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March Medium Range Discussion


nzucker

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with surface  temps above freezing mid to upper 30's at least   during the day and closer to lower 30's at night - in order  for any snow that falls to actually stick in the immediate NYC metro the precip has to fall at night and be moderate to heavy - which is questionable this far out - areas further north and west would probably be cold enough - so there is no guarantee this is an all snow event with surface temps near or above freezing in mid march the closer you get to the coast

 

IF the forecast guidance is correct in its idea, I strongly disagree with this post. There would be significant -- almost mid-winter like -- cold air drainage into the Northeast with very strong blocking to the north and a high pressure forced underneath into New England. You can see this idea on the afternoon DGEX with low to mid 20's surface temperatures and snow falling with a weak disturbance aloft.

 

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BIG signal here for mid/late March. Major arctic blocking, mid winter style on tap -- AO is progged to plummet down to near -4 SD by the 17th-20th period. So whether it's early next week's storm that does the dirty work, the potential several days later, or both, the potential is through the roof for the next couple weeks.

Classic severe AO drop akin to what we experienced in the 2009-10 winter.

I honestly don't ever remember being this excited for a mid/late March pattern. I'd be both shocked and disappointed if there isn't another accumulating snow event of at least 3" in NYC.

 

Couldn't be in any stronger agreement. I'm tingling just looking at the GEFS which has gotten more impressive each run as we get closer.

 

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I haven't lost hope yet in Westchester...it's not just the -NAO signal but also the -EPO signal with the cut-off ridge north of Alaska forcing a lot of cold air into Canada and allowing for the PV to shift into Eastern Canada. 

 

 

Agreed. If we had this set-up a couple months ago, we'd probably be talking sub zero potential with the PV shifting around southern Canada and impressive blocking across the top. The AO values falling to around -4 SD is what really gets me excited as that's a very strong signal for cold and storminess in the CONUS. The fact that it's now mid March and the seasonal retreat of the jet is beginning, the threat of suppression is also lower than it'd be 3-4+ weeks ago. I'm really not worried around a miss to the south at this point. We'll see.

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you said it all in the first sentence " if the forecast guidance is correct in the idea " which is impossible to determine at this point - so my statement has just as much chance of verifying as yours does at this point............

IF the forecast guidance is correct in its idea, I strongly disagree with this post. There would be significant -- almost mid-winter like -- cold air drainage into the Northeast with very strong blocking to the north and a high pressure forced underneath into New England. You can see this idea on the afternoon DGEX with low to mid 20's surface temperatures and snow falling with a weak disturbance aloft.

f138.gif

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you said it all in the first sentence " if the forecast guidance is correct in the idea " which is impossible to determine at this point - so my statement has just as much chance of verifying as yours does at this point............

 

Think you're missing the point, your statement above was pretty general, of course having precip fall at night helps. Earthlight is saying how right now the airmass progged could be cold enough where it doesn't matter what time it falls. Models are still trying to distinguish which wave(s) to focus on. While the block is pretty I am not sure I totally am in love with the positioning. If the PV heads too far west it would allow the SE ridge to rise a bit. If you look at March 58. Notice the differences in the block location. It would also be nice if we lucked on timing of the shortwaves. Even if you have a good pattern it can still help to have minor shortwaves head east and dampen the heights before a larger shortwave comes across. 

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The ULL to the north of NE is much different at 111(stronger based on the expanse of the 498 dm isopleth) but also further north, so we'll see what it does from here compared to the 12z

Shortwave entering the PAcific NW looks a bit more robust as well

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There's just no digging, so the moment the storm finds a weakness it cuts

It's only a 1030ish high but as usual the GFS runs it right into the high. I agree though without any ridging over the western/central US its gonna have a tough time making it all the way to our longitude without amplifying and moving to the north. There is some hope. That incoming s/w over the west coast while the storm were talking about is moving east, could trend in any number of ways affecting what happens downstream. Also the high pressure to our north could very well change location and strength, both dependent on many factors. Anyway, this pattern becomes very convoluted with high latitude blocking and an active pattern with sufficient cold air.

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Geez the GFS is kind of a disaster. Although I think it's completely off base. With a -NAO and ULL sitting up around Atlantic Canada, as soon D truncation occurs the GFS finds a weakness and shoots the heights up with. Se ridge connecting into the higher latitudes. Common bias the GFS has in breaking down blocking too quickly especially around truncation

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It's only a 1030ish high but as usual the GFS runs it right into the high. I agree though without any ridging over the western/central US its gonna have a tough time making it all the way to our longitude without amplifying and moving to the north. There is some hope. That incoming s/w over the west coast while the storm were talking about is moving east, could trend in any number of ways affecting what happens downstream. Also the high pressure to our north could very well change location and strength, both dependent on many factors. Anyway, this pattern becomes very convoluted with high latitude blocking and an active pattern with sufficient cold air.

 

Yeah, and if this run is right, winter is done. But the GFS is driving lows into blocks like nothing, really weird. 

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Geez the GFS is kind of a disaster. Although I think it's completely off base. With a -NAO and ULL sitting up around Atlantic Canada, as soon D truncation occurs the GFS finds a weakness and shoots the heights up with. Se ridge connecting into the higher latitudes. Common bias the GFS has in breaking down blocking too quickly especially around truncation

Shouldn't be too surprising, the gfs has been back and forth with this pattern. One day it shows a mid winter like air mass and the next it's full on spring.

Wouldn't be surprised to Euro be the complete opposite.

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I realize it's still early but Upton and almost all t.v outlets have rain for this Saturday with temps in the low 40's and they again have rain for next Mon and tueasday with temps in the mid 40's Monday and upper 40's on Tuesday... Sorry Upton has rain and snow Monday night going back to all rain Tuesday........ Is there a chance that we remain dry on Saturday?? Atleast in the morning. I'm supposed to move that morning and nothing sucks more then moving in the rain I would rather move in the snow!!!

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Still about 0.4ish for a lot of the area with temps around freezing. Timing is great comes in at 7pm sun night and is over by 7 am Monday morning

Nice! Perfect timing to close schools on monday and mess up the commute, as well as for snow to stick :) so a 3-5" advisory type of deal then.

-skisheep

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What did the EURO have for the overrunning event sunday into monday? Guessing it backed off from the 6" idea...

-skisheep

 

Well the snowmap from Accuweather pro still shows 6+ inches. It's the only model that shows the overrunning event this far north.

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Well the snowmap from Accuweather pro still shows 6+ inches. It's the only model that shows the overrunning event this far north.

It still shows 6"+ on the 0z run? Wow...

 

I've got to say, if I have to choose one model to have on my side, it's the EURO, so I'm optimistic for this one. Doubt we see 6", but I think 2-4" is realistic...

-skisheep

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From a big picture view, both the 0z ECMWF and 6z GFS are really exciting for the NYC area.

 

First, if the blocking develops as forecast, the magnitude of blocking would be historic for the second half of March. For the second day in a row, a number of ensemble members forecast the AO to drop to between -5 and -4. The lowest figure on record for the March 16-31 timeframe is -4.202, which was achieved on 3/24/2001. Once the blocking becomes severe, any storminess could create at least some opportunities for snowfall.

 

Second, the current blocking is not severe at present. The AO is presently at -1.039. Until the blocking becomes severe, which likely won't occur until just after 3/20, there will be opportunities for systems to cut. The system early next week is a prime example and the idea of its cutting is not unreasonable. A late-week system would have greater difficulty cutting and the probability of a coastal storm or coastal redevelopment would be greater.

 

Third, even as the modeling currently stands, both the 0z ECMWF and 6z GFS point to at least two occasions in which snow could accumulate in NYC. Multiple accumulations of snow after 3/15 have not been common in recent years. The two most recent cases were:

 

1996: March 28-29 4.1" and April 9-10 0.7" (much more fell on Long Island)

2000: March 17 0.4" and April 9 1.2"

 

The last time NYC had accumulating snow after March 15 was March 24, 2011 (1.0"). The last moderate or larger snowstorm (4" or more) after March 15 occurred on March 16, 2007 when 5.5" fell.

 

In short, this is an exciting pattern as currently modeled. It is also a dramatic contrast with what we saw last year at this timeframe en route to the nation's experiencing its warmest March on record.

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