Area Forecast Discussion
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000 FXUS61 KPBZ 300832 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 432 AM EDT WED JUL 30 2014 .SYNOPSIS... SHOWER CHANCES TODAY AS ANOTHER WEAK DISTURBANCE MOVES THROUGH THE BROAD LOW PRESSURE SYSTEM. TEMPERATURES WILL BEGIN TO MODERATE TOWARD NORMAL BY LATE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A FEW THUNDERSTORMS LINGER NORTH OF THE AREA AS OF ABOUT 06Z. THESE DEVELOPED EARLIER ALONG THE NOSE OF A RELATIVELY WEAK H5 JET MAX. AS WE PROGRESS FURTHER INTO THE EARLY MORNING HOURS...THESE THUNDERSTORMS SHOULD CONTINUE TO WANE WITH LACK OF SUFFICIENT INSTABILITY AND WITH THE UPPER LEVEL JET DIMINISHING. THUS...HAVE DECREASED POPS NORTH OF I80 OVER THE NEXT SEVERAL HOURS. MOSTLY CLEAR SKIES PERSISTING AS MID-LEVEL CLOUDS MOVING IN FROM THE NW ARE DISSIPATING AS THEY ENCROACH. LLVL DEWPOINT DEPRESSIONS REMAIN SUFFICIENT ENOUGH TO CURTAIL ANY WIDESPREAD FOG DEVELOPMENT...HOWEVER A FEW SHELTERED AREAS COULD SEE SOME PATCHY FOG THIS MORNING. CURRENT WATER VAPORY LOOP SHOWS AN UPPER LEVEL VORT DROPPING SOUTH THROUGH THE WRN GREAT LAKES. THIS QUICK MOVING DISTURBANCE WILL GENERATE SCATTERED SHOWERS TODAY AS IT PIVOTS AROUND THE EXPANSIVE LOW PRESSURE SYSTEM STILL RESIDING NEAR JAMES BAY. STEEPENING LLVL LAPSE RATES AND DEEPER MOISTURE AVAILABILITY WILL HELP FUEL CONVECTIVE SHOWER DEVELOPMENT. HOWEVER...INSTABILITY OVERALL IS STILL LACKING WITH VERY LITTLE CAPE IN THE CHARGE SEPARATION LAYER. WILL KEEP THE MENTION OF THUNDER OUT OF THE FORECAST FOR THIS AFTERNOON. SHOWER CHANCES DISSIPATE QUICKLY THIS EVENING AS THE WAVE PULLS AWAY TOWARDS SUNDOWN. SEVERAL HI-RES MODELS INDICATING A SECONDARY WAVE OF PRECIPITATION OVERNIGHT INTO THURS MORNING ASSOCIATED WITH ANOTHER UPPER LEVEL TROF AXIS SWINGING THROUGH. THIS FEATURE IS CORROBORATED AMONG THE MORE BROAD SOLNS OF THE 00Z NAM AND GFS. THE DEEPER MOISTURE WILL REMAIN CLOSE TO THE UPPER LOW ACROSS OUR NORTH...THIS WILL BE THE AREA THAT IS THE FOCUS OF SLGT AND CHC POPS THROUGH ABOUT 12Z. TAX && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
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SHOWERS WILL DIMINISH THIS EVENING AS THE SHORTWAVE TROUGH EXITS TO THE EAST. MEANWHILE THE LONGWAVE WILL PIVOT EAST AND WEAKEN AS THE MAIN JET CORE MIGRATES FURTHER BEYOND INFLECTION POINT OF THE FRONT SIDE OF THE TROUGH AS A SECOND WEAK SHORTWAVE TRANSITIONS THROUGH THE FLOW THURSDAY MORNING/EARLY AFTERNOON. THIS DISTURBANCE SHOULD ONLY IMPACT NORTHERN ZONES AS THE LONGWAVE LIFTS TO THE NORTH. FLOW ALOFT WILL SWITCH TO THE SOUTHWEST ON FRIDAY AND ALLOW FOR DEEPER MOISTURE TO ADVECT NORTH. THIS ALONG WITH A SHORTWAVE PASSING ACROSS THE REGION ON FRIDAY WILL RESULT IN SCATTERED SHOWERS/THUNDERSTORMS FRIDAY AFTERNOON AND EARLY EVENING...WITH THE BEST CHANCES ACROSS THE RIDGES AND SOUTHEASTERN PORTIONS OF THE FORECAST AREA WHERE THERE WILL BE BETTER UPPER LEVEL SUPPORT.
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&& .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
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MOISTURE ADVECTION WILL CONTINUE OVERNIGHT FRIDAY AND SATURDAY BUT RECENT MODEL RUNS HAVE NOT SHOWN THE BEST CONTINUITY IN REGARDS TO TIMING THE NEXT SHORTWAVE TO PASS THROUGH AND HELP SUPPORT ACTIVITY SO HAVE OPTED TO LEAVE CHANCE POPS IN THE FORECAST FOR BOTH SATURDAY AND SUNDAY AFTERNOONS UNTIL GUIDANCE SHOWS BETTER RUN TO RUN CONTINUITY WITH THE FEATURE. DRY CONDITIONS ARE FORECAST BY NEXT MONDAY AS OPERATIONAL RUNS SHOW THE LONGWAVE PATTERN BECOMING MORE ZONAL...BUT REMAIN CAUTIOUSLY OPTIMISTIC IN FINALLY BREAKING THE PATTERN AS MODELS HAVE BEEN FAIRLY INCONSISTENT IN PROGGING THIS OVER THE PAST 10 OPERATIONAL RUNS.
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&& .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... VFR CONDITIONS PREVAIL UNDER MAINLY CLEAR SKIES. HOWEVER...ANOTHER AREA OF CLOUDS WILL SWING THROUGH FROM THE NORTHWEST WITH THE NEXT UPPER LEVEL WAVE. WILL KEEP IN A VFR FORECAST FOR MOST PORTS ON WEDNESDAY. THE EXCEPTION WILL BE AT FKL AND DUJ WHERE MVFR CIGS WITH SHOWERS ARE POSSIBLE WITH THE PASSAGE OF A WEAK SURFACE BOUNDARY WEDNESDAY AFTERNOON. OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/... NO WDSPRD RSTRNS EXPD. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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