Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 312322 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 722 PM EDT FRI JUL 31 2015 .SYNOPSIS... HIGH PRESSURE OVER THE CENTRAL U.S. WILL NOSE INTO THE REGION THIS WEEKEND. A PERSISTENT UPPER LEVEL TROUGH WILL SIT OVER THE GREAT LAKES AND NORTHEAST STATES THIS WEEKEND...AND SEND A SERIES OF WEAKENING COLD FRONTS SOUTHEAST ACROSS PENNSYLVANIA...BRINGING THE POSSIBILITY OF SOME SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... A WEAK SHORTWAVE AND COLD FRONT MOVING INTO THE EASTERN GREAT LAKES IS ACTING ON A NARROW RIBBON OF INSTABILITY AND TRIGGERING SCATTERED CONVECTION FROM CENTRAL OHIO UP OVER LAKE ERIE UP INTO SOUTHERN CANADA. HIGH RES SHORT RANGE GUIDANCE SUGGESTS THE BEST CHANCE FOR A STRAY SHOWER OR THUNDERSTORM WILL BE OVER MY FAR NWRN AREAS THIS EVENING AND OVERNIGHT. LOWS TONIGHT WILL VARY FROM THE MID 50S ACROSS THE NW MTNS...TO THE LOWER AND MID 60S THROUGHOUT THE SOUTHERN VALLEYS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... THE WEAK COLD FRONT WILL EXIT OUR EASTERN ZONES DURING THE MID TO LATE MORNING HOURS WITH ISOLATED-SCATTERED SHOWERS. AFTERWARD /AND VERY SIMILAR TO FRIDAY/...SFC HIGH PRESSURE RIDGE WILL BUILD BACK INTO THE REGION FROM THE OHIO RIVER VALLEY. SFC DEWPOINTS SHOULD EDGE DOWN BY 3-5 DEG F COMPARED TO FRIDAY/S VALUES. THIS WILL LEAD TO MAINLY SCATTERED FAIR WEATHER CU...WITH LITTLE IF ANY CHC FOR AFTERNOON SHOWERS TO THE SOUTH OF I-80. SLIGHTLY STEEPER MID-LEVEL LAPSE RATES /AROUND 6C PER KM/ ACROSS THE NRN MTNS WILL LEAD TO AREAS OF MDT TO TCU WITH A FEW SHOWERS DOTTING THE RADAR SCOPE AFTER 17Z. MAX TEMPS WILL BE NEAR NORMAL OVER THE CENTRAL AND SE VALLEYS...BUT A FEW DEG COOLER THAN NORMAL ACROSS THE NRN AND WRN MTNS. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... LITTLE CHANGE IS ANTICIPATED IN LARGE SCALE FLOW PATTERN ACROSS THE CONUS THROUGH THE EXTENDED PERIOD. A BROAD UPPER TROUGH EXTENDS SOUTHWARD FROM EASTERN CANADA ACROSS THE ERN U.S. TEMPERATURES SHOULD AVG NEAR NORMAL INTO EARLY NEXT WEEK BEFORE TRENDING COOLER LATER IN THE WEEK. SEVERAL SHORT WAVES WILL ROTATE AROUND THE UPPER LOW IN A FASHION REMINISCENT OF WINTER. AS IS THE CASE WITH MOST UPPER LOW VS. SHORT WAVE SPOKES...CONFIDENCE IS LOW ON TIMING OF PCPN CHANCES. && .AVIATION /23Z FRIDAY THROUGH WEDNESDAY/... NICE MID SUMMER AFTERNOON OUTSIDE. VFR CONDITIONS PREVAIL ACROSS THE AREA. SOME SHOWERS AND STORMS NEAR THE LOWER LAKES...BUT THESE SHOULD STAY NORTH OF OUR AREA. ONLY MINOR CHANGES NEEDED FOR 21Z TAF PACKAGE. EARLIER DISCUSSION BELOW. SFC HIGH PRESSURE RIDGING NE INTO THE REGION FROM THE OHIO RIVER VALLEY...WILL SAG SE LATE TODAY AND TONIGHT...ALLOWING A WEAK SFC TROUGH...THEN MOISTURE CHALLENGED CFRONT TO SLIDE SE OVERNIGHT. ISOLATED TO SCTD SHOWERS AND TSRA ARE POSSIBLE LATE THIS AFTERNOON AND TONIGHT...MAINLY AT TAF SITES TO THE NORTH OF INTERSTATE 80. OTHERWISE...WIDESPREAD VFR WILL CONTINUE THROUGH THIS WEEKEND. OUTLOOK... SAT...MAINLY VFR...SCATTERED SHOWERS/THUNDERSTORMS. SUN...MAINLY VFR. MON-WED...VFR...EXCEPT FOR BRIEF MVFR IN ISOLATED-SCATTERED MAINLY AFTERNOON AND EVENING SHOWERS/THUNDERSTORMS. && CLIMATE... THE WILLIAMSPORT ASOS HIGH OF OVER 100 TODAY WAS THE RESULT OF A FAULTY SENSOR. TECHNICIANS ARE WORKING ON THE PROBLEMS AND SHOULD HAVE IT FIXED THIS EVENING. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE/LAMBERT NEAR TERM...LA CORTE/LAMBERT SHORT TERM...LAMBERT LONG TERM...MARTIN/TYBURSKI AVIATION...LAMBERT/MARTIN

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