Area Forecast Discussion
Issued by NWS State College, PA

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990 FXUS61 KCTP 301444 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1044 AM EDT SAT APR 30 2016 .SYNOPSIS... MOIST EAST TO NORTHEAST LOW-LEVEL FLOW WILL BRING WIDESPREAD CLOUDS AND PATCHY LIGHT DRIZZLE TO THE REGION THIS MORNING. A BRIEF PERIOD OF DRYING AND SOME FLEETING SUNSHINE IN A FEW SPOTS WILL OCCUR FOR THIS AFTERNOON...A LARGE AREA OF LIGHT TO MODERATE RAIN MOVES IN FOR TONIGHT AND SUNDAY. CLOUDY SKIES WITH SCATTERED SHOWERS WILL LINGER THROUGH AT LEAST MONDAY MORNING. PARTIAL CLEARING AND MAINLY DRY CONDITIONS WILL RETURN FOR MONDAY NIGHT THROUGH TUESDAY. && .NEAR TERM /UNTIL 7 PM THIS EVENING/...
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LOOKING PRETTY DARK FOR MOST OF CENTRAL PA - BUT THERE IS A VERY BRIEF WINDOW OF OPPORTUNITY FOR SMALL BREAKS IN THE CLOUDS. THE BREAKS WHICH ALREADY OCCURRED IN THE E AND FAR SW HAVE BEGUN TO FILL BACK IN VERY QUICKLY WITH DIURNAL CU AND SOME SLOUGH OFF OF THE LARGER SHIELD TO THE WEST. THE MID CLOUD DECK OVER OH/WV IS ADVANCING VERY QUICKLY AND THE RACE IS ON. HAVE NUDGED MAXES DOWN A DEG OR TWO DUE TO DISMAL CONDITIONS IN THE CENTRAL MTNS. HAVE ALSO REMOVED THE POPS FOR THE SW BEFORE 21Z...AND IT COULD EVEN STAY DRY THERE THRU 00Z. PREV... WIDESPREAD...SHALLOW LOW CLOUDS AND FOG (MAINLY LIGHT) WILL PERSIST THROUGH DAYBREAK. BASED ON THE 0-3 DEG F SFC T/TD SPREAD AT ALL LOCATIONS, TEMPS WILL ONLY FALL A FEW DEG F THROUGH 11Z. EARLY MORNING LOWS WILL RANGE FROM NEAR 40F ACROSS THE NORTHERN MTNS...TO THE MID AND UPPER 40S IN THE SOUTH. WINDS WILL BE LIGHT FROM THE NE. FOR TODAY...WE SHOULD REMAIN BASICALLY PRECIPITATION FREE OVER MOST OF THE AREA FOR MOST OF THE DAY. HOWEVER...I`M NOT OPTIMISTIC FOR SIGNIFICANT IMPROVEMENT SKY COVER-WISE. A 1-2 KFT THICK LAYER OF BKN-OVC STRATO CU SHOULD PERSIST AT MOST LOCATIONS DURING THE LATE MORNING AND AFTERNOON HOURS. THE NEXT SYSTEM APPROACHING FROM THE OHIO VALLEY WILL WARRANT THE MENTION OF AT LEAST CHANCE POPS OVER THE SW BY THE LATTER HALF OF THE AFTERNOON. WITH NO RAIN TO ADD TO THE ALREADY COOL AIRMASS...WE SHOULD MANAGE TO BE ABOUT 5-8 DEG WARMER THAN FRIDAY ON AVERAGE...OR BETWEEN 55-60F FOR A MID AFTERNOON HIGH TEMP.
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&& .SHORT TERM /7 PM THIS EVENING THROUGH 6 AM SUNDAY/... A SURGE OF MOISTURE WILL MOVE INTO THE STATE FOR TONIGHT AND SUNDAY MORNING...VIA A 2 SIGMA SOUTHERLY 850 MB JET. A LARGE SHIELD OF LIGHT (TO BRIEFLY MODERATE) RAIN WILL MOVE INTO THE SW COUNTIES NEAR OR SHORTLY BEFORE THE BEGINNING OF THIS PERIOD...BEFORE OVERSPREADING THE REST OF CENTRAL PENN AND THE SUSQ VALLEY THIS EVENING. EXPECT ABOUT ONE-QUARTER TO ONE-HALF INCH OF RAINFALL BY 12Z SUNDAY ACROSS THE CWA WITH THE GREATER AMOUNTS LIKELY ACROSS THE SOUTHERN HALF OF THE STATE. LOW TEMPS TONIGHT WILL VARY FROM THE MID TO UPPER 40S ACROSS CENTRAL AND NORTHERN PENN...TO AROUND 50F OVER THE SOUTHERN TIER COUNTIES. && .LONG TERM /SUNDAY THROUGH FRIDAY/... WAVE OF LOW PRESSURE TRACKING FROM THE MID MS/OH VALLEYS INTO THE MID ATLANTIC REGION WILL BRING MUCH NEEDED RAINFALL TO CENTRAL PA EARLY IN THE PERIOD. PERIODS OF RAIN...AND A CHANCE OF TSRA ARE THE GENERAL FORECAST FOR SUNDAY INTO EARLY MONDAY. THE NORTHERN EDGE OF AN AREA OF 3-4 SIGMA 850 MB MOISTURE FLUX SLIDES EAST...ACROSS THE SOUTHERN THIRD OF PENN SUNDAY INTO SUNDAY EVENING. THE TRACK OF THE ASSOCIATED AREA OF SFC LOW PRESSURE IS A TRICKY CALL AT THIS POINT. LATEST OPER AND ENS GUIDANCE INDICATES THAT A LEAD SFC LOW WILL HEAD NE ACROSS OHIO AND INTO NW PENN OR SWRN NEW YORK BEFORE OCCLUDING WITH A SECONDARY TRIPLE POINT LOW FORMING NEAR KHTS LATE SUNDAY. UNSTABLE AIR WITH SFC BASED CAPES OF SVRL HUNDRED TO APPROX 1000 J/KG WILL NOSE OVER THE WRN PENN LOWLANDS AND WESTERN ALLEGHENY PLATEAU SUNDAY AFTERNOON AND NIGHT - SUPPORTING THE CHC FOR TSRA. SPC`S MRGL RISK STAYS JUST SW OF THE FCST AREA...THOUGH 850 MB LI/S DIPPING TO MINUS 2 TO MINUS 4 SPREAD EAST AND OVER THE CLOUDY...SHALLOW COOLER AIRMASS ENTRENCHED ACROSS THE CENTRAL RIDGE AND VALLEY REGION OF THE STATE...PROMPTING SPC TO BLANKET ALL BUT THE NW CORNER OF OUR CWA UNDER GENERAL TSRA. 0-1 KM EHI`S OF 0.5 TO 1.5 M2/S2 COULD SUPPORT SOME ROTATING UPDRAFTS ACROSS THE REGION NEAR AND TO THE WEST OF RT 219 LATE SUNDAY AFTERNOON AND EVENING. 48-HOUR FORECAST RAINFALL TOTALS ENDING 00Z TUESDAY ARE 0.75 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 TUESDAY BEFORE THE PATTERN TURNS UNSETTLED INTO THE MIDDLE AND SECOND HALF OF NEXT WEEK. THE GLOBAL ENSEMBLE MEANS ALL SHOW AN AMPLIFIED/ANOMALOUS MEAN UPPER TROUGH DEVELOPING OVER THE ERN CONUS BUT THERE ARE STILL MULTIPLE SHORTWAVE PIECES OF THE FCST PUZZLE TO RESOLVE. THE GUIDANCE AGREES IN PRINCIPLE THAT AN ELONGATED AREA OF SFC LOW PRESSURE WILL BE NEAR OR ALONG THE EAST COAST/WRN ATLANTIC. HOWEVER QUESTION MARKS WITH THE DETAILS ALOFT LEADS TO LOW CONFIDENCE/PREDICTABILITY IN THE RAINFALL TIMING AND COVERAGE PATTERN. BELOW NORMAL HEIGHTS AND DEEPENING UPPER TROUGH SHOULD FAVOR RELATIVELY COOL TEMPERATURES VS. SEASONAL CLIMATOLOGY. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
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ALL IS ON TRACK. VISBYS AND CIGS UP FOR ALL BUT AOO. EVEN JST HAS THE CIG RISING. PREV... WHILE THE CLOUDS ARE SLOWLY BREAKING UP IN SOME LOCATIONS...LOW DEWPOINT DEPRESSIONS...CALM OR EASTERLY WINDS WILL KEEP IFR CIGS AND VSBYS AT AOO...UNV THROUGH MID MORNING. CONDITIONS WILL SLOWLY IMPROVE FOR A TIME TODAY AS WEAK HIGH PRESSURE MOVES INTO THE REGION...BUT CONDITIONS WILL DETERIORATE ONCE AGAIN TONIGHT INTO SUNDAY WITH THE APPROACH OF ANOTHER FRONTAL SYSTEM. EXPECT RAIN TO MOVE IN FROM THE SOUTHWEST BETWEEN 00Z TO 03Z SUNDAY. OUTLOOK... MON...WIDESPREAD MVFR/IFR WITH OCCASIONAL RAIN. TUE...NO SIG WX. WED...MVFR WITH AREAS OF RAIN.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...DANGELO/LAMBERT SHORT TERM...LAMBERT LONG TERM...LAMBERT/STEINBUGL AVIATION...DANGELO/CERU

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