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Area Forecast Discussion
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000
FXUS61 KPBZ 252132
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
432 PM EST TUE NOV 25 2014

.SYNOPSIS...
LOW PRESSURE SYSTEM IS EXPECTED TO DEVELOP AND RIDE NORTHWARD
ALONG THE COAST ON WEDNESDAY...BRINGING ACCUMULATING SNOW TO AREAS
SOUTH AND EAST OF PITTSBURGH. A SECOND WEAKER SYSTEM WILL USHER IN
COLDER TEMPERATURES AND LINGERING SNOW SHOWER CHANCES THROUGH THE
END OF THE WEEK.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
QUIET WEATHER IN THE INTERIM AS A SURFACE LOW PRESSURE SYSTEM
BEGINS TO DEVELOP ALONG THE SOUTHEAST COAST THIS EVENING. THIS LOW
WILL THEN LIFT NORTHEASTWARD WITH THE HELP OF A DIGGING UPPER
LEVEL SHORTWAVE OVER THE PLAINS AND A STRENGTHENING UPPER LEVEL
JET....RIDING ALONG THE COLD FRONT THAT CROSSED THE REGION
YESTERDAY. DESPITE THE EXPECTED INCREASE IN CLOUDS IN ADVANCE OF
THE LOW...CLEARING SKIES EARLY SHOULD HELP TO DROP TEMPERATURES
INTO THE 30'S TONIGHT ACROSS MUCH OF THE REGION. 

THE GENERAL MODEL CONSENSUS IS THAT SNOW WILL BEGIN TO OVERSPREAD
THE REGION EARLY TOMORROW MORNING FROM SOUTHEAST TO NORTHWEST AS
THE LOW IS LIFTED NORTHWARD. THE NAM SEEMS TO BE THE
OUTLIER...WITH VERY HIGH OMEGA VALUES AND THUS SNOWFALL
ACCUMULATIONS IN COMPARISON TO ALL OF THE OTHER MODELS...AND
SEVERAL RUNS OF THE MODELS. WITH THAT BEING SAID...THE QPF VALUES
HAVE INCREASED A BIT AMONG ALL OF THE MODELS...WHICH EVEN WITH
MODEST SNOW RATIOS LEADS TO WARNING CRITERIA SNOW IN THE HIGHER
ELEVATIONS OF GARRETT...PRESTON...AND TUCKER COUNTIES AND JUST
EXCEEDING WARNING CRITERIA IN THE CHESTNUT AND LAUREL RIDGES. A
BIT OF AN EXPANSION WESTWARD IN THE TRACK HAS ALSO LEAD TO THE
ISSUANCE OF AN ADVISORY FOR 2-4 INCHES IN THE COUNTIES IMMEDIATELY
ADJACENT TO THE WARNING...WITH LESSER AMOUNTS EXPECTED FURTHER
NORTH AND WEST.

IT IS EXPECTED THAT THE BULK OF THE SNOWFALL WILL BE OVER BY LATE
AFTERNOON AS THE SYSTEM PULLS OFF TO THE EAST. WITH WETBULBING
EXPECTED...HIGH TEMPERATURES WILL STRUGGLE TO MOVE OUT OF THE LOW
TO MID 30'S TOMORROW. 

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
DIGGING SHORTWAVE INTO THE WESTERN GREAT LAKES WILL BRING LIGHT SNOW 
SHOWERS EARLY THURSDAY...WITH A TRANSITION TO LAKE ENHANCED SNOW 
SHOWERS LATER THURSDAY AFTERNOON AND THURSDAY NIGHT. MODELS STILL 
PROG 850MB TEMPS TO FALL TO NEAR -10C BY THURSDAY NIGHT AND WITH A 
DECENT LAKE FETCH EXPECT SOME LIGHT ACCUMULATIONS IN THE RIDGES AND 
I-80 CORRIDOR. TEMPERATURES WILL BE AROUND 10 DEGREES BELOW SEASONAL 
AVERAGE. DRY HIGH PRESSURE WILL MOVE ACROSS THE REGION FRIDAY WITH 
CONTINUED COLD TEMPERATURES.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
A STREAM OF MOISTURE FROM THE CANADIAN ROCKIES WILL KEEP CLOUDS AND 
PRECIPITATION CHANCES IN THROUGH THE WEEKEND AS NW FLOW HOLDS INTO 
EARLY SUN. HIGH PRESSURE WILL SLIDE SOUTH INTO THE NRN PLAINS OVER 
THE LATTER PART OF THE WEEKEND...DISLODGING A WEAK COLORADO LOW WITH 
RELATIVELY LOW MOISTURE INTO OUR AREA. WHILE THIS MEANS MORE LIGHT 
PRECIPITATION...THE GOOD NEWS IS A TRANSITION TO SWERLY FLOW AND 
OVERALL WARMING INTO NEXT WEEK. MODELS HAVE MADE REMARKABLE PROGRESS 
IN CONSISTENCY OVER THE LAST 24HRS LENDING TO HIGHER CONFIDENCE IN 
THE EXTENDED TRENDS.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
GENERAL VFR OVERNIGHT UNTIL CLOUDS AND MOISTURE SPREAD NORTHWEST
FROM COASTAL LOW DEVELOPING TONIGHT. PRECIP SHIELD WILL SPREAD IFR
SNOW FROM PITTSBURGH AND MORGANTOWN EAST MAINLY FROM 12-18Z THEN
IMPROVING LATE DAY. GUSTY WEST WINDS WILL DIMINISH THIS EVENING.
LIGHT NORTH TO NORTHEAST WINDS LATER TONIGHT THROUGH WEDNESDAY.

OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/...
RESTRICTIONS POSSIBLE THURSDAY IN SNOW SHOWERS. A FRONT WILL BRING
POSSIBLE RESTRICTIONS IN SHOWERS SUNDAY INTO MONDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING FROM 4 AM TO 6 PM EST WEDNESDAY FOR 
     MDZ001.
OH...NONE.
PA...WINTER STORM WARNING FROM 4 AM TO 6 PM EST WEDNESDAY FOR 
     PAZ074-076.
     WINTER WEATHER ADVISORY FROM 4 AM TO 6 PM EST WEDNESDAY FOR 
     PAZ023-073-075.
WV...WINTER STORM WARNING FROM 4 AM TO 6 PM EST WEDNESDAY FOR 
     WVZ023-041.
     WINTER WEATHER ADVISORY FROM 4 AM TO 6 PM EST WEDNESDAY FOR 
     WVZ021-022.

&&

$$







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