Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 300653 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 253 AM EDT TUE JUN 30 2015 .SYNOPSIS... A WARM FRONT WILL MOVE NORTHEAST ACROSS THE STATE OVERNIGHT BRINGING SHOWERS TO PRIMARILY THE NORTHWEST HALF OF THE STATE. WARMER AND MORE UNSTABLE AIR WILL ENCOMPASS THE REGION TUESDAY HELPING TO TRIGGER NUMEROUS SHOWERS AND SCATTERED AFTERNOON THUNDERSTORMS AS A TROUGH OF LOW PRESSURE AT THE SURFACE AND ALOFT APPROACHES FROM THE WEST. EXPECT AN UNSETTLED WEATHER PATTERN TO PERSIST INTO THE UPCOMING HOLIDAY WEEKEND AS A BROAD BUT WEAKENING UPPER LEVEL TROUGH REMAINS POSITIONED OVER THE LOWER 48 EAST OF THE CONTINENTAL DIVIDE. && .NEAR TERM /UNTIL 8 AM THIS MORNING/... MID LVL SHORTWAVE LIFTING NE THRU THE E GRT LKS EARLY THIS MORNING. SOUTHERLY LL JET AND ASSOC WAA/ISENTROPIC LIFT IN ADVANCE OF THIS FEATURE IS PRODUCING PERIODS OF RAIN ACROSS WESTERN/CENTRAL PA AS OF 06Z. LATEST RADAR TRENDS AND HRRR OUTPUT SUPPORT RAISING OVERNIGHT POPS TO BTWN 80-90 PCT ACROSS THE ALLEGHENY PLATEAU...WHILE CHC OF RAIN LOOKS MUCH LOWER ACROSS THE LOWER SUSQ VALLEY...FURTHER FROM SHORTWAVE AND ASSOC LG SCALE FORCING. A FEW LIGHTNING STRIKES NOTED AT NOSE OF LL JET ACROSS SW PA AT 06Z AND MDL SOUNDINGS SHOW SOME MARGINAL ELEVATED INSTABILITY ACROSS MUCH OF CENTRAL PA EARLY THIS AM...AS LL JET SWEEPS EASTWARD. THEREFORE...WILL MAINTAIN THE SLIGHT CHC OF THUNDERS ACROSS THE CENTRAL MTNS AND ALLEGHENY PLATEAU EARLY THIS AM. TEMPS ON TRACK TO BOTTOM OUT EARLY THIS AM FROM THE U50S ACROSS THE N MTNS...TO THE M60S ACROSS THE SE COUNTIES. && .SHORT TERM /8 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... THE LEAD SHORTWAVE IS FCST TO WEAKEN AS IT LIFTS THRU THE E GRT LKS LATER TODAY. LATEST HRRR/NAM SIM REFLECTIVITY INDICATE A DWINDLING BATCH OF SHOWERS ASSOC WITH THIS FEATURE WILL LIFT THRU THE NE COUNTIES BTWN 12Z-15Z. AT THE SFC...WARM FRONT WILL BE PUSHING NE ACROSS THE REGION DURING THE LATE AM AND EARLY AFTN...BRINGING BRIGHTENING SKIES EARLY IN THE DAY ACROSS THE ALLEGHENIES...AND BY EARLY AFTN ACROSS THE SUSQ VALLEY. DIABATIC HEATING RESULTS IN MODERATE MODEL CAPES OF ARND 1000 J/KG BY AFTN ACROSS CENTRAL PA...WITH SOMEWHAT GREATER INSTABILITY NOTED ACROSS THE SUSQ VALLEY...WHERE TRAILING LL JET/PLUME OF HIGHER PWATS LIE IN ASSOC WITH WEAKENING SHORTWAVE OVR THE E GRT LKS. HAVE THUS...PLACED THE HIGHEST /LIKELY/ CHC OF PM TSRA ACROSS THE EASTERN COUNTIES. MDL 0-6KM SHEAR OF ARND 40KTS SUPPORTS THE POSSIBILITY OF A FEW SUPERCELLS AND A SLIGHT RISK OF DAMAGING WGUSTS FROM THE CENTRAL MTNS EASTWARD THIS AFTN. WEAKER MID LVL WINDS IMPLY LESS CHC OF SVR WX ACROSS THE NW MTNS. OTHER AREA OF CONCERN WILL BE THE POSSIBILITY OF LOCALIZED FLOODING...DUE TO WET GROUND AND EXPECTATION OF ISOLD RAINFALL AMTS OF ARND 3 INCHES BASED ON OUTPUT FROM CONVECTION-ALLOWING MDLS. WILL MENTION IN HWO FOR NOW...BUT A FFA COULD BE CONSIDERED FOR THE SUSQ VALLEY...WHERE PLUME OF HIGHEST MOISTURE WILL LIE. PTSUNNY SKIES SHOULD PUSH TEMPS INTO THE M70S OVR THE ALLEGHENIES THIS AFTN...AND THE L80S ACROSS THE SUSQ VALLEY. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... THE LARGE UPPER LEVEL LOW OVER NORTHERN CANADA THAT WILL BE DOMINATING THE WEATHER PATTERN OVER THE NEXT WEEK WILL BRING A DEEPENING TROUGH THAT WILL CONTINUE TO ADVECT WARM MOIST SOUTHWESTERLY FLOW INTO THE REGION TUESDAY NIGHT INTO WEDNESDAY. MID LEVEL PERTURBATIONS AND SHORT WAVE TROUGHS SHOULD ENHANCE LAPSE RATES. DAY 2 OUTLOOK IS CURRENTLY MARGINAL FOR ALMOST ALL OF PENNSYLVANIA. SO EXPECT ANY TSTMS THAT FORM TUESDAY AFTERNOON INTO EVENING TO LINGER TUESDAY NIGHT INTO POSSIBLY WEDNESDAY. AS THE MAIN TROUGH LIFTS AND EXITS THE REGION WEDNESDAY THE CONVECTIVE ENVIRONMENT SHIFTS THE BEST INSTABILITY WITH LARGER VORTICIES DUE TO A SHORT WAVE THAT SHOULD ALLOW FOR LOW LVL LAPSE RATES TO BE STRONGER THROUGH ALONG A FRONTAL BOUNDARY. MODELS CONTINUING TO TREND MORE ZONAL FLOW LATE WEDNESDAY NIGHT INTO THURSDAY. WITH AN AMPLIFYING TROUGH SWINGING THROUGH THURSDAY AFTERNOON. THIS TREND SHOULD ALLOW FOR MORE A MORE SUMMERTIME REGIME THURSDAY INTO THE WEEKEND. IN THE WAKE OF THURSDAY/S TROUGH THE GFS/GEFS/EC BEGIN TO DIVERGE IN SOLUTIONS. HOWEVER WITH DRIER AIR ADVECTING IN AND THE CONSENSUS, THOUGH THE TIMING DIFFERS, THAT A RIDGE SHOULD BUILD OVER PA THROUGH THE FIRST HALF OF THE WEEKEND. THIS COULD LIMIT ANY CONVECTION TO ALONG THE MASON DIXON LINE AND ONLY A SLIGHT CHANCE FOR PRECIPITATION CURRENTLY SUNDAY EVENING. SO DESPITE A SERIES OF MID- LEVEL DISTURBANCES MOVING DOWNSTREAM FROM THE UPPER/MID MISSISSIPPI VALLEY THROUGH THE MID ATLC REGION...500MB HEIGHTS SHOULD BE IN RECOVERY MODE WHICH SHOULD ALLOW DAYTIME TEMPERATURES TO TREND WARMER INTO THE JULY 4TH HOLIDAY WEEKEND. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS DOMINATING THE REGION THIS EVENING...WITH LIGHT SHOWERS DRIFTING IN FROM THE SW. THIS AREA OF SHOWERS WILL EXPAND OVERNIGHT TO ALL BUT SE COUNTIES AS A WELL-DEFINED SHORT WAVE TROUGH HELPS TO LIFT A WARM FRONT NORTHWARD. MAY SEE AN ISOLATED TSTM IN FAR WESTERN COUNTIES...BUT VERY UNLIKELY THROUGH 12Z. LOW LEVEL SW JET OF AROUND 30 KTS SWINGS IN FROM THE SW...AND WILL BRING MARGINAL LLWS TO KJST-KAOO ALONG WITH MVFR CIGS FOR MAINLY WESTERN HIGHER TERRAIN. SURFACE WINDS WILL REMAIN LIGHT AREAWIDE. MVFR CONDITIONS WILL REMAIN LIKELY FOR WESTERN HIGHER TERRAIN THROUGH LATE MORNING TUE /WITH BRIEF MVFR CIGS POSS CENTRAL MTNS/. AN UPPER LEVEL DISTURBANCE OFF TO OUR WEST WILL BRING A COUPLE ROUNDS OF SHOWERS AND SCT AFTERNOON TSRA. AN UNSETTLED PATTERN WITH A SERIES OF FRONTS WILL BE AFFECTING THE REGION MUCH OF THIS WEEK. THE BEST CHANCES OF RESTRICTIONS WILL BE TUESDAY INTO WEDNESDAY. OUTLOOK... TUE...MVFR CIGS LIKELY WEST. OTHERWISE MAINLY VFR. LOCAL RESTRICTIONS IN SHRA/SCT TSRA. ISO TSTMS MAY BE STRONG IN THE AFTERNOON. WED...MVFR CIGS LIKELY WEST. OTHERWISE MAINLY VFR. LOCAL RESTRICTIONS IN SCT SHRA/TSRA. THU...MAINLY VFR. ISOLATED TSRA MAINLY SOUTH OF I-80. FRI...MAINLY VFR. ISOLATED TSRA SOUTH. SAT...MAINLY VFR. CHANCE SHRA/TSRA. && .CLIMATE... JUNE 2015 HAS BEEN A WET MONTH ACROSS MUCH OF CENTRAL PA. THROUGH 6/28...OUR TWO LCD CLIMATE SITES /HARRISBURG AND WILLIAMSPORT/ ARE RANKED 8TH AND 6TH RESPECTIVELY FOR THE WETTEST JUNE ON RECORD. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD/LAMBERT LONG TERM...CERU/STEINBUGL AVIATION...RXR CLIMATE...

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