Area Forecast Discussion
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FXUS61 KPBZ 041309
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
909 AM EDT WED MAY 4 2016

.SYNOPSIS...
COOL LOW PRESSURE WILL KEEP SHOWERS IN THE FORECAST THROUGH
THURSDAY. MAINLY DRY FRIDAY BEFORE SHOWER CHANCES RETURN SATURDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
SEVERAL MINOR ADJUSTMENTS NEEDED THIS MORNING BUT OVERALL THE
FORECAST LOOKS TO BE IN GOOD SHAPE. HOURLY TEMPERATURES WERE
ADJUSTED DOWN SLIGHTLY TO BETTER ALIGN WITH LATEST OBSERVATIONAL
TRENDS AND MENTION OF THUNDER WAS REMOVED FOR THIS AFTERNOON AS
LATEST GUIDANCE PROGS MINIMAL INSTABILITY AND 12Z SOUNDINGS SHOW A
WEAK CAP AT 600MB. IF DEWPOINTS STAY STEADY OR RISE SLIGHTLY AND
TEMPERATURES ALOFT COOL MORE THAN FORECAST THEN THERE IS A CHANCE
OF CONVECTION BUT AT THIS TIME THAT LOOKS UNLIKELY. LATEST WATER
VAPOR IMAGERY SHOWS UPPER LOW DEEPENING TO OUR WEST...WHICH WILL
RESULT IN SHOWERS DEVELOPING AND SPREADING FROM WEST TO EAST THIS
AFTERNOON AS THE LOW CONTINUES TO SHIFT SOUTH AND THE FORECAST
AREA SITS UNDER THE DEFORMATION ZONE. THIS SETUP WILL CONTINUE
THROUGH THE NIGHT.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
COOL MID LEVEL CLOSED SYSTEM WILL SLOWLY TRANSLATE TOWARD THE MID
ATLANTIC STATES INTO THURSDAY NIGHT. THIS WILL KEEP TEMPERATURES
NEAR 10 DEGREES BELOW AVERAGE. SHORTWAVES ROTATING AROUND CLOSED
LOW COMBINED WITH COLD POOL ALOFT WILL KEEP SHOWERS IN THE
FORECAST INTO THURSDAY NIGHT. BY FRIDAY LOW MAY BECOME BECOME
MORE ELONGATED NEAR THE COAST...ALTHOUGH NEWEST LONGER RANGE
MODELS DISAGREE ON PLACEMENT AND SPEED OF LOW LIFTING OUT. HAVE
KEPT LOW CHANCE POPS INTO THE RIDGES FRIDAY WITH A DRYING TREND
ELSEWHERE. GENERAL MODEL AGREEMENT ON A STRONG SHORTWAVE DIVING
SOUTHEAST OUT OF CENTRAL CANADA FRIDAY NIGHT TO SHUNT LOW TOWARD
NEW ENGLAND. THIS TROUGH WILL BRING BACK SHOWER CHANCES SATURDAY
WITH WARM ADVECTION AHEAD OF IT PUSHING TEMPERATURES BACK NEAR NORMAL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
UPR TROF AND SFC BOUNDARY PASSAGE IS PROGGED ERLY IN THE PERIOD
WITH THE BEST CHCS FOR SHOWERS. OTHERWISE...BUILDING RIDGING
SHOULD RESULT IN DRY WEATHER UNTIL AN APPROACHING UPR TROF
ADVANCES OUT OF THE MID WEST BY MID WEEK. TEMPS NEAR SEASONAL LVLS
ARE EXPECTED TO WARM TO ABOVE AVG BY MID WEEK. THE SUPERBLEND
GUIDANCE...WITH DOWNWARD MID WEEK POP ADJUSTMENT...WAS USED FOR
THE LONG TERM FCST.

&&

.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
OTHER THAN ISOLATED ERLY MRNG FOG...VFR CONDITIONS ARE EXPECTED
THRU THE AFTN. APPROACHING LOW PRESSURE SHOULD RESULT IN SCT LGT
SHOWERS FOR WHICH A VCSH MENTION WAS MAINTAINED TODAY...THOUGH
BETTER CHCS FOR SHOWERS AND MVFR RESTRICTIONS ARE EXPECTED BY
EVENING AND OVERNIGHT WHEN THE BEST MOISTURE AND LIFT IS EXPECTED.

.OUTLOOK /THURSDAY THROUGH SUNDAY/...
PERIODIC RESTRICTIONS ARE LIKELY THU/FRI WITH PERSISTENT LOW
PRESSURE...AND AGAIN WITH A SAT NGT COLD FRONT.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$


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