Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 300946 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 546 AM EDT SUN AUG 30 2015 .SYNOPSIS... INCREASING MOISTURE WILL BE CHANNELED NORTHEAST FROM THE OHIO VALLEY TODAY...AND INTERACT WITH A STATIONARY FRONTAL BOUNDARY TO PRODUCE SCATTERED SHOWERS AND A FEW THUNDERSTORMS ACROSS MAINLY THE NORTHWESTERN HALF OF THE STATE. HIGH PRESSURE OFF THE MID ATLANTIC COAST WILL BE MORE INFLUENTIAL ON KEEPING FAIR AND DRY WEATHER INTACT ACROSS THE SOUTHEASTERN HALF OF PENNSYLVANIA. VERY WARM AND INCREASINGLY HUMID WEATHER WILL CONTINUE INTO THE MIDDLE OF THE UPCOMING WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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RIGHT ENTRANCE REGION OF AN APPROX 60KT UPPER LEVEL WILL SLIDE ACROSS SRN NEW YORK AND NRN PENN THIS MORNING AND EARLY AFTERNOON. REGIONAL 88D MOSAIC LOOP SHOWS A COMPACT SHORT WAVE EMBEDDED BENEATH THE TAIL END OF THIS JETLET /JUST NW OF KPIT AT 09Z/. THE DISTINCT FEATURE AND ITS SPIN WILL CONTINUE TO TRACK TWD THE NORTHEAST AND IMPACT PRIMARILY THE NW AND NORTH-CENTRAL MTNS OF THE STATE WITH HUMEROUS SHOWERS. AREAL COVERAGE OF TSRA IS STEADILY DECREASING /AS ONE WOULD EXPECT IN THE MORNING DURING THE LATE SUMMER/. SFC BASED CAPE WILL SLOWLY INCREASE TO BETWEEN 300-500 J/KG ACROSS THE NW MTNS THIS MORNING WITH THE ADVECTION OF 1.5 INCH PWAT AIR FROM THE OHIO VALLEY. THE PRESENCE OF A QUASI-STNRY FRONTAL BOUNDARY AND THE INCREASING MOISTURE FROM THE OHIO VALLEY...WILL LEAD TO NEWRD EXPANSION OF SHOWERS AND A FEW ISOLATED TSRA EARLY TODAY. TIMING OF THIS FEATURE PLACES IT ACROSS NCENT PENN DURING THE CLIMATOLOGICALLY CONVECTIVE MIN PORTION OF THE DAY...SO EXPECT VERY LITTLE IF ANY THUNDER THIS MORNING. CLEAR TO PTLY CLOUDY SKIES WILL CONTINUE ACROSS MUCH OF CENTRAL AND SOUTHERN PENN THROUGH THE LATE MORNING HOURS. PATCHY LIGHT RIVER VALLEY FOG IS EXPECTED ACROSS SOUTH CENTRAL AND SERN PENN THROUGH 13Z. TEMPS AT SUNRISE SHOULD RANGE FROM THE UPPER 50S TO AROUND 60F ACROSS MUCH OF THE CWA...WITH LOW-MID 60S FOUND ACROSS THE METRO AREAS OF THE LOWER SUSQ VALLEY. AFTER THE PASSAGE OF THE MESO-B SHORT WAVE LATE THIS MORNING... DIFF NEG VORT ADVECTION WILL LEAD TO A MIN IN CONVECTION BETWEEN 15-18Z. INDICATIONS /VIA A BLEND OF THE HRRR AND WRF ARW/ ARE THAT CONVECTIVE...SHRA/ISOLATED TSRA WILL BE CONFINED TO MAINLY THE NRN MTNS LAUREL HIGHLANDS DURING THE AFTERNOON HOURS. MUCH MORE ISOLATED SHRA/TSRA WILL BE FOUND NEAR...AND TO THE SE OF A LINE FROM KFIG AND KIPT...TO KAVP. THERE WILL BE A TRANSITION TO VIRTUALLY NO CHC OF RAIN OVER THE SE COUNTIES OF OUR CWA. BASIN AVG QPF WILL BE LESS THAN ONE TENTH OF AN INCH TODAY. HOWEVER...A FEW COMMUNITIES UP NORTH COULD SEE 0.25-0.50 BY MIDNIGHT TONIGHT. MAX TEMPS THIS AFTERNOON WILL VARY FROM THE U70S ACROSS THE NRN AND WRN MTNS...TO THE UPPER 80S ACROSS THE LOWER SUSQ VALLEY AND SURROUNDING AREAS WHERE MUCH MORE SUNSHINE WILL BE FOUND TODAY.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
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RIDGE AT THE SFC AND ALOFT IS STARTING TO GET PRESSED A LITTLE TO THE EAST BY AN ADVANCING UPPER TROUGH AND SLIGHT FEED OF GULF MOISTURE. THUS...SUPPORT IN THE FORM OF INSTABILITY AND MOISTURE WILL BE AVAILABLE TODAY. AFTER THE INITIAL...RATHER COMPACT SHORTWAVE ALOFT LIFTS INTO SOUTHCENTRAL NEW YORK LATER THIS MORNING...THE ATMOS WILL RECHARGE TO OVER 1000 J/KG CAPE IN SOME AREAS...AND BE CAPABLE OF FIRING OFF SCTD SHRA/TSRA ACROSS THE CENTRAL MTNS...AND ALLEGHENIES THIS AFTERNOON. HIGHS THIS AFTERNOON WILL VARY FROM THE U70S ACROSS THE NRN AND WRN MTNS...TO THE UPPER 80S ACROSS THE LOWER SUSQ VALLEY AND SURROUNDING AREAS.
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&& .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... ANOMALOUS UPPER LEVEL RIDGE WILL DOMINATE THE OHIO VALLEY AND EASTERN UNITED STATES MUCH OF THE UPCOMING WEEK...WITH 850HPA TEMPS RUNNING 16-18C WHICH WILL TRANSLATE TO WELL ABOVE-NORMAL SFC TEMPS. THIS WARMTH AND INCREASING HUMIDITY SHOULD ALLOW FOR AT LEAST A SLIGHT CHC FOR DIURNAL CONVECTION EACH DAY...BUT THE PROBABILITY OF WIDESPREAD RAINFALL IS LOW. THERE ARE A COUPLE OF INTERESTING FEATURES THAT BEAR WATCHING FOR LATE IN THE LONG TERM PERIOD. THE FIRST IS THE REMNANTS OF ERIKA...WHICH ARE FCST TO BE IN THE VICINITY OF THE FL/GA COAST BY THE MIDDLE OF NEXT WEEK. AS THIS MOISTURE DIFFUSES OVER THE SOUTHEAST U.S....SOME OF IT WILL GRADUALLY CRAWL INTO THE MID ATLANTIC REGION. THE OTHER INTERESTING FEATURE IS A BACKDOOR COLD FRONT THAT SOME MODELS BRING INTO THE MID-ATLANTIC STATES NEXT THURS/FRI. THESE FEATURES COMBINED WITH THE WARM AND INCREASINGLY HUMID AIR THAT WILL ALREADY BE IN PLACE WILL KEEP MENTION OF AT LEAST A SLIGHT CHC FOR DIURNAL CONVECTION EACH DAY. THE LATTER FEATURE COULD HAVE AN IMPACT ON TEMPS LATE NEXT WEEK...TAPERING BACK TEMPS A BIT. && .AVIATION /09Z SUNDAY THROUGH THURSDAY/... CONVECTION OUT AHEAD OF AN APPROACHING TROUGH IS CURRENTLY STREAMING THROUGH NORTHWEST PA...AND SHOULD ALLOW FOR SOME LIGHT SHOWERS BRINGING POSSIBLE MVFR CIGS/VSBYS TO BFD. OTHERWISE PATCHY AREAS OF FOG MAINLY MVFR WITH SOME ISOLATED AREAS OF IFR. THOUGH GENERALLY LIGHT WINDS...ANY REGION THAT DECOUPLES SHOULD SEE INCREASE FOG FORMATION. IFR CONDITIONS HAVE THE HIGHEST CHANCE AT UNV...AOO AND BFD. CONSIDERING THE SHORT RANGE MODELS...EXPECT A HIGH CHANCE FOR SHOWERS ACROSS NORTHERN PENNSYLVANIA THIS MORNING. BY 16Z SHOWERS MOVE INTO SOUTHWEST MOUNTAINS. USED MAINLY VCSH/VCTS TO HANDLE SHOWERS AS THE PROBABILITIES ARE GENERALLY 20 TO 40 PERCENT. HIGHEST PROBABILITIES OF SHOWERS/THUNDER IN NORTHWEST. OUTLOOK... MON...STILL SOME SHRA/TSRA POSS. TUE-THU...NO SIG WX EXPECTED AREAS MVFR OVERNIGHT PATCHY FOG. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...LAMBERT LONG TERM...LAMBERT/RXR AVIATION...GRUMM/CERU

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