Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 300811 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 411 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 8 AM THIS MORNING/... STABLE STRATIFICATION UNDER CLEAR TO PTLY CLOUDY SKIES WILL CONTINUE ACROSS MUCH OF CENTRAL AND SOUTHERN PENN THROUGH THE MID MORNING HOURS. OVER NWRN PENN. 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. PATCHY LIGHT RIVER VALLEY FOG EXPECTED ELSEWHERE AS SFC DEWPOINTS SLOWLY RISE. MIN TEMPS SHOULD RANGE FROM THE MID TO UPPER 50S OVER THE NORTH... TO THE LOWER 60S IN THE SOUTHEAST. && .SHORT TERM /8 AM THIS MORNING THROUGH 6 PM MONDAY/... SOME EARLY MORNING FOG IN THE VALLEYS - WHICH SHOULD BE OF LESSER COVERAGE THAN SAT MORNING. THEN...THE TEMPS RISE EVEN BETTER...ADDING ANOTHER 3-4F ONTO SAT/S MAXES. 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. PLAN TO INCREASE POPS INTO THE LIKELY CATEGORY ACROSS THE NW MTNS DURING THE MID TO LATE MORNING HOURS. THERE WILL BE A TRANSITION TO VIRTUALLY NO CHC OF RAIN OVER THE SE COUNTIES OF OUR CWA. CONVECTIVE ALLOWING HRRR MODEL SUGGEST EVEN CATEGORICAL ARE WARRANTED ACROSS PARTS OF THE NW AND NCENT MTNS /AND EVEN FOR A MORE BRIEF TIME PERIOD OF A FEW HOURS OVER THE LAUREL HIGHLANDS CENTERED ON DAYBREAK/. THIS SECOND...AND MORE SIGNIFICANT CLUSTER OF CONVECTION WILL IMPACT THE NW MTNS OF PENN BETWEEN 10-14Z.SOME LOCATIONS WILL SEE BETWEEN 0.25 AND 0.50 INCH OF RAIN...WHERE TWO OR MORE MDT-HVY SHOWERS OCCUR. 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. && .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 /08Z 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...DANGELO/LAMBERT LONG TERM...RXR AVIATION...GRUMM/CERU

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