Area Forecast Discussion
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000
FXUS61 KPBZ 051335
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
935 AM EDT WED AUG 5 2015

.SYNOPSIS...
GENERALLY DRY AND SUNNY CONDITIONS ARE EXPECTED WITH A SLIGHT
CHANCE OF SHOWERS MAINLY SOUTH OF I-70 THURSDAY AND FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
VISIBLE SATELLITE AND KPBZ RAOB SHOWING GENERALLY DRY AND CLEAR
CONDITIONS THIS MORNING. SUNNY AND DRY CONDITIONS CAN BE EXPECTED THROUGH
THE DAY...WITH A SLIGHT CHANCE OF RAIN NORTH OF I-80.

PREVIOUS DISCUSSION...

SHORTWAVE STILL LOOKS TO SKIM THE NORTHERN FRINGE OF THE CWA
DURING THE MORNING HOURS...WITH H250 JET MAX PASSING OVER THE
EASTERN END OF LAKE ERIE. STILL DO NOT THINK AVAILABLE MOISTURE
AND LIFT WILL BE ENOUGH TO PRODUCE A SIGNIFICANT SHRA
CHANCE...BUT THERE MAY BE JUST ENOUGH INSTABILITY IN THE LOW
LEVELS TO ALLOW FOR A FEW SPRINKLES MAINLY NORTH OF I-80. HAVE
ADDED THIS INTO THE FORECAST. OTHERWISE...MORNING DEBRIS CI ACROSS
THE SOUTH WILL TRANSITION TO SCT-BKN CU AS THE DAY WEARS ON.
SURFACE HIGH PRESSURE WILL BUILD IN THE WAKE OF THE DEPARTING
UPPER DISTURBANCE.

NORTHEAST U.S. UPPER TROUGH EASES EASTWARD A BIT TONIGHT...BUT
FLOW IN THE LOWER AND MID LEVELS WILL CONTINUE TO HAVE MORE A
WEST/NORTHWEST COMPONENT...WHICH WILL KEEP MOISTURE BOTTLED UP TO
THE SOUTH. HOWEVER...JET STREAM LEVEL WINDS WILL SLOWLY TURN
TOWARDS THE WEST AND SOUTHWEST BY 12Z...ALLOWING SOME HIGH CLOUDS
TO INVADE FROM THE SOUTHWEST TOWARDS SUNRISE.

SEASONABLE MAX TEMPERATURES ARE FORECAST FOR THE AFTERNOON...WITH
H850 TEMPS OF AROUND 13C SUPPORTING HIGHS IN THE LOWER 80S ACROSS
THE SOUTH. DRY DEWPOINTS TONIGHT WILL ALLOW LOW TEMPS TO SINK A
FEW DEGREES BELOW CLIMATOLOGY.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
THURSDAY MORNING REMAINS DRY...ALTHOUGH A SHORTWAVE TROF DIGGING
INTO THE LOWER OHIO VALLEY WILL PUSH OUT THE DRIER CONDITIONS
HEADING INTO THE AFTERNOON. MODELS CONTINUE TO STRUGGLE WITH THE
PLACEMENT AND TIMING OF THE SYSTEM...COMPLETELY FLIP-FLOPPING FROM
THE EARLIER TRENDS. THIS TIME IT IS THE 00Z NAM/GFS SUPPRESSING THE
TRACK FURTHER SOUTH...TO THE POINT OF KEEPING PRECIPITATION ALMOST
COMPLETELY OUT OF THE FORECAST AREA. AT ONE POINT TONIGHT...ONLY THE
SREF SPILLED PRECIPITATION NORTH OF THE MASON-DIXON LINE AND IN THE
VICINITY OF PITTSBURGH. SINCE THEN...THE 00Z ECMWF HAS COME IN
FURTHER NORTH THAN ITS PREVIOUS RUN AND ITS BRETHREN.

THE RESULTANT FORECAST REFLECTS THE MORE SOUTHERLY TRACK OFFERED BY
MOST MODEL GUIDANCE...WITH LOWER POPS OVERALL. WITH THE WAFFLING OF
THE MODELS OVER THE LAST SEVERAL DAYS...DONT THINK ELIMINATING
CHANCE POPS ALONG THE I-70 CORRIDOR IS NECESSARILY
PRUDENT...HOWEVER. STILL THINK THAT AREAS IN NORTHERN WV AND WESTERN
MD WILL SEE SOME PRECIPITATION THURSDAY...BUT EXACT TIMING AND
NORTHERN EXTENT IS STILL QUITE SHAKY. ALSO...FAIRLY CERTAIN THAT
AREAS ALONG I-80 AND NORTH DONT SEE ANY RAINFALL AS THEY SHOULD STAY
WELL NORTH OF THE PRECIPITATION SHIELD.  MODEL SOUNDINGS SHOW
LIMITED INSTABILITY OVER NORTHERN WV AND WESTERN MD...SO HAVE
CONFINED SLIGHT CHANCE OF THUNDERSTORMS TO THOSE LOCATIONS. BULK OF
RAIN SHOULD BE EAST OF THE REGION BY FRIDAY MORNING...WITH
CONDITIONS CLEARING OUT FRIDAY EVENING.
TAX

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
FORECAST REMAINS ON THE DRY SIDE OVER THE WEEKEND...ALTHOUGH
RESIDUAL MOISTURE WILL LINGER AND MAY FUEL A FEW AFTERNOON SHOWERS.
TEMPERATURES WILL GRADUALLY INCREASE THROUGH THE WEEKEND...CLIMBING
BACK TO NEAR NORMALS. MODELS COMING INTO BETTER AGREEMENT ON THE
PROGRESSION OF A SHORTWAVE TROF MOVING OUT OF THE UPPER PLAINS. THIS
TROF WILL DIG IN AROUND THE SOUTHERN GREAT LAKES LATE MONDAY OR
EARLY TUESDAY...BRINGING THE NEXT BEST ORGANIZED CHANCE OF RAIN AREA-
WIDE. THIS PROGRESSIVE SYSTEM MOVES QUICKLY THROUGH LEAVING A DRYING
TREND HEADING INTO THE MIDDLE OF NEXT WEEK.
TAX

&&

.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
MOSTLY VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. SOME
FOG MAY LINGER FOR AN HOUR OR TWO AT ZZV...OTHERWISE HIGH CLOUDS
WILL TRANSITION TOWARDS SCT-BKN CU DURING THE AFTERNOON. A
SPRINKLE IS POSSIBLE NORTH OF I-80...TOO INSIGNIFICANT TO INCLUDE
IN TAFS. W/NW WINDS WILL GUST TO BETWEEN 15 AND 20 KNOTS THIS
AFTERNOON. AFTER 00Z...WINDS DIE OFF ONCE AGAIN AND ONLY HIGH
CLOUDS WILL REMAIN THROUGH THE NIGHT.

OUTLOOK...WEDNESDAY NIGHT THROUGH SUNDAY...
SOME RESTRICTIONS REMAIN POSSIBLE SOUTH OF PIT THURSDAY AND
THURSDAY NIGHT...ALTHOUGH MODELS ARE TRENDING TOWARDS KEEPING
PRECIPITATION TO THE SOUTH.

&&

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

&&

$$


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