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Potential Winter Storm March 6-7


NEG NAO

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that will certainly be funny.. if Boston is the winner at the end of this.

I can see how it gets to that point though-the initial storm and upper low produce for DC/Baltimore, and the fully phased and stalled low produce for Boston, and there's a "sucker zone" in the middle when the low is in somewhat of a transitioning state. I can see that happening if the phase wth the northern stream energy happens too late. Regardless, even on the GFS the city and east get swiped pretty good for a while.

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Sigh, we see this every year, once we get to March.  Accumulation = snowfall rate - snow melt rate, so as long as the snow is falling at least at a moderate rate, snow will accumulate.  And then, once there is a snow layer on the ground, the melting rate decreases, as that snow layer, by definition, is at 32F, so the melting from "the ground" no longer is an issue.  Melting from air temps above 32F and indirect sunlight, during the day, are still an issue, but the overall melting rate is decreased. 

The problem is we're looking at no more than .25" of liquid during any 6 hour interval so essentially snow falling at less than a half inch/hour rate with temps around 34/35. No way that sticks during the day in urban areas.

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Wouldn't it be mostly snow if the better dynamics shifted 50 miles further NW?

The Canadian is often too warm with these and overdoes WAA. But we need the better dynamics to be sure that we get snow or instead we risk losing much of the precip to rain or slop near the coast and for the city. It was encouraging to see the NAM colder but it's the NAM. Light-mod precip won't do it most likely.

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The problem is we're looking at no more than .25" of liquid during any 6 hour interval so essentially snow falling at less than a half inch/hour rate with temps around 34/35. No way that sticks during the day in urban areas.

True - but you're actually providing an analysis rather than saying "the snow won't stick" without any rationale.  I'd guess melting rates during the day at 34-35F are probably around 0.25" of snow per hour, but I could see it being as high as 0.5" per hour at midday (say, 10 am to 2 pm), at least.  That's an interesting question, really - has anyone ever published snowfall melting rates at various temps above freezing at various times during the day (sun angle, really)?  When I was 23, I probably could've written and solved the equations - not now, lol, as I've forgotten most of that stuff.  Our best hope is to have most of the snow falling after about 3 pm on Wednesday and have the temps drop a bit closer to 32F - could then see several inches of snow accumulate. 

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The Canadian is often too warm with these and overdoes WAA. But we need the better dynamics to be sure that we get snow or instead we risk losing much of the precip to rain or slop near the coast and for the city. It was encouraging to see the NAM colder but it's the NAM. Light-mod precip won't do it most likely.

I'm not really concerned about the coast or the city. Slop in the city is usually a heavy wet paste 20 miles inland. The GFS is more of a slop for me and rain for the coast.

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The new Canadian is north now as well...but also very warm. Looks like mostly rain for everybody despite much more precipitation.

There is something wrong with the Canadian thermal profiles...it's been showing rain for our neighbors down in the Mid-Atlantic for many runs now and the mets have discounted its precip maps...with that said there is still mixing issuing for a lot of people...we probably lose 50% of qpf to rain/mix

 

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True - but you're actually providing an analysis rather than saying "the snow won't stick" without any rationale.  I'd guess melting rates during the day at 34-35F are probably around 0.25" of snow per hour, but I could see it being as high as 0.5" per hour at midday (say, 10 am to 2 pm), at least.  That's an interesting question, really - has anyone ever published snowfall melting rates at various temps above freezing at various times during the day (sun angle, really)?  When I was 23, I probably could've written and solved the equations - not now, lol, as I've forgotten most of that stuff.  Our best hope is to have most of the snow falling after about 3 pm on Wednesday and have the temps drop a bit closer to 32F - could then see several inches of snow accumulate. 

Yeah absolutely snow can stick in march, i'm not saying otherwise. One example I can give of melting snow was in the March 92 storm. We had temps right around freezing overnight and picked up around 6-7" of heavy wet snow. Snow continued through the day even at heavy rates but we got no more accumulation after say 10/11am as temps crept above freezing. It was one of those days where its snowing hard but so bright it looks like the sun is coming out.

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The GEFS are a tick northwest of the 06z run...still a monster hit at 60-66 hr.

Where is your head at on this now (of course I know part of that is "I need to see the Euro")? 

 

Btw --- Your analysis last night was really awesome.  Thanks for taking the time to do that. 

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Even given the GFS's overdoing of BL warmth, its definitely going to be a prolonged period of rain on the GFS followed by a prolonged period of snow...

From BUFKIT precip types its about 0.7 inches rain followed by 0.4 inches frozen at KJFK...

Also, high lapse rates up to around 910 mb would lead to some strong mixing... very strong, gusty winds at the surface with sustained of between 25-30 mph...

An intriguing storm to say the least

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