April 1st-2nd Nor'Easter Potential

[Ericjcrash]

I texted this to earthlight earlier that I would be shocked if the kicker didn't at least have some sort of impact. I'm much more worried about a storm going OTS or being a graze because of interference from the kicker than I am worried about an all-rain event/too far west track, honestly.

As am I. 0z is big.

[A-L-E-X]

Alex, how about if ECMWF is right, April '97 100 miles S? All depends where the H5 can close off.

Yes, that would be the ideal situation for us. I saw DT's map and he has 12+ from C CT north and east..... we need the storm to close off sooner to get into those heavier bands. There actually is a really sharp cut off on his map with Philly and Trenton getting nil (and nothing over C NJ either).... and what looks like 1-3 for NYC, LI, NE NJ and the south coast of NE all the way up to Boston with 12-18 inches just west and north of those locations (outside of NW/N NJ where he has 6-12).

[IsentropicLift]

At some point......and probably sooner than later, I fully expect the NAM to come in with a big coastal and calm alot of nerves.

[atownwxwatcher]

18 Z UK

[yoman1126]

Hi all i am supposed to fl yout of atlantic city airport on friday afternoon. what are the chances of that happening?

[tmagan]

Hi all i am supposed to fl yout of atlantic city airport on friday afternoon. what are the chances of that happening?

100%.

[tmagan]

18Z RGEM MSLP three hour precip. hour 54.

[eduggs]

The thing that scares me about this storm is that the AO is + and there is no blocking. We need either a perfect track or great dynamics to have an all snow event for the coast. Hopefully the ensembles are much better than the op.

All snow along the coast is a completely unreasonable hope or expectation. There's a chance some places approach 50F on Thursday. Accumulating snow of any kind is a more reasonable goal. If we get that then we can look at the radar and get a little greedy.

[Mitchel Volk]

Temps seems slightly warm at the coast, but who knows it has been a crazy year for NYC weather. If this storm hit last Saturday it would have been snow, but the air is modifying a little every day and the calendar is clicking towards summer. I think that the chance for a decent snow for NYC and the coast is less then 30%.

[A-L-E-X]

All snow along the coast is a completely unreasonable hope or expectation. There's a chance some places approach 50F on Thursday. Accumulating snow of any kind is a more reasonable goal. If we get that then we can look at the radar and get a little greedy.

And the best chance will definitely be at night-- so one positive is that the best dynamics will occur after midnight and into the early morning hours. I wonder how much snow we can expect out of this if DT's forecast of 40-50 pct snow works out.

[A-L-E-X]

Temps seems slightly warm at the coast, but who knows it has been a crazy year for NYC weather. If this storm hit last Saturday it would have been snow, but the air is modifying a little every day and the calendar is clicking towards summer. I think that the chance for a decent snow for NYC and the coast is less then 30%.

The best chance for the coast is if the storm drags down colder air from the north and the storm occurring in the midnight - 9 am timeframe. We would have been toast if this was a daytime event.

[eduggs]

18z GFS actually bring .25" QPF up to Staten Island through 48 hours with snow from the first event..it occurs mostly at night.

You mean NAM, no?

This could surprise a few if correct, though I suspect the NAM is holding onto the SLP too long with the mid-level low dampening. I see this as more of a threat for elevated central Pa.

[winterwarlock]

At some point......and probably sooner than later, I fully expect the NAM to come in with a big coastal and calm alot of nerves.

and what is your basis for this thinking

[Sundog]

and what is your basis for this thinking

Model consensus I assume.

[A-L-E-X]

You mean NAM, no?

This could surprise a few if correct, though I suspect the NAM is holding onto the SLP too long with the mid-level low dampening. I see this as more of a threat for elevated central Pa.

Tombo's combined EURO map for both storms was pretty interested-- he had the highest "yellow" QPF area up to Staten Island and the south shore of Long Island-- we were in the 1.75-2" QPF range on the Euro I think.

[A-L-E-X]

Model consensus I assume.

I think we may have that by 12z tomorrow.

[eduggs]

And the best chance will definitely be at night-- so one positive is that the best dynamics will occur after midnight and into the early morning hours. I wonder how much snow we can expect out of this if DT's forecast of 40-50 pct snow works out.

8"+ ?

As most everyone can see, this has the potential to be a major snow producer. We have a deep, high amplitude, increasingly negatively tilted longwave trof, with potent, high vorticity s/w embedded. That's really all you need to get a major snowstorm with some luck. But I think chances are heavily against heavy snow near the coast at low elevations.

[Chris L]

Tombo's combined EURO map for both storms was pretty interested-- he had the highest "yellow" QPF area up to Staten Island and the south shore of Long Island-- we were in the 1.75-2" QPF range on the Euro I think.

18-24 inches of snow, if it works out.... we beat 1995-1996.

but we have a long long way to go.

[nzucker]

8"+ ?

As most everyone can see, this has the potential to be a major snow producer. We have a deep, high amplitude, increasingly negatively tilted longwave trof, with potent, high vorticity s/w embedded. That's really all you need to get a major snowstorm with some luck. But I think chances are heavily against heavy snow near the coast at low elevations.

I agree with Alex that it's going to help NYC/LI a lot that this falls at night. Temperatures have been running well below average for late March; if you can keep them low Thursday due to showers/flurries from the initial overrunning, the metro should be OK with the event occurring at the wee hours of Friday AM.

[A-L-E-X]

8"+ ?

As most everyone can see, this has the potential to be a major snow producer. We have a deep, high amplitude, increasingly negatively tilted longwave trof, with potent, high vorticity s/w embedded. That's really all you need to get a major snowstorm with some luck. But I think chances are heavily against heavy snow near the coast at low elevations.

Even if it's 8"+ that "falls" I doubt that much would stick-- my upper end for the coast would be about half that amount.

[A-L-E-X]

18-24 inches of snow, if it works out.... we beat 1995-1996.

but we have a long long way to go.

Yeah, but no way can we make a forecast like that right now-- the only time you can make a forecast like that this late in season is when it's already snowing heavily and you see that there's a nice conveyor belt of snow that will keep you in heavy snow for hours lol. Even April 1982 didn't have those kind of totals but it sure had the cold air.

[supermeh]

SREFS came NW...850s are below zero the entire time for NYC. The half an inch line starts just Southwest of NYC and go NE from there.

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/sref/21/images/sref_x24_066s.gif

[ag3]

new srefs appear to be east and develops the low a little too late.

Precip is .50"-.75" for NYC east:

For some reason 850's are very cold but surface temps are very warm.

[eduggs]

18-24 inches of snow, if it works out.... we beat 1995-1996.

but we have a long long way to go.

For a liquid equivalent of 1.75-2" and a favorable storm evolution close to the Euro depiction, but assuming a mostly snow ptype, my calculations come to 6" at NYC, 12"+ above 500ft, and a 16-20" max on the hilltops.

[A-L-E-X]

850s might be colder because of the east trend but the surface is warmer because the precip is not as heavy?

[SnowGoose69]

Some people have said you need -10 or -12C 850s...but if you have heavy enough precipitation or a strong enough low thats not the case...April 1982 the 850s were -5C or so as you can see here and it was snowing heavily during that time.

http://www.meteo.psu.edu/~gadomski/NARR/1982/us0406.php

[Chris L]

Yeah, but no way can we make a forecast like that right now-- the only time you can make a forecast like that this late in season is when it's already snowing heavily and you see that there's a nice conveyor belt of snow that will keep you in heavy snow for hours lol. Even April 1982 didn't have those kind of totals but it sure had the cold air.

yes for sure. In '97, the amounts for SNE didn't even increase until the event was already going. No forecast had Boston getting 25+ inches of snow, unlike January 2005, which was a winter event of course, they predicted Boston would get 24-30" amounts well before.

[A-L-E-X]

For a liquid equivalent of 1.75-2" and a favorable storm evolution close to the Euro depiction, but assuming a mostly snow ptype, my calculations come to 6" at NYC, 12"+ above 500ft, and a 16-20" max on the hilltops.

So you think 6" for NYC? That's actually higher than what I was thinking.... which was 4"

[ag3]

Here's sref surface temps during height of storm. Weird that its so warm:

freezing line almost in MAINE:

[supermeh]

new srefs appear to be east and develops the low a little too late.

Precip is .50"-.75" for NYC east:

For some reason 850's are very cold but surface temps are very warm.

NW of 15z