Winter 2011/2012 Pattern Discussion

John1122 wrote:
The GFS ens also initialize with a strongly positive AO on his site. The Euro is the only one who initializes properly there.

Thoughts for the 2/8-15/2012 Timeframe:

For the first time this winter, my medium-term forecast shows cold anomalies in the eastern U.S., southern Ontario, and southern Quebec. There is risk that a warmer outcome could still unfold and much will depend on the Arctic Oscillation. Currently, there is a huge spread among the ensemble members for the AO.

The following chart shows (clockwise):

1. The composite temperature anomalies for ENSO Region 3.4 anomalies in the -1.45°C to -0.65°C range, an AO in the -1.25 to -0.25 range, and the PNA in a +0.25 to +1.25 range.

2. The 1/29/2012 0z GFS Ensemble forecast of the Arctic Oscillation.

3. Composite temperature anomalies for MJO Phase 8 (Amplitude 1-2) during La Niñas in February.

4. The Objective Analogs centered on 2/9 rolled forward 3 days (GFS ensembles).



I'm pretty much in agreement with the chart based on the teleconnections (1st one). The only adjustment would be that Maine and possibly eastern Canada could be near normal to slightly above normal based on a combination of the blocking and decadal observed warming in that area for February. More than likely, this cold period won't lock in. Instead, it will be similar to what happened a little earlier in January where periodic cold shots occurred over a 7-14-day period before the warmth regained hold. The magnitude of the cold shots might be similar and possibly somewhat less harsh. As a result, my February forecast continues to call for widespread warm anomalies.



The 1/29/2012 run of the CFSv2 is even more aggressive on the February warm anomalies (virtually all of the U.S. and Canada, including Alaska).

This morning, the AO was -4.441. That is the lowest AO reading since December 19, 2010 when the AO was -4.695. Since 1950, there were 14 prior cases on which the AO fell to -4.000 or below in January. In 13/14 (93%) of those cases, the AO averaged < 0 in February. February 1959 was the lone exception. In 11/14 (79%) of those cases, the AO averaged -1.000 or below in February. In 6/14 (43%) of those cases, the AO averaged -2.000 or below in February. Hence, this latest data gives me strong confidence that the AO will average negative in February, and possibly -1.000 or below.

What is likely to be unprecedented for January 2012 is that none of the prior cases during which the AO fell to -4.000 or below in January had a January AO average > -1.000. The highest January average among those cases was -1.204 in January 1956. January 2012 has had an average AO of +0.069 (1/1-1/29). The month will likely finish with an average AO of -0.200 to -0.100. February 1956 had a monthly AO average of -2.029. Nevertheless, February 1956 saw the eastern portion of the U.S. have warmer than normal readings. Some of the data used for my February 2012 guess was based on February 1956.

Don,

What analogs are you using/weighting the highest right now? I'm curious how the large scale progression in those years compares to what we've seen this year.

1998-99 probably compares closest winter to what has been seen so far this winter but does not necessarily mean that February would be identical to February 1999. 1955-56 has been a rising analog especially with the recent developments related to the AO, 1975-76 is another analog year, and smaller contributions were taken from 1970-71 and 1995-96. What happened in the past 1-2 months is one factor, but a small one. How the pattern has evolved in the current month is far more important factor e.g., the breakdown of the AO+ regime is a key development. Then assumptions about various parameters for the month ahead is another. Adjustments are then made given my confidence in a variety of ensemble solutions (ENSO, MJO, anomalies, etc.) and also the observed decadal temperature trend in various parts of North America.

FWIW, the monthly map for February based on the latest objective analog years (1957, 1970, 1980, 1983, 1986, 1993, 1998, and 2005) also shows widespread warm anomalies. The possible message from that composite is that the objective analogs might be highlighting a period of cold embedded in a larger period of warmth. Time will tell.

1956 is among a number of cases that I used in coming up with my February idea. I give some weight to past months, a lot of weight to the current month, and also factor in my expectations for the coming month. I'll be curious to see if 1956 remains relevant for March, as March 1956 was a fun month for cold and snow.

Stovepipe wrote:Re AmericanWx: Odds are by 12z tomorrow there will be a tumble weed rolling through the forum as everyone will have cut themselves and jumped off a cliff.

snowdog wrote:12z Ensembles weren't all that great either. Minus a couple of good model runs a day or two ago I haven't seen anything to get too excited about (well I guess there is crazy old uncle NOGAPS to fall back on)....yet. Euro Ens shows the long range cold dumping too far east to really do anything for us. GFS ensemble members are still undecided on just how much cold we will have to work with.

I think this may be a deal where we won't see a good set-up evolve until the mid to late month (if then) and by then it is just not a good time for this area (middle-TN). Probably will waste a good pattern at the end of Feb beginning of March and get a cold spring.

I'm still in the Winter Cancel boat. Save the cold and snow for next year after the cards have been reshuffled.

snowdog wrote:By the way Tom or Biscuits and Gravy or whatever his new name will be in the future...I propose, FROM THIS YEAR FORWARD HE WILL NEVER...EVER...BE ALLOWED TO START ANOTHER WINTER 20XX PATTERN DISCUSSION THREAD. Sorry Tom but somewhere somehow you have angered Old Man Winter. Not just for this area either, you screwed pretty much the whole country.

snowdog wrote:By the way Tom or Biscuits and Gravy or whatever his new name will be in the future...I propose, FROM THIS YEAR FORWARD HE WILL NEVER...EVER...BE ALLOWED TO START ANOTHER WINTER 20XX PATTERN DISCUSSION THREAD. Sorry Tom but somewhere somehow you have angered Old Man Winter. Not just for this area either, you screwed pretty much the whole country.

snowdog wrote:well I guess there is crazy old uncle NOGAPS to fall back on

Wow. Holy -NAO block on the weeklies. Holds strong from Week 2 through Week 4. I don't have the temp anomalies, only H5 this week, but would be a much more conducive pattern if it verifies. Standby until Thursday to see if this is hiccup or not.

Week 2 is a +PNA with an east based -NAO, Week 3 is a -EPO/-NAO, and Week 4 is -PNA/-NAO

Well I didn't mean to sound like I'm not optimistic later on, just pointing out that its a false early start...again. I do think we'll have a better pattern mid month and probably later in Feb, but we still have to wait a while. The models built up the northwest portion of the west Canada ridge too tall, and way too fast. Instead its getting knocked down initially and rolling toward southern Canada and that causes the trough in Canada that was going to drop into the east, instead to drop more into the extreme Northeast and the Atlantic ocean. Several hundred mile miss there if not a thousand miles. The ensembles did just as badly for the weekend, but eventually I think it will finally get colder. It may happen after the Gulf system around Feb 10 to 12, and that goes up the coast pulling down much colder air. The fast flow and strong Alaskan vortex this season has been hard to make a good western ridge, and the fast flow and lack of blocking in Atlantic is skewing the models, causing pretty big errors around day 7 and beyond. The cold continues to avoid the Southeast. I'm still optimistic that nature evens out later on with a complete flip (western ridge +Greenland blocking ) which would be a good pattern to finally comine cold and storm track. That might come mid month (or begin around the time GFS and ECMWF develop the Gulf system). We will wait and see, since its going to be hard to forecast cold air , until it staring you in the face this season.