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March Medium Range Discussion


nzucker

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March has started out on the colder side with a -1.2F departure before a decent negative today at KNYC.

 

The 12z ECM shows a significant trough in the East at 144 with a low well off the coast, a minor threat, then cold air crashes in:

post-475-0-03918200-1362700480_thumb.gif

 

As Don Sutherland pointed out, the chance of an arctic outbreak is increasing with the -AO...the 12z ECM at Day 9 has -16C 850s over NYC:

 

The 18z GFS has a large coastal tracking over Cape Cod, giving some backend snows to the area, at Day 7-8:

post-475-0-95544100-1362700653_thumb.gif

 

People who are talking about this as the last of winter's cold and snow are probably kidding themselves. 

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While I am not sure how the individual storm details are going to play out, my guess is that this

period will be the coldest departures in our area for  the entire month of March. This will probably

represent the best chance this month for NYC to record temperature departures of -10 or lower.

 

 

 

 

 

The Euro ensembles are forecasting that the next round of blocking will be found further

north which will allow the coldest temperature departures to be directed over the Northeast.

The departures this week were lowest in the Southeast with the further south block.

 

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Strongly agree Bluewave...in a week, NYC's average high is around 50F and models are showing 30s for highs with 850s in the -10C to -16C range. Near-freezing temperatures produce much greater departures in mid-March than they do now, when averages are still in the 40s. With the block developing further north, we should get in on much more arctic air rather than the modified continental airmass that has produced the modestly cold start to March. Snow threats should extend out until March 20th or so before blocking breaks down and the month ends on a spring-like note. 

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I agree. The question is where that gradient will set up. The 6z GFS pretty much cancelled spring after this brief warm up we are expected to get after this system.

According to HM legitimate thraet end of next week and I understand Euro has storm end of next week.

 

Any comments?

 

Rossi

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ggem looks like a 3-5in clipper assuming its timed right...it looks like areas just south and sw of the get in on the heavier stuff. Granted its a week out so I'm sure we'll see many changes. BTW euro pattern at 240 is awesome for mid march. If only we had this in january lol. Who knows march could end up our snowiest month!

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ggem looks like a 3-5in clipper assuming its timed right...it looks like areas just south and sw of the get in on the heavier stuff. Granted its a week out so I'm sure we'll see many changes. BTW euro pattern at 240 is awesome for mid march. If only we had this in january lol. Who knows march could end up our snowiest month!

 

Im encouraged that the euro is fairly similar to the ggem for the day 7 threat.

 

And yeah, the pattern right after this screams potential with a nive PV in Maine funneling in cold air.

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Snowy marches can be a lot of fun. Its almost unexpected at this point so its like all bonus snow lol. Truth of the matter is NYC averages around 3 (not positive just guessing) for the month of march but they've become stinker winter months over the last 10 years. Notably 2009 had a KU and there were others with storm threats but no real overall solid wintry marches in a while. Lets hope March 2013 makes up for the first half of winter. 2004 and 2005 weren't bad though.

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Snowy marches can be a lot of fun. Its almost unexpected at this point so its like all bonus snow lol. Truth of the matter is NYC averages around 3 (not positive just guessing) for the month of march but they've become stinker winter months over the last 10 years. Notably 2009 had a KU and there were others with storm threats but no real overall solid wintry marches in a while. Lets hope March 2013 makes up for the first half of winter. 2004 and 2005 weren't bad though.

March averages 3.6" in Central Park; the snowiest March was 30.5" in 1896.

 

There have been some very snowy Marches in Westchester, using the Dobbs co-op much more recently:

 

1958...10.1" storm on 3/14 and then a 17.5" storm on 3/21....high of only 34F on 3/21...28.4" fell.

1960...27.4" storm on 3/3 and 2.5" on 3/17...9/12 nights with teens to start month...32.3" fell

1967...3.5" on 3/7, 12.1" on 3/17, 11.7" on 3/22, last accumulation 4/24 with 0.2"...high of 21F on 3/18, low of 2F 3/19...27.3" fell.

1994...6.3" on 3/3, 3.3" 3/18, low of 13F on 3/1 and 19F on 3/17...9.6" fell, much more to the northwest in Poconos/Catskills

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The model guidance has been fairly persistent in developing another elongated upper level height field over Southeast Canada. With a changing pattern in the Pacific and out west, this creates a bit of a gradient across the Northern 1/3 of the CONUS. So long as this develops similarly to modeled, I wouldn't be surprised to see this northern stream feature (north of the International Border in the Northern Plains on this image) amplify southeast and develop into a weak Miller B.

 

Our struggle will be with the sun angle and boundary layer.

 

f144.gif

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The model guidance has been fairly persistent in developing another elongated upper level height field over Southeast Canada. With a changing pattern in the Pacific and out west, this creates a bit of a gradient across the Northern 1/3 of the CONUS. So long as this develops similarly to modeled, I wouldn't be surprised to see this northern stream feature (north of the International Border in the Northern Plains on this image) amplify southeast and develop into a weak Miller B.

Our struggle will be with the sun angle and boundary layer.

f144.gif

As currently modeled, it comes a night. Which would be perfect.

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I also think the winter weather potential could continue well past that first clipper threat with two potential threats emerging from Pacific energy around the 20th and 24th. We'll have to carefully watch the MJO progression and the modeling of the blocking setup over the high latitudes. But we could be entering a two week stretch with multiple snowstorm threats.

 

f168.gif

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I also think the winter weather potential could continue well past that first clipper threat with two potential threats emerging from Pacific energy around the 20th and 24th. We'll have to carefully watch the MJO progression and the modeling of the blocking setup over the high latitudes. But we could be entering a two week stretch with multiple snowstorm threats.

 

f168.gif

 

The GFS has snow threats into the long range, including the Day 10 system that the 12z ECMWF had. Very cold pattern on the GFS.

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The model guidance has been fairly persistent in developing another elongated upper level height field over Southeast Canada. With a changing pattern in the Pacific and out west, this creates a bit of a gradient across the Northern 1/3 of the CONUS. So long as this develops similarly to modeled, I wouldn't be surprised to see this northern stream feature (north of the International Border in the Northern Plains on this image) amplify southeast and develop into a weak Miller B.

 

Our struggle will be with the sun angle and boundary layer.

Besides the event coming at night, I don't see a lot of issues with the boundary layer if the GFS and ECM are correct. We have -10C 850s draped over our area with 510 thicknesses moving into Northern New England/Southeast Canada due to the very potent Greenland block. I think with the upper levels that cold, you're going to snow regardless of the date on the calendar. Also, I consider sun angle issues to be more of a problem in late March and April...March 14th is easily fair game for a snowfall in the NYC metro, especially the NW suburbs, and we saw snow sticking today during the day...we've had a ton of threats around St. Patty's Day...it just takes a better than usual H5 pattern since average highs are near 50F, but we definitely have a +PNA/-NAO developing after the brief warm-up. I'd like to see the PNA ridge stronger and further west to create the threat of a larger Nor'easter.

 

I also think the winter weather potential could continue well past that first clipper threat with two potential threats emerging from Pacific energy around the 20th and 24th. We'll have to carefully watch the MJO progression and the modeling of the blocking setup over the high latitudes. But we could be entering a two week stretch with multiple snowstorm threats.

Winter could continue for a while with the forecast pattern....the 12z ECM shows 850s dropping to around -13C here at Day 8 with a 552dm block over the Davis Strait/Baffin Island. This is a very potent pattern, and the two Pacific shortwaves forecast for the 20th and 24th could become major threats, although I become skeptical of snow threats after the equinox (although the latest accumulating snowfall here was on 4/24, so there is time left). Here is the great pattern on the Euro:

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The Euro was very close to blowing up the clipper. The ridge axis initially being a bit to the east does not really bother me since the wavelengths are getting shorter. There's no real southern stream involved with the clipper so it won't have that much moisture, but there will be plenty of energy with it. Almost kinda like a warmer version of a January of '04 clipper, considering the PV position.

 

The block that develops is just sick and in a perfect position. 

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I like the March 20-25 period better for something significant. The west-based -NAO block and PV looks too strong before that. That period coincides better with the dynamical and statistical model forecasts for the MJO to loop back into between phases 7,8, and 1. As well the weakening west-based -NAO model forecasts:

 


post-187-0-24178500-1362832687_thumb.gif

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The Euro was very close to blowing up the clipper. The ridge axis initially being a bit to the east does not really bother me since the wavelengths are getting shorter. There's no real southern stream involved with the clipper so it won't have that much moisture, but there will be plenty of energy with it. Almost kinda like a warmer version of a January of '04 clipper, considering the PV position.

 

The block that develops is just sick and in a perfect position. 

this the clipper from '04 you talkin bout ?

 

http://www.raymondcmartinjr.com/weather/2004/15-Jan-04-SurfaceMaps.html

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