Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 010954 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 554 AM EDT SUN MAY 1 2016 .SYNOPSIS...
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SEVERAL WEAK AREAS OF LOW PRESSURE WILL MOVE NORTHEAST UP THE OHIO RIVER VALLEY TODAY INTO MONDAY BRINGING RAIN THIS MORNING. THERE WILL BE A LULL IN THE PRECIPITATION LATER THIS MORNING AND THIS AFTERNOON. SCATTERED SHOWERS WILL DEVELOP ACROSS THE STATE LATER THIS AFTERNOON AND EVENING...WITH A CHANCE OF THUNDERSTORMS OVER THE WESTERN HALF OF PENNSYLVANIA. ANOTHER PERIOD OF STEADY LIGHT TO MODERATE RAIN WILL OCCUR LATE TONIGHT AND EARLY MONDAY MORNING. PERIODS OF UNSETTLED WEATHER WITH MODERATING TEMPERATURES WILL OCCUR INTO THE MIDDLE OF THE UPCOMING WEEK...FOLLOWED BY A COOLING TREND WITH SHOWERY CONDITIONS LATER IN THE WEEK.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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A LARGE SHIELD OF WARM ADVECTION GENERATED RAIN CONTINUES TO MARCH EAST ACROSS THE CWA. THE BACK EDGE OF THE STEADIER RAIN IS MOVING JUST TO THE EAST OF THE RT 219 CORRIDOR AT 09Z. RELATIVELY SMALL AREAS OF MDT (TO BRIEFLY HEAVY RAIN) RAIN WERE NOTED ACROSS THE SUSQ VALLEY AND PORTIONS OF SCENT PENN WITH REFLECTIVITIES IN THE 30-40 DBZ ON REGIONAL 88D MOSAIC LOOP. BY 12Z...THE BULK OF THE STEADIEST/HEAVIEST RAIN WILL BE ACROSS THE SUSQ VALLEY AND POINTS EAST...WITH PERHAPS A SECONDARY BAND OF SHOWERS ACROSS THE NRN MTNS. ADDITIONAL RAINFALL OVER THE NEXT 6 HOURS WILL AVERAGE 3-4 TENTHS OF AN INCH ACROSS THE EASTERN THIRD OF THE CWA AND GENERALLY LESS THAN ONE TENTH OF AN INCH WEST OF THE I-99/RT220 CORRIDOR. RAINFALL TOTALS BY NOON WILL BE INTO THE 0.5 TO 1 INCH RANGE. TEMPS WILL START THE DAY IN THE U40S TO AROUND 50F. WE WILL LIKELY BE IN AN AREA OF NVA AND DRYING ALOFT FOR THE MIDDAY AND AFTERNOON HOURS TODAY...AND THIS SHOULD BRING A LULL IN THE SHOWERS (ESPECIALLY ACROSS THE SOUTHERN TIER COUNTIES). HOWEVER...IF SOME BREAKS CAN DEVELOP AND SOME MEAGER FORCING PASSES OVERHEAD...WE MAY BE ABLE TO POP A FEW TALL SHRA /LOW- TOPPED TSRA BY AROUND 18-20Z. SFC LOW PRESSURE OVER THE LOWER OHIO RIVER VALLEY WILL MOVE NORTHEAST...REACHING NORTHWESTERN PENNSYLVANIA TONIGHT. BLENDED OPER/ENS AND HIGH RES MODEL GUIDANCE INDICATES THAT A SOUTH TO SEWD EXTENDING WARM FRONT...AND WARMER/UNSTABLE AIR TO ITS WEST SHOULD MAKE IT TO NEAR THE ALLEGHENY FRONT LATE TODAY AND TONIGHT. 850 MB LIFTED INDICES DROP TO BETWEEN -3 AND -5C WEST OF THIS BOUNDARY AND SFC BASED CAPE CLIMBS TO BETWEEN 1000-1500 J/KG...WHICH WILL BE SUPPORTIVE OF AT LEAST SCTD TSRA. THE ELEVATED INSTABILITY WILL STREAM EAST OVER THE SHALLOW COOLER AIRMASS (ENTRENCED THROUGHOUT THE CENTRAL RIDGE AND VALLEY REGION) BRINGING A LOWER CHC FOR TSRA. HIGH TEMPS THIS AFTERNOON USING A CONSENSUS BLEND WILL RANGE FROM ONLY NEAR 50F ACROSS THE NE MTNS /SULLIVAN COUNTY/...TO THE MID 60S ACROSS THE LAUREL HIGHLANDS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
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A SECOND WAVE OF DECENT LIFT WILL COINCIDE WITH THE TRIPLE POINT INCHING INTO CENTRAL PA SUNDAY EVENING. THE WARM FRONT WILL BE DRAPED NNW TO SSE CLOSE TO THE ALLEGHENY FRONT...AND LLVL SHEAR COULD BE MAXIMIZED THERE. A FEW ROTATING STORMS ARE POSSIBLE WITH THE RELATIVELY HIGHER INSTABILITY IN THAT SOUTHERN AND WESTERN PORTION OF THE CWA. DUE TO THE PRESENCE OF ELEVATED INSTABILITY AND POSSIBILITY OF MIXING ACROSS THE REST OF THE AREA...WILL KEEP CHC/SCT TS IN THE FCST THROUGH THE EVENING HOURS. ANOTHER FAIRLY LARGE AREA OF SHOWERS OR EVEN STEADY LIGHT TO MDT RAIN SPREADS NE ACROSS THE REGION LATE TONIGHT INTO EARLY MONDAY WITH A FEW TO SVRL TENTHS OCCURRING ON AVERAGE. LOW TEMPS TONIGHT WILL VARY FROM THE U40S ACROSS THE EAST...TO THE LOWER AND MID 50S IN THE SOUTHWEST.
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&& .LONG TERM /MONDAY THROUGH SATURDAY/...
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RAIN WILL COME TO AN END AROUND MIDDAY MONDAY AS MAIN WAVE LIFTS INTO NEW ENGLAND. 48-HOUR FORECAST RAINFALL TOTALS ENDING 00Z TUESDAY ARE AROUND 1.00 NORTH TO 1.25 INCHES SOUTH...WITH HIGHER AMOUNTS OVER THE WESTERN ALLEGHENIES AND SOUTHERN TIER COUNTIES WHERE MARGINAL INSTABILITY MAY ALLOW FOR CONVECTIVE ENHANCEMENT. THE FCST RAINFALL SHOULD HELP THE AREA RECOVER FROM /60-90+ DAY/ DEFICITS GENERALLY ON THE ORDER OF -2.00 TO -4.00 INCHES. THE LATEST DROUGHT MONITOR NOW HAS OVER HALF OF PENNSYLVANIA IN ABNORMALLY DRY /D0/ CONDITIONS WITH A SMALL AREA OF MODERATE DROUGHT /D1/ CONDITIONS FOCUSED OVER BEDFORD COUNTY. A PERIOD OF IMPROVING/DRY WEATHER IS LIKELY FROM MONDAY AFTERNOON THROUGH MONDAY EVENING...BEFORE ANOTHER WAVE OF LOW PRESSURES RIDES NE ALONG THE SLOW MOVING CFRONTAL BOUNDARY TO BRING MORE SHOWERS...MAINLY TO THE SE HALF OF THE STATE. INTO THE MID OR LATE MORNING HOURS TUESDAY. THE PATTERN TURNS QUITE UNSETTLED INTO THE MIDDLE AND SECOND HALF OF NEXT WEEK AS SEVERAL CHUNKS OF ENERGY DIG SE AND CARVE OUT A DEEP...SLOW MOVING COLD TROUGH ACROSS THE OHIO VALLEY AND CENTRAL APPALACHIANS. CRITICAL THICKNESSES AND LLVL TEMPS GET COLD ENOUGH TO SUPPORT A MIX OR CHANGE TO SNOW ACROSS THE WESTERN MTNS OF PENN LATE WED NIGHT INTO THURSDAY...BASED ON A BLEND OF THE 00Z EC/00Z GFS AND GEFS. DID FOCUS HIGHEST POPS ON THE WED NIGHT-FRI PERIOD WITH THE UPPER CLOSED LOW AND SURFACE LOW STACKING...WHICH WILL ALSO BE POTENTIAL FOR HEAVIEST RAIN THIS PERIOD. OTHERWISE IT LOOKS LIKE A CLOUDY AND WET WEEK WITH PERIODS OF GENERALLY LIGHT PRECIPITATION AND RELATIVELY COOL TEMPERATURES VS. SEASONAL CLIMATOLOGY.
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&& .AVIATION /10Z SUNDAY THROUGH THURSDAY/...
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LOW PRESSURE APPROACHING THE OHIO VALLEY OVERNIGHT HAS CAUSED WIDESPREAD RAIN SHOWERS ACROSS THE REGION AND WILL AFFECT ALL TAF SITES. MVFR TO IFR CONDITIONS EXPECTED AT ALL TAF SITES...WITH THE WORST PERIOD BEING 09Z TO 13Z. A WARM FRONT EXTENDING IN FROM THE MAIN LOW WILL TRY TO LIFT INTO THE CENTRAL MTNS...BUT WILL LIKELY STALL OVER SWRN/WRN PA. HOWEVER...SOME CLEARING IN THE DAYTIME COULD PRODUCE SCT SHRA/TSRA ACROSS ALL OF THE AREA. THE MAIN THREAT AREA FOR TSRA IS VCTY JST/AOO. A SECOND WIDE AREA OF RAIN/LOW CIGS/VIS WILL PUSH ACROSS AS THE MAIN SFC LOW PUSHES THROUGH SUN NIGHT/EARLY MONDAY MORNING. DRIER AIR WILL WORK IN FOR A VERY BRIEF TIME ON MONDAY. A WAVE RIDING THROUGH THE DEEP SOUTH AND MID-ATLANTIC STATES ON TUESDAY WILL PROBABLY SPREAD MORE RAIN INTO THE SE HALF OF THE AREA MON NIGHT/TUES. OUTLOOK... MON PM-TUE...RA POSS SE. TUE PM...NO SIG WX. WED...SHRA POSS. THU...IFR POSS IN RA/FG.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...LAMBERT LONG TERM...LAMBERT/RXR AVIATION...CERU/GARTNER

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