Area Forecast Discussion
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FXUS61 KPBZ 041008
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
608 AM EDT SAT JUL 4 2015

.SYNOPSIS...
SHOWER CHANCES ARE EXPECTED TO GRADUALLY DIMINISH TODAY AS AN
UPPER LOW PRESSURE TROUGH SLIDES EASTWARD. BUILDING HIGH PRESSURE
WILL ENSURE A DRY AND SEASONABLY WARM SUNDAY...BUT RAIN CHANCES
CAN BE ANTICIPATED AGAIN FOR MONDAY AS ANOTHER UPPER DISTURBANCE
IS FORECAST TO ENCROACH IN UPPER OHIO VALLEY AIRSPACE.

&&

.NEAR TERM /THROUGH TONIGHT/...
THE PRE DAWN UPDATE FEATURED SKY AND PRECIP PROBABILITY
ADJUSTMENT BASED ON THE LATEST RADAR TRENDS AS WELL AS PROGRESS OF
THE RAIN-SUPPORTING SHORTWAVE WHICH IS MOVING THROUGH SOUTHWEST
FLOW ALOFT.

AS THE MAIN TROUGH...ANALYZED FROM LAKE ERIE ACROSS THE LOWER
OHIO VALLEY...SHIFT EASTWARD DURING THE NEXT 18 HOURS...PRECIP
PROBS WILL GRADUALLY DIMINISH IN THE INCREASING SUBSIDENCE AND DRY
ADVECTION REGIME. HAVE ADJUSTED TEMPS UPWARD WITH THE LATEST
GUIDANCE TRENDS GIVEN EXPECTATIONS OF IMPROVED INSOLATION FOR MOST
COUNTIES DURING THE AFTERNOON...BUT ADJUSTMENTS WERE NOT DECISIVE
AND HIGHS A COUPLE DEGREES UNDER THE AVERAGES ARE STILL ANTICIPATED.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
DRY...AND WARMER WEATHER IS THEN EXPECTED AS HIGH PRESSURE BUILDS
THROUGH SUNDAY. HOWEVER...MODELS NOW DIFFER SIGNIFICANTLY IN
DEPICTIONS OF MONDAY WEATHER AS ANOTHER DISTURBANCE IN FLOW...ALBEIT
WEAK AND BROAD...IS NOW PROJECTED TO INVADE FROM THE SOUTH AND
ERODE THE RIDGE.

GIVEN THE INCONSISTENCY...WILL NOT HIT THIS TOO HARD AT
MOMENT...BUT THE ENSEMBLE AND DETERMINISTIC TREND CAN NOT BE
IGNORED SO FORECAST WILL INCLUDE SOME DIURNALLY SUPPORTED CHANCE
POPS FOR MONDAY...AS WELL AS INCREASING CHANCE NUMBERS WITH THE
TUESDAY FRONTAL SYSTEM.

THE SHORT TERM TEMP FORECAST WITH THESE CHANGES STILL LOOKS WARM...BUT
READINGS WERE TEMPERED CLOSER TO THE SEASONAL AVERAGES.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
A DEAMPLIFIED...FLATTENED UPPER FLOW IS PROGGED BY MODEL
ENSEMBLES THROUGH THE LONG TERM PERIOD. INDIVIDUAL SHORTWAVES
ADVANCING THROUGH THE FLOW ACROSS THE UPPER OHIO VALLEY ARE
EXPECTED TO BRING PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS.
USED WPC ENSEMBLE BASED GUIDANCE TO SMOOTH OUT MODEL
DIFFERENCES...WITH SOME ADJUSTMENTS TO POPS AND THE PROGGED
SEASONALLY WARM TEMPERATURES.

&&

.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
A SHORTWAVE TROUGH ADVANCING ACROSS THE REGION IS EXPECTED TO
BRING SHOWERS E OF PIT THIS MORNING...WITH IFR CONDITIONS IN
LINGERING LOW LEVEL MOISTURE. DRY ADVECTION BEHIND THE EXITING
TROUGH SHOULD ALLOW FOR CELINGS TO LIFT AND EVENTUALLY SCATTER OUT
LATER THIS MORNING AND EARLY AFTERNOON WITH A RETURN TO VFR. MVFR
TO POSSIBLE IFR IS EXPECTED AGAIN LATE TONIGHT AS FOG FORMS WITH
A MOIST GROUND.

.OUTLOOK.../SUNDAY THROUGH WEDNESDAY/...
RESTRICTION CHANCES ARE EXPECTED TO INCREASE EARLY NEXT WEEK WITH
SEVERAL CROSSING DISTURBANCES.

&&

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

&&

$$

15/07


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