Area Forecast Discussion
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000 FXUS61 KPBZ 260543 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 143 AM EDT TUE MAY 26 2015 .SYNOPSIS... WARMTH AND HUMIDITY HAVE RETURNED TO THE UPPER OHIO VALLEY REGION...BUT SHOWER AND THUNDERSTORM CHANCES CAN BE EXPECTED FOR MOST OF THE COMING WEEK. && .NEAR TERM /THROUGH TODAY/... THE UPDATE FOR THE EVENING FEATURES FAIRLY SMALL ADJUSTMENTS TO POPS AS A WEAK VORT RIBBON MOVING ACROSS EASTERN OHIO WITH STRONG SOUTHWESTERLY FLOW AND WARM ADVECTION HAS YIELDED NO THUNDERSTORM ACTIVITY DUE TO WARM TEMPERATURES ALOFT. LIKEWISE...WHAT MEAGER SHOWERS DID MANAGE TO BE MUSTERED DURING THE EVENING HAVE DISSIPATED AT THIS HOUR. THE FORECAST THINKING OF ANOTHER INCREASE IN POPS TOWARD MORNING STILL SEEMS ON TARGET PER THE 18Z NAM GUIDANCE AS ANOTHER SHORT WAVE RIDES NORTHEASTWARD. POPS WERE MAINTAINED FOR THIS. HOWEVER...IN THE INTERIM BETWEEN NOW AND THEN...SKIES WERE REDUCED FOR MOST AREAS TO BE GENERALLY PARTLY CLOUDY THROUGH THE BULK OF THE EVENING AND EARLY OVERNIGHT PERIOD. FRIES && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... CONTINUED SOUTHWEST FLOW WILL MAINTAIN THE FUNNEL OF DEEP MOISTURE OVER THE UPPER OHIO REGION...AT LEAST UNTIL THE ADVANCING MID LEVEL TROUGH AXIS PROGRESSION SHUNTS THE PLUME EASTWARD BY THURSDAY AS PER THE GFS AND NAM SOLUTIONS. CHANCE...TO LIKELY SHOWER AND THUNDERSTORM WILL THUS BE MAINTAINED FOR THE PERIOD. THE BEST OVERALL POPS AT MOMENT ARE STILL PROGGED FOR WEDNESDAY...ALTHOUGH TODAYS MODEL RUNS ARE FASTER IN PUSHING THE PARENT MID/UPR LEVEL TROUGH AXIS AND SUSTAINED MOISTURE TAP EASTWARD...SO THOSE LIKELY NUMBERS WERE TRENDED SLIGHTLY EASTWARD AS WELL. THE SHORT TERM SEVERE POTENTIAL STILL LOOKS TO BE COMPROMISED BY WARM MID LEVELS AND A MARGINAL DEEP LAYER SHEAR PROFILE...BUT WARM RAIN PROCESSES AND TRAINING MAY SUPPORT LOCALLY HEAVY RAINFALL UNTIL MOISTURE AND WARM CLOUD DEPTH WANES LATER ON WEDNESDAY. NO MAJOR CHANGES WERE NEEDED FOR THE SEASONABLY WARM TEMP PROGNOSIS. && .LONG TERM /FRIDAY THROUGH MONDAY/... PRECIP CHANCES WILL INCREASE AGAIN FOR THE WEEKEND...AND PERSIST INTO NEXT WEEK AS MODELS AGREE ON A WEAK SPLIT FLOW REGIME CONVERGING OVER THE GREAT LAKES/UPPER OHIO REGION. THE SURFACE FRONT IS PROJECTED TO SAG SOUTHWARD UNTIL REDEVELOPING NORTHWARD AS A WARM FRONT IN RESPONSE TO GREAT PLAINS TROUGHING EARLY NEXT WEEK. GIVEN MODEL MAGNITUDE...POSITIONING...AND TIMING DISPUTES...PERSISTENCE WILL RULE THE LONG TERM FORECAST STRATEGY. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... VFR IS FORECAST IN THE MEAN OVER THE NEXT 24 HOURS...BUT THERE WILL BE OPPORTUNTIES FOR BRIEF RESTRICTIONS. MOIST SOUTHWEST FLOW WILL ALLOW FOR SCATTERED SHOWERS AND THUNDERSTORMS THROUGH THE PERIOD...MOST NUMEROUS DURING THE AFTERNOON AND EVENING HOURS. WITH UNCERTAIN TIMING...HAVE ELECTED TO CONTINUE WITH VCSH/VCTS FOR THE BULK OF THE TAF PERIOD. BRIEF DROPS TO MVFR AND EVEN IFR CIG/VSBY WILL BE POSSIBLE IN ANY SHOWER OR STORM...BUT DID NOT WANT TO INCLUDE LONG TEMPO PERIODS. EXPECT COVERAGE TO WANE PAST SUNSET AS INSTABILITY DROPS. WINDS WILL GENERALLY BE AROUND 10 KNOTS OR LESS OUT OF THE SOUTH AND SOUTHWEST. CL .OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/... ABUNDANT MOISTURE AND DISTURBANCES IN SOUTHWEST FLOW ARE LIKELY TO SPAWN PERIODIC RESTRICTIONS THROUGH WEDNESDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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