Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 191528 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1128 AM EDT TUE AUG 19 2014 .SYNOPSIS... AN UPPER LOW OVR THE W GRT LKS WILL DRIFT SLOWLY SE ACROSS UPSTATE NY AND NEW ENG BY LATE THIS WEEK. A LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL RIDGE SOUTHWARD INTO PA DURING THE UPCOMING WEEKEND AND EARLY NEXT WEEK. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... LOW CLOUDS SLOWLY LIFTING AND MOVING TO THE EAST. RADAR HAS DETECTED SHOWERS WHICH DEVELOPED ON THE WESTERN EDGE OF THIS CLOUD SHIELD AND HAS MOVED INTO CLEARFIELD COUNTY. SOME HINTS OF WEAK CONVECTION IN THE HRRR AND 4KM NAM. USED THESE MODELS TO ADD TEXTURE TO THE FORECAST SHOWING SHOWERS AND ISOLATED THUNDERSTORMS DRIFTING ACROSS PENNSYLVANIA THIS MORNING AND AFTERNOON. TRIED TO KEEP POPS IN CHANCE RANGE AS THERE IS LIMITED ORGANIZATION TO THE CONVECTION. HOWEVER...3KM HRRR UPDATES FROM NCEPS EXPERIMENTAL HRRR SHOW DIFFERENT AREAS OF SHOWERS IN CENTRAL PA ALL AFTERNOON AND NOW IMPLY MORE ORGANIZED THUNDERSTORMS IN S-SE COUNTIES IN LATE AFTERNOON EVENING. SEE HOW THIS EVOLVES. SKIES SHOULD SLOWLY GET BETTER DURING DAY CENTRAL AREAS. && .SHORT TERM /8 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... SREF AND NAM CONTINUE TO SHOW CHANCE TO SLIGHT CHANCE OF SHOWERS OVERNIGHT. THE SURGE OF CAPE AND PW INTO WESTERN PA IN THE SREF AND NAM...SIMILAR TO OLDER GEFS/GFS IMPLY SOME MORE ORGANIZED RAIN POSSIBLE ON WEDNESDAY. USED A BLEND TO GET THE POPS AND THE 12KM NAM TO ADD SOME TEXTURE TO CONVECTION AND RAIN AREA THAT APPEARS TO BE POISED TO MOVE WEST TO EAST ACROSS THE REGION WEDNESDAY. THE SREF POPS/PDF IMPLIES SHOWERS COMING INTO WEST AROUND 1500 UTC AND MOST OF CENTRAL TWO THIRDS OF REGION BY LATE EVENING. SREF IS KIND OF OPTIMISTIC SOUTHEAST PA COULD HAVE YET ANOTHER MOSTLY RAIN FREE DAY WEDNESDAY. THE KEY FEATURES ARE THE RETROGRADING RIDGE OVER EASTERN CANADA WHICH IS TAKING THE UMPH OUT OF THE SYSTEMS CUTTING UNDER THIS FEATURE. IN MOST MODELS THE NEAR 1SD ABOVE NORMAL PW SURGES WEAKEN AS THE MOVE INTO PA. THUS MORE OPTIMISTIC...SREF-LIKE IN THE WEST THAN THE EAST WITH RAINFALL AND NOT REALLY CONFIDENT GOING LIKELY. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... THURSDAY LOOKS LIKE ANOTHER UNSETTLED DAY...AS UPPER LOW MAKES IT/S CLOSEST PASS TO PA...TRACKING ACROSS UPSTATE NY. COOL TEMPS ALOFT...COMBINED WITH DIURNAL HEATING...SHOULD YIELD NUMEROUS SHRA AND TSRA BY AFTN. HAVE RAISED POPS TO THE LIKELY CATEGORY BASED ON 00Z OPER AND GEFS OUTPUT. SOUTHERLY LL JET AND PLUME OF HIGH PWATS WILL HAVE PASSED NE OF THE AREA THURSDAY...LIMITING THE THREAT OF ANY HVY RAINFALL. MDL BLENDED QPF IS IN THE QUARTER TO HALF INCH RANGE THURSDAY. THE NUMEROUS SHOWERS AND COOLER TEMPS ALOFT WILL RESULT IN HIGH TEMPS BLW NORMAL FOR AUGUST...WITH MAXES MAINLY IN THE 70S. LATEST MED RANGE GUIDANCE POINTING TOWARD DRIER WX FRIDAY INTO EARLY NEXT WEEK...AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD THE REGION FROM THE MIDWEST. DAILY RING OF FIRE CONVECTION ON NE PERIPHERY OF THIS RIDGE WILL THREATEN WESTERN PA DURING THE FRI-SUN TIME FRAME...WHILE EASTERN PA IS LIKELY TO REMAIN DRY. DESPITE APPROACH OF UPPER RIDGE...NO BIG WARMUP EXPECTED...AS LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN EASTERLY FLOW INTO CENTRAL PA. THERE MAY BE ISSUE WITH AM LOW CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA. && .AVIATION /16Z TUESDAY THROUGH SATURDAY/... STILL LINGERING AREAS OF MVFR AND ISOLATED IFR AS THE LOW CLOUDS AND PATCHY FOG FROM EARLY THIS MORNING AND LIFT AND SLOWLY DRIFT TO THE EAST. A LINE OF SHOWERS WITH ISOLATED THUNDER HAS DEVELOPED OVER THE CENTRAL MOUNTAINS. THIS COULD BRING SHOWERS FROM KFIG SOUTH TO KAOO AND KJST AND EVENTUALLY THE KUNV AREA. ADDED SHOWERS VICINITY TO THESE SITES. THIS COULD MOVE FARTHER EAST. MODELS SHOW ISOLATED TO SCATTERED SHOWERS RANDOMLY PLACED ABOUT CENTRAL AND SOUTHERN PA OVER NEXT 12 HOURS. THINGS SETTLE DOWN OVERNIGHT...MORE PATCHY FOG AND LOW CLOUDS. RAIN AND SHOWERS LIKELY IN WESTERN PA BY MID-LATE MORNING SLOWLY SPREADING EAST. VFR IN EAST BUT AREAS MVFR LIKELY IN AM FOG AND THEN SHOWERS IN WESTERN AREAS. OUTLOOK... TUE...MAINLY VFR...WITH SHRA/TSRA POSSIBLE. WED...MORNING FOG/LOW CLOUDS SHRA/TSRA LIKELY WEST CHANCE EAST. THU-FRI...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT INCREASING CHANCES OF MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED RESTRICTIONS. SAT...MAINLY VFR. STILL CHANCE OF SHRA...BUT DECREASING CHANCES. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD NEAR TERM...GRUMM SHORT TERM...GRUMM LONG TERM...FITZGERALD AVIATION...GRUMM

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