mitchnick Posted November 24, 2012 Share Posted November 24, 2012 The issue is in the 925-850mb layers on the models. the wind backs from the south, and thats deadly if you want a snowstorm. Also the 925 and 850mb lows, which seen below tracks overhead, you want to be north of that. agreed but that one map is for 81 hrs and at 84 hrs there is still precip overhead in central MD no doubt, as currently modeled, the big cities won't see accum snow, but there's plenty of time if we can take another couple of steps in the right direction, which is where I'm going....especially considering the 5H low placement maybe the lower levels will be adjusted as time goes on (or some other weenie magic!) Link to comment Share on other sites More sharing options...
tombo82685 Posted November 24, 2012 Share Posted November 24, 2012 agreed but that map is for 81 hrs and at 84 hrs there is still precip overhead in central MD no doubt, as currently modeled, the big cities won't see accum snow, but there's plenty of time if we can take another couple of steps in the right direction, which is where I'm going....especially considering the 5H low placement maybe the lower levels will be adjusted as time goes on (or some other weenie magic!) Yea, like i said to Ian, i wouldnt give the nam consideration until inside 48hrs. Link to comment Share on other sites More sharing options...
Ian Posted November 24, 2012 Share Posted November 24, 2012 If we get a decent track etc I would bet this event ends up colder than forecast. Prime season for that once you get precip going. air mass isnt super by any means but there's cold enough air around with reinforcements coming in with the storm. Link to comment Share on other sites More sharing options...
Ian Posted November 24, 2012 Share Posted November 24, 2012 Yea, like i said to Ian, i wouldnt give the nam consideration until inside 48hrs. you're the one that pulled out the twister data maps. Link to comment Share on other sites More sharing options...
tombo82685 Posted November 24, 2012 Share Posted November 24, 2012 If we get a decent track etc I would bet this event ends up colder than forecast. Prime season for that once you get precip going. air mass isnt super by any means but there's cold enough air around with reinforcements coming in with the storm. heavy precip rates will help, just ask nj and nyc 2 weeks ago. Link to comment Share on other sites More sharing options...
tombo82685 Posted November 24, 2012 Share Posted November 24, 2012 you're the one that pulled out the twister data maps. Lol i was just illustrating a point. All the models are showing the southerly wind carnage to some degree or other. Link to comment Share on other sites More sharing options...
Ian Posted November 24, 2012 Share Posted November 24, 2012 Lol i was just illustrating a point. All the models are showing the southerly wind carnage to some degree or other. yeah it's an uphill battle particularly without elevation but that's standard early season. Link to comment Share on other sites More sharing options...
Amped Posted November 25, 2012 Share Posted November 25, 2012 GFS almost pulls a PDI day 7 something to watch. Big warmup after that. Link to comment Share on other sites More sharing options...
midatlanticweather Posted November 25, 2012 Share Posted November 25, 2012 Larry Cosgrove stating something big may be coming Dec 7 - 9 time frame Link to comment Share on other sites More sharing options...
eurojosh Posted November 25, 2012 Share Posted November 25, 2012 I have to say, it's much more fun to be sitting in the last week of November and seeing this than to be in the last week of February and knowing it's the last chance... Link to comment Share on other sites More sharing options...
Ian Posted November 25, 2012 Share Posted November 25, 2012 Larry Cosgrove stating something big may be coming Dec 7 - 9 time frame Lol Link to comment Share on other sites More sharing options...
Amped Posted November 25, 2012 Share Posted November 25, 2012 Larry Cosgrove stating something big may be coming Dec 7 - 9 time frame We'll see, the pattern gets a better after day 12. Dec 5-10 typically brings a first winter threat. I would never call for something big in DCA at that range. Link to comment Share on other sites More sharing options...
CAPE Posted November 25, 2012 Share Posted November 25, 2012 We'll see, the pattern gets a better after day 12. Dec 5-10 typically brings a first winter threat. I would never call for something big in DCA at that range. Not sure the pattern is going to be better. Yeah the AO is going pretty strongly negative per most models, But that big ass ridge west of Alaska isnt budging. That means cold for parts of AK and western Canada and maybe Pac NW at times, but the PNA is negative which means downstream ridging and generally mild over central/eastern US. And the NAO doesnt look to be persistently negative. See the latest CFS monthly temp anomalies for Dec. Looks quite toasty. Need that ridge to retrograde. Link to comment Share on other sites More sharing options...
usedtobe Posted November 25, 2012 Share Posted November 25, 2012 we may see a -EPO/+PNA/-NAO pattern develop after the 5th....probably would be transient, but we could maybe eek out a mixy event then....LC may be on to something...too far out now, but I'd say 60-40 we average -departures in the 12/7-12/12 range..December will start out warm Matt, I think that is too early to get the positive PNA. To me the pattern looks warmer than normal with a crappy PNA through the 9th. The CPC superensemble has a strongly negative ao but has a really crappy look to it. one that lets lots of warm air flood the conus as lots of pac air crashes into coast. I composited the analog dates to make sure their 500h looked similar to the center mean. They did, then I looked at the temp anomalies for date of the centered mean from the anomalies and got this warm look. Based on the 500h anomaly pattern, I think this temp anomaly look is reasonable for that dec 5th or 6th. I then composited the 500h for 3 days beyond the centered man and got this composite which still holds onto the neg pna and positive heights across the east despite the neg ao look. That;s still a warm look overall for us. My guess is that the temps for the dec 4-9 period will be warmer than normal and that any snow chances will have to wait. That said, I'm relying on a mean model pattern and have little skill past day 4 or 5 so I could be totally wrong. Link to comment Share on other sites More sharing options...
Ian Posted November 25, 2012 Share Posted November 25, 2012 writing's on the wall. snowy winter casts are gonna bust. Link to comment Share on other sites More sharing options...
usedtobe Posted November 25, 2012 Share Posted November 25, 2012 writing's on the wall. snowy winter casts are gonna bust. despite thinking early december looks bad the strongly negative ao suggest the ao will probably average in the negative range for the next 2 months and I doubt the pna stays negative through that entire period so I think there is potential for us to get more than the median. I wouldn't yet pull the trigger on such a forecast but think the probability has gone up since my post of the other day. Link to comment Share on other sites More sharing options...
usedtobe Posted November 25, 2012 Share Posted November 25, 2012 I always thought we would be backloaded, but maybe Dec 15-30 could be decent... I think the AO will be negative more than positive so we'll eventually get the pos pna, neg ao and neg epo look we want sometime in later in Dec or in Jan. I also think this might be one of those years where we get a 5.5" inch or greater event but.....that could be wishful, weenie thinking. Link to comment Share on other sites More sharing options...
Ian Posted November 25, 2012 Share Posted November 25, 2012 I always thought we would be backloaded, but maybe Dec 15-30 could be decent... I'm just being disagreeable. I can't even forecast low temps 24 hours out correctly. Link to comment Share on other sites More sharing options...
ravensrule Posted November 25, 2012 Share Posted November 25, 2012 I'm just being disagreeable. I can't even forecast low temps 24 hours out correctly. How come you have a pro forecaster tag then . Link to comment Share on other sites More sharing options...
Ian Posted November 25, 2012 Share Posted November 25, 2012 How come you have a pro forecaster tag then . pro forecasters are the lol Link to comment Share on other sites More sharing options...
ravensrule Posted November 25, 2012 Share Posted November 25, 2012 pro forecasters are the lol I like the old Ian better. Link to comment Share on other sites More sharing options...
WxUSAF Posted November 26, 2012 Share Posted November 26, 2012 1st measurable snow event 12/12-12/16 GFS ensembles look decent in the long-range as far as 500mb pattern. Has a bit of a ridge out west and puts us in a trough along with a strong -AO and -NAO. Is it that sort of pattern evolution you're riding? Adam (am19psu) and HM seem to like this general period as well. Link to comment Share on other sites More sharing options...
Bob Chill Posted November 26, 2012 Share Posted November 26, 2012 1st measurable snow event 12/12-12/16 Pretty much on the same page. Maybe a tad later? After a bit of a rough start to Dec I'm thinking the pattern goes favorable in noticeable steps with one of them having decent vort track below us as a ridge builds out west and then potentially a clipperish event after that. A slightly educated guess at best. lol Link to comment Share on other sites More sharing options...
yoda Posted November 26, 2012 Share Posted November 26, 2012 I would agree Zwyts... EURO ensemble mean 2m temps looked atrocious first week of December per Maue Link to comment Share on other sites More sharing options...
bjohnson102184 Posted November 26, 2012 Share Posted November 26, 2012 I would agree Zwyts... EURO ensemble mean 2m temps looked atrocious first week of December per Maue Pretty sure most people are talking about the 2nd and third week of DEC......pretty sure we all know its going to be above normal the 1st week Link to comment Share on other sites More sharing options...
Bob Chill Posted November 26, 2012 Share Posted November 26, 2012 The big bowling ball in the pac is a perfect example of how a -ao can be rendered ineffective. This loops pretty much sums it up: http://mag.ncep.noaa...el=&imageSize=M The PNA has been negative sine the first week of Nov and looks to remain that way for another week or two. The good thing is that even though the pac sucks it's not "locked in". When it reshuffles a bit we'll have a much better idea of where we are going in Dec. A warm (and dry) start is all but a lock thanks to a crapacific. Edit: Just wanted to add that the gfs is hinting at a nice ridge centered just off the socal coast in fantasy range. Nice look. Chilly in these parts. Link to comment Share on other sites More sharing options...
Bob Chill Posted November 26, 2012 Share Posted November 26, 2012 I'm kind of not worried about the PAC as long as it is not hostile which it doesn't look to be this winter...A ridge over the Aleutians has been our mean winter pattern since 2004....In our outlook I probably overestimate the importance of having a trough out there....I am not sure it matters that much....The AO/NAO will be even more important than usual.... You definitely know the pac a heck of a lot better than I do. I'm still working on understanding the various patterns and how it affects the sensible wx downstream. I think the PNA may be more important than usual too. If the stj doesn't do anything we are going to need the amplified pattern to get any decent sized snows. I have done zero research but I have to assume that NS vorts cannot produce large (5"+) storms with a +pna. I could be wrong. Link to comment Share on other sites More sharing options...
usedtobe Posted November 26, 2012 Share Posted November 26, 2012 CFS2 model weekly forecasts are really warm for the 1st two weeks of Dec especially the 1st week and then moderate and become cooler than normal by week 4. The good news is they are not particularly skillful though all the models look pretty warm during the 1st week of the month. Link to comment Share on other sites More sharing options...
Ian Posted November 26, 2012 Share Posted November 26, 2012 CFS2 model weekly forecasts are really warm for the 1st two weeks of Dec especially the 1st week and then moderate and become cooler than normal by week 4. The good news is they are not particularly skillful though all the models look pretty warm during the 1st week of the month. Shorts on Dec 5? Link to comment Share on other sites More sharing options...
usedtobe Posted November 26, 2012 Share Posted November 26, 2012 Shorts on Dec 5? Who knows. I never make guesses about temps for a individual day so far out there in time. Does look like a warmer than normal period, also drier than normal. Link to comment Share on other sites More sharing options...
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