Isotherm Posted March 2, 2013 Share Posted March 2, 2013 The pattern for the first week of March is one that's more conducive for snowfall than we've seen most of this winter. A westward retrograding Atlantic block has suppressed the jet and allowed for continental, Canadian air to rush as far south as the Gulf Coast. With the coming of spring, wavelenths are shortening, and the mean trough on the PAC NW coast does not necessarily mean a ridge in the East at this time of year.The synoptics prior to the March 6th-7th period are quite favorable for strong negative height anomaly development in the United States. This is b/c we have a tanking AO w/ rapid height rises in the Arctic, higher than normal heights across much of Canada, forcing a deep, meridional, trough to develop underneath the immense blocking feature.The potential problem here is that the blocking in eastern Canada might be too strong and suppressive as the short wave / bowling ball upper low emerges from the northern stream by 84hrs or so.On the 12z GFS at H5, we can see the unfavorable upper low orientation to the east of the New England shore. This promotes a NWLY flow across the NE US, meaning the bowling ball in the OH valley cannot progress to the classic Delmarva "slot" region for bombing. The upper low actually acquires a SE trajectory due to the strong blocking further south than normal in Canada. A block slightly further north would have been ideal.The ECMWF has a similar scenario, with the upper low near the New England coast.At this point in time, we need to hope that modelling is incorrect in the depiction of a persistent H5 low near the New England coast through D 3-4. Hopefully that features becomes weaker and/more progresses east faster than progged. This would allow the upstream bowling ball / closed low to remain on an eastward trajectory rather than dive SE toward Cape Hatteras. The current depiction of an H5 bomb near VA beach is most favorable for a mid atlantic / sern mid atlantic snow event, with little accumulations to the north of Baltimore-Atlantic City line.I continue to think the pattern is favorable through the next week to 10 days, but the synoptics leading up to this event could be better. The blocking orientation is too far south, the H5 low is too far SW, and thus we can't capitalize on the bowling. Hope to see changes on this. The 12z ECMWF looks worse, but there is still plenty of time for change. Link to comment Share on other sites More sharing options...
nzucker Posted March 2, 2013 Share Posted March 2, 2013 Do you think we see another favorable period in March? Link to comment Share on other sites More sharing options...
LongBeachSurfFreak Posted March 2, 2013 Share Posted March 2, 2013 I have a very good feeling the block is being "overdone" by the models. While a Feb 11 type scenario is still on the table I really truly believe things will trend north... Regardless this low ill be prodigious swell maker for East coast swell starved surfers such as myself! Link to comment Share on other sites More sharing options...
green tube Posted March 2, 2013 Share Posted March 2, 2013 I continue to think the pattern is favorable through the next week to 10 days, but the synoptics leading up to this event could be better. The blocking orientation is too far south, the H5 low is too far SW, and thus we can't capitalize on the bowling. Hope to see changes on this. The 12z ECMWF looks worse, but there is still plenty of time for change. good clean, concise presentation as usual. you note there's plenty of time for change, but all change the last 2 days has been bad.... yet you seem somewhat optimistic? Link to comment Share on other sites More sharing options...
Isotherm Posted March 3, 2013 Author Share Posted March 3, 2013 Thanks guys. Do you think we see another favorable period in March? Problem will be the warming temps and greater difficulty getting accumulating snow w/ most pattern. The later we progress in March, the more favorable pattern we need for snowfall. Right now I think we might have one more shot in the March 12th-15th period as the AO begins to climb and we get a s/w emerging from the STJ. Again it could be a coastal rain/elevation snow type event by that point. The cold air source for this week's event is already marginal, and thus necessitates a bombing low for accumulating wet/hvy snow. Link to comment Share on other sites More sharing options...
nzucker Posted March 3, 2013 Share Posted March 3, 2013 Great posts as usual, Tom. I've also eyed the March 15th time frame as a potential with renewed NAO blocking and the GFS signaling cold air entering the region with -10C 850s rushing in behind some sort of cutter, However, I also think the favorable period lasts longer because the GEFS and ECM ENS have been showing a more classic Greenland block, instead of the Quebec/Hudson Bay block, developing by mid-month. Low heights are forced underneath that block and could set up some late-season opportunities, Average highs here hit 50F by around March 20th, but historically our snow season continues until the equinox...god knows we are much overdue in March. Here are two favorable images from the 0z GEFS showing why I don't think winter is over...the models should sense some more cold air given the pattern: Thanks guys. Problem will be the warming temps and greater difficulty getting accumulating snow w/ most pattern. The later we progress in March, the more favorable pattern we need for snowfall. Right now I think we might have one more shot in the March 12th-15th period as the AO begins to climb and we get a s/w emerging from the STJ. Again it could be a coastal rain/elevation snow type event by that point. The cold air source for this week's event is already marginal, and thus necessitates a bombing low for accumulating wet/hvy snow. Link to comment Share on other sites More sharing options...
nzucker Posted March 3, 2013 Share Posted March 3, 2013 The models are showing some signs of a very cold, blocky pattern emerging mid-March with the -NAO also being enhanced by a -EPO/Alaskan block (Aleutian Low). Having this type of double block would greatly increase the chances of a late-season snowstorm as well as a cold outbreak. Here is what the 18z GFS shows at Day 10, with -10C 850s moving into the Deep South: Given that a southern shortwave has been progged in the flow around 3/13, there may be another chance mid-month for a significant snowstorm. If not, we deal with this type of cold potentially: Link to comment Share on other sites More sharing options...
uncle W Posted March 4, 2013 Share Posted March 4, 2013 the arctic oscillation is almost at the -3.00 level and forecast to go lower... 20 out of the last 62 March's have an ao as low as -3.000 or below...The lowest reading so far this year was -3.902 on 12/8..I'm hoping it gets to -4 because it raises the chances for a cold wave, snowstorm or both... I made a quick search and came up with these numbers for March... year....low AO date....monthly AO -6.365... 3/05/1970...-2.084...cold month...4" snow 3/29... -4.417... 3/04/1962...-2.848...Ash Wed. storm 3/6...a little snow... -4.318... 3/04/1981...-1.645...8" of snow 3/5... -4.202... 3/24/2001...-1.687...a little snow on 3/26... -4.030... 3/11/1958...-2.522...4" snow 3/14...12" snow 3/21... -3.856... 3/10/1999...-1.492...4" of snow 3/15... -3.822... 3/04/2006...-1.604...1" on 3/2... -3.805... 3/04/1952...-1.859...4" on 3/2... -3.766... 3/04/1957...-2.013...3" of snow 3/1-2... -3.758... 3/21/1955...-1.568...3" of snow 3/18... -3.706... 3/13/1984...-2.386...7" of snow 3/9... -3.469... 3/19/1969...-1.582...3" of snow 3/7... -3.381... 3/09/1991...-0.527...cold spell with no snow... -3.320... 3/31/1996...-1.483...4" of snow 3/29... -3.254... 3/01/1965...-0.905...2" of snow 3/21... -3.217... 3/04/1978... 0.502...5" on 3/3...only month with a plus ao average... -3.200... 3/10/1960...-1.625...14" on 3/3... -3.200... 3/21/1987...-1.746...2" 3/13... -3.188... 3/17/1980...-1.433...5" of snow 3/13-14... -3.032... 3/16/1979...-0.814...cold spell with only flurries... I think we have a good chance the AO ends up averaging negative and if we can get as low as -3.500 we have a good chance of seeing a significant snowfall... Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 4, 2013 Share Posted March 4, 2013 I would be careful to not assume that the block is overdone. It's not the typical block that we normally see. It's the pesky ULL Link to comment Share on other sites More sharing options...
Isotherm Posted March 4, 2013 Author Share Posted March 4, 2013 Great posts as usual, Tom. I've also eyed the March 15th time frame as a potential with renewed NAO blocking and the GFS signaling cold air entering the region with -10C 850s rushing in behind some sort of cutter, However, I also think the favorable period lasts longer because the GEFS and ECM ENS have been showing a more classic Greenland block, instead of the Quebec/Hudson Bay block, developing by mid-month. Low heights are forced underneath that block and could set up some late-season opportunities, Average highs here hit 50F by around March 20th, but historically our snow season continues until the equinox...god knows we are much overdue in March. Here are two favorable images from the 0z GEFS showing why I don't think winter is over...the models should sense some more cold air given the pattern: Thanks, and good post as well Nate. Looks like we reload the pattern w/a brief temp moderation period from this weekend into early next week, but the March 12th-20th period could offer more potential. Models seem to be advertising plenty of cold/polar air available for mid March relative to normal, in addition to an active STJ. We might be looking at one of the most wintry March's in several years here. Gradual consensus forming for the Wed-Thurs storm. I think it may begin as a few hrs of rain but the majority of the pcpn should be snow given strong vv's and dynamic cooling. Right now I think a wet snow bomb / SECS type event is possible for much of the PHL-BOS corridor. Classic March snowstorm potentially. Link to comment Share on other sites More sharing options...
nzucker Posted March 4, 2013 Share Posted March 4, 2013 Thanks, and good post as well Nate. Looks like we reload the pattern w/a brief temp moderation period from this weekend into early next week, but the March 12th-20th period could offer more potential. Models seem to be advertising plenty of cold/polar air available for mid March relative to normal, in addition to an active STJ. We might be looking at one of the most wintry March's in several years here. Gradual consensus forming for the Wed-Thurs storm. I think it may begin as a few hrs of rain but the majority of the pcpn should be snow given strong vv's and dynamic cooling. Right now I think a wet snow bomb / SECS type event is possible for much of the PHL-BOS corridor. Classic March snowstorm potentially. Big snows coming... Link to comment Share on other sites More sharing options...
Isotherm Posted March 4, 2013 Author Share Posted March 4, 2013 Big snows coming... If so, I'd pencil in an above normal season in CNJ, into the 30s. 28" right now. Not a bad run since 2000 (and thats the understatement of the year). Only 4 winters below avg, 01-02, 06-07, 07-08, and 11-12. Link to comment Share on other sites More sharing options...
nzucker Posted March 5, 2013 Share Posted March 5, 2013 If so, I'd pencil in an above normal season in CNJ, into the 30s. 28" right now. Not a bad run since 2000 (and thats the understatement of the year). Only 4 winters below avg, 01-02, 06-07, 07-08, and 11-12. We've had a stretch of very snowy winters, even if we're missing the arctic cold. I had 70" here in both 09-10 and 10-11, 60" here in 02-03, 50" in 00-01, 03-04, and 04-05, and over 45" in 05-06 and 08-09. My average is around 37-38", so that's a very impressive stretch. This year I'm at 37.25" for Dobbs Ferry's seasonal total, and this could bring me close to the 50" benchmark. Another storm after this and we'd be talking about a really good winter. I give extra credit for the wonderfully cold and snowy November, but the meat of winter was rather poor until early February had some bitter cold and a blizzard. Having a snowy March is important to me, though, as it gives me chances to enjoy winter when I know the season is fleeting. Link to comment Share on other sites More sharing options...
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