2013 Fall Medium Range Discussion

[blizzard1024]

In Message #243, I talked about why I believe winter 2012-13 is not likely to be a repeat of the non-winter of 2011-12.

Last winter, week after week, most of the guidance and the ENSO-teleconnection analogs were painting warm outlooks. After a pause following November, the scenario is a cold one.

Below are the latest monthly forecasts for January 2013 from the CFSv2 and also what's showing up on the analogs for January 1-7, 2013 coupled with the month as a whole for those analogs. Notice how similar the CFSv2 and analog ideas for January are.

The ENSO-teleconnection analogs are based on ENSO Region 3.4 anomalies in the -0.35°C to +0.40°C range, AO in the -3 to -1 range, and the PNA in the -1 to 0 range for January 1-10, 1950-2012. The analog years that came up were 1960, 1969, 1979, 1982, 1994, and 2004. March 1960, February 1969, February 1979, April 1982, and February 1994 had KU snowstorms. January 2004 had a major snowstorm in the Plains States and a massive lake effect snowstorm.

Don,

Overall I agree with your assertions but the CFSv2 January 2013 temperature anomalies look

ridiculous IMO. We just don't get extreme cold months like this anymore over such a widespread area. It is so rare. On the flip-side, we seem to easily get warm months almost this widespread...so maybe finally we will begin a switch in our climate system toward cold? I know JB has been talking about coast to coast cold...but JB always hypes up cold air in winter. I am very skeptical of a very cold January being this widespread. The east, and/or midwest, or south, or west or some part of the country...yes probably will have a great cold month....but this widespread cold would be historic IMO. Maybe we are due for such. I hope.

[donsutherland1]

Large-Scale Pattern Change Imminent...

A blizzard is currently raging in parts of Iowa and Wisconsin. That storm represents yet another event in the ongoing evolution of the pattern that will culminate in a much colder pattern locking in over a large part of the United States and southern Canada. Already, parts of Wisconsin have picked up 10" or more of snow. Strawberry Point has received 12.2".

Meanwhile, this morning was the 6th consecutive day on which Fairbanks, Alaska registered a low of -40°F or colder. To date, the monthly mean temperature is a frigid -19.4°F (16.3°F below normal). However, there are hints on the ensembles and also the CFSv2 that Alaska could grow notably warmer in the extended forecast range. As that happens, Arctic air could press southward, leading to what will likely be a colder than normal January across much of the U.S. (except for perhaps the Southwest and Florida) and southern Canada, if the leading analogs are accurate. The CFSv2 has been signaling a cold January for some time now.

Such a break in the pattern featuring the warming in Alaska is not without precedent. For example, November 1977 saw Fairbanks come out with a mean temperature of -7.6°F (10.4°F below normal). November 2012 had very similar readings, with a mean temperature of -8.8°F (11.4°F below normal). The first 17 days of December 1977 were brutally cold in Fairbanks. The mean temperature was -32.8°F. 3 days had high temperatures of -40°F or colder. The lowest temperature during that period was -52° on December 13 and the highest temperature was -11°F on December 1. A rapid transition to milder condtions took place afterward. The December 20-31 period had a mean temperature of a toasty 10.8°F. 11/12 days had high temperatures above 10°F and 4/12 had highs in the lower 20s. 10/12 days had low temperatures above 0°F. The lowest temperature was -8°F on December 25 and the highest was 22° on December 26.

January 1978 had a mean temperature of +0.1°F (12.0°F above normal). January1978 had temperature anomalies that were fairly similar to those forecast on the December 20, 2012 run of the CFSv2 for January 2013.

Through December 19, the mean temperature in Fairbanks has been -19.4°F. The lowest temperature has been -48°F on December 17.

The latest ensemble forecasts suggest that the EPO could go neutral or negative toward the end of December. The PNA could go neutral or positive (and support for a turn to positive has been growing). The AO will likely remain negative. As a result, the forecast teleconnections suggest that the focus of the cold could shift south and eastward from Alaska into the CONUS and southern Canada. As 2013 begins, the risk of an Arctic outbreak appears likely to increase. One has seen such an outbreak appear on a few of the recent runs of the GFS for the start of January (including today's 12z run).

[blizzard1024]

Large-Scale Pattern Change Imminent...

A blizzard is currently raging in parts of Iowa and Wisconsin. That storm represents yet another event in the ongoing evolution of the pattern that will culminate in a much colder pattern locking in over a large part of the United States and southern Canada. Already, parts of Wisconsin have picked up 10" or more of snow. Strawberry Point has received 12.2".

Meanwhile, this morning was the 6th consecutive day on which Fairbanks, Alaska registered a low of -40°F or colder. To date, the monthly mean temperature is a frigid -19.4°F (16.3°F below normal). However, there are hints on the ensembles and also the CFSv2 that Alaska could grow notably warmer in the extended forecast range. As that happens, Arctic air could press southward, leading to what will likely be a colder than normal January across much of the U.S. (except for perhaps the Southwest and Florida) and southern Canada, if the leading analogs are accurate. The CFSv2 has been signaling a cold January for some time now.

Such a break featuring the warming in Alaska is not without precedent. For example, November 1977 saw Fairbanks come out with a mean temperature of -7.6°F (10.4°F below normal). November 2012 had very similar readings, with a mean temperature of -8.8°F (11.4°F below normal). The first 17 days of December 1977 were brutally cold in Fairbanks. The mean temperature was -32.8°F. 3 days had high temperatures of -40°F or colder. The lowest temperature during that period was -52° on December 13 and the highest temperature was -11°F on December 1. A rapid transition to milder condtions took place afterward. The December 20-31 period had a mean temperature of a toasty 10.8°F. 11/12 days had high temperatures above 10°F and 4/12 had highs in the lower 20s. 10/12 days had low temperatures above 0°F. The lowest temperature was -8°F on December 25 and the highest was 22° on December 26.

January 1978 had a mean temperature of +0.1°F (12.0°F above normal). January1978 had temperature anomalies that were fairly similar to those forecast on the December 20, 2012 run of the CFSv2 for January 2013.

Through December 19, the mean temperature in Fairbanks has been -19.4°F. The lowest temperature has been -48°F on December 17.

The latest ensemble forecasts suggest that the EPO could go neutral or negative toward the end of December. The PNA could go neutral or positive (and support for a turn to positive has been growing). The AO will likely remain negative. As a result, the forecast teleconnections suggest that the focus of the cold could shift south and eastward from Alaska into the CONUS and southern Canada. As 2013 begins, the risk of an Arctic outbreak appears likely to increase. One has seen such an outbreak appear on a few of the recent runs of the GFS for the start of January (including today's 12z run).

I hope you are right brother!!

[Ottawa Blizzard]

Large-Scale Pattern Change Imminent...

A blizzard is currently raging in parts of Iowa and Wisconsin. That storm represents yet another event in the ongoing evolution of the pattern that will culminate in a much colder pattern locking in over a large part of the United States and southern Canada. Already, parts of Wisconsin have picked up 10" or more of snow. Strawberry Point has received 12.2".

Meanwhile, this morning was the 6th consecutive day on which Fairbanks, Alaska registered a low of -40°F or colder. To date, the monthly mean temperature is a frigid -19.4°F (16.3°F below normal). However, there are hints on the ensembles and also the CFSv2 that Alaska could grow notably warmer in the extended forecast range. As that happens, Arctic air could press southward, leading to what will likely be a colder than normal January across much of the U.S. (except for perhaps the Southwest and Florida) and southern Canada, if the leading analogs are accurate. The CFSv2 has been signaling a cold January for some time now.

Such a break in the pattern featuring the warming in Alaska is not without precedent. For example, November 1977 saw Fairbanks come out with a mean temperature of -7.6°F (10.4°F below normal). November 2012 had very similar readings, with a mean temperature of -8.8°F (11.4°F below normal). The first 17 days of December 1977 were brutally cold in Fairbanks. The mean temperature was -32.8°F. 3 days had high temperatures of -40°F or colder. The lowest temperature during that period was -52° on December 13 and the highest temperature was -11°F on December 1. A rapid transition to milder condtions took place afterward. The December 20-31 period had a mean temperature of a toasty 10.8°F. 11/12 days had high temperatures above 10°F and 4/12 had highs in the lower 20s. 10/12 days had low temperatures above 0°F. The lowest temperature was -8°F on December 25 and the highest was 22° on December 26.

January 1978 had a mean temperature of +0.1°F (12.0°F above normal). January1978 had temperature anomalies that were fairly similar to those forecast on the December 20, 2012 run of the CFSv2 for January 2013.

Through December 19, the mean temperature in Fairbanks has been -19.4°F. The lowest temperature has been -48°F on December 17.

The latest ensemble forecasts suggest that the EPO could go neutral or negative toward the end of December. The PNA could go neutral or positive (and support for a turn to positive has been growing). The AO will likely remain negative. As a result, the forecast teleconnections suggest that the focus of the cold could shift south and eastward from Alaska into the CONUS and southern Canada. As 2013 begins, the risk of an Arctic outbreak appears likely to increase. One has seen such an outbreak appear on a few of the recent runs of the GFS for the start of January (including today's 12z run).

Interesting that JB has pointed to 1978 a couple of times as a year in which the pattern flipped right around the solstice. As with blizzard, I'm skeptical of much of what JB says these days, but feel more confident about a change after what Don has posted.

Perhaps we are due for an extreme cold month over a widespread area. January 1994 was the first such month in years if I recall.

[uncle W]

JB always stresses extreme analogs...Does he do this for drama?...Stay tuned...January 1978 is the second wettest on record for NYC...Had a major 14" winter storm...Was one of the coldest over the last 60 years...Had a cold wave mid December...He can't help himself...

[GaWx]

After further analysis, I admittedly like what I see on the new Euro weeklies even a bit more. Here's why:

1) Both the NAO and AO are more negative (stronger blocking) than the Euro weekly run from four days ago, which covered the same exact four weeks.

2) After a slightly warmer week #1 in the E US (no surprise after the warm adjustments of the last few days), the 2 meter temp.'s for the subsequent three weeks in the E 1/2 of the US are overall significantly colder vs. the Euro weekly run from four days ago, which as I mentioned covers the same exact four weeks (through 1/13). Weeks 2 and 4 are much colder than that from the prior run whereas week 3 is a little colder. As a matter of fact, weeks 2-4 actually have colder than normal covering most of the country from coast to coast.

I, of course, do take these with a big grain of salt. However, so that the reader doesn't just think that I'm a nonobjective cynic, I will point out two encouraging things about the weeklies that may mean there's some credibility:

1) This is the coldest week 2-4 run two meter anomalywise for the US as a whole by a good margin since at least early Sep. (as far as I went back). That covers 31 Euro weekly runs. Actually, I saw no other run having all of weeks 2-4 with such widespread below normal U.S. temp.'s

2) The runs in late Nov. for Dec. were largely warm. The 11/29 run had a torch for four weeks.

Folks,

The brand new Euro weeklies look similarly chilly and wet for much of the E US for the entire four week period. Also, the west based -NAO and the -AO blocks look impressive.

[blizzard1024]

Interesting that JB has pointed to 1978 a couple of times as a year in which the pattern flipped right around the solstice. As with blizzard, I'm skeptical of much of what JB says these days, but feel more confident about a change after what Don has posted.

Perhaps we are due for an extreme cold month over a widespread area. January 1994 was the first such month in years if I recall.

January 1978 was epic in the east for cold and snow. I can't imagine such a switch since this December so far for the CONUS has averaged a full 6F above the

warm 1981-2010 normal period!!!! This would also be an epic switch for the CONUS. It's possible I guess. The midwest certainly is getting pounded

and colder weather there and eventually in the east will no doubt reduce this +6F departure by the end of the month. I have

NEVER seen a December so warm. I have yet to fall below 20 degrees and our normal lows are now in the high teens!!! This is upstate NY.

The degree of mildness has been unprecedented for the first 20 days of December, it has been the warmest first 20 days on record in December for Binghamton by more than 2 degrees. A switch to normal or slightly below normal temperatures would be more likely in my opinion for the first part of January. Certainly it could be snowy, but cold....not so certain of this. The CONUS climate has been running warm lately IMO. Maybe this is the beginning of a dramatic drop in temperature...now wouldn't that be awesome..

[ORH_wxman]

The last widespread cold December in the CONUS was 2009...2010 was cold but mostly just the eastern half of the country.

[Ottawa Blizzard]

January 1978 was epic in the east for cold and snow. I can't imagine such a switch since this December so far for the CONUS has averaged a full 6F above the

warm 1981-2010 normal period!!!! This would also be an epic switch for the CONUS. It's possible I guess. The midwest certainly is getting pounded

and colder weather there and eventually in the east will no doubt reduce this +6F departure by the end of the month. I have

NEVER seen a December so warm. I have yet to fall below 20 degrees and our normal lows are now in the high teens!!! This is upstate NY.

The degree of mildness has been unprecedented for the first 20 days of December, it has been the warmest first 20 days on record in December for Binghamton by more than 2 degrees. A switch to normal or slightly below normal temperatures would be more likely in my opinion for the first part of January. Certainly it could be snowy, but cold....not so certain of this. The CONUS climate has been running warm lately IMO. Maybe this is the beginning of a dramatic drop in temperature...now wouldn't that be awesome..

Were the first 20 days of December 1993 not also abnormally warm in upstate New York? They were in southern Ontario.

[blizzard1024]

Were the first 20 days of December 1993 not also abnormally warm in upstate New York? They were in southern Ontario.

You are correct sir. It was very mild...not quite as much as this year around here but close. We know what happened in January 1994.

The end of December got bitterly cold in the east the last 10 days...one can hope the recent GFS runs are correct. The euro would return us to normal

or slightly below. The 12z GFS was awesome with a big snowstorm and then pouring arctic air into the conus...the ensembles supported

it. The 12z euro had another westward tracking storm and maintains the southeast ridge suggesting more of the same...except a little colder

than normal. that would suck.

[Srain]

Excellent discussion from FWD tonight about the possible senarios on the table and why the forecast remain so uncertain at this range regarding the Christmas Storm:

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE FORT WORTH TX

845 PM CST THU DEC 20 2012

.UPDATE...

THE DEWPOINTS ARE NEAR 0 DEG F AND THE PRECIPITABLE WATER VALUE IS

NEAR A TENTH OF AN INCH. THIS IS ABOUT THE DRIEST AIR I CAN RECALL

IN MANY YEARS. THE DRY AIR AND CLEAR SKIES WILL HELP TEMPS FALL

INTO THE TEENS AND 20S TONIGHT...WITH BIG VARIATIONS IN OVERNIGHT

LOWS FROM LOCATION TO LOCATION BASED ON LOCAL TOPOGRAPHY AND SOIL

TYPE. SURFACE HIGH WILL SETTLE IN OVER THE HILL COUNTRY WHICH

WILL KEEP A LIGHT WEST WIND IN PLACE TONIGHT...AND THIS LIGHT WIND

COMBINED WITH HEAT STORED UP IN THE SOIL WILL KEEP TEMPS 10-20

DEGREES ABOVE THEIR DEWPOINT. NO CHANGES WERE MADE...WITH COLDEST

TEMPS GENERALLY IN THE SW ZONES NEARER TO THE HIGH CENTER.

YOUR REGULARLY SCHEDULED UPDATE AFD ENDS HERE. SINCE IT IS A QUIET

NIGHT...ITS WEATHER CLASSROOM AND LAB TIME FOR THOSE INTERESTED...

THE CHRISTMAS NIGHT FORECAST IS ON EVERYONE/S MIND. WE HAVE BEEN

WATCHING THIS SYSTEM IN THE EXTENDED MODELS FOR SEVERAL DAYS...AND

CONTINUE TO RIGHTLY ASSESS THAT A POTENTIAL FOR A WINTER EVENT

EXISTS. UNFORTUNATELY MODEL GUIDANCE DOES NOT HAVE THE SKILL IN

THAT TIME RANGE TO ACCURATELY PREDICT THE INTENSITY AND LATITUDE

THE UPPER LEVEL SYSTEM WILL TAKE BECAUSE OF THE UNCERTAINTY ON

EXACTLY WHERE A COLD FRONT WILL BE ON TUESDAY. AS WE HAVE SAID IN

THE LAST 2 AFDS...THIS COLD FRONT IS THE KEY TO THE FORECAST.

BUT TO UNDERSTAND WHY...IT IS HELPFUL TO DISCUSS BAROCLINICITY

AND ITS AFFECTS ON THE MOVEMENT AND STRENGTH OF WEATHER SYSTEMS.

ESSENTIALLY THESE STORM SYSTEMS ARE BLOBS OF UPPER LEVEL

ENERGY...OR VORTICITY...OFTEN CALLED SHORTWAVES OR DISTURBANCES.

IN AN ATMOSPHERE WHERE THERE IS VERY LITTLE TEMPERATURE DIFFERENCE

FROM LOCATION TO LOCATION...THE MOTION OF THESE DISTURBANCES IS

BASICALLY DICTATED BY THE FLOW THEY ARE A PART OF. THEY BEHAVE

MUCH LIKE A LEAF WOULD IF IT WERE FLOATING DOWN A RIVER.

HOWEVER WHEN HORIZONTAL TEMPERATURE GRADIENTS EXIST...SUCH AS

WHEN A COLD FRONT IS NEARBY...THIS SIMPLE RULE GOES OUT THE

window. THIS IS CALLED A BAROCLINIC ATMOSPHERE. A DISTURBANCE THAT

MOVES INTO A BAROCLINIC ZONE WILL INTENSIFY. THIS IS BECAUSE LOW

LEVEL TEMPERATURE ADVECTION BEGINS TO INTERFACE WITH THE UPPER

LEVEL SYSTEM. IN SHORT...THERMAL ADVECTION IN THE LOW LEVELS

CAUSE HEIGHT CHANGES IN THE UPPER LEVELS...WHICH IN TURN

STRENGTHEN THE UPPER LEVEL VORTICITY CENTER...WHICH IN TURN

STRENGTHENS THE LOW LEVEL THERMAL ADVECTION...AND ETC. THE WHOLE

THING BECOMES A FEEDBACK LOOP. AN UPPER DISTURBANCE UNDERGOING

BAROCLINIC INTENSIFICATION WILL TRANSFORM INTO A CYCLONE AND WILL

NO LONGER MOVE WITH THE MEAN FLOW...BUT WILL CURVE TOWARD THE

POLE. IN THE PROCESS OF TURNING TOWARD THE POLE THE CYCLONE

OFTEN OCCLUDES...MEANING THEY LOSE THEIR ACCESS TO THE TEMPERATURE

GRADIENTS AND THEY WEAKEN. WE HAVE ALREADY SEEN MANY MODEL RUNS OF

A BIG WINTER CYCLONE DEVELOPING OVER THE SOUTHERN PLAINS AND

CURVING OFF TO THE NORTH. IN THE LATEST MODELS WE NO LONGER SEE

THAT SOLUTION AND SEE A WEAK TROUGH MOVING OVERHEAD.

THE REASON WHY THE MODELS HAVE BEEN ALTERNATING BETWEEN A POWERFUL

WINTER CYCLONE IN THE PLAINS AND A WEAK DISTURBANCE HAS BEEN DUE

TO THE LOCATION OF THE BAROCLINIC ZONE /OR COLD FRONT/ WHEN THE

DISTURBANCE REACHES THE SOUTHERN PLAINS. THE TREND IN MOST OF THE

MODELS HAS BEEN TO MOVE THE FRONT/BAROCLINIC ZONE INTO SOUTH

TEXAS. AS A RESULT THE UPPER LEVEL DISTURBANCE TRAVELS OVER TEXAS

WITHOUT STRENGTHENING BECAUSE THE TEMPERATURE GRADIENTS ARE WEAK

SO FAR BEHIND THE FRONT. THE SYSTEM THUS DOES NOT INTENSIFY UNTIL

IT REACHES THE NORTHERN GULF COAST WHERE A BAROCLINIC ZONE EXISTS.

THIS SCENARIO...WHICH WE ARE CURRENTLY FORECASTING...IS ONE THAT

WOULD ONLY PRODUCE LIGHT AMOUNTS OF WINTER PRECIP. THIS IS BECAUSE

THE SYSTEM WILL BE WEAK AND HAS NO ACCESS TO THE THERMAL GRADIENTS

IT NEEDS TO INTENSIFY. AN INTENSIFYING LOW WOULD BE ABLE AUGMENT

THE WIND FIELDS AND THUS TAP INTO THE GULF FOR MOISTURE.

IN ORDER TO GET A SIGNIFICANT SNOW STORM HERE...WE WOULD NEED THE

FRONT TO BE FARTHER NORTH THAN CURRENTLY FORECAST...BUT NOT SO FAR

NORTH THAT THE SYSTEM BEGINS ITS POLEWARD TURN AND STAYS NORTH OF

THE REGION ALTOGETHER. WE NEED A GOLDILOCKS POSITION OF THIS

FRONT. AGAIN...KNOWING THE PRECISE LOCATION OF A FRONT BEYOND 5

DAYS IS THE DIFFICULTY WITH THIS FORECAST. THANKFULLY THE LEAD

SHORTWAVE RESPONSIBLE FOR THE LOCATION OF THIS FRONT WILL BE

ONSHORE IN CALIFORNIA SATURDAY AND WILL BE SAMPLED BY THE BALLOON

NETWORK. IN ADDITION...WE WILL BE IN RANGE OF THE NAM BY TOMORROW

FOR HAVING ANOTHER OPINION ON THIS FRONT/S STRENGTH AND LOCATION

MONDAY NIGHT AND TUESDAY...EVEN IF WE DONT GET AN EXPLICIT DEC

25TH FORECAST FROM THE NAM UNTIL SATURDAY.

[The_Global_Warmer]

JB always stresses extreme analogs...Does he do this for drama?...Stay tuned...January 1978 is the second wettest on record for NYC...Had a major 14" winter storm...Was one of the coldest over the last

60 years...Had a cold wave mid December...He can't help himself... :arrowhead

I believe STL was below freezing almost the entire month. Overall we were around 21f for the monthly mean.

There Is ZERO chance we repeat that on the wide scale that happened then. There is almost zero chance anyone East of the Rockies goes -10f for the month.

On top of that December of 1977 was nothing like this one except similar over the SW.

The guy is a swindler, snake, like a siren.

People pay cash money for this Man's expertise. Unbelievable.

This Message forum is loaded with Mets giving their knowledge and expertise out for free. No one needs to pay this Man money to be sold a winter fairytale.

[Srain]

There are some positive signs for the cold weather lover as the Christmas Storm passes suggesting a colder regime will become established and maintain throughout the week leading up to the New Year. It also appears it could be rather stormy as the sub tropical jet remains noisy and storm tracks continue across the 4 Corners Region into the Southern Plains.

[mahk_webstah]

i wonder how suppressive that west based nao block would become? always a concern up here. The 50-50 looks to be quite north and east (so not a 50-50) and I guess that would reduce the possibility of suppression. Maybe we get some full on coastal runners from the MA all the way up the coast. We do best when you MA guys are on the edge in terms of cold air. I don't mind visiting NYC of Philly for a storm if need be.

[donsutherland1]

Quick thoughts...

On 12/15, some ensemble members had begun to hint that the PNA, which has now been negative for 46 consecutive days, could go positive near the end of December. Historical cases related to long-lived PNA- regimes also suggested that such guidance might have some merit. Today, there is developing consensus that the PNA is likely to go positive toward the end of the month or near the beginning of January.

The AO, which has again fallen below -3 is likely to remain negative through the extended period consistent with a number of long-lived blocking regimes, including those of winters 2009-10 and 2010-11.

With the blizzard departing the Great Lakes region after having brought more than 15" snow to Madison and Chicago its first measurable snowfall since March 4, 2012, along with a surge of warmth and moderate-to-heavy rain in the East, the final pieces of a pattern change to generally colder than normal weather across much of the U.S. and southern Canada are now falling into place.

As the colder pattern unfolds, the active subtropical jet suggests that storminess could coincide with the cold. Hence, opportunities for at least some accumulation of snow appear likely.

Finally, once the PNA goes neutral and then probably positive, the risk of an Arctic outbreak could increase. The potential exists that sometime during the next 2-3 weeks, Albany could see its first subzero temperature since February 11, 2011 when the mercury fell to -5° and New York City could see its first single-digit reading since January 24, 2011 when the temperature fell to 6°.

[Srain]

Quick thoughts...

On 12/15, some ensemble members had begun to hint that the PNA, which has now been negative for 46 consecutive days, could go positive near the end of December. Historical cases related to long-lived PNA- regimes also suggested that such guidance might have some merit. Today, there is developing consensus that the PNA is likely to go positive toward the end of the month or near the beginning of January.

The AO, which has again fallen below -3 is likely to remain negative through the extended period consistent with a number of long-lived blocking regimes, including those of winters 2009-10 and 2010-11.

With the blizzard departing the Great Lakes region after having brought more than 15" snow to Madison and Chicago its first measurable snowfall since March 4, 2012, along with a surge of warmth and moderate-to-heavy rain in the East, the final pieces of a pattern change to generally colder than normal weather across much of the U.S. and southern Canada are now falling into place.

As the colder pattern unfolds, the active subtropical jet suggests that storminess could coincide with the cold. Hence, opportunities for at least some accumulation of snow appear likely.

Finally, once the PNA goes neutral and then probably positive, the risk of an Arctic outbreak could increase. The potential exists that sometime during the next 2-3 weeks, Albany could see its first subzero temperature since February 11, 2011 when the mercury fell to -5° and New York City could see its first single-digit reading since January 24, 2011 when the temperature fell to 6°.

Very impressive +PNA via the 12Z Operational ECMWF.

[WxMidwest]

Here is a model of mine I ran with regards to the Global wind Oscillation, it support's much of Don's Early January Idea's. Just ran my GWO model (Fortran),It is supporting the CFSv2 for about nearly a CONUS wide Colder then normal January with correct blocking regimes over the Pac and ATL. this is the January 2013 Roll Forward Forecast using the Global Wind Oscillation data.

It used the top 5 analogs since 1958 with regards to atmospheric base state characterization.

[blizzard1024]

Quick thoughts...

On 12/15, some ensemble members had begun to hint that the PNA, which has now been negative for 46 consecutive days, could go positive near the end of December. Historical cases related to long-lived PNA- regimes also suggested that such guidance might have some merit. Today, there is developing consensus that the PNA is likely to go positive toward the end of the month or near the beginning of January.

The AO, which has again fallen below -3 is likely to remain negative through the extended period consistent with a number of long-lived blocking regimes, including those of winters 2009-10 and 2010-11.

With the blizzard departing the Great Lakes region after having brought more than 15" snow to Madison and Chicago its first measurable snowfall since March 4, 2012, along with a surge of warmth and moderate-to-heavy rain in the East, the final pieces of a pattern change to generally colder than normal weather across much of the U.S. and southern Canada are now falling into place.

As the colder pattern unfolds, the active subtropical jet suggests that storminess could coincide with the cold. Hence, opportunities for at least some accumulation of snow appear likely.

Finally, once the PNA goes neutral and then probably positive, the risk of an Arctic outbreak could increase. The potential exists that sometime during the next 2-3 weeks, Albany could see its first subzero temperature since February 11, 2011 when the mercury fell to -5° and New York City could see its first single-digit reading since January 24, 2011 when the temperature fell to 6°.

I am liking what I am seeing between euro and GFS....winter is coming. wow. winter....hard to believe.

[QVectorman]

Since things are kinda slow in here I figured I would add my posts from the other day in the NE forum here to give some thing for discussion or add some additional hope to Don and Midwest's posts.

With the MJO going into phase 1 and the 5-7 day lag for MJO induced waves to traverse the eastern US it would set us up for a wave to arrive in the east between Dec. 18-20 which is progged on the 180hr GFS and Euro moving across the upper Midwest or Great Lakes. The same wave also ushers in relatively "colder" air and plays nicely into the idea I spoke of the other day in my post about the pocket of relatively "colder" air arriving during the Dec. 21-23 time frame based off of GWO analogs for the eastern US.Using that same concept for the GWO I expect another batch of colder air Dec. 27-30. And Following the spike in the 10 and 30 mb temps that peaked back on Dec. 6 seems we should see a good shot of colder air Dec 30-Jan 3.

I don't know if this wave was directly attributable to the MJO since some raise valid arguments that this wasn't a true MJO signal in the phase 1 region but we have our wave moving through the GLKS as discussed on Dec. 13 and temps for example in Detroit will be dropping from the upper 40's Thursday-Dec. 20 down to highs in the low 30's for Dec. 22. GFS and Euro both hinting at another wave moving through the GLKS Dec. 27-28 which would allow colder air to settle into the region for Dec. 28 by current models. Models indicate another pocket of cold air arriving to reinforce the prior batch with a short wave Jan 2-3 across the Eastern US which falls into the Dec. 30-Jan 3 date I laid out previously. The Euro and GFS both give credence to this time frame with a shortwave modeled off the coast of CA for 0z Dec. 30 giving it 4-5 days for it make it out into the Plains to the GLKS/EC. Although the GFS has been wavering in the magnitude of the cold air for this time frame, which I was expecting to be some of the coldest of the season guessing along the lines of -15C to -20C 850mb over southern Michigan and eastward. So the GFS is still not modeling that type of air mass as of right now I will leave that TBD as we get closer.

With the newest GWO numbers today the latest analogs indicate a 15-20F warm up in sfc temps Jan 3-Jan 6 compared to prior days highs across Midwest or NE (the Dec. 31-Jan 3 cold episode) and analogs suggest a stair stepped 15-20F temperature fall behind the warm up 1-2 days after that, meaning another spell of colder air Jan 5-8.

I extended my outlook through Jan 8 on Dec. 14. I still feel comfortable with those dates and with the newest GWO analogs and latest 10 and 30 mb temp forecast it appears the time frame between Jan 8-10 will see a warm up over the east with a short wave moving through the east Jan 10-11 with cooler air dropping in behind it for Jan 10-13 across the MW/GLKS and then pockets of cooler air arriving Jan 15-19 time frame for the east followed by a second reinforcement of cooler air Jan 20-24. My GWO analogs only take me out to Jan 9 so there may be another short wave or two to add to the 2 already expected for the Jan 9-24 time frame. I will update as the newest GWO numbers come out over the next week and half.

[Mike.Ventrice]

Hi all,

The time-longitude plot of unfiltered 850 hPa velocity potential with GFS 7-day forecast indicates we may be seeing a coherent MJO signal develop. The active phase of the MJO will be over the Indian Ocean, with suppression over the Pacific (~Real-time multivariate MJO phases 1-3). An Indian Ocean MJO is commonly associated with a cold air outbreak over the US, which is suggested in the GFS forecast. While the GFS forecast damps the eastward progressing VP850 anomaly signature and holds it stationary, the GFS occassionally struggles with correctly representing MJO or Kelvin waves (even though this year has been quite good), and therefore will stop progressing these disturbances eastward in the forecast.

The real-time multivariate MJO indices suggest there has been a weak MJO signature over the past 2 weeks:

Most dynamical models suggest a noisy evolution of the MJO signal in the upcoming 1-2 weeks: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

The partial fraction contribution of the RMM for today is as follows for OLR, U850, U200: (0.1422979, 0.1796938, 0.6780083). U200 is driving the show, and therefore taking a look at the time-longitude plot of U200 could provide some information with regards to interpreting the MJO-forecast in week 1-2.

The upper-level easterly wind phase is located over the Indian Ocean in the analysis, however in forecast mode, it damps out and switches to westerlies east of 120E. The primary easterly wind anomaly is in the form of a CCKW over east Africa (2.0 sigma event). You can see in the GFS forecast this eastward propagating CCKW become stationary at 60E (don't buy it!).

While we might enjoy winter in the early half of Janaury, if this MJO signal evolves into a coherent event, we might experience some anomalous warmth over the US somewhere down in week 3-4. Not great news for snow lovers... but the current state in the tropics would support potential for a snowy February... but then again, this is just one piece of the puzzle.

[am19psu]

Agree Mike. We have a three week shot of winter in the cards from Christmas through Jan 15 before the tropics turn unfavorable again. Also of note is the generally unfavorable upper stratosphere, which means the general winter base state is likely what we saw in December and that we'll need significant forcing elsewhere (like the upcoming MJO wave) for winter on the east coast.

[uncle W]

Hi all,

The time-longitude plot of unfiltered 850 hPa velocity potential with GFS 7-day forecast indicates we may be seeing a coherent MJO signal develop. The active phase of the MJO will be over the Indian Ocean, with suppression over the Pacific (~Real-time multivariate MJO phases 1-3). An Indian Ocean MJO is commonly associated with a cold air outbreak over the US, which is suggested in the GFS forecast. While the GFS forecast damps the eastward progressing VP850 anomaly signature and holds it stationary, the GFS occassionally struggles with correctly representing MJO or Kelvin waves (even though this year has been quite good), and therefore will stop progressing these disturbances eastward in the forecast.

The real-time multivariate MJO indices suggest there has been a weak MJO signature over the past 2 weeks:

Most dynamical models suggest a noisy evolution of the MJO signal in the upcoming 1-2 weeks: http://www.cpc.ncep....clivar_wh.shtml

The partial fraction contribution of the RMM for today is as follows for OLR, U850, U200: (0.1422979, 0.1796938, 0.6780083). U200 is driving the show, and therefore taking a look at the time-longitude plot of U200 could provide some information with regards to interpreting the MJO-forecast in week 1-2.

The upper-level easterly wind phase is located over the Indian Ocean in the analysis, however in forecast mode, it damps out and switches to westerlies east of 120E. The primary easterly wind anomaly is in the form of a CCKW over east Africa (2.0 sigma event). You can see in the GFS forecast this eastward propagating CCKW become stationary at 60E (don't buy it!).

While we might enjoy winter in the early half of Janaury, if this MJO signal evolves into a coherent event, we might experience some anomalous warmth over the US somewhere down in week 3-4. Not great news for snow lovers... but the current state in the tropics would support potential for a snowy February... but then again, this is just one piece of the puzzle.

there are a few winters that had a warm December...Cold January...Warm February in this area...1953-54...1956-57...1984-85 come to mind...the window of opportunity comes at the same time as 1954...January 10-11th storm was the highlight for that winter...Then February 54 became the warmest on record (since beaten a few times)...

[NaoPos]

so if i read you right Adam, we basically are looking @ a 2,maybe 3, week relaxation in the current pattern and then back to an early december pattern?

[am19psu]

so if i read you right Adam, we basically are looking @ a 2,maybe 3, week relaxation in the current pattern and then back to an early december pattern?

That's my current thoughts

[CoastalWx]

Mike those partical fractions are pretty cool, are those from your website? I noticed you had those graphics on your page, but the numbers were different...perhaps they updated.

[Ottawa Blizzard]

Can't say that I like the blowtorch depicted at the end of the 0z GFS run.

[Mike.Ventrice]

Mike those partical fractions are pretty cool, are those from your website? I noticed you had those graphics on your page, but the numbers were different...perhaps they updated.

The partial fractions that I were discussing are given directly on Matt and Harry's webpage for the real-time mutivariate MJO (RMM) indices:

http://cawcr.gov.au/staff/mwheeler/maproom/RMM/RMM1RMM2.02toRealtime.P.txt

I have a couple MJO indices on my webpage with partial fractions. The first is the Velocity Potential MJO (VPM) indices, where I follow Matt and Harry's methodology and swap OLR for VP200. Those indices suggest VP200 is running the show today.

For the manuscript submitted to the monthly weather review:

http://www.atmos.albany.edu/student/ventrice/documents/VPM_Manuscript.pdf

I also have a new MJO index that I have been playing around with. The EOFs are built from 6 different variables. I don't know too much about this index yet, since I haven't done the research on it.

[CoastalWx]

Sweet, thanks Mike. You guys have some great stuff in the Albany site.

[blizzard1024]

I have been looking at both the Euro Ensembles and GEFS and both are

starting to show a major Pacific Jet with the GEFS actually bringing it

closer to the west coast (ala Postive EPO!). FWIW look at the day 16

GEFS. UGH. I will admit I haven't really watched how well the EPO

is handled by models. Anyone care to comment? see below. Could this end

any winter that we might squeeze out in the next week or two???

I hope not!!

see below...

[GaWx]

I have been looking at both the Euro Ensembles and GEFS and both are

starting to show a major Pacific Jet with the GEFS actually bringing it

closer to the west coast (ala Postive EPO!). FWIW look at the day 16

GEFS. UGH. I will admit I haven't really watched how well the EPO

is handled by models. Anyone care to comment? see below. Could this end

any winter that we might squeeze out in the next week or two???

I hope not!!

see below...

Blizzard,

The 12Z GEFS fwiw is quite a bit colder late in the 11-15 vs the prior two runs. Also, neither the 12Z Euro ens. nor the CDN ens. suggest a relaxation of the +PNA then. Actually, all three runs suggest a reloading of the +PNA late in the 11-15 fwiw. I say fwiw because we all know how models can change on a dime that late in the fcast period.

Edit: Anyway, the last two runs of the Euro weeklies suggest a reloading of cold then as they keep it solidly cold through mid-January. Again, fwiw, but the weeklies have done reasonably well. Keep in mind that they were largely warm looking ahead to the warm 1st three weeks of Dec.