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March Medium Range Discussion


nzucker

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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.

great post Don...March 29th is the last date on the calendar that had multiple snowstorms...April 5-9 is another period that produced some late season snowfalls...

March 29th..............

1.1"... 28-29th, 1959...was snow and sleet for my tenth birthday...I remember it well...

3.0"... 1885...

4.1"... 28-29th 1996...started as wet snow...changed to rain/sleet...Changed back to heavy wet snow...

3.3"... 28-29th 1984...major storm...started as wet snow...changed to rain and sleet...back to snow and sleet...ends as mix...26" in the Poconos...

3.2"... 1974...Starts as rain...changed to snow in the afternoon...ended as rain...10" in the Poconos...

4.0"... 1970...Started as rain...Changed to snow in the afternoon...Got very cold at the end of the storm...

April 5-9th.........

4.0"...4/7/2003...7" on Staten Island...stayed cold after the storm...

9.6"...4/6/1982...13" in the Poconos...record cold followed...

4.2"...4/8/1956...started as heavy rain...

6.5"...4/5/1944

6.4"...4/7/1938

6.5"...4/9/1917

5.0"...4/9/1907

If the AO falls to record levels later this month it will snow or get cold for the season...2001 had a little snow and one last cold spell when the ao was that low...i expect at least that this year if the stronger blocking develops...

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The 12z NAM has some decent stuff making it into the area from the clipper. 0.10-0.25" for northern NJ. Less south and east.

Surface temperatures are in the upper 30s to lower 40s for most of that over most of the area. And we need intensity at this time of year to get snow. We may have more significant snow coming, but I doubt that this is it.

WX/PT

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Surface temperatures are in the upper 30s to lower 40s for most of that over most of the area. And we need intensity at this time of year to get snow. We may have more significant snow coming, but I doubt that this is it.

WX/PT

I'm not enthusiasic about it either, was just pointing it out. Clippers never favor this area, wouldn't be surprised to see this fizzle out to nothing more than sprinkles as time goes on.

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The gfs is starting to show the overrunning event, that one could be significant with a lot of cold air available.

have to wait and see if the EURO has it more north overrunning the cold air  into the metro - because the GFS continues to suppress it and its not overrunning into the cold air - also have to wait and  see if the GFS ensembles handle it differently then the OP .................

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Good hit at hr 126, everyone from I-78 north is below freezing. Moderate precip over the area. North shore is below freezing, south shore isn't. Good hit at hr 132, especially for northern NJ. Only problem is that most of it falls during the day on Tuesday. The city remains below freezing for the whole event. The city west is 0.75"+

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To break it down for everyone (12z Euro) snow begins falling between 12z and 18z Monday and stops between 00z and 06z Tuesday. Probably a warning criteria snowfall for the western burbs. We might lose some accumulations to the March sun and relatively warm ground, but it should come down at a good clip for awhile. (12z Euro verbatim)

 

The Euro was really close to showing a huge solution. There isn't much of a gap between the miller B and the over running.

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I'm guessing here is below freezing and .5"-.75"? That should be a solid 4-6" after dealing with the sun and temps, probably closes Stamford schools on monday verbatim. Gets washed away very quickly, might not even bother to have the plow guy come and save some $$$, I'll just park on the street...

-skisheep

Total precip is about 0.3-0.4 for all

Not sure where yanksfan sees 0.75 for city west. There are 3 frames where there is precip and temps supportive of snow. Combined it is 0.1-0.25 for two of them and the last frame is 0.05-0.1

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Total precip is about 0.3-0.4 for all

Not sure where yanksfan sees 0.75 for city west. There are 3 frames where there is precip and temps supportive of snow. Combined it is 0.1-0.25 for two of them and the last frame is 0.05-0.1

OK that makes much more sense, that would have been a major jump from the 0z run, and the whole event shifted south according to New England Forum.

-skisheep

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About .30-.40 qpf. Most likely an advisory event

Yup, 3-4". Ratios should be 10-1 maybe a bit higher if it really gets down into the 20s, so 4" is probably a good bet VERBATIM on the EURO. It has been trending to the southern GFS though, so caution flags out in full force.

-skisheep

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