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Medium/Long Range Discussion


tombo82685

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18z gfs continues colder, weaker trend towards Euro. Gives I-95 a couple of inches.

18Z GFS is all snow!

might have a little snow in the beginning but its still rain or rain/snow for the city and nearby burbs...once to the ptw-ukt area sounding is more supportive of snow but the surface temps are in the mid 30s. the little inverted trof feature is not snow either..bl is to warm, with a departing high under us the southerly winds warm it.

skew t for phl at hr 96

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Im more interested in the Dec 3-6 range, the 12z GFS long range pattern was absolutely drooling. Retrograding block. Yeah it showed a cutter because of its low resolution, but it was seriously a classic setup. I think were going to see a lot of changes in the LR because its really dependent on how the Pacific energy is handled, and that is always tough for models to forecast

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Yep...it's a 30's & rain setup. It's not helping that the system is pretty flat coming through.

HPC tossing the Euro now.

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD

311 AM EST SAT NOV 24 2012

VALID 12Z WED NOV 28 2012 - 12Z SAT DEC 01 2012

...HEAVY PRECIPITATION EXPECTED IN CALIFORNIA LATE THIS WEEK INTO

THIS WEEKEND...

...MODERATE TO HEAVY SNOWS POSSIBLE FOR THE NORTHERN MID-ATLANTIC

STATES AND INTERIOR NEW ENGLAND MID TO LATE NEXT WEEK...

GENERAL FLOW PATTERN

====================

A REPETITION OF THE PATTERN SEEN OVER THE PAST FEW WEEKS IS

EXPECTED, WITH AN AMPLIFIED TROUGH MOVING SLOWLY THROUGH THE

EASTERN PACIFIC, WITH DOWNSTREAM RIDGING FORMING ACROSS THE WEST

AND PLAINS, AND RENEWED TROUGHING ANTICIPATED ACROSS THE NORTHEAST

WHICH IS EXPECTED TO CLOSE OFF INTO A DEEP CYCLONE AS IT MOVES

INTO QUEBEC AND ATLANTIC CANADA. THE RIDGE/TROUGH COUPLET OVER

THE LOWER 48 IS EXPECTED TO BE COMPOSED OF BROAD FEATURES OF

RELATIVELY LOW AMPLITUDE, WHICH LEADS TO QUICK SHORTWAVE

MOVEMENT/SYSTEM PROGRESSION THROUGH THE LOWER 48.

MODEL PREFERENCES

=================

THE 00Z ECMWF IS QUICK WITH A SHORTWAVE MOVING THROUGH THE

EAST/WESTERN ATLANTIC EARLY IN THE PERIOD AND OUTPACES THE

REMAINDER OF THE GUIDANCE LATE IN THE PERIOD NEAR THE WEST COAST,

INCLUDING ITS OWN 12Z ENSEMBLE MEAN. ALOFT, THE NON-ECMWF

GUIDANCE FITS THE 12Z ECMWF ENSEMBLE MEAN BEST ACROSS EASTERN

CANADA FROM THURSDAY ONWARD (AND PLAYS INTO THE SLOWING/WESTWARD

SHIFT SEEN IN THE OPERATIONAL ECMWF NEAR THE EAST COAST OVER ITS

PAST COUPLE DAYS OF RUNS), THOUGH THE ECMWF ENSEMBLE MEAN SURFACE

LOW NEVER COUPLES WITH ITS 500 HPA CIRCULATION (WHICH SEEMS

UNLIKELY), SHOWING MINIMAL INTERNAL CONSISTENCY. BASED ON THE

ABOVE, THE PRESSURES WERE BASED ON A 40/30/30 BLEND OF THE 00Z

UKMET/00Z GFS/00Z CANADIAN THROUGH FRIDAY BEFORE SWITCHING TO A

50/50 BLEND OF THE 00Z GFS/00Z GEFS MEAN SOLUTION THEREAFTER.

WHILE THIS MAINTAINED GOOD CONTINUITY NEAR THE WEST COAST, IT LED

TO A MORE COASTAL CYCLONE TRACK LATE TUESDAY AND WEDNESDAY WHEN

COMPARED TO FRIDAY AFTERNOON'S PROGS AND A GREATER SNOW THREAT FOR

THE NORTHEAST.

WEATHER IMPACTS

===============

MODERATE PRECIPITATION IS EXPECTED TO SPREAD UP THE CENTRAL

APPALACHIANS THROUGH NEW ENGLAND AND NORTHERN MID-ATLANTIC STATES

TUESDAY THROUGH THURSDAY AS A LOW SWINGS OFFSHORE THE NEW ENGLAND

COAST BEFORE MOVING INTO ATLANTIC CANADA THURSDAY. THIS

PRECIPITATION COULD BE IN THE FORM OF MODERATE TO HEAVY SNOW

ACROSS THE NORTHERN MID-ATLANTIC STATES AND INTERIOR NEW ENGLAND.

RIDGING ACROSS THE WEST AND PLAINS SHOULD MINIMIZE ANY SIGNIFICANT

GULF MOISTURE INFLUX THROUGH THE PERIOD, THOUGH LIGHT RAINS COULD

RETURN INTO TEXAS AND THE MIDWEST THURSDAY THROUGH NEXT WEEKEND,

LURED NORTHWARD BY WEAK FRONTAL WAVES ACROSS THE MID-SECTION OF

THE COUNTRY CAUSED BY WEAK SHORTWAVES MOVING OVER THE TOP OF THE

WESTERN AND PLAINS RIDGE. OUT WEST, HEAVY PRECIPITATION IS

EXPECTED TO BEGIN IN CALIFORNIA AND PORTIONS OF THE NORTHWEST

THURSDAY, AND CONTINUE THROUGH NEXT SATURDAY, WITH AREAL AVERAGE

LIQUID EQUIVALENT (LEQ) AMOUNTS OF 4-6 INCHES EXPECTED...LOCAL LEQ

AMOUNTS COULD EXCEED 10 INCHES IN THE TOPOGRAPHY OF NORTHERN

CALIFORNIA WHICH COULD FALL IN THE FORM OF SIGNIFICANT HIGH

ELEVATION SNOWS.

ROTH

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HPC tossing the Euro now.

BTW, by 30's and rain -- I'm referring to Philly proper (which the GFS outside of a possible front end hit is suggesting for a chunk of the event). Allentown, Central PA, Poconos are more in play for *some* snow although it's not a lock yet. ;)

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which is what i have been tryinng to tell people. The BL gets warm due to the influx of southerly winds. so ISo its pretty much a cold rain with a little snow in the begining for the vast majority of us outside the far n and w burbs and lehigh valley.

New Jersey already had their November snow, to get any more would be to tempt fate if you know what I mean... ;)

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12z GFS is weaker and further South, GGEM is status quo and further North. Going to be a tough call as to where the RN/SN line sets up here. May be a case without the precip being heavy enough, the temps at the surface remain above freezing even in Allentown, and it is falling as snow but melting, until dusk anyway... case in point, the Canadian:

post-8610-0-87970600-1353776186_thumb.pn

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wunderground has light snow falling from the NJ Turnpike on northwest. 1-3 Philly & NW with some 4"+ totals thrown in.

edit: didn't realize wunderground changed the graphics on snow accums when I made the initial first post. Has been corrected. smile.png

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Hearing conflicting views....EURO looks good for Philly, however can't tell if lower levels are too warm, any input guys? I mean on other sub forums I'm heasring 3-7" for our area, I'd expect for excitement though so I guess LLs look warm.

Philly is snowier side of the r/s line but not by much.

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post-105-0-28448300-1353783241_thumb.jpg

1-2" in the 3 hrs before, about an inch after that just NW of the city.

I think 7" is probably pushing your luck on what the model is showing. It's probably 1-3 city, 2-5 nw burbs...factoring in time (day) it probably ends up being mostly grass and notsomuch on the roads except in those spots that get heavier precip.

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Really close on 12Z EC for snow (PHL) . Maybe a touch to warm at 925 mb. We're going to be splitting hairs on the rain/snow line for the next couple of days.

Agree with this.. I think after looking at several soundings this may be a deal where it is snowing and melting on contact. Even in ABE for a time. Personally because of this and still some intensity in question, certainly no more than a WWA for anywhere. Lancaster, Berks, Lehigh, Northampton and Monroe... points NW. But IMHO 1-3" or perhaps a 4" lollipop. Ratios aren't that great either. Going to be a fun 72 hours...

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