Area Forecast Discussion
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000 FXUS61 KPBZ 310744 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 334 AM EDT MON AUG 31 2015 .SYNOPSIS... WARM...HUMID CONDITIONS AND SPARSE RAIN CHANCES ARE EXPECTED THROUGH THE UPCOMING WEEK. && .NEAR TERM /THROUGH TONIGHT/...
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A WEAKENING AND OPENING UPPER LOW WILL SLOWLY TRANSITION EAST OF THE APPALACHIANS PRIMARILY TO OUR SOUTH THROUGH THE DAY. THIS WILL LARGELY FOLLOW THE WEAKLY COUPLE UPPER JET STRUCTURE THAT TRANSITIONS TOWARD NEW JERSEY AT THE DAY PROGRESSES. THIS WILL LEAVE OUR AREA IN AN AREA OF WEAK MID-LEVEL TROUGHING AS AN UPPER RIDGE POPS FROM THE HIGH PLAINS TOWARD THE NORTHERN GREAT LAKES THROUGH THE DAY. THIS WILL STRETCH OUT WHAT LITTLE SHEARED VORTICITY THERE IS LARGELY ALONG AND SOUTH OF I-70. DEEPER MOISTURE WILL LARGELY REMAIN ALONG AND SOUTH OF THIS CORRIDOR...THUS THIS IS WERE LOW END POPS WERE CONCENTRATED ON FOR THE AFTERNOON AND EVENING HOURS. DEEPER MOISTURE AND EXCEEDINGLY WEAK FORCING MAY BE JUST ENOUGH TO OVERCOME WARM AIR ALOFT AND A GENERALLY UNFAVORABLE ENVIRONMENT FOR CONVECTION DUE TO EXCEEDINGLY LOW SHEAR VALUES THROUGH THE DAY. EVEN THOUGH SUNSHINE WILL BE UNLIKELY TO BE PERVASIVE UNTIL LATER IN THE MORNING AND INTO THE AFTERNOON DUE TO HIGH CLOUDS AROUND THE OPENING UPPER LOW...850 MB TEMPERATURES JUMP TOWARD +18C...WHICH MEANS THAT GENERALLY MIDDLE TO A FEW UPPER 80S WILL BE POSSIBLE BY AFTERNOON. THIS IS EVEN WITH POOR MIXING. HOWEVER...THE TEMPERATURE WILL ONLY BE PART OF THE EQUATION. DUE TO DEWPOINTS CURRENTLY LARGELY IN THE UPPER 60S AND LITTLE CHANCE OF DRY AIR BEING ENTRAINED DOWNWARD DUE TO POOR MIXING TODAY...HEAT INDEX VALUES WILL LIKELY RUN UP TOWARD 90F BY AFTERNOON IN MANY PLACES. COOLING TONIGHT WILL LIKELY BE A SLOW PROCESS. AMPLE BOUNDARY LAYER MOISTURE SEEMS POISED TO INTERACT A VIRTUALLY CLEAR SKY WITH LITTLE WIND. HOWEVER...RESIDUAL HEATING IN URBAN AREAS SEEMS LIKELY TO KEEP LOWS IN THE CITY CENTER NEAR 70F AGAIN...WHILE OUTLYING AREAS SATURATE TO THE DEWPOINTS IN THE MIDDLE AND UPPER 60S YET AGAIN WITH PATCHY FOG DEVELOPING...ESPECIALLY AROUND THE RIVER VALLEYS. FRIES
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&& .SHORT TERM /TUESDAY THROUGH THURSDAY/...
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SYNOPTIC PATTERN FAVORS THE BUILDING OF A LARGE RIDGE OVER THE EASTERN CONUS TUESDAY. DESPITE THIS...LOW-LEVEL MOISTURE LINGERS ACROSS SOUTHERN ZONES ENOUGH TO GENERATE ISOLATED SHOWERS/THUNDERSTORMS WITH STRENGTHENING LOW-LEVEL LAPSE RATES. WITH WARM MID-LEVEL TEMPS IN PLACE...KEEPING POPS LIMITED TO SLIGHT REALM...EVEN AS AN EMBEDDED WEAK TROF PASSES THROUGH THE RIDGE TUESDAY EVENING. THE UPPER RIDGE THEN AMPLIFIES BY MID-WEEK RE- INFORCING THE TREND TO DRIER AND WARMER CONDITIONS. TAX
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&& .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
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NO MAJOR CHANGES TO THE EXTENDED PERIOD AS THE IMPRESSIVE EASTERN CONUS RIDGE FURTHER AMPLIFIES REACHING INTO EASTERN CANADA. CANNOT RULE OUT DIURNAL RAIN CHANCES...ESPECIALLY IN THE HIGHER TERRAIN AS THE CENTER OF THE UPPER HIGH MOVES NORTH OF THE AREA AND RETURN FLOW ESTABLISHES A MOISTURE FEED FROM THE MID-ATLANTIC. STILL...LARGELY DRY CONDITIONS WILL PERSIST INTO AND THROUGH THE WEEKEND. TEMPERATURES WILL PLAY OUT LIKE A BROKEN RECORD...NEARLY THE SAME EVERYDAY...SEVERAL DEGREES ABOVE AVERAGE THROUGH THE PERIOD. THE NEXT REAL CHANCE OF A RAIN PRODUCING SYSTEM FOR THE ENTIRE FORECAST AREA COULD COME WITH A FRONT SLATED SOMETIME EARLY TO MIDDLE OF NEXT WEEK. TAX
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&& .AVIATION /07Z MONDAY THROUGH FRIDAY/...
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AREAS OF MVFR AND SOME IFR FOG SHOULD DEVELOP OVERNIGHT WITH LOW LEVEL MOISTURE IN PLACE AND WEAK FLOW. THIS SHOULD BURN OFF TOWARD 14Z. WINDS WILL BE LIGHT AND VARIABLE. OUTLOOK...MONDAY NIGHT THROUGH FRIDAY... GENERAL VFR EXCEPT FOR PATCHY MORNING FOG THE REMAINDER OF THE WEEK.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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