Area Forecast Discussion
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000 FXUS61 KPBZ 260742 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 342 AM EDT TUE MAY 26 2015 .SYNOPSIS...
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WARM AND HUMID CONDITIONS WILL PERSIST THROUGH THE SHORTENED WORK WEEK...WITH SHOWER AND THUNDERSTORM CHANCES EACH DAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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FIRST IN A SERIES OF SHORTWAVES IS CURRENTLY RIDING NORTHEASTWARD ACROSS THE AREA WITH SOME SHRA. NO THUNDER SO FAR AS WARM AIR ALOFT IS KEEPING INSTABILITY IN CHECK. EXPECT THIS ACTIVITY TO CONTINUE TO LIFT NORTHWARD THIS MORNING...WITH A LULL IN ACTIVITY DURING THE LATE MORNING HOURS. DAYTIME HEATING WILL HELP TO INCREASE CAPE DURING THE AFTERNOON HOURS...BUT A TRIGGER WILL BE LACKING THROUGH MIDAFTERNOON AND THUS WILL KEEP POPS AT THE LOWER END OF CHANCE. THIS WILL CHANGE TOWARD THE END OF THE DAY AS A MORE POTENT SHORTWAVE TROUGH APPROACHES FROM THE SOUTHWEST. HAVE LIKELY POPS SPREADING ACROSS THE REGION THROUGH TONIGHT AS A RESULT. SPC HAS A SLIGHT RISK OF SEVERE THUNDERSTORMS UP OVER MOST OF OHIO. THINK THAT BETTER MIDLEVEL FLOW AND INSTABILITY WILL BE REALIZED TO THE SOUTH AND WEST OF OUR CWA DURING THE AFTERNOON/EVENING...TOWARDS THE MIDDLE AND LOWER OHIO VALLEY. HOWEVER STORMS THAT DEVELOP COULD PROPAGATE TOWARDS THE WV/OH BORDER LATE TODAY WITH SOME STRONG AND POTENTIALLY DAMAGING WIND GUSTS. WILL MENTION POTENTIAL IN HWO BUT DO NOT FORESEE A SIGNIFICANT SEVERE OUTBREAK. STORMS HAVE THE POTENTIAL TO BE EFFICIENT RAIN PRODUCERS AS WELL. PWATS IN THE 1.5 TO 1.75 RANGE ARE NEAR THE HIGH END OF CLIMATOLOGY...AND WARM CLOUD DEPTHS WILL LIKELY EXCEED 10K FEET TONIGHT. IT DOES APPEAR THAT STORMS WILL MOVE WITH SUFFICIENT SPEED TO DETER EXCESSIVE RAINFALL FOR THE MOST PART...BUT POOR DRAINAGE LOCATIONS MAY NEED TO BE WATCHED. TEMPERATURES WERE MAINLY TWEAKED DOWNWARD SLIGHTLY TODAY TO GET MORE IN LINE WITH MODEL CONSENSUS. LITTLE CHANGE NEEDED FOR TONIGHT. CL
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&& .SHORT TERM /WEDNESDAY THROUGH SATURDAY/...
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THE FIRST HALF OF THE PERIOD WILL CONSIST OF UNSETTLED WEATHER AS AN UPPER LEVEL SHORTWAVE TROUGH IS PROGGED TO BE OVER THE GREAT LAKES AND SHIFT EASTWARD. DEEP MOISTURE WILL BE MAINTAINED OVER THE REGION ALLOWED BY SOUTHWEST FLOW. THEREFORE...CHANCE TO LIKELY POPS WERE MAINTAINED AND ADJUSTED SLIGHTLY BASED ON LATEST GUIDANCE. A LULL IN PRECIPITATION CAN BE EXPECTED LATE THURSDAY INTO FRIDAY AS BRIEF HIGH PRESSURE BUILDS UNDER A WEAK RIDGE IN THE WAKE OF THE SHORTWAVE TROUGH. PRECIPITATION CHANCES RISE AGAIN ON SATURDAY SUPPORTED BY AN APPROACHING SURFACE BOUNDARY AND A WEAK SPLIT FLOW ALOFT. THE FRONT IS EXPECTED TO SLOWLY SAG ACROSS THE FORECAST AREA THROUGH SATURDAY AS PREDICTED BY ECMWF AND GFS SOLUTIONS. FORECASTED TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE PERIOD.
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/...
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VARIOUS LONG RANGE SOLUTIONS AGREE ON STUBBORN BOUNDARY LAID ACROSS THE FORECAST AREA THROUGH THE WEEKEND. THEREFORE CHANCE POPS WERE PRESERVED WITH THE SUPPORT OF A SERIES OF UPPER LEVEL DISTURBANCES ACROSS THE UPPER OHIO VALLEY. GFS AND ECMWF DIFFER OVER THE OUTCOME OF AN APPROACHING TROUGH FROM THE MIDWEST IN TERMS OF MAGNITUDE...POSITION...AND TIMING. THEREFORE PERSISTENCE WAS HEAVILY USED IN THE LATTER HALF OF THE PERIOD AND LOW CHANCE POPS WERE INTRODUCED.
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&& .AVIATION /08Z 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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