Medium Range Discussion Winter 2011-12

[am19psu]

It doesn't look like (to me anyway) that we will have a chance at a huge pattern shift to colder in the east (sustained) until at least a week deep into December, perhaps two weeks in. The extreme vortex in Alaska doesn't really have a good reason to be dislodge before then as a robust MJO wave enters phases 3/4 which actually supports keeping it there. Once it moves out of those phases, then other factors can help in dislodging and perhaps the MJO itself if it can remain strong into phase 6.

Until then, the cool downs should be transient in nature.

I agree, Will. I thought the shift to P2 could be a signal to a more sustained string of cold weather, but it's not in the cards. Until something dislodges the GoA low/-PNA couplet, we're going to be warm for a while.

[Alpha5]

EPO continues to be a problem.....

[tacoman25]

I'm beginning to wonder if the -NAO will kick in as strongly this winter as many have expected. It has definitely been higher than the last couple falls were, preceding mega -NAO periods in the winter.

[OKpowdah]

classic torch pattern for the east. I'm confident it continues through the first 10 days of December. And hopefully it breaks after that as the MJO forcing moves through Indonesia into the West Pacific

[am19psu]

The new Euro op is interesting today... that said, it has zero ensemble support

[ORH_wxman]

Today's Euro weeklies shows some signs of change for mid-December. Week 4 is pretty far out (Dec 13-19) so take it FWIW, but we finally see the AK vortex get knocked out and the first signs of a -EPO...Aleutian ridge flexes poleward more trying to poke into the Bering Straight region and we see a pretty good arctic dump of cold air into western/central Canada. That would be step 1 in trying to shuffle out the milder pattern.

[Midlo Snow Maker]

Today's Euro weeklies shows some signs of change for mid-December. Week 4 is pretty far out (Dec 13-19) so take it FWIW, but we finally see the AK vortex get knocked out and the first signs of a -EPO...Aleutian ridge flexes poleward more trying to poke into the Bering Straight region and we see a pretty good arctic dump of cold air into western/central Canada. That would be step 1 in trying to shuffle out the milder pattern.

be nice if could bring some of this down here

AKZ218>222-225-181015-

PUBLIC INFORMATION STATEMENT

NATIONAL WEATHER SERVICE FAIRBANKS AK

110 PM AKST THU NOV 17 2011

...ANOTHER DAY OF RECORD COLD TEMPERATURES IN THE INTERIOR...

THE FIRST COLD WEATHER OUTBREAK OF THE SEASON HAS SETTLED IN OVER

INTERIOR ALASKA. UNUSUALLY FRIGID TEMPERATURES FOR MID-NOVEMBER HAVE

BEEN OBSERVED ACROSS MUCH OF THE REGION. TEMPERATURES COLDER THAN

40 BELOW ZERO ARE BEING REPORTED IN VALLEYS IN THE CENTRAL AND

NORTHEASTERN INTERIOR. INFRARED SATELLITE IMAGES ALSO INDICATE

TEMPERATURES UNDER 50 BELOW ZERO IN SOME OF THE COLDEST VALLEY

LOCATIONS.

SEVERAL RECORD LOW TEMPERATURES WHICH WERE SET MORE THAN 40 YEARS

AGO WERE BROKEN OVERNIGHT IN THE FAIRBANKS AREA. THIS INCLUDES

RADIO STATION KJNP IN NORTH POLE WHICH BOTTOMED OUT AT 49 BELOW

THIS MORNING...BREAKING THE PREVIOUS RECORD OF 46 BELOW SET BACK

IN 1969. OTHER RECORDS FROM 1969 THAT WERE BROKEN THIS MORNING

INCLUDE EIELSON AIR FORCE BASE AT 43 BELOW...THE FAIRBANKS AIRPORT

WITH 41 BELOW AND THE UNIVERSITY EXPERIMENTAL STATION AT 41 BELOW

WHICH BROKE RECORD SET IN 1918. OUTSIDE OF FAIRBANKS... MANLEY HOT

SPRINGS REPORTED A BONE CHILLING TEMPERATURE OF 54 BELOW WHICH

BROKE THE PREVIOUS LOW OF 51 BELOW SET IN 1956.

RECORD OR NEAR RECORD LOW TEMPERATURES ARE POSSIBLE AGAIN FRIDAY

MORNING. THE RECORD LOW FOR NOVEMBER 18TH AT THE FAIRBANKS AIRPORT

IS 33 BELOW...38 BELOW AT EIELSON AIR FORCE BASE...AND 41 BELOW

AT KJNP IN NORTH POLE.

TEMPERATURES FROM 15 TO 35 DEGREES BELOW NORMAL WILL PERSIST OVER

MUCH OF THE INTERIOR THE NEXT COUPLE OF DAYS. SOME MODERATION IS

EXPECTED ON THE WEEKEND...THOUGH HIGH TEMPERATURES WILL REMAIN

WELL BELOW ZERO. THE COLDER AIRMASS IS EXPECTED TO SETTLE IN OVER

THE INTERIOR AGAIN EARLY NEXT WEEK.

THE AVERAGE TEMPERATURE IN FAIRBANKS THIS WEEK IS AROUND 9 ABOVE

WITH AN AVERAGE LOW OF 7 BELOW ZERO.

BELOW IS A SUMMARY OF OFFICIAL LOW TEMPERATURES AS OF NOON

THURSDAY UNLESS OTHERWISE NOTED.

FAIRBANKS AREA:

NORTH POLE (KJNP).......................49 BELOW (NEW RECORD)

NORTH POLE WOODSMOKE SUBDIVISION........47 BELOW

FORT YUKON #2...........................44 BELOW

EIELSON AIR FORCE BASE..................43 BELOW (NEW RECORD)

CLEAR SKY...............................42 BELOW

FAIRBANKS AIRPORT.......................41 BELOW (NEW RECORD)

UNIVERSITY EXPERIMENTAL STATION.........41 BELOW (NEW RECORD)

UAF WEST RIDGE..........................40 BELOW (NEW RECORD)

GOLDSTREAM CREEK........................40 BELOW

OUTSIDE OF FAIRBANKS:

MANLEY HOT SPRINGS......................54 BELOW (NEW RECORD)

TELIDA RAWS.............................47 BELOW (UNOFFICIAL)

CHALKYITSIK RAWS........................46 BELOW (UNOFFICIAL)

FORT YUKON AIRPORT......................46 BELOW

NIKOLAI.................................45 BELOW

TANANA AIRPORT..........................42 BELOW

NENANA AIRPORT..........................42 BELOW

COLDFOOT RAWS...........................41 BELOW (UNOFFICIAL)

BETTLES AIRPORT.........................40 BELOW

$$

APW/DJH

[tacoman25]

Today's Euro weeklies shows some signs of change for mid-December. Week 4 is pretty far out (Dec 13-19) so take it FWIW, but we finally see the AK vortex get knocked out and the first signs of a -EPO...Aleutian ridge flexes poleward more trying to poke into the Bering Straight region and we see a pretty good arctic dump of cold air into western/central Canada. That would be step 1 in trying to shuffle out the milder pattern.

Nice. Hopefully it evolves a little differently than the current Arctic dump.

[ORH_wxman]

Nice. Hopefully it evolves a little differently than the current Arctic dump.

It looks like if the pattern evolved the way it shows...the cold would definitely affect the northern tier the most as there is a still a robust ridge in the southern and southeastern states. No real blocking in the Atlantic NAO region and a -PNA. Probably one of those arctic air masses that affects the northern Rockies and northern plains first and then seeps to the lakes and NE as the mechanism for really driving is south deep into the CONUS is still absent. But its a definite start and a bit more blocking could certainly show up as we get closer.

It looks kind of unstable in that setup so I'm sure we'll see some changes. The biggest feature of note was dislodging the AK vortex.

[Ginx snewx]

The winds of change are in the air, probably later than sooner but there is light at the end of the warm tunnel. Hopefully NCEP is right

[wxmx]

There's little indication of high latitude blocking, other than regional/transient/weak in at least 2/3 weeks... Polar night jet is in full force, and I see no forcing messing with it in the medium range.

OTOH, tropical forcing will become even less favorable, with a typical Niña setup, with +OLR anomalies in the C and W Pac and -OLR translating from the IO to around Indonesia...this will only help enhance the Aleutian ridge. Air masses source region will be mostly from the Pacific, and this setup usually chokes any kind of artic air intrusion, so even if it doesn't look like we will be immersed in a zonal flow regime, any amplification will lack artic cold air.

Whatever pattern change that might occur, it looks like it will happen after Dec 10th, not before.

[thunderbolt]

There's little indication of high latitude blocking, other than regional/transient/weak in at least 2/3 weeks... Polar night jet is in full force, and I see no forcing messing with it in the medium range.

OTOH, tropical forcing will become even less favorable, with a typical Niña setup, with +OLR anomalies in the C and W Pac and -OLR translating from the IO to around Indonesia...this will only help enhance the Aleutian ridge. Air masses source region will be mostly from the Pacific, and this setup usually chokes any kind of artic air intrusion, so even if it doesn't look like we will be immersed in a zonal flow regime, any amplification will lack artic cold air.

Whatever pattern change that might occur, it looks like it will happen after Dec 10th, not before.

so are you optamistic about patter change?

[am19psu]

There's little indication of high latitude blocking, other than regional/transient/weak in at least 2/3 weeks... Polar night jet is in full force, and I see no forcing messing with it in the medium range.

OTOH, tropical forcing will become even less favorable, with a typical Niña setup, with +OLR anomalies in the C and W Pac and -OLR translating from the IO to around Indonesia...this will only help enhance the Aleutian ridge. Air masses source region will be mostly from the Pacific, and this setup usually chokes any kind of artic air intrusion, so even if it doesn't look like we will be immersed in a zonal flow regime, any amplification will lack artic cold air.

Whatever pattern change that might occur, it looks like it will happen after Dec 10th, not before.

[CoastalWx]

The european models (both UK and EC) continue to shift the wave through P4-5 and into p6. That american models don't seem as bullish right now. IMO, I really would like to see a modest wave go into p6 and eventually 7 so that we can try to get some tropical forcing help, to dislodge the vortex up north. All the ensembles look somewhat better, but it still is no where near ideal, even at the end of their runs. Some runs show ridging into the GOA and western Canada. That's nice, but we still have lower heights across AK and the EC ensembles of troughing in the sw which will try and pump up the se ridge. Of course it doesn't mean some can sneak in 1 or 2 snow events, but the overall pattern still looks rather balmy for many in the east and southeast.

[CoastalWx]

On the EC ensembles, there does appear to be some split flow with weak ridging in western Canada and a trough in the sw. It may set up for a gradient pattern somewhere in the nrn US or southern Canada as colder air tries to come south, but the trough over the sw acts to pump up heights over the east.

[JBG]

this November reminds me of 1975 when we set the record for the warmest November at the time...It came after a brief cold shot minus the snow at the end of October...I had a handfull of analogs this year but only a few were mild into January with colder endings...1971 and 1974 were on the list and as of today they are my top two for now...1973 is not far behind...

All probably good analog as they were cold PDO phase La Ninas. And all depressing in varying degrees.

[Srain]

The medium range guidance continues to advertise a significant trough with a robust storm complex in the S Plains next weekend. While a lot of details remain to be seen, there does appear to be a cool down lurking in the medium range for the Great Plains Region. As yet another in a series of upper lows tap into some deep tropical moisture associated with the STJ and with a future Hurricane Kenneth in the EPAC added to the mix, there could be an active period to end the long Thanksgiving Holiday period for the Eastern 2/3rds of the CONUS...

[Hailstorm]

Those ECMWF medium-range maps also show the potential for an organized severe weather event for some parts of the Eastern US after Thanksgiving, given the strong temperature gradient in the mid-levels and low-levels combined with the tropical moisture and the deep trough.

[am19psu]

Another transient cool shot Mon-Wed next week for the East Coast. After that, MJO guidance would suggest that the warm pattern will continue for a while across the East. The new Euro ensembles show the MJO stalling near the P3/P4 border, but the statistical guidance from Paul Roundy shows the wave continuing as normal into P5/P6 by mid-December. All of those phases are generally warm ones for the EC in December.

[OKpowdah]

Another transient cool shot Mon-Wed next week for the East Coast. After that, MJO guidance would suggest that the warm pattern will continue for a while across the East. The new Euro ensembles show the MJO stalling near the P3/P4 border, but the statistical guidance from Paul Roundy shows the wave continuing as normal into P5/P6 by mid-December. All of those phases are generally warm ones for the EC in December.

As the Euro started to let on last night, I think we'll see a more permanent trough set up over the center of the nation by no later than the 15th. Depending on synoptic specifics, this can offer some snow/ice possibilities for interior New England. The east will really get into the game by the end of the month, and into January

[Srain]

This could make for an interesting return home from the long Thanksgiving Holidays...

HPC Update:

12Z UPDATE... THE 12Z ECMWF HAS MADE A SIGNIFICANT TREND TOWARD

00Z-12Z RUNS OF THE GFS/UKMET/CANADIAN... NAMELY TRENDING FASTER

WITH THE INITIAL SRN STREAM TROF MOVING INTO THE SWRN STATES AND

THEN TOWARD A DEEP TROF/CLOSED LOW DEVELOPING OVER THE E-CNTRL

CONUS LATER IN THE PERIOD. THE 12Z GEFS MEAN IS NOW THE LONE

HOLDOUT IN SHOWING AN EVOLUTION REMOTELY CLOSE TO THE OLD 00Z

ECMWF. AS TIME PERMITTED THE FINAL FCST REFLECTS A PARTIAL

ADJUSTMENT TO ACCOUNT FOR INCREASED CLUSTERING OF OPERATIONAL

GUIDANCE... THOUGH NOT COMPLETELY DUE TO TYPICAL FCST ERRORS TO BE

EXPECTED BY DAY 7.

TROF ALOFT MOVING EWD FROM THE WEST COAST WILL BRING NEAR TO BELOW

NORMAL TEMPS AND AREAS OF PCPN TO THE WEST LATE THIS WEEK WITH A

WARMER/DRIER TREND DURING THE WEEKEND/EARLY NEXT WEEK AS A RIDGE

ALOFT BUILDS INTO THE SOUTHWEST. ALTHOUGH GUIDANCE IS NOT

UNANIMOUS... DURING THAT TIME PCPN WILL MOST LIKELY BE CONFINED TO

THE EXTREME NW. MEANWHILE OVER THE ERN HALF OF THE CONUS TEMPS

SHOULD TREND COOLER AFTER STARTING THE PERIOD ABOVE NORMAL... WITH

INCREASING PCPN CHANCES. THE CURRENT MOST LIKELY SCENARIO OVER

THE ERN HALF OF THE CONUS MID-LATE PERIOD WOULD BRING INCREASINGLY

UNSETTLED WEATHER OVER THIS REGION FROM THE WEEKEND INTO NEXT

WEEK... WITH WELL BELOW NORMAL TEMPS ALSO PSBL UNDER/W OF THE TROF

ALOFT. DEPENDING ON HOW THE TROF ALOFT EVOLVES... SOME LOCATIONS

MAY BE COLD ENOUGH TO SEE SOME SNOW. WITH ARRIVAL OF 12Z GUIDANCE

THE LOWER PROBABILITY SCENARIO OF A MORE PROGRESSIVE SYSTEM

FOLLOWED BY MODERATE TEMPS IS NOW MORE IN THE MINORITY THAN

BEFORE.

[am19psu]

So, snow for Madison or Pittsburgh next week? What a mess of a forecast this is going to be.

[Ellinwood]

So, snow for Madison or Pittsburgh next week? What a mess of a forecast this is going to be.

Anything past the end of the week is almost dartboard-worthy.

Euro's coming around to the GFS a bit WRT the cut-off low over the Midwest/TN Valley region. I imagine the Euro will get a decent grasp of it by tomorrow's 12z run, then the GFS will slowly move towards whatever solution the Euro gets.

-----

Also, for anyone who uses the EarthSat Models page, we have incorporated new maps for 10mb, 30mb and 50mb including heights, temps, anomalies and 12hr changes for both on all of our available models (only no 30mb stuff for the Canadian). These new maps will help out with some of the medium range and long range forecasting

[wxmx]

12z Euro is showing the first real artic shot entering the CONUS @day 10, thanks to a huge omega EPO ridge. Skeptical right now of course. Good news (for cold lovers), is that we're probably getting a somewhat favorable Pacific with an Aleutian low, but I'm not sure if it can pump the ridge to go all the way into the Artic circle.

[usedtobe]

12z Euro is showing the first real artic shot entering the CONUS @day 10, thanks to a huge omega EPO ridge. Skeptical right now of course. Good news (for cold lovers), is that we're probably getting a somewhat favorable Pacific with an Aleutian low, but I'm not sure if it can pump the ridge to go all the way into the Artic circle.

That's the way the pattern needs to change but it still aims the cold at the west and plains with the east probably warming back up until a major low goes into the great lakes and then somewhere off the east coast. That's probably gives up the 1st week of dec providing the euro amplification and pattern is right. That's a huge assumption as none of the models seem to be handling the longer ranges very well.

[wxmx]

That's the way the pattern needs to change but it still aims the cold at the west and plains with the east probably warming back up until a major low goes into the great lakes and then somewhere off the east coast. That's probably gives up the 1st week of dec providing the euro amplification and pattern is right. That's a huge assumption as none of the models seem to be handling the longer ranges very well.

I agree, if verified, it would be a west of the Mississippi special. With no Atlantic blocking and a continuous ridging over the eastern third, pattern looks fickle and mediocre at best for that part of the CONUS. One more reason to be cautious about a real pattern change. Still, if it verified verbatim, that's a huge artic high showing up, and a modified version of it would probably slid east after freezing the plains.

[Ginx snewx]

Jerry WXFella has been banging the 93/94 drum for a long time, seeing that evolution now.

[okie333]

I agree, if verified, it would be a west of the Mississippi special. With no Atlantic blocking and a continuous ridging over the eastern third, pattern looks fickle and mediocre at best for that part of the CONUS. One more reason to be cautious about a real pattern change. Still, if it verified verbatim, that's a huge artic high showing up, and a modified version of it would probably slid east after freezing the plains.

I'd be OK with it just "freezing the plains" lol

[SnowGoose69]

The pattern on the GFS runs in the medium longer range looks very December 2003 and 2004-2005 ish, that ridge or progressive flow that encompasses most of the country west of the Lakes and the trough which dips in and out of the NE and OH valley...interestingly enough this month has very much resembled November 2003 at least in terms of the temp departures, I know the hemispheric height pattern has not been exactly identical. December 2003 was not a very cold month at all but we lucked out in the NE with 2 snow events in a relatively so-so pattern otherwise. It wasn't til January the AO and NAO tanked. I know one of the Mets mentioned December 1988 as a match as well, there was a small pool of below normal departures in the rockies, but that month was mainly above for the West and Central and slightly below in the East, again with that shallow eastern trough and +AO and NAO.

[Srain]

That's the way the pattern needs to change but it still aims the cold at the west and plains with the east probably warming back up until a major low goes into the great lakes and then somewhere off the east coast. That's probably gives up the 1st week of dec providing the euro amplification and pattern is right. That's a huge assumption as none of the models seem to be handling the longer ranges very well.

The 00Z Euro held sevre and does suggest the west and the plains will see the best shot for some very cold air to head S into the Great Basin. The GFS is not as amplified with the +PNA ridge. The euro would dump that cold air into Western Canada and points S that has been building for the last several weeks in Alaska during the first week of December. As you and others have stated, the models have struggled beyond the medium range.