following for the December 8-14, 2013 period:

 

Overall, my thoughts are that the Pacific Northwest, Northern/Central/Southern Plains, Great Lakes area, and northern New England are likely to wind up colder than normal. The Middle Atlantic and southern New England regions will probably wind up near normal. The Southeast and Gulf Coast will probably be warmer than average. The Southwest will probably also be somewhat warmer than normal.

 

Even large parts of the idea verified with the cold anomalies, the cold proved more expansive than what I had mentioned. It was also more widespread than either the ensembles, partial teleconnection cases, and ENSO-Teleconnection cases suggested. Only Florida and a portion of Georgia were warmer than normal. The remainder of the U.S. and also Canada were generally colder to much colder than normal.

 

[donsutherland1]

Don, unlike most east coast cities, December is BUF's snowiest month with the normal being near 27".  Also, December snowfall has the highest correlation with seasonal snowfall.  

 I suspect LES probably plays a key role in making December Buffalo's snowiest month. The December snowfall correlation is quite useful for gaining insight into the rest of the winter snowfall for Buffalo, as well.  

[Rjay]

I suspect LES probably plays a key role in making December Buffalo's snowiest month. The December snowfall correlation is quite useful for gaining insight into the rest of the winter snowfall for Buffalo, as well.

Oh def. It has to be the LES. With warm lake waters and no parts of Lake Erie frozen yet.

[donsutherland1]

The big weather story in the near-term will be the potential bout of record warmth in parts of the East that could occur ahead of an approaching cold front on Sunday, December 22. The GFS ensembles indicate a large area of readings 1.5σ to 2.5σ above normal for December 23 0z.

 

 

That would translate into readings into at least the 60s in the northern Mid-Atlantic and possibly some areas reaching or exceeding 70°.

 

 

For the longer range, there are some hints that a period where the EPO goes neutral or even slightly positive (recent ensemble runs) may yield to a renewed EPO- regime.As a result, while it is too early to have much confidence in the overall North American temperature anomalies for January, odds are increasing that at least a large portion of Canada could be colder than normal. That would be in marked contrast to the recent runs of the CFSv2 that have been depicting a classic EPO+/WPO+ pattern.

 

Finally, the AO+ regime still looks to hold through the ensemble range. Through today, the AO has been positive on 86% of days during the November 1-December 19 period. During November-December 2006, the AO was positive on 90% of days and during the same timeframe in 2011, it was positive on 95% of days. If winters 2006-07 and 2011-12 (the only case where the AO averaged +1 or above for both November and December) have some relevance, a period of blocking could develop at some point in January, probably during the second half of the month. Both winter 2006-07 and winter 2011-12 saw a period of blocking develop on January 21. For winter 2006-07, the blocking lasted just 6 days, but marked the start of a dramatic pattern change that saw blocking redevelop and persist through almost all of February. In winter 2011-12, the period of blocking lasted 22 days and a persistent AO+ regime returned afterward. Given both the Snow Advance Index (SAI) and October Pattern Index (OPI), odds probably favor a resumption of the AO+ regime should blocking develop later in January. Needless to say, one can’t be confident in the development of a period of blocking in January, but recent persistent November-December AO+ regimes have led to such an outcome. Those AO+ regimes include 1994-95 (period of blocking developed 1/19) and 1999-00 (blocking developed 1/17).

[tacoman25]

No indication currently among the models that any meaningful period of +EPO is coming. All models now show the EPO dropping again around Christmas.

 

 

[thunderbolt]

The big weather story in the near-term will be the potential bout of record warmth in parts of the East that could occur ahead of an approaching cold front on Sunday, December 22. The GFS ensembles indicate a large area of readings 1.5σ to 2.5σ above normal for December 23 0z.

 

 

That would translate into readings into at least the 60s in the northern Mid-Atlantic and possibly some areas reaching or exceeding 70°.

 

 

For the longer range, there are some hints that a period where the EPO goes neutral or even slightly positive (recent ensemble runs) may yield to a renewed EPO- regime.As a result, while it is too early to have much confidence in the overall North American temperature anomalies for January, odds are increasing that at least a large portion of Canada could be colder than normal. That would be in marked contrast to the recent runs of the CFSv2 that have been depicting a classic EPO+/WPO+ pattern.

 

Finally, the AO+ regime still looks to hold through the ensemble range. Through today, the AO has been positive on 86% of days during the November 1-December 19 period. During November-December 2006, the AO was positive on 90% of days and during the same timeframe in 2011, it was positive on 95% of days. If winters 2006-07 and 2011-12 (the only case where the AO averaged +1 or above for both November and December) have some relevance, a period of blocking could develop at some point in January, probably during the second half of the month. Both winter 2006-07 and winter 2011-12 saw a period of blocking develop on January 21. For winter 2006-07, the blocking lasted just 6 days, but marked the start of a dramatic pattern change that saw blocking redevelop and persist through almost all of February. In winter 2011-12, the period of blocking lasted 22 days and a persistent AO+ regime returned afterward. Given both the Snow Advance Index (SAI) and October Pattern Index (OPI), odds probably favor a resumption of the AO+ regime should blocking develop later in January. Needless to say, one can’t be confident in the development of a period of blocking in January, but recent persistent November-December AO+ regimes have led to such an outcome. Those AO+ regimes include 1994-95 (period of blocking developed 1/19) and 1999-00 (blocking developed 1/17).

Don, what do you think of 1992/93 to your list  of November and December? Of those 2 months the AO was only negative for 10 days. It also stayed positive for the month of Jaunary. It wasnt until February 2nd til March 3rd that the AO was either neutral or negative. The most it was negative during that time period was March 2nd (-2.288) Oh and by the way the most positive it was between November and January was 5.245 and that was on January 14, 1993.

[donsutherland1]

Don, what do you think of 1992/93 to your list  of November and December? Of those 2 months the AO was only negative for 10 days. It also stayed positive for the month of Jaunary. It wasnt until February 2nd til March 3rd that the AO was either neutral or negative. The most it was negative during that time period was March 2nd (-2.288) Oh and by the way the most positive it was between November and January was 5.245 and that was on January 14, 1993.

1992-93 is definitely a relevant case. It's 1 of 13 cases that saw December's AO average +1 or above. Of those 13 cases, 10 had a lower January-February AO average, but 1992-93 was an exception to that rule.

[OSUmetstud]

 I suspect LES probably plays a key role in making December Buffalo's snowiest month. The December snowfall correlation is quite useful for gaining insight into the rest of the winter snowfall for Buffalo, as well.  

yes, for sure Don.  There are some notable exceptions, like 1985 with the epic turnaround.  

[Srain]

The 00Z Global deterministic and ensemble medium/long range guidaince continue to advertIse a return to a -EPO/+PNA regime as we near the end of 2013. It will be interesting to see if the suggestions of a negative EPO of -3 prove correct with the return of a slightly postive PNA and increasing sub tropical jet activity as some of the guidance is suggesting.

[mahk_webstah]

The 00Z Global deterministic and ensemble medium/long range guidaince continue to advertIse a return to a -EPO/+PNA regime as we near the end of 2013. It will be interesting to see if the suggestions of a negative EPO of -3 prove correct with the return of a slightly postive PNA and increasing sub tropical jet activity as some of the guidance is suggesting.

This is suggestive of a -AO developing yes?  And does the east part of the vortex move more east allowing some ridging to build down into Greenland?  That looks like a great pattern for New England and one that could become great for the mid atlantic.  Am I reading that right? 

[donsutherland1]

This is suggestive of a -AO developing yes?  And does the east part of the vortex move more east allowing some ridging to build down into Greenland?  That looks like a great pattern for New England and one that could become great for the mid atlantic.  Am I reading that right? 

If those model forecasts verify, the AO could be at least close to neutral. Some ensemble members take it negative in the extended range, but they have done so previously only to move away from that outcome.

[mahk_webstah]

If those model forecasts verify, the AO could be at least close to neutral. Some ensemble members take it negative in the extended range, but they have done so previously only to move away from that outcome.

perhaps it depends if the vortex is able to be pushed far enough south so that the ridging can develop over the top?  Would the emerging +PNA allow more room for the vortex to drop/

[donsutherland1]

perhaps it depends if the vortex is able to be pushed far enough south so that the ridging can develop over the top?  Would the emerging +PNA allow more room for the vortex to drop/

It certainly could. The start of January is definitely no slam dunk to be warm. Cold is probably favored for that week and perhaps the first half of the month. IMO, there is a growing probability that New England might wind up colder than normal for January. Still January is far in the future, so things could still change.

[rcannaday]

Has anyone seen a model where the vortex drops, maybe I am missing something, but it seems that the Vortex stays very close to the Candian border, and does not seem to drop down that much into the US as a whole?

[mahk_webstah]

Has anyone seen a model where the vortex drops, maybe I am missing something, but it seems that the Vortex stays very close to the Candian border, and does not seem to drop down that much into the US as a whole?

When I say "drops" I mean into southern Canada.  That could leave enough room for a -AO above the vortex.  I don't think the PV comes bodily into the US too much. 

[donsutherland1]

Record Warmth Now Underway...

 

Already, Atlantic City, Baltimore, Charleston, SC, Norfolk, Savannah, Washington, DC, and Wilmington, DE have broken daily record high temperatures. At Savannah, the temperature had reached 81° as of 1 pm. That was the 5th time this month Savannah has had a temperature of 80° or above. Only 1931 with 6 such dates has had more.

[Ottawa Blizzard]

Both DT and Joe Bastardi are drawing attention to 1993-1994 as one of their analogs. JB says that the European model is actually coming around to a January 1994-like signal. Sounds interesting...

[donsutherland1]

January 1-7, 2014 Thoughts:

Already, this morning record high temperatures had fallen in many cities in the eastern U.S. Cities included Atlanta, Baltimore, New York, Newark, and Philadelphia. Temperatures in that part of North America were running in the 60s and even 70s. However, if one looks ahead to the first week of January, a return of more winterlike conditions appears increasingly likely. 

 

The ensemble guidance have been suggesting a change in both the AO and PNA heading into the first week in January. Today's run shows the most decided signal yet for an AO- and PNA+ pattern. The EPO is forecast to remain predominantly negative. Nevertheless, given the PDO- and persistent AO+, some consideration has to be given to a more modest change in the indices.

 

 

The outcomes based on the forecast teleconnections and those shown on the GFS ensembles for 1/5/2014 0z are quite similar. As a result, my guess is that much of Canada, except for the extreme north and western portions will likely wind up colder than normal. A cold January looks increasingly likely across much of Canada, as well. Much of the CONUS will also wind up colder than normal with perhaps the coldest anomalies located somewhere near the Great Lakes region. Exceptions will be the western quarter of the U.S., particularly the Southwest and Pacific Northwest where warmer conditions appear likely. The Southeast and Gulf Coast may wind up close to normal with some warmer than normal anomalies, particularly across Florida where winter has been largely absent so far.

 

As an added bonus, the ensembles have consistently signaled the possibility of a storm that could develop somewhere in the Gulf region and then move off the coast of the Southeastern U.S./lower Mid-Atlantic. Storm tracks are low skill at this time, but the important point is that the cold might coincide with some storminess in parts of the eastern CONUS.

[GaWx]

Record Warmth Now Underway...

 

Already, Atlantic City, Baltimore, Charleston, SC, Norfolk, Savannah, Washington, DC, and Wilmington, DE have broken daily record high temperatures. At Savannah, the temperature had reached 81° as of 1 pm. That was the 5th time this month Savannah has had a temperature of 80° or above. Only 1931 with 6 such dates has had more.

 

 It appears that the lowest for today so far at Savannah is 70 (though there's a small chance it is 69). With a forecasted high in the low 80's and with little to no rain forecasted through midnight today, the 70 has a good chance to hold up.  If it does, it would be the warmest low temp. at Savannah on record for any date in Dec.-March going back at least to when records started in 1874!! Exciting times in wx history!

[donsutherland1]

 It appears that the lowest for today so far at Savannah is 70 (though there's a small chance it is 69). With a forecasted high in the low 80's and with little to no rain forecasted through midnight today, the 70 has a good chance to hold up.  If it does, it would be the warmest low temp. at Savannah on record for any date in Dec.-March going back at least to when records started in 1874!! Exciting times in wx history!

So far, the lowest is 70°. The high today was 83°, tying the monthly record high. Today was also a record-tying 6th day with readings 80° or above in December, tying the record set in 1931.

 

Later this evening, I'll post a number of record high temperatures. Tomorrow morning, I'll post record high minimum readings.

[donsutherland1]

Record-tying and record-breaking high temperatures from select cities for December 22, 2013:

 

[donsutherland1]

Record-tying and record-breaking high minimum temperatures for select cities for December 22, 2013:

 

 

NOTE: The December record high minimum temperature for IAD is 61°, which was set on December 23, 1990.

[donsutherland1]

A final note on the 12/22/2013 record high minimum temperatures...

 

Below is a chart showing the records for select cities and standardized anomalies relative to the normal 12/22 low temperature:

 

[donsutherland1]

Ensembles: EPO-, AO-, PNA+ Combination Growing More Likely...

 

The ensemble data has maintained continuity with the idea that the AO will go negative and the PNA+, while the EPO remains generally negative, near or during the first week in January. Such a combination has, in the means, seen cold anomalies in a large part of eastern North America.

 

Consistent with that outcome, the GFS ensembles are currently showing cold anomalies of 1σ - 2σ below normal for the start of January. Below are the maps for 1/1 and 1/2, along with high and low temperatures associated with a standardized anomalies ranging from 1σ to 3σ below normal for select cities (1/1-3 for the 1981-2010 base period) for select cities. 

 

 

Although this outcome is not yet cast in proverbial stone, odds favor the first week of January averaging colder than normal in the eastern half of North America. Also, the timing of the cold shot could shift a little making the 12/30/2013-1/3/2014 period perhaps the most likely timeframe. The possibility of the kind of strong cold shot shown on the GFS ensembles is a realistic one if the AO- and PNA+ develop as currently modeled.

[icebreaker5221]

Record-tying and record-breaking high minimum temperatures for select cities for December 22, 2013:

 

 

NOTE: The December record high minimum temperature for IAD is 61°, which was set on December 23, 1990.

 

 

Don't forget Florida, we've been absolutely torching.  Record high minimums the last 2 nights in Miami and Ft Lauderdale:

 

KMIA

12-22: 76° (75°, 1911)

12-21: 75° (tie, 1925)

 

KFLL

12-22 77° (75°, 2006)

12-21 75° (tie, 2006)

 

We also had a record high on the 15th and another record high min on the 10th. 

 

In fact, the lowest low so far this month at KMIA has been 60°, and we have a legitimate shot at finishing the month without having gone below 60°.

[donsutherland1]

Don't forget Florida, we've been absolutely torching.  Record high minimums the last 2 nights in Miami and Ft Lauderdale:

 

KMIA

12-22: 76° (75°, 1911)

12-21: 75° (tie, 1925)

 

KFLL

12-22 77° (75°, 2006)

12-21 75° (tie, 2006)

 

We also had a record high on the 15th and another record high min on the 10th. 

 

In fact, the lowest low so far this month at KMIA has been 60°, and we have a legitimate shot at finishing the month without having gone below 60°.

Thanks for this update on Florida. It has been a remarkably warm month so far.