Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 211959 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 359 PM EDT THU MAY 21 2015 .SYNOPSIS... AN UNSEASONABLY COOL WEATHER PATTERN WILL CONTINUE THROUGH THE END OF THE WEEK WITH A RATHER CHILLY START TO THE WEEKEND. A GRADUAL WARMING TREND IS FORECAST THROUGH THE EARLY TO MIDDLE PART OF NEXT WEEK ALONG WITH AN INCREASING RISK FOR SHOWERS AND THUNDERSTORMS. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... FLOW AROUND AN AREA OF LOW PRESSURE OVER NORTH CAROLINA THIS AFTN WILL CONTINUE TO SUPPORT A LARGE AREA OF CLOUDS ACROSS PA. RADAR IMAGERY SHOWS THAT SHOWERS HAVE MOVED EAST OF THE STATE FOR THE TIME BEING. HOWEVER...A SHORTWAVE CURRENTLY MOVING ACROSS THE OHIO VALLEY WILL LIKELY HELP FIRE SOME MORE SHOWERS ACROSS THE NRN MTNS AND LAURELS LATE THIS AFTN AND EVENING. LATEST HRRR GUIDANCE SUGGESTS THOUGH THAT THEY SHOULD REMAIN ISOLATED IN COVERAGE. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
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THE MAIN LARGE SCALE UPPER TROUGH AXIS IS PROGGED TO ROTATE THROUGH THE ERN GREAT LAKES AND NRN NEW ENGLAND ON FRIDAY WHICH SHOULD DRIVE A RE-ENFORCING SFC COLD FRONT THROUGH CENTRAL PA. MODEL CONSENSUS CONTINUES TO SUGGEST ISOLD/WDLY SCT SHOWERS WITH THE FRONTAL PASSAGE BUT WITH VERY LIMITED MSTR KEPT POPS AOB 20 PCT. MAX TEMPS SHOULD MODERATE SOME BUT STILL AVG BELOW NORMAL FOR THIS TIME OF YEAR. BEHIND THE COLD FRONT ACROSS THE REGION...A SPRAWLING AREA OF HIGH PRESSURE /1030MB+/ WILL BUILD UNDER A DEVELOPING LARGE UPPER RIDGE OVER THE REGION. A REINFORCING SHOT OF COLDER AIR AHEAD OF RIDGE AXIS WILL BRING QUITE CHILLY TEMPS FOR SAT MORNING...WHERE A FREEZE IS LOOKING MORE LIKELY ACROSS MUCH OF THE NORTHERN MTNS. A /WELL COORDINATED/ FREEZE WATCH REMAINS IN EFFECT THERE...WITH SCT FROST EXTENDING INTO THE LAUREL HIGHLANDS AND PORTIONS OF THE CENTRAL MTNS. POTENTIAL FLY IN THE OINTMENT COULD BE THE WINDS...THOUGH LIGHT...REMAINING JUST HIGH ENOUGH TO KEEP TEMPS FROM BOTTOMING OUT COMPLETELY. THE COLD AIR IS QUICKLY REPLACED BY MODERATING TEMPS ON SAT...AS HIGHS REBOUND INTO THE 60S UNDER FULL SUN. NOT QUITE AS CHILLY FOR SAT NIGHT WITH LOWS SETTLING BACK INTO THE 40S IN MOST LOCALES...UPPER 30S POSS IN THE NW MTNS.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/...
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SUNDAY MARKS BEGINNING OF A ROBUST WARM-UP THAT WILL CONTINUE THROUGH NEXT WEEK. ALL GUIDANCE SIGNALS THIS WARMING TREND...WITH HIGH CONFIDENCE IN ABOVE NORMAL TEMPERATURES BY MEMORIAL DAY AS ANOMALOUS 500MB RIDGE BUILDS OVER THE EASTERN U.S. SOME DIFFERENCES ON PLACEMENT OF A WARM FRONTAL ZONE LIFTING NWD FROM THE SRN PLAINS/LWR MS VLY WHICH WILL HAVE IMPACTS ON PCPN RISK EARLY NEXT WEEK...THOUGH BEST DAILY POPS /HIGH CHANCE TO LOW LIKELY/ WILL BE OVER THE NW WITH CHANCE POPS IN THE SE. SLOW EVOLVING FLOW PATTERN GRADUALLY TAKES RIDGE AXIS EASTWARD AS TROUGH OVER THE CENTRAL PORTION OF THE COUNTY WEAKENS...WITH JET STREAM RETREATING NORTHWARD AND BECOMING MORE ZONAL. THIS WILL STRETCH A SLOWLY APPROACHING COLD FRONTAL BOUNDARY MORE W-E...AND LIKELY REMAINING OFF TO OUR NW. WE/LL REMAIN ON THE VERY WARM AND MUGGY SIDE OF THE FRONT IN A VERY SUMMER-LIKE PATTERN...KEEPING DAILY SHOWER/TSTM CHANCES IN THE FORECAST. HIGHS FROM MONDAY ONWARD WILL RANGE FROM THE UPPER 70S NORTH TO THE MID/UPPER 80S SE...WITH MILD LOWS IN THE 60S TO AROUND 70 IN THE SE.
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&& .AVIATION /20Z THURSDAY THROUGH TUESDAY/... FLOW AROUND AN AREA OF LOW PRESSURE OVER NORTH CAROLINA THIS AFTN WILL CONTINUE TO SUPPORT A LARGE AREA OF CLOUDS ACROSS PA. MOST OF THE CIGS ARE...AND WILL REMAIN VFR...BUT UPSLOPE FLOW IS CAUSING SOME LOWERED CIGS AT KAOO AND KUNV AND IFR AT KJST. SHOWERS HAVE MOVED EAST OF THE STATE FOR THE TIME BEING. HOWEVER...A SHORTWAVE MOVING ACROSS THE OHIO VALLEY WILL LIKELY HELP FIRE SOME MORE SHOWERS ACROSS THE WRN AND NRN MTNS LATE THIS AFTN AND EVENING....THOUGH THEY SHOULD REMAIN ISOLATED IN COVERAGE. IMPROVING FLYING CONDS ARE EXPECTED LATER THIS EVENING...AS WINDS SHIFT TO THE NW...DRAWING DRIER AIR AND CLEARING SKIES INTO THE REGION. HIGH PRESSURE WILL BUILD ACROSS THE REGION FRIDAY INTO THE WEEKEND. OUTLOOK... FRI-SUN...NO SIG WX EXPECTED. MON-TUE...MAINLY VFR...MVFR POSS IN SHRA/TSRA. && .CTP WATCHES/WARNINGS/ADVISORIES...
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FREEZE WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY MORNING FOR PAZ004>006-010-011-017-037.
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&& $$ SYNOPSIS...GARTNER NEAR TERM...GARTNER SHORT TERM...GARTNER/RXR LONG TERM...RXR/STEINBUGL AVIATION...FITZGERALD/GARTNER

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