Area Forecast Discussion
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000 FXUS61 KPBZ 050803 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 403 AM EDT WED AUG 5 2015 .SYNOPSIS... GENERALLY DRY AND SUNNY CONDITIONS ARE EXPECTED THROUGH WEDNESDAY NIGHT. RAIN CHANCES INCREASE ON THURSDAY AS AN UPPER LEVEL DISTURBANCE APPROACHES THE REGION. && .NEAR TERM /THROUGH TONIGHT/...
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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.
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&& .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
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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
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/...
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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
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&& .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
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EXPECT VFR CONDITIONS TO CONTINUE OVERNIGHT WITH MAINLY HIGH CLOUDS SOUTH OF PIT...AND SOME HIGH-BASED SC NEAR FKL/DUJ. ELECTED TO REMOVE FOG MENTION FROM TAFS WITH DECENT MIXING AT THE TOP OF THE BOUNDARY LAYER...BUT WILL MONITOR. CANNOT RULE OUT A SPRINKLE NORTH OF I-80 AS WELL BUT TOO INSIGNIFICANT TO MENTION. SCT CU THIS AFTERNOON WITH W/NW WINDS OF 10-15 MPH ANTICIPATED. WINDS WILL LIGHTEN AFTER 00Z WITH SOME PATCHY HIGH CLOUDS REMAINING. 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.
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&& .EQUIPMENT... GREGS KNOB NOAA WEATHER RADIO IS OFF THE AIR WITH A FAILED TRANSMITTER. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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