Area Forecast Discussion
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000 FXUS61 KPBZ 301732 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 132 PM EDT WED JUL 30 2014 .SYNOPSIS... A WEAK DISTURBANCE WILL MOVE THROUGH THE REGION THIS AFTERNOON WITH SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. TEMPERATURES WILL BEGIN TO MODERATE TOWARD SEASONAL AVERAGES BY LATE WEEK. && .NEAR TERM /THROUGH TONIGHT/... UPDATE FOR AFTERNOON ONLY TO ADJUST SKY GRIDS. TEMPERATURES LOOK TO GET TO CONVECTIVE TEMPERATURES AHEAD OF APPROACHING SHORTWAVE SO PREVIOUS POPS AND WX UNCHANGED. SHOWER AND THUNDERSTORM ACTIVITY BEGINNING TO INCREASE SPATIALLY AND IN INTENSITY OVER THE SRN SHORES OF LAKE ERIE THIS MORNING. THESE SHOWERS ARE IN RESPONSE TO A SHORT WAVE TROF DROPPING SOUTH THROUGH THE GREAT LAKES CURRENTLY. THIS QUICK MOVING DISTURBANCE WILL CONTINUE TO 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. WHILE INSTABILITY IS STILL PRETTY LACKLUSTER WITH BUFR PROFILES SHOWING TALL SKINNY CAPE...CURRENT RADAR TRENDS SHOWING VIGOROUS ENOUGH CONVECTION TO GENERATE LIGHTNING. LIGHTNING COUNTS SHOULD GENERALLY DECREASE AS THESE SHOWERS/THUNDERSTORMS MOVE FURTHER INLAND AND ENCROACH THE CWA...BUT CANNOT RULE OUT A COUPLE OF RUMBLES OVER OUR AREA. WILL INCLUDE THE MENTION OF ISOLATED THUNDER IN THE FORECAST. SHOWER CHANCES WILL 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 /THURSDAY THROUGH FRIDAY/... 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. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... 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. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS HAVE BEEN INCREASING IN COVERAGE DURING THE EARLY AFTERNOON HOURS. WILL CONTINUE VCSH IN ALL TAFS EXCEPT FOR MORGANTOWN...WHICH HAS THE SMALLEST CHANCE OF RECEIVING A SHOWER. CANNOT RULE OUT A PASSING MVFR OBSERVATION OR TWO IN SHOWERS/THUNDERSTORMS...BUT DID NOT HAVE ENOUGH CONFIDENCE TO INCLUDE IN TAFS. SHOWER COVERAGE WILL DROP SUBSTANTIALLY AFTER 00Z...BUT ANOTHER WEAK WAVE WILL PASS THROUGH LATE TONIGHT AND THURSDAY MORNING WITH ADDITIONAL LIGHT SHOWER CHANCES AT FKL/DUJ. A CHANCE FOR AN ISOLATED SHOWER WILL CONTINUE INTO THURSDAY. OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/... NO WDSPRD RSTRNS EXPD. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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