Medium Range Discussion Winter 2011-12

[am19psu]

Time to fire this thread up again for winter. Hopefully, this year it will be more than Jorge and me talking to ourselves.

For the next ten days or so, it looks to be cool west/warm east with intermittent shots of cool behind shortwaves in a typical -PNA/gradient flow pattern. The big question is when will the pattern change? Judging by the tropical convection forecasts, I'd guess some time around Thanksgiving. As convection fires over the Western Indian Ocean, we should see ridging go up across the Rockies and allow cold air to filter down into the CONUS.

[wxmx]

Time to fire this thread up again for winter. Hopefully, this year it will be more than Jorge and me talking to ourselves.

For the next ten days or so, it looks to be cool west/warm east with intermittent shots of cool behind shortwaves in a typical -PNA/gradient flow pattern. The big question is when will the pattern change? Judging by the tropical convection forecasts, I'd guess some time around Thanksgiving. As convection fires over the Western Indian Ocean, we should see ridging go up across the Rockies and allow cold air to filter down into the CONUS.

Real pattern change or more like a transitory one? I bet is the latter, a real one would probably need to involve high latitude blocking. In a strengthening Niña (even though it's only weak now) a real pattern change would probably need tropical and polar mechanisms to consistenly flood the CONUS east of the Rockies and outside the N Plains/Midwest of below normal temps.

[#NoPoles]

Time to fire this thread up again for winter. Hopefully, this year it will be more than Jorge and me talking to ourselves.

For the next ten days or so, it looks to be cool west/warm east with intermittent shots of cool behind shortwaves in a typical -PNA/gradient flow pattern. The big question is when will the pattern change? Judging by the tropical convection forecasts, I'd guess some time around Thanksgiving. As convection fires over the Western Indian Ocean, we should see ridging go up across the Rockies and allow cold air to filter down into the CONUS.

i'm wondering if we actually get locked into a predictable pattern this year...just by what i've been seeing (and i'm not a professional) this winter might be highly variable...

[am19psu]

Real pattern change or more like a transitory one? I bet is the latter, a real one would probably need to involve high latitude blocking. In a strengthening Niña (even though it's only weak now) a real pattern change would probably need tropical and polar mechanisms to consistenly flood the CONUS east of the Rockies and outside the N Plains/Midwest of below normal temps.

Going outside my realm here, but there is a pretty big block forecasted over the East Atlantic/Scandanavia. It wouldn't take a major change in the orientation of that block to change the pattern into December.

[am19psu]

i'm wondering if we actually get locked into a predictable pattern this year...just by what i've been seeing (and i'm not a professional) this winter might be highly variable...

Glad to see you've met my friend La Nina

[#NoPoles]

Glad to see you've met my friend La Nina

is she hot? j'k

glad you started up this thread...i've been wondering about the winter pattern this year...started a thread about it in OT

[wxmx]

i'm wondering if we actually get locked into a predictable pattern this year...just by what i've been seeing (and i'm not a professional) this winter might be highly variable...

I'll probably have a predictable pattern this year... you're in MA, and if the high latitudes behave as I expect, yes, you are for a wild ride.

Going outside my realm here, but there is a pretty big block forecasted over the East Atlantic/Scandanavia. It wouldn't take a major change in the orientation of that block to change the pattern into December.

Yep, it could well be, this things are hard to predict, unless there's some strong planetary wave aimed north and up.

BTW we are off to a good start talking to ourselves . Fortunately Diane is making things more diverse

[#NoPoles]

I'll probably have a predictable pattern this year... you're in MA, and if the high latitudes behave as I expect, yes, you are for a wild ride.

Yep, it could well be, this things are hard to predict, unless there's some strong planetary wave aimed north and up.

BTW we are off to a good start talking to ourselves . Fortunately Diane is making things more diverse

well, i do love listening to you both bounce ideas off each other...great analytical minds talking about the atmosphere is at the top of my list of things that make me smile...

Jorge, I'm actually interested in the winter pattern for Mexico because I'm fascinated by the Monarch butterfly, and how the weather patterns affect the region where the Monarchs over-winter...

[Ellinwood]

Models have been just awful with the recent longwave and shortwave patterns, as well as run-to-run consistency in the medium range. With the last two on-run cycles of the GFS and ECM ensembles, both run a neutral NAO and negative heading neutral PNA. Big difference comes out of the AO, with is well into the positive phase on the Euro and near neutral on the GFS.

Either way, it's could to be short notice on any discernible pattern change as we head into the back half of the month as long as the models continue to struggle with the strength and placement of the cold pool and any potential blocking.

[wxmx]

well, i do love listening to you both bounce ideas off each other...great analytical minds talking about the atmosphere is at the top of my list of things that make me smile...

Jorge, I'm actually interested in the winter pattern for Mexico because I'm fascinated by the Monarch butterfly, and how the weather patterns affect the region where the Monarchs over-winter...

Thanks for your kind words

Some years I'm (Monterrey) in the middle of the Monarch path and you can see all day, for many days, thousands of butterflies in the middle of it's way to either Michoacan/Mexico state or back to the US and Canada. I'm not sure the winter pattern affects them much where they over-winter, since they prefer to do it in mostly stable, temp-wise locations, in the Sierra Madre between Mexico state and Michoacan which has little variation year to year...probably a reason why they choose that place. I have been there, and have seen impressive clusters hanging off big pines.

Too bad, this year wasn't one of those years... it's probably 3-4 years since I have seen a big monarch migration...and probably weather has more influence in that than what it does for over-winter siting.

You can see I'm very close to the bullseye of the migration path.

[Srain]

Models have been just awful with the recent longwave and shortwave patterns, as well as run-to-run consistency in the medium range. With the last two on-run cycles of the GFS and ECM ensembles, both run a neutral NAO and negative heading neutral PNA. Big difference comes out of the AO, with is well into the positive phase on the Euro and near neutral on the GFS.

Either way, it's could to be short notice on any discernible pattern change as we head into the back half of the month as long as the models continue to struggle with the strength and placement of the cold pool and any potential blocking.

Boy is this statement true. It's good to see some general discussion on the main page which has been lacking for a while. Kudos to Adam for getting this ball rolling. I'm looking forward to seeing what late December/earlyJanuary will as well...

[CoastalWx]

Overall models seemed to have lost some of the blocking in the NAO region and really hit hard on the trough out west. This means East Coast weenies will have to wait a while.

[VAwxman]

Overall models seemed to have lost some of the blocking in the NAO region and really hit hard on the trough out west. This means East Coast weenies will have to wait a while.

Yeah I'm starting to think we may have to wait longer yet. While there is a window next week where things look much improved in the Bering Sea region, and okay in Greenland, though a little farther east than optimal, it seems that it cannot last, as models shoot that down and actually look quite hideous from Asia across the Pacific. MJO forecasts are to head toward p2-p33 around day 15, and if that is real and we carry that forward (assuming we continue to see a fairly active MJO), that doesn't bode well for early December given a lack of blocking beforehand. Still, western Canada looks to be quite cold, so any amplification the models may be missing would make things interesting.

[#NoPoles]

Thanks for your kind words

Some years I'm (Monterrey) in the middle of the Monarch path and you can see all day, for many days, thousands of butterflies in the middle of it's way to either Michoacan/Mexico state or back to the US and Canada. I'm not sure the winter pattern affects them much where they over-winter, since they prefer to do it in mostly stable, temp-wise locations, in the Sierra Madre between Mexico state and Michoacan which has little variation year to year...probably a reason why they choose that place. I have been there, and have seen impressive clusters hanging off big pines.

Too bad, this year wasn't one of those years... it's probably 3-4 years since I have seen a big monarch migration...and probably weather has more influence in that than what it does for over-winter siting.

You can see I'm very close to the bullseye of the migration path.

thanks for posting this...some years back there was a hard freeze and some snow/ice in (the Sierra Madre between Mexico state and Michoacan) and you could see clusters of monarchs that had fallen from their hibernating spots in the trees and were just lying on the ground in the ice and snow...it was very sad...

habitat destruction in the US, as well as clear cutting in Mx where they over winter is the main stressor on their decline in number...as a species, we just don't know how to share...or live and let live...

[uncle W]

from 1968-69 to 1970-71 the AO was pretty negative at times during the winter months helping bring down arctic air or big snows in 69...1971-72 diden't see much blocking until February when it became colder and snowier...We could end up seeing a more negative AO later this year...December might not be as cold as some think if the AO remains mostly positive...last look it was near neutral...It's been way positive since the NE snowstorm passed...

[Bob Chill]

67-68 had a +AO during Sept - Nov before turning negative for DJF. There are some similarities to this analog w/ enso and pdo stuff. AO index was -.347, -.409, and -2.154 for the respective months of DJF.

Edit: I just compared the NAO too. Pretty similar too. Both the NAO and AO indexes kinda went to sleep after mid august and have been within neutral range one way or the other for a while.

[easternsnowman]

Overall models seemed to have lost some of the blocking in the NAO region and really hit hard on the trough out west. This means East Coast weenies will have to wait a while.

The models have been really struggling with this pattern. As mentioned previously it is very hard over the past 15 or 20 years to bet below average temps for november.

[BethesdaWX]

67-68 had a +AO during Sept - Nov before turning negative for DJF. There are some similarities to this analog w/ enso and pdo stuff. AO index was -.347, -.409, and -2.154 for the respective months of DJF.

Edit: I just compared the NAO too. Pretty similar too. Both the NAO and AO indexes kinda went to sleep after mid august and have been within neutral range one way or the other for a while.

The Sun, QBO, and PDO are all perfect matches to 1967/68, it has been my favorite analog though many don't agree with me. I can't find anything more similar overall in comparison to this year. The difference in the month anomalies was November 1967 was cool in the East while December was torchy, but the progression seems quite similar just delayed in 1967/68 or so it seems which might make sense with a likely slower and less defined MJO and ENSO.

Assuming what is being shown is correct, my rookie opinion lures me into the December 15 to December 30 period for action along the East Coast, if there were to be an "opportunity for an opportunity".

[nycsnow]

The Sun, QBO, and PDO are all perfect matches to 1967/68, it has been my favorite analog though many don't agree with me. I can't find anything more similar overall in comparison to this year. The difference in the month anomalies was November 1967 was cool in the East while December was torchy, but the progression seems quite similar just delayed in 1967/68 or so it seems which might make sense with a likely slower and less defined MJO and ENSO.

Assuming what is being shown is correct, my rookie opinion lures me into the December 15 to December 30 period for action along the East Coast, if there were to be an "opportunity for an opportunity".

How was that winter for east coast?

[Ellinwood]

MEDIUM RANGE thread... not long range thread.

-----

I'm interested in seeing what happens after the cold push that moves across the northern areas at the end of the 6-10 day... seems like it could be the last chance to try to flip the pattern before the end of the month. We could be sneaking into MJO phase 2 around the time that cold tries to make its way into the north-central US around the 21st-23rd, and the MJO could facilitate a stronger cold push. The problem is that it would likely be transient in nature as there is little evidence to suggest that blocking could develop and lock in the pattern at that time.

Yeah I'm starting to think we may have to wait longer yet. While there is a window next week where things look much improved in the Bering Sea region, and okay in Greenland, though a little farther east than optimal, it seems that it cannot last, as models shoot that down and actually look quite hideous from Asia across the Pacific. MJO forecasts are to head toward p2-p33 around day 15, and if that is real and we carry that forward (assuming we continue to see a fairly active MJO), that doesn't bode well for early December given a lack of blocking beforehand. Still, western Canada looks to be quite cold, so any amplification the models may be missing would make things interesting.

Bolded parts will be the two biggest things to watch as we get closer... as was said earlier, models have been horrible in trying to sniff out the pattern, so really anything is still possible at this point. Sustained cold remains one of the more unlikely scenarios as the more transient pattern with a semi-sustained -PNA seems to be the common theme amongst the model suite.

[kab2791]

Wow, one of the best threads I've seen in a while. Thanks to all that contribute.

[NJHurricane]

Normally I wouldn't bother to cluttter a thread by saying "great thread" but a place for non-region specific medium range disco is sorely needed, I hope this thread stays active. I have to admit I bought into the "pattern change by Turkey Day hype"...now not so much. Curious, which of the global models had the best verification scores in the medium range the last couple winters?

[am19psu]

Normally I wouldn't bother to cluttter a thread by saying "great thread" but a place for non-region specific medium range disco is sorely needed, I hope this thread stays active. I have to admit I bought into the "pattern change by Turkey Day hype"...now not so much. Curious, which of the global models had the best verification scores in the medium range the last couple winters?

Euro. Always the Euro.

[#NoPoles]

Adam, the only thing your girl- La Nina- has managed to bring to the east coast this year...is a stretch of 4-5 days in the 60's-70's followed by a minor FROPA getting temps down to the 50's for two days...rinse wash repeat...I'm thinking this year is going to be a banner snow season in the Northern Rockies- ID, MT, WY, UT, CO

[Ginx snewx]

Adam, the only thing your girl- La Nina- has managed to bring to the east coast this year...is a stretch of 4-5 days in the 60's-70's followed by a minor FROPA getting temps down to the 50's for two days...rinse wash repeat...I'm thinking this year is going to be a banner snow season in the Northern Rockies- ID, MT, WY, UT, CO

Looking back at last year, the mid range pattern is remarkedly similar. The AO and NAO values averaged positive through the same period. Sustained pattern change did not evolve until the second week of Dec culminating in the Boxing day storm. Mid range, things look very similar to this period last year when a sustained pattern change was not in the cards. Looking at SST anomaly it appears that SST wise the world is very similar. The cold at 7H levels and above is notable. Transience would seem to be the theme for the medium range.With a raging positive EPO, a negative PNA and a slightly neg NAO with the MJO hanging around phase 2-3 it appears that an extended period of cold stormy weather will affect the West Coast with shots of cold bleeding East but with more of a transient nature. Predicted Ens indexes.

[JBG]

I think that the key to the pattern heading into December will still be the dominant +EPO pattern that has really locked in since last August.

As long as the EPO stays positive, we'll continue to see a similar pattern. I put together a +EPO December composite showing

what a December version of the pattern would look like if the pattern continues.

Doesn't the pattern break in most La Niña years around the beginning of December? Well except 1971, 1998?

[Srain]

HPC Final Update:

12Z SHORTWAVE TRAFFIC THRU THE FAST FLOW/BROAD TROF ACROSS THE

LOWER IS QUITE COMPLEX...WITH WILDY DIFFERENT RESULTS FOR THE

SURFACE PATTERNS ESPECIALLY AROUND WED DAY 4. LOW

CONFIDENCE...WITH NO COMPELLING REASON FOR BIG CONTINUITY CHANGES

FROM THE UPDATED PRELIM. THE 12Z UKMET..FOR EXAMPLE...HAS A WAVY

FRONT NEAR THE OH VLY WHILST THE CANADIAN HAS COLD CYCLONIC FLOW

OVER THE OH VLY WITH A SURFACE FRONT IN THE NRN GULF OF MEXICO!

HOWEVER...THE NEW ECMWF ALSO SUPPORTED A WAVY FRONT OVER THE

CENTRAL APLCHNS DAY 4...THOUGH NOT AS FAR N AS THE UKMET.

OVERALL...THE 12Z RUN THE 12Z GFS GAVE THE BEST FIT TO OUR EARIER

THINKING ON MOST FEATURES AFFECTING THE CONUS. FINAL MANUAL PROGS

ADJUSTED THE FRONT A BIT N OF THE PRELIM POSITION IN THE SE STATES

WHICH WAS A GOOD FIT TO A 12Z/12 ECMWF/GFS COMPROMISE. BY DAYS 6-7

THE MODELS ARE IN SOMEWHAT BETTER AGREEMENT ON THE OVERALL PATTERN

AFFECTING THE NATION ...A NEW WRN TROF AND SERN RIDGE...BUT AGAIN

DIFFER ON FAST TO BRING COLD AIR SWD OUT OF CANADA INTO THE WEST.

THE UKMT HOLDS MOST OF THE COLD AIR N OF THE CANADIAN BORDER WHILE

THE GFS/UKMET/CANADIAN BEGIN TO BLEED SOME COLD AIR SWD E OF THE

NRN ROCKIES.

TELECONNECTIONS ON THE REDEVELOPING MEAN TROF NEAR/JUST OFF THE W

COAST LATE NEXT WEEK GENERALLY FAVOR ABOVE NORMAL HEIGHTS OVER THE

MS VLY AND GREAT LAKES LAKES. WE PREFERRED THE 12Z/11 ECENS MEAN

OVER THE CORRESPONDING NEWER 00Z/12 MEAN AS IT KEEPS HEIGHTS

HIGHER IN THE ERN CONUS...A BETTER FIT TO TELECONNECTIONS. THE

00Z/12 GEFS ENSEMBLE MEMBERS DEVELOP A SHARPER TROF FARTHER W THAN

THE CORRESPONDING ECMWF ENSEMBLE MEMBERS EARLY NEXT WEEKEND. I

WOULD LIKE TO HOLD OFF ON MAKING A JUDGMENT CALL HERE UNTIL WE GET

A BETTER FEEL FOR HOW THE UPSTREAM RIDGE BUILDS IN THE ERN

PACIFIC. THE EARLY PRELIM DISCUSSION FOLLOWS BELOW.

SYNOPTIC EVOLUTION SHOWS GOOD AGREEMENT THROUGH NEXT WEEK BUT THE

FIRST PART OF THE MEDIUM RANGE FORECAST CONTINUES TO BE PLAGUED BY

DISAGREEMENT COMING OUT OF THE SHORT RANGE PERIOD. THOSE

DIFFERENCES SETTLE OUT AS THE EASTERN TROUGH EXITS INTO THE

ATLANTIC AND BUILDING HEIGHTS SLOWLY FOLLOW. WELL UPSTREAM...

ENERGY CURRENTLY NEAR THE NORTH SLOPE OF ALASKA WILL PUSH SOUTH

AND EASTWARD WED/D4 TOWARD THE PAC NW AS RIDGING BUILDS STRONGLY

NORTHWARD THROUGH THE ALEUTIANS AND BERING SEA. THIS WILL BRING

MUCH COLDER THAN NORMAL AIR INTO MUCH OF THE WESTERN STATES LATE

NEXT WEEK. 00Z GFS/ECMWF GENERALLY AGREE ON OVERALL PATTERN WITH

BIGGEST DIFFERENCES OVER THE HIGH PLAINS AS THE GFS DOES NOT TAKE

LOW PRESSURE INTO MN FRI/D6 LIKE THE 00Z ECMWF/CANADIAN. GIVEN THE

INCONSISTENCIES SEEN IN RECENT MODEL RUNS RIGHT FROM THE SHORT

TERM... USED A BLEND OF THE 00Z GFS/ECMWF AND 12Z/11 ECMWF/ECMWF

ENSEMBLE MEAN TO DAMPEN ANY TIMING/AMPLITUDE DIFFERENCES.

[WidreMann]

HPC Final Update:

12Z SHORTWAVE TRAFFIC THRU THE FAST FLOW/BROAD TROF ACROSS THE

LOWER IS QUITE COMPLEX...WITH WILDY DIFFERENT RESULTS FOR THE

SURFACE PATTERNS ESPECIALLY AROUND WED DAY 4. LOW

CONFIDENCE...WITH NO COMPELLING REASON FOR BIG CONTINUITY CHANGES

FROM THE UPDATED PRELIM. THE 12Z UKMET..FOR EXAMPLE...HAS A WAVY

FRONT NEAR THE OH VLY WHILST THE CANADIAN HAS COLD CYCLONIC FLOW

OVER THE OH VLY WITH A SURFACE FRONT IN THE NRN GULF OF MEXICO!

HOWEVER...THE NEW ECMWF ALSO SUPPORTED A WAVY FRONT OVER THE

CENTRAL APLCHNS DAY 4...THOUGH NOT AS FAR N AS THE UKMET.

OVERALL...THE 12Z RUN THE 12Z GFS GAVE THE BEST FIT TO OUR EARIER

THINKING ON MOST FEATURES AFFECTING THE CONUS. FINAL MANUAL PROGS

ADJUSTED THE FRONT A BIT N OF THE PRELIM POSITION IN THE SE STATES

WHICH WAS A GOOD FIT TO A 12Z/12 ECMWF/GFS COMPROMISE. BY DAYS 6-7

THE MODELS ARE IN SOMEWHAT BETTER AGREEMENT ON THE OVERALL PATTERN

AFFECTING THE NATION ...A NEW WRN TROF AND SERN RIDGE...BUT AGAIN

DIFFER ON FAST TO BRING COLD AIR SWD OUT OF CANADA INTO THE WEST.

THE UKMT HOLDS MOST OF THE COLD AIR N OF THE CANADIAN BORDER WHILE

THE GFS/UKMET/CANADIAN BEGIN TO BLEED SOME COLD AIR SWD E OF THE

NRN ROCKIES.

TELECONNECTIONS ON THE REDEVELOPING MEAN TROF NEAR/JUST OFF THE W

COAST LATE NEXT WEEK GENERALLY FAVOR ABOVE NORMAL HEIGHTS OVER THE

MS VLY AND GREAT LAKES LAKES. WE PREFERRED THE 12Z/11 ECENS MEAN

OVER THE CORRESPONDING NEWER 00Z/12 MEAN AS IT KEEPS HEIGHTS

HIGHER IN THE ERN CONUS...A BETTER FIT TO TELECONNECTIONS. THE

00Z/12 GEFS ENSEMBLE MEMBERS DEVELOP A SHARPER TROF FARTHER W THAN

THE CORRESPONDING ECMWF ENSEMBLE MEMBERS EARLY NEXT WEEKEND. I

WOULD LIKE TO HOLD OFF ON MAKING A JUDGMENT CALL HERE UNTIL WE GET

A BETTER FEEL FOR HOW THE UPSTREAM RIDGE BUILDS IN THE ERN

PACIFIC. THE EARLY PRELIM DISCUSSION FOLLOWS BELOW.

SYNOPTIC EVOLUTION SHOWS GOOD AGREEMENT THROUGH NEXT WEEK BUT THE

FIRST PART OF THE MEDIUM RANGE FORECAST CONTINUES TO BE PLAGUED BY

DISAGREEMENT COMING OUT OF THE SHORT RANGE PERIOD. THOSE

DIFFERENCES SETTLE OUT AS THE EASTERN TROUGH EXITS INTO THE

ATLANTIC AND BUILDING HEIGHTS SLOWLY FOLLOW. WELL UPSTREAM...

ENERGY CURRENTLY NEAR THE NORTH SLOPE OF ALASKA WILL PUSH SOUTH

AND EASTWARD WED/D4 TOWARD THE PAC NW AS RIDGING BUILDS STRONGLY

NORTHWARD THROUGH THE ALEUTIANS AND BERING SEA. THIS WILL BRING

MUCH COLDER THAN NORMAL AIR INTO MUCH OF THE WESTERN STATES LATE

NEXT WEEK. 00Z GFS/ECMWF GENERALLY AGREE ON OVERALL PATTERN WITH

BIGGEST DIFFERENCES OVER THE HIGH PLAINS AS THE GFS DOES NOT TAKE

LOW PRESSURE INTO MN FRI/D6 LIKE THE 00Z ECMWF/CANADIAN. GIVEN THE

INCONSISTENCIES SEEN IN RECENT MODEL RUNS RIGHT FROM THE SHORT

TERM... USED A BLEND OF THE 00Z GFS/ECMWF AND 12Z/11 ECMWF/ECMWF

ENSEMBLE MEAN TO DAMPEN ANY TIMING/AMPLITUDE DIFFERENCES.

Does the 10-day Euro show a -NAO with one of the worst possible patterns over the US?

[am19psu]

Guys, I appreciate the knowledge being dropped in this thread re: analog patterns and the character of the winter overall, but can we keep the focus of this thread in the 5-15 day timeframe? Thanks.

[Ginx snewx]

Guys, I appreciate the knowledge being dropped in this thread re: analog patterns and the character of the winter overall, but can we keep the focus of this thread in the 5-15 day timeframe? Thanks.

Looking back over last years pattern at this time the similarities are striking. One thing for sure models have huge issues in Nina years outside your 5-15 day time frame, probably even outside one week.