Medium Range Discussion Winter 2011-12

[okie333]

Forget them, there's blocking over the pole!

Very good pattern for CP flow setting up... the NAO doesn't matter much for most of the nation as long as the ridge amplifies over Alaska and the trough over Greenland is east-based. AO/NAO blocking to lock the cold air in will have to wait until after the SSW. PV is already split at 500mb in both models as well.

[usedtobe]

Very good pattern for CP flow setting up... the NAO doesn't matter much for most of the nation as long as the ridge amplifies over Alaska and the trough over Greenland is east-based. AO/NAO blocking to lock the cold air in will have to wait until after the SSW. PV is already split at 500mb in both models as well.

Looks pretty nina-ish with the arctic air plunging down the plains and the southeast staying warmer than normal with the mid atlantic in the area between the colder and warmer than normal air.

[Srain]

Heh...

[Chinook]

What a huge difference from last winter: no blocking. All of Greenland had below normal heights a few days ago. I guess it is changing up a bit. Definitely seeing some ridging from British Columbia on northward to the north pole coming up, but probably that cold air mainly stays north. ECMWF showing some -28C temps in northern Manitoba on 12/19. That's something to consider.

[usedtobe]

Heh...

By 240 hrs the euro looks inteesting and does start bringing the 1st true arctic air into the country if it is correct. We'll pretty much be heading to the nina type cycle with the pna pattern in the positive phase which probably would get some cold air into the east by xmas. With the nao so positive it might not have true staying power for the southeast and the mid alt and it might be hard to get a good snow but there would be some chance instead of the almost no chance that we've had and will have until after day 10.

[donsutherland1]

For those who are interested, the temperature anomalies for the 12/1-10 timeframe were as follows:

[Alpha5]

For those who are interested, the temperature anomalies for the 12/1-10 timeframe were as follows:

SW ski resorts must be in heaven....

[Met1985]

For those who are interested, the temperature anomalies for the 12/1-10 timeframe were as follows:

Wow i wonder what the temp departures were in the NE.

[loafnut]

SW ski resorts must be in heaven....

Heard its actually been awful most places. Very dry, no snow.

[Srain]

Another Southern Rockies/S Plains winter storm appears to be in the works for Sunday into the early part of next week heading into the Holiday travel period.

[#NoPoles]

Heard its actually been awful most places. Very dry, no snow.

actaully, it's the Tahoe area resorts that are suffering...storm track to the north, and an active subtrop jet to the south, have left them stuck in the middle in the doldrums with awful temps for snow making...here is snippet from an article discussing the favorable conditions for the SW Resorts...

http://www.bizjourna...open-dec-3.html

Ski New Mexico officials said the mountains have had some good early snow and low temperatures that have facilitated making snow. The Enchanted Forest cross country ski resort near Red River opened in early November and Sipapu Ski Resort opened Nov. 19. Red River Ski Resort, Taos Ski Valley and Ski Apache are open as well.

Angel Fire is slated to open Dec. 15 and Pajarito on Dec. 18. Sandia Peak Ski Area has set a tentative opening date of Dec. 17. It will hold a hiring fair on Dec. 3 at the Ski Area Base Lodge from 9 a.m. to 3 p.m. for full-time and part-time seasonal positions. Applicants should come in person with a current driver’s license and Social Security card.

[wxmx]

Another Southern Rockies/S Plains winter storm appears to be in the works for Sunday into the early part of next week heading into the Holiday travel period.

Yep. The map Don posted won't probably change much for Dec. 11th-20th...maybe even thru the 25th.

[am19psu]

Yep. The map Don posted won't probably change much for Dec. 11th-20th...maybe even thru the 25th.

Do I hear Jan 10?

[tacoman25]

For those who are interested, the temperature anomalies for the 12/1-10 timeframe were as follows:

DEN is running -10.9 for the month so far.

[#NoPoles]

Do I hear Jan 10?

i'm calling for a pattern change around ground hog day...i'll bet you beer at the conference?

[am19psu]

i'm calling for a pattern change around ground hog day...i'll bet you beer at the conference?

I'll take the under

[wxmx]

Do I hear Jan 10?

Yeah, mid Jan would have been my guess. PV will weaken to more normal values, same with the AO for the 2nd half of Dec...10-15 days after that for a possible pattern change to much colder for the East. Mostly a WAG right now.

[CoastalWx]

The EC ensembles continue the trend of trying to get ridging into AK and believe it or not...actually have it branch right across the NPole and combine it with the Caspian Ridge. They also have some decent warm anomalies >+12C at 50mb pushing into northern Canada during this time. While the se ridge appears from time to time, it at least offers some better meridional transport of cold into the US. It's not a great pattern, but for the time being...the insane + temp departures over the northeast may subside with some better chances of a little more wintry weather. Can't really get too excited yet with the tendency of things to always come in warmer in the 1-5 day, but at least the PAC is getting temporarily better.

[usedtobe]

The EC ensembles continue the trend of trying to get ridging into AK and believe it or not...actually have it branch right across the NPole and combine it with the Caspian Ridge. They also have some decent warm anomalies >+12C at 50mb pushing into northern Canada during this time. While the se ridge appears from time to time, it at least offers some better meridional transport of cold into the US. It's not a great pattern, but for the time being...the insane + temp departures over the northeast may subside with some better chances of a little more wintry weather. Can't really get too excited yet with the tendency of things to always come in warmer in the 1-5 day, but at least the PAC is getting temporarily better.

The blocking and ridging over Alaska is not as unusual with a strong ao then blokcing over greenland and the north atlantic. Essentially, a strong ao means you almost always at a positive nao.

http://www.jisao.washington.edu/wallace/ncar_notes/#4Signatures

[#NoPoles]

I'll take the under

ok, I call first week in Feb...for a beer at the Conference

[OKpowdah]

I still like the idea of a major storm in the east around the start of the second week of January. Major reversal of the NAM following a significant warming.

[CoastalWx]

I wonder just how low the AO/NAO will go. I think the stats say that a strong +AO from end of Novie through mid December argue that the avg Jan AO will be +. But given that, we'll have to watch to see if the warming can split the vortex up north into two which it seems like it could do..and also follow the MJO as the weeklies seem to have a decent burst into p7. Lately, it's been a good bet to place the odds in p2-4, but it is the best looking burst we've seen on the progs...so who knows. Like usual, models may rush things, but there is some hope for a relaxation of this pattern.

[usedtobe]

I wonder just how low the AO/NAO will go. I think the stats say that a strong +AO from end of Novie through mid December argue that the avg Jan AO will be +. But given that, we'll have to watch to see if the warming can split the vortex up north into two which it seems like it could do..and also follow the MJO as the weeklies seem to have a decent burst into p7. Lately, it's been a good bet to place the odds in p2-4, but it is the best looking burst we've seen on the progs...so who knows. Like usual, models may rush things, but there is some hope for a relaxation of this pattern.

Bob Chill's stats certainly argue for the AO to average in the positive direction but most of his cases had double digit snow in DC so I'm guessing there were splits and that the AO probably dropped to zero of below fro short periods.

[am19psu]

I'm hopeful that Paul Roundy's site will update today. There are some fairly large differences in the MJO evolution between the European model and the statistical progression Roundy produces. The Euro shows no hints of -OLR anomalies near the dateline anywhere in the near future, however Roundy's stuff has been advocating a brief interlude of P7-P8 conditions around Dec 18-23, which would have implications for the strength of the ridge on the West Coast and the depth of the system in the Eastern half of the US early next week.

Also, for you stratosphere watchers, Roundy shows the MJO heading back to the IO around New Year's, which will set off another Himalayan mountain torque and possibly produce more disruption to the polar vortex.

This forecast is trickier than it seems on the surface.

[weathafella]

Thanks for the insight folks. This is an excellent learning thread.

[Quakertown needs snow]

Himalayan mountain torque

i think i learned something new today.

great stuff in this thread.

thanks folks

[Alpha5]

Just out of curiosity, what caused the NAO/AO reversal in early february last year? With the exception of 1 event, winter ended here after the January 26-27th storm.

[donsutherland1]

The latest run of the NAEFS suggests that Canada is likely to be warmer than normal for the 12/24-31/2011 timeframe, while the Gulf Coast will likely be cooler than normal.

A look at composite data based on the ENSO, AO, and PNA, as well as the objective analogs argues that not all of Canada will be warmer than normal. At the same time, that data suggests the presence of a southeast ridge, which could keep the Gulf Coast warmer than normal.

Below is a chart that compares the NAEFS with the results of:

1. Composite 500 mb height anomalies based on an AO in the +1 to +2 range; PNA in the -0.75 to +0.75 range, ENSO R3.4 anomalies in the -1.50 to -0.75 range, for the 12/20-31 timeframe (1950-2010)

2. Composite 850 mb temperature anomalies based on an AO in the +1 to +2 range; PNA in the -0.75 to +0.75 range, ENSO R3.4 anomalies in the -1.50 to -0.75 range, for the 12/20-31 timeframe (1950-2010)

3. 500 mb height anomalies based on the objective analogs centered on 12/25 from the 12/14 12z run of the GFS ensembles

4. Temperature anomalies based on the objective analogs centered on 12/25 from the 12/14 12z run of the GFS ensembles

Even as the pattern is the type that could allow a cold shot into the East, with its greatest impact from the Mid-Atlantic region northward, warm anomalies will again likely outduel the cold ones. As has been the case for December to date, a large portion of the western third to half of the U.S. could wind up on the cold side of normal.

[brad1551]

Winter"s official date is in a week and I think everyone has been spoiled the past couple of years in the east. Especially the North East. NAO/AO are not living up to there October & November winters forecast. Lots were wrong as I was too. For the real snow lovers in the Mid Atlantic and Northeast are going to be pulling there hair out this year. I see a major ice storm

brewing for the mid Atlantic this year. To me they are far worse then any snowstorm. I know it is early but what the heck, Winter 2012-2013 is one I

am already thinking about with the solar activity supposedly plummeting and a back to back la Nina coming off of. What happened at the last back

to back la Nina"s ? Weak to mod El Nino of 2009-2010 winter. I know it's

early but this years winter seems like an almost bust for me. I hope I am

wrong. If we are in a neutral phase buy early fall, I am feeling good. Sorry for the early insight.

[donsutherland1]

The persistence of the absence of blocking and continuing warmth has led to some forecasts being revised toward the warmer side for this winter. From Bloomberg.com:

The biting cold of the past two winters in the U.S. may be delayed until January, if it comes at all, easing demand for heating fuels during their peak season.

While cold weather may make brief appearances in much of the U.S. this month, overall December temperatures will be above-normal and that may be a pattern for the winter of 2011- 2012, said Jim Rouiller, senior energy meteorologist at Planalytics Inc. in Berwyn, Pennsylvania.

The complete story can be found at: http://www.bloomberg.com/news/2011-12-14/u-s-winter-to-miss-biting-cold-of-past-two-seasons.html