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3/30 Snow/Rain Threat


Thunder Road

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Look at how warm surface temps are on the NAM as the precip moves in. :yikes:

Granted, it's the 84 hour NAM, but it's definitely possible that some areas as far north as Allentown see a sloppy mix of rain/wet snow.

You're 32.6 as precip begins falling. Interesting though that at hr 78 ABE is warmer than PHL (42.6 versus 40.0)

EDIT: 78, not 72

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GFS has the Coastal closer to the coast but still jogs it OTS at the last minute, brings in 0.25" south of the Turnpike, 0.10"-0.25" north of it.

850s are cold enough (0C line hovers just south of Philly) but the sfc frz line is pretty far north, runs along I-81 for most of the event.

Two things in our favor, however, are that it looks like precip falls mostly between 5pm Wed. and 8am Thurs., and there is a High up north in the traditional spot, although it is rather weak. (~1020mb)

Given that this has an Archambault signal to it, I think it may be a winter storm for many, even if the coastal plain stays rain.

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You're 32.6 as precip begins falling. Interesting though that at hr 78 ABE is warmer than PHL (42.6 versus 40.0)

EDIT: 78, not 72

thats prob because phl prob gets cloudier earlier and evap cooling earlier.

GFS has the Coastal closer to the coast but still jogs it OTS at the last minute, brings in 0.25" south of the Turnpike, 0.10"-0.25" north of it.

850s are cold enough (0C line hovers just south of Philly) but the sfc frz line is pretty far north, runs along I-81 for most of the event.

Two things in our favor, however, are that it looks like precip falls mostly between 5pm Wed. and 8am Thurs., and there is a High up north in the traditional spot, although it is rather weak. (~1020mb)

Given that this has an Archambault signal to it, I think it may be a winter storm for many, even if the coastal plain stays rain.

the gfs for immediate phl burbs is rain to start then wet bulbs down and switches to snow, with a pretty isothermal sounding.

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Elevation will really help as usual for a spring event. EC literally has 0.83" at TTN from 0Z Thursday to 0Z Friday, but temps are extremely marginal. I'd guess that the absolute most snow they could get is 4", probably more like 1-2". Sfc temps remain 34 or higher at the 6-hour intervals even at night and 850's are only 1-3 degrees C below freezing. Ratios, even when its snowing, will be atrocious.

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Elevation will really help as usual for a spring event. EC literally has 0.83" at TTN from 0Z Thursday to 0Z Friday, but temps are extremely marginal. I'd guess that the absolute most snow they could get is 4", probably more like 1-2". Sfc temps remain 34 or higher at the 6-hour intervals even at night and 850's are only 1-3 degrees C below freezing. Ratios, even when its snowing, will be atrocious.

my work and paul's location should do well, with 500 plus ft in elevation. Ray do you have soundings for phl? the thicknesses are right around 545 546 on the euro, screams some mid level warmth. You are right though, this is a 6 to 8-1 snow ratio kind of event. I can only imagine what the snow growth region looks like, pretty putrid.

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my work and paul's location should do well, with 500 plus ft in elevation. Ray do you have soundings for phl? the thicknesses are right around 545 546 on the euro, screams some mid level warmth. You are right though, this is a 6 to 8-1 snow ratio kind of event. I can only imagine what the snow growth region looks like, pretty putrid.

KPHL

THU 00Z 31-MAR 2.3 -1.5 1018 97 99 0.09 558 544

THU 06Z 31-MAR 1.1 -0.8 1011 98 99 0.58 554 545

THU 12Z 31-MAR 1.0 -0.3 1009 96 96 0.25 550 543

THU 18Z 31-MAR 2.7 -1.0 1008 89 36 0.03 547 541

FRI 00Z 01-APR 1.7 -3.0 1008 96 35 0.03 543 537

FRI 06Z 01-APR 0.7 -3.7 1007 98 28 0.01 540 535

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KPHL

THU 00Z 31-MAR 2.3 -1.5 1018 97 99 0.09 558 544

THU 06Z 31-MAR 1.1 -0.8 1011 98 99 0.58 554 545

THU 12Z 31-MAR 1.0 -0.3 1009 96 96 0.25 550 543

THU 18Z 31-MAR 2.7 -1.0 1008 89 36 0.03 547 541

FRI 00Z 01-APR 1.7 -3.0 1008 96 35 0.03 543 537

FRI 06Z 01-APR 0.7 -3.7 1007 98 28 0.01 540 535

and big time bl warmth. This looks like a suburb with elevation mash potato feast

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Keep in mind these were the 850s last event & temps were about the same..though in some locations this time even colder..

FWIW

RECENT ECMWF RUNS HAVE GENERALLY OFFERED PLAUSIBLESOLUTIONS BUT THEY HAVE ALSO BEEN SUBJECT TO SIGNIFICANTCONTINUITY CHANGES OVER THE PAST 2-3 DAYS. THE 00Z VERSION ANDEVEN MORE PROGRESSIVE 12Z RUN SEEM TOO FAST CONSIDERING HOW WELLORGANIZED THE TWO MAIN SYSTEMS CURRENTLY LOOK OVER THE NORTHPACIFIC APPROACHING AND EXITING FROM JUST SOUTH OF THE ALEUTIANS. ANOTHER COMPLICATING FACTOR FOR CONTINUITY ASSESSMENT IS THAT ONLYTHE 00Z GLOBAL GUIDANCE HAD ACCESS TO ADDITIONAL DATA FROM WSRTARGETING RECON FLIGHTS OVER THE NERN PACIFIC.

The above could explain the change with the most recent ECM run..

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my work and paul's location should do well, with 500 plus ft in elevation. Ray do you have soundings for phl? the thicknesses are right around 545 546 on the euro, screams some mid level warmth. You are right though, this is a 6 to 8-1 snow ratio kind of event. I can only imagine what the snow growth region looks like, pretty putrid.

Yea man we'll do much better than the city for this event!

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