FXUS61 KPBZ 280140 AAB
AFDPBZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
840 PM EST FRI NOV 27 2009
.SYNOPSIS...
SCATTERED SNOW SHOWERS AND FLURRIES WILL DIMINISH BY EARLY SATURDAY
MORNING AS HIGH PRESSURE BUILDS IN FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH SATURDAY/...
PREVIOUS FORECAST APPEARS TO BE ON TRACK. AS EXPECTED...SNOW
SHOWERS HAVE PICKED UP AS UPPER LEVEL SHORTWAVE HAS CROSSED LAKE
ERIE AND MOVES INTO THE FORECAST AREA...BUT SNOW SHOWERS HAVE NOT
BEEN ABLE TO HOLD TOGETHER AS THEY MOVE SOUTH OF INTERSTATE 80.
SOME ACCUMULATING SNOW IS POSSIBLE SOUTH OF I-80 WITH THE HELP OF
THE SHORTWAVE...BUT SNOW SHOWERS SHOULD BE ON THE DECREASE AFTER
MIDNIGHT. NO CHANGES ARE NEEDED AT THE CURRENT TIME FOR THE WINTER
WEATHER ADVISORY IN THE SOUTHEASTERN COUNTIES. BIGGEST CONCERN
OVERNIGHT MAY BE PRECIPITATION FROM EARLIER TODAY FREEZING ON AREA
ROADWAYS.
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 INDUCED 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 /02Z SATURDAY THROUGH WEDNESDAY/...
CONDITIONS WILL IMPROVE OVERNIGHT AND EARLY SATURDAY MORNING.
CIGS IN THE MVFR TO VFR RANGE WITH GENERALLY UNLIMITED VISIBILITY
THIS EVENING. EXCEPTION WILL BE ACROSS THE NORTH AND RIDGES AS
LOWER CLOUDS AND SNOW SHOWERS WILL PROVIDE INTERMITTENT IFR
CONDITIONS THROUGH 06Z.
WINDS WILL CONTINUE TO DECREASE AS SFC PRESS GRADIENT RELAXES.
EXPECT CONDITIONS TO GO VFR FROM WEST TO EAST SAT MORNING AS WAA
KICKS IN.
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.
&&
$$
