ORH_wxman Posted December 6, 2012 Share Posted December 6, 2012 We've been discussing the pattern with some greay insight from many posters in the general banter thread...but the posts get buried quickly so I decided to start this thread where we can post some thoughts and it will be easier for people to find the posts: A few things that have been discussed already in the other thread: 1. NAO blocking...where will it set up? Ensembles have been pushing the blocking further west, especially starting with yesterday's runs. But its been generally on the all of the ensembles (both Euro/GEFS) for about a week now. The only difference is it was more pronounced yesterday and it seems to finally be getting closer...at least the big east based block is now inside of 10 days. There is still plenty of reason to be skeptical of the west based blocking idea. HM has brought up the stratospheric state in the North Atlantic going forward in the near-term which would try to inhibit blocking from retrograding westward into the Davis straight region. 2. Aleutian ridge reconfiguration...temporary GOA ridge retrogrades west. This is something that is also becoming a bit more clear with guidance. The temporary GOA ridge (which originally was going to be more of a +PNA, but never got far enough east) that builds for the lakes cutter next week looks to retrograde back and then feed into the Aleutian ridge building poleward again...it temporarily has been beaten down a bit which is contributing to our recent torching in the CONUS. A more poleward Aleutian ridge is going to be key for sustaining arctic intrusion into the CONUS beyond the initial shot behind the Lakes cutter. As the GOA ridge is undergoing this rebuilding, we seem to have another window for a torch in the Dec 13-15 range. 3. Snow. A poleward Aleutian ridge and a -NAO (even if east based) has historically been a very snowy pattern for New England in December. Its not a guarantee but it increases the odds quite a bit. There is a chance we don't cash in because it is impossible to predict the nuances of any given shortwave or synoptic feature, but I think you can at least count on some legit chances as we move into the week of Dec 17-24. The pattern will look a lot different 10 days from now...of course whether we actually get snow events from it or not will decide whether weenies scream boom or bust. Here's a look at the GEFS prog for Dec 17-18...the EC ensembles are not quite as enthusiastic about the NAO, but definitely still have it and the overall longwave pattern is similar. Link to comment Share on other sites More sharing options...
CoastalWx Posted December 6, 2012 Share Posted December 6, 2012 GEFS -NAO forecasts so far have been too aggressive on the 10 and 14 day timeframes. Link to comment Share on other sites More sharing options...
Lava Rock Posted December 6, 2012 Share Posted December 6, 2012 Is this all going to play out like last year, where snow and cold is just another week away. Link to comment Share on other sites More sharing options...
CoastalWx Posted December 6, 2012 Share Posted December 6, 2012 Is this all going to play out like last year, where snow and cold is just another week away. This belongs in the other thread. Link to comment Share on other sites More sharing options...
ORH_wxman Posted December 6, 2012 Author Share Posted December 6, 2012 Is this all going to play out like last year, where snow and cold is just another week away. I highly doubt it. We don't have a persistent AK vortex this year. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted December 6, 2012 Share Posted December 6, 2012 HM has said the pattern change is complete this weekend as we move into a LaNina gradient based pattern. I kind of liked the cold, snowy November pattern. Hopefully this new pattern produces. It's def a different year with muted torches, and cold shots over performing. Lets just get to the snowy part Link to comment Share on other sites More sharing options...
CoastalWx Posted December 6, 2012 Share Posted December 6, 2012 If the models are right and the -NAO builds west, there's a weak signal for some sort of storm moving up from near the Gulf on the 19th give or take. Wouldn't that be nice. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted December 6, 2012 Share Posted December 6, 2012 If the models are right and the -NAO builds west, there's a weak signal for some sort of storm moving up from near the Gulf on the 19th give or take. Wouldn't that be nice. Miller A. I'd like to get one on xmas eve. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted December 6, 2012 Share Posted December 6, 2012 HM has said the pattern change is complete this weekend as we move into a LaNina gradient based pattern. I kind of liked the cold, snowy November pattern. Hopefully this new pattern produces. It's def a different year with muted torches, and cold shots over performing. Lets just get to the snowy part My catch up begins. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted December 6, 2012 Share Posted December 6, 2012 My catch up begins. doubtful but always possible. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted December 6, 2012 Share Posted December 6, 2012 doubtful but always possible. The past two times we have seen that pattern, I've buried you. Link to comment Share on other sites More sharing options...
CoastalWx Posted December 6, 2012 Share Posted December 6, 2012 Definitely a little weaker with the -NAO, but a bit less of a -PNA. Link to comment Share on other sites More sharing options...
CoastalWx Posted December 6, 2012 Share Posted December 6, 2012 Euro really tries to do something with that follow up wave. Link to comment Share on other sites More sharing options...
CoastalWx Posted December 6, 2012 Share Posted December 6, 2012 Dendrite special. Link to comment Share on other sites More sharing options...
CT Rain Posted December 6, 2012 Share Posted December 6, 2012 Dendrite special. Yeah... nice!!! Probably nothing for us southerners but I'd watch it if I was up north a bit. Link to comment Share on other sites More sharing options...
OSUmetstud Posted December 6, 2012 Share Posted December 6, 2012 CPC GFS ensemble daily AO hits about -4 in a few days. That's some serious blocking. Link to comment Share on other sites More sharing options...
CT Rain Posted December 6, 2012 Share Posted December 6, 2012 12z GEFS looks pretty good or some retro NAO block action Link to comment Share on other sites More sharing options...
Ginx snewx Posted December 6, 2012 Share Posted December 6, 2012 This belongs in the other thread. Euro really tries to do something with that follow up wave. Dendrite special. Yeah... nice!!! Probably nothing for us southerners but I'd watch it if I was up north a bit. Pattern Discussion 12/15 and beyond LOL Goose/Gander Link to comment Share on other sites More sharing options...
Clinch Leatherwood Posted December 6, 2012 Share Posted December 6, 2012 No mention of the euro ensembles? Link to comment Share on other sites More sharing options...
Go Kart Mozart Posted December 6, 2012 Share Posted December 6, 2012 The operational ecmwf seems to hint at a low trying to cut-off in the southwest. That usually forces ridging over the top of the cut-off. It seems like in the 80s and 90s southwest cut-offs were a regular feature. I can't remember one since the turn of the century! Link to comment Share on other sites More sharing options...
weathafella Posted December 6, 2012 Share Posted December 6, 2012 The operational ecmwf seems to hint at a low trying to cut-off in the southwest. That usually forces ridging over the top of the cut-off. It seems like in the 80s and 90s southwest cut-offs were a regular feature. I can't remember one since the turn of the century! But the Euro does this routinely....it's a known bias of the model. Sometimes it's right. Link to comment Share on other sites More sharing options...
michsnowfreak Posted December 6, 2012 Share Posted December 6, 2012 We've been discussing the pattern with some greay insight from many posters in the general banter thread...but the posts get buried quickly so I decided to start this thread where we can post some thoughts and it will be easier for people to find the posts: Thanks for making this thread! Several of us in the Lakes forum love to read your guys insight and analysis but it gets lost in the long banter threads...not anymore! Heres to lots of snow for all! Link to comment Share on other sites More sharing options...
CoastalWx Posted December 6, 2012 Share Posted December 6, 2012 Week2 still has a good -NAO signal albeit east based. Strong Aleutian ridge with a ribbon of lower height anomalies over the US with temps a little below normal. Week 3 started a relaxation of the -NAO with a small slightly above avg contour near the Davis Straits. This likely indicated weakening -NAO through week 3. Still a good Aleutian ridge, and we have a stout -PNA and modest SE ridge. Week 4 still featured an Aleutian ridge with a -PNA and stronger SE ridge signal. Temps verbatim were just above normal, but looks like a classic SWFE track. Of course, the typical week 3 and 4 caveats apply. Link to comment Share on other sites More sharing options...
HM Posted December 6, 2012 Share Posted December 6, 2012 Week2 still has a good -NAO signal albeit east based. Strong Aleutian ridge with a ribbon of lower height anomalies over the US with temps a little below normal. Week 3 started a relaxation of the -NAO with a small slightly above avg contour near the Davis Straits. This likely indicated weakening -NAO through week 3. Still a good Aleutian ridge, and we have a stout -PNA and modest SE ridge. Week 4 still featured an Aleutian ridge with a -PNA and stronger SE ridge signal. Temps verbatim were just above normal, but looks like a classic SWFE track. Of course, the typical week 3 and 4 caveats apply. This is the relaxation period I was worried about a while back. The two scenarios were either a SE ridge / gradient pattern to end December or a full blown torch. If the PV retrogrades to Alaska, 18z GFS style, then the holiday period will be exceptionally warm. Link to comment Share on other sites More sharing options...
Mr Torchey Posted December 6, 2012 Share Posted December 6, 2012 Thanks Scott Link to comment Share on other sites More sharing options...
Alpha5 Posted December 7, 2012 Share Posted December 7, 2012 I highly doubt it. We don't have a persistent AK vortex this year. Its still present, AK has been in the freezer for the past couple weeks http://newsminer.com/view/full_story/21018013/article-Cold-deepens-as-Fairbanks-officially-drops-to-minus-40?instance=home_news_window_left_top_1 Link to comment Share on other sites More sharing options...
CoastalWx Posted December 7, 2012 Share Posted December 7, 2012 This is the relaxation period I was worried about a while back. The two scenarios were either a SE ridge / gradient pattern to end December or a full blown torch. If the PV retrogrades to Alaska, 18z GFS style, then the holiday period will be exceptionally warm. Well I guess the good news is that the 11-15 day on the GEFS don't bring this into the AK area of Bering Sea. I suppose heights could lower in the GOA and part of AK for a time near the 15th briefly. The EC ensembles do show this which then really strengthens the Pacific jet. The ridge does rebuild on the models shortly after. I think your biggest danger down there is the -PNA and a possible +NAO developing. At least IMHO, I don't see the vortex moving into the AK or Bering Sea for a long period of time,yet. I hope it stays like that. The one thing that is interesting to me, are the euro ensembles. So we have the Aleutian ridge. The ensembles then develop short wavelengths with a shortwave GOA trough and then a weak ridge out west, especially Canada. At the same time, there are residual higher heights near Hudson Bay and just east, albeit weak signal. At the same time, we have the lower heights out west. It almost looked like a split flow pattern with something ejecting out of the SW and some sort of weak split flow potential leading to possible cyclogenesis off the EC. For our area, I do like the confluence lobe at H5 over Newfoundland. It obviously is in la la land, but the GEFS also try to hint at something when these features are in play too. Right around the 19th or 20th. Link to comment Share on other sites More sharing options...
CoastalWx Posted December 7, 2012 Share Posted December 7, 2012 Bumped from other thread. Hey HM, one question I have. You mentioned to Adam about the 30mb temps being warm over the Tropical pacific, but I noticed 50mb temps are cold. Why would the 30mb level have a larger result to suppress convection down that way? Link to comment Share on other sites More sharing options...
Bobby EPAWA Posted December 7, 2012 Share Posted December 7, 2012 This is the relaxation period I was worried about a while back. The two scenarios were either a SE ridge / gradient pattern to end December or a full blown torch. If the PV retrogrades to Alaska, 18z GFS style, then the holiday period will be exceptionally warm. Looks pretty solidly that no big daddy blockbuster storm will come to fruition for the remainder of this month, but SWFE events can be decent for interior mid-Atlantic and New England. Especially with the active SJT. It may be all we can hope for, down side is no large NESIS storm, but... something to track every 3-5 days with SWFE/gradient storms. I am hoping you are NOT on to something with the retrograding PV... Link to comment Share on other sites More sharing options...
HM Posted December 7, 2012 Share Posted December 7, 2012 So we have the Aleutian ridge. The ensembles then develop short wavelengths with a shortwave GOA trough and then a weak ridge out west, especially Canada. At the same time, there are residual higher heights near Hudson Bay and just east, albeit weak signal. At the same time, we have the lower heights out west. It almost looked like a split flow pattern with something ejecting out of the SW and some sort of weak split flow potential leading to possible cyclogenesis off the EC. For our area, I do like the confluence lobe at H5 over Newfoundland. It obviously is in la la land, but the GEFS also try to hint at something when these features are in play too. Right around the 19th or 20th. This is the Chris storm and he is too modest to credit for seeing this potential. But anyway, I agree there is a threat then. If there is going to be a good storm, it is going to be when the NAO signal fades westward with split flow underneath. You still got to favor New England with this setup, given the teleconnections. If the NAO-west idea becomes legitimate, then perhaps the northern Mid Atlantic will be snowier than I thought. But I'm still not feeling a west-based NAO yet so I think this ultimately is for you guys. Link to comment Share on other sites More sharing options...
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