FXUS61 KPBZ 272052
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
352 PM EST FRI NOV 27 2009
.SYNOPSIS...
AN INTENSIFYING EAST COAST LOW PRESSURE SYSTEM WILL CONTINUE TO
BRING NORTHWEST WINDS ACROSS THE FORECAST AREA TONIGHT ALONG
WITH LAKE EFFECT SNOW SHOWERS. SNOW SHOWERS WILL DIMINISH BY
SATURDAY MORNING AS HIGH PRESSURE BUILDS IN FOR THE WEEKEND. THE
MAJORITY OF THE WEEKEND WILL BE DRY BEFORE A COLD FRONT APPROACHES
FROM THE WEST LATE ON SUNDAY.
&&
.NEAR TERM /THROUGH SATURDAY/...
UPSLOPING ACROSS THE EASTERN REGIONS WILL CONTINUE TONIGHT...ALTHOUGH
COVERAGE AND INTENSITY OF SNOW SHOWERS IS DIMINISHING FOR NOW. WITH
INITIAL SHORT WAVE TROF HAVING ADVECTED SE OF THE AREA...THE PRIMARY
CONCERN FOR SNOWFALL THIS EVENING AND OVERNIGHT WILL BE THE CLOSED
LOW MOVING SEWD FROM LAKE ERIE INTO CNTRL PA. WITH THE SHORT WAVE
DIPPING SOUTHEAST...LAKE ENHANCED SNOW SHOWERS WILL DEVELOP ACROSS
NWRN PA THIS EVENING WITH THEIR FOCUS ALONG AND NORTH OF INTERSTATE
80...PRIMARILY IN VENANGO AND FOREST COUNTIES. THE BEST WINDOW OF
ACCUMULATING SNOWFALL SEEMS TO BE 22Z-04Z ACROSS THIS AREA...WITH
1 TO 3 INCHES EXPECTED THROUGH THIS PERIOD. AS THE SHORT WAVE
DIVES SOUTHEAST...ENHANCED UPSLOPING ACROSS THE EASTERN RIDGES
WILL BE TRIGGERED ONCE AGAIN. WITH ONGOING ACCUMULATIONS FROM
TODAY AND SNOW SHOWERS CONTINUING...THE WINTER WX ADVISORY REMAINS
IN EFFECT FOR GARRETT...PRESTON...AND TUCKER COUNTIES THROUGH 06Z SAT.
LOW TEMPS TONIGHT WILL BE SLIGHTLY BELOW NORMAL.
SATURDAY...FLOW OFF OF LAKE ERIE WILL GAIN MORE OF A WRLY
COMPONENT...WITH A FEW LINGERING SNOW SHOWERS AND FLURRIES ALONG AND
NORTH OF INTERSTATE 80 AND ACROSS THE EASTERN RIDGES IN THE
MORNING. SNOW SHOWERS WILL CUT OFF BY THE EARLY AFTERNOON AS HIGH
PRESSURE AT THE SFC AND RIDGING ALOFT BUILDS IN. CLOUD COVERAGE
WILL DECREASE FROM THE SOUTHWEST THROUGH THE DAY SATURDAY...WITH
INCREASING SUNSHINE ALLOWING TEMPS TO RECOVER TO MORE SEASONABLE
LATE NOVEMBER VALUES FOR HIGHS.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/...
HIGH PRESSURE WILL CONTINUE TO BUILD IN FROM THE SOUTH...WITH A DRY
FCST THROUGH SUNDAY AFTERNOON. A SFC LOW WILL DEVELOP ACROSS THE
CENTRAL PLAINS ON SATURDAY NIGHT...CROSSING THE GREAT LAKES ON
SUNDAY AND BRINGING THE NEXT CHC OF RAIN LATE SUNDAY. THE GFS/NAM/ECMWF
ARE IN FAIRLY GOOD AGREEMENT THAT THE ASSOCD COLD FRONT WILL CROSS
THE AREA 12Z MON. THUS...LIKELY POPS ARE FCST ACROSS THE AREA AS THE
FRONT PROGRESSES EWD MONDAY MORNING. WITH THE TROF AXIS MOVING EAST
OF THE AREA...CHC POPS ARE FCST INTO MONDAY EVENING WITH A NWRLY
FLOW ALLOWING FOR LAKE ENDUCED SHOWERS.
FOR TEMPS...HIGHS ACROSS THE AREA WILL BE 5 TO 10 DEGREES ABOVE
NORMAL ON SUNDAY WITH WAA AND A SRLY FLOW AHEAD OF THE COLD FRONT.
WITH THE FRONTAL PASSAGE...TEMPERATURES WILL BE MORE STEADY NEAR
NORMAL VALUES FOR HIGHS ON MONDAY. FOR LOWS...FCST TEMPS ARE CLOSE
TO A MAV/MET BLEND...SLIGHTLY ABOVE NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
FORECAST GENERALLY BASED ON HPC GUIDANCE AND ECMWF SOLUTION.
OPERATIONAL GFS CONTINUES TO BE TOO FAST WITH COASTAL LOW ON
WEDNESDAY NIGHT AND THURSDAY. FEEL ECMWF MAY BE A BIT SLOW AND TOO
FAR WEST WITH SYSTEM MOVING NORTH ON THURSDAY. WILL SPREAD RAIN
ACROSS REGION WEDNESDAY NIGHT AND CONTINUE THROUGH THURSDAY. COLD
AIR MOVES INTO REGION BY FRIDAY MORNING WITH CHANCE OF SNOW
SHOWERS.
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
CONDITIONS IMPROVING THROUGH THE SATURDAY. CIGS LIFTING TO
025-035 WITH GENERALLY UNLIMITED VISIBILITY THIS EVENING.
EXCEPTION IS SHORTWAVE AND PUSH OF COLD AIR THIS EVENING IN NORTH
CENTRAL PENNSYLVANIA THAT WILL BRING PERIOD OF IFR SNOW TO FKL AND
DUJ THIS EVENING. SOME SNOW MAY SPREAD SOUTH INTO LBE.
GUSTY WINDS WILL CONTINUE INTO EARLY EVENING AND THEN BECOME WEST AT
10 MPH OR LESS.
EXPECT CIGS 025-035 AFTER MIDNIGHT WITH CLEARING SATURDAY MORNING.
NEXT FRONT REACHES BEGINS TO AFFECT REGION LATE SUNDAY NIGHT WITH
MVFR CONDITIONS AND RAIN SHOWERS THROUGH MONDAY.
HIGH PRESSURE BUILDING IN FROM SOUTHWEST ON TUESDAY WILL BRING AND
VFR CONDITIONS THROUGH WEDNESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY UNTIL 1 AM EST SATURDAY FOR MDZ001.
OH...NONE.
PA...NONE.
WV...WINTER WEATHER ADVISORY UNTIL 1 AM EST SATURDAY FOR WVZ023-041.
&&
$$
