Area Forecast Discussion
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FXUS61 KPBZ 031458
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1058 AM EDT FRI JUL 3 2015

.SYNOPSIS...
A CROSSING UPPER DISTURBANCE WILL INCREASE RAIN CHANCES FOR THE
START OF THE HOLIDAY WEEKEND. WARMER WEATHER CAN BE EXPECTED FOR
THE START OF THE NEW WEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
MID AND UPPER CLOUDS ARE RATHER SLOW TO OVERSPREAD THIS REGION
LATE THIS MORNING...RESULTING IN SOME DECENT TEMPERATURE
INCREASES. HOWEVER...THEY ARE LURKING IN A QUITE PERVASIVE WAY
JUST TO THE SOUTHWEST OF THE AREA...AND GIVEN THE TRAJECTORY OF
THE UPPER FLOW...THEY WILL ENVELOPE THE AREA WITHIN THE NEXT FEW
HOURS. UPPER DIFFLUENCE IS SET TO INCREASE THROUGH THE DAY AS A
WEAK SHORT WAVE AND CLOSED 850 MB CIRCULATION TRACK TOWARD THE
UPPER OHIO VALLEY AHEAD OF THE UPPER WAVE. THIS WILL ALLOW FOR
SHOWER ACTIVITY TO INCREASE FROM SOUTH TO NORTH GOING INTO THE
AFTERNOON. INSTABILITY IS FAR FROM IMPRESSIVE...AND GIVEN MODEL
SOUNDINGS REALLY ONLY PROJECTING POSITIVE AREA MAINTAINING ITSELF
ABOVE THE FREEZING LEVEL IN THE SOUTHEASTERNMOST PORTIONS OF THE
CWA...THUNDERSTORM CHANCES WERE RELEGATED GENERALLY TO THE RIDGES
AND POINTS NEARBY. HOWEVER...GIVEN DECENT LIFT AND FAIRLY HEFTY
LAYER RH VALUES...CHANCES OF RAIN WERE INCREASED TO CATEGORICAL
ACROSS THE SOUTHEASTERN QUARTER OF THE CWA FROM LATE THIS
AFTERNOON INTO THIS EVENING.

THE AFOREMENTIONED UPPER WAVE IS SLOW TO MOVE EASTWARD GOING INTO
THE OVERNIGHT HOURS. THIS SHOULD ALLOW FOR SOUTHERLY FLOW TO
DOMINATE THE SCENE. WITH JET CURVATURE INCREASING THROUGH THE
NIGHT AND THE RIGHT ENTRANCE REGION REMAINING IN THE
REGION...SHOWER CHANCES WILL REMAIN QUITE HIGH...PARTICULARLY
ACROSS THE EASTERN HALF OF THE CWA. HOWEVER...BY SATURDAY...THE
JET AXIS STARTS TO SLINK EASTWARD...RESULTING IN AN IMPROVEMENT OF
CONDITIONS FROM WEST TO EAST DURING THE DAY. FRIES

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
SCATTERED/CHANCE POP NUMBERS WERE MAINTAINED THROUGH SATURDAY AS
MODELS PERSIST IN LINGERING THE UPPER TROUGH OVER THE
REGION...ALBEIT WITH DRY ADVECTION IN THE MID AND UPPER LEVELS.
DESPITE THE TROUGHING...MID LEVEL TEMPS IN THIS SCENARIO ARE
WARM...HENCE THE LIMITED POPS AND ONLY A SLIGHT CHANCE OF THUNDER
DUE TO INHIBITED INSTABILITY.

BY SUNDAY...THE SURFACE REFLECTION PROGNOSIS IS SUFFICIENTLY SOUTH
THAT RAIN CHANCES HAVE BEEN OMITTED WITH BUILDING HIGH PRESSURE.
WARMER TEMPS WILL THEN BE THE FOCUS AS HEIGHTS RISE DRAMATICALLY
FOR THE START OF THE NEW WEEK. FOR NOW...HAVE PERSISTED WITH
AVERAGE READINGS FOR SUNDAY...AND A COUPLE DEGREES ABOVE FOR
MONDAY.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
THE UPPER FLOW IS PROGGED TO FLATTEN THROUGH MUCH OF THE PERIOD.
INDIVIDUAL SHORTWAVES IN THE FLOW ARE EXPECTED TO BRING PERIODIC
CHANCES FOR SHOWERS AND THUNDERSTORMS. USED AN ENSEMBLE BASED WPC
GUIDANCE TO SMOOTH OUT DIFFERENCES IN INDIVIDUAL MODELS...WITH
DOWNWARD ADJUSTMENTS TO WPC POPS. SEAONALLY WARM TEMPERATURES ARE
EXPECTED.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
MAINLY VFR CONDITIONS ARE EXPECTED THROUGH THE MORNING. A
SHORTWAVE IS PROGGED TO BRING INCREASING SHOWER CHANCES THIS
AFTERNOON AND EVENING...WITH EVENTUAL CONDITION DETERIORATION
SOUTH OF I 80 TO AT LEAST MVFR SPREADING IN FROM THE SOUTHWEST
WITH IFR CONDITIONS LIKELY OVERNIGHT.

.OUTLOOK.../SATURDAY THROUGH TUESDAY/...
RESTRICTION ARE POSSIBLE THROUGH EARLY SATURDAY WITH AN EXITING
SHORTWAVE.

&&

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

&&

$$


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