Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 150550 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 150 AM EDT MON SEP 15 2014 .SYNOPSIS... HIGH PRESSURE OVERHEAD WILL MAINTAIN A RATHER LONG STRETCH OF COOL AND MAINLY DRY WEATHER. A WEAK FRONTAL SYSTEM WILL PASS THROUGH MONDAY NIGHT AND EARLY TUESDAY MORNING...AND WILL BE THE ONLY TIME WHEN RAIN IS POSSIBLE THROUGH THE END OF THE COMING WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 23Z RAP /AND LATEST REGIONAL SFC OBS/ INDICATES THAT A SECONDARY CENTER OF SFC-925 MB HIGH PRESSURE WILL DRIFTING ACROSS SWRN AND SCENT PENN OVERNIGHT. THIS WEATHER FEATURE WILL SUPPLY MAINLY CLEAR SKIES AND L/V WIND ACROSS MUCH OF THE FCST AREA TONIGHT WITH JUST SOME PATCHY STRATO CU OR RIBBONS OF THIN CIRRUS DRIFTING BY. HOWEVER...THE LIGHT/WNW FLOW ACROSS THE NW AND NCENT MTNS /COMBINED WITH LIMITED LLVL MOISTURE OFF THE UPSTREAM GLAKES AND 1-2 DEG C OF COOLING IN THE 925-850 MB LAYER/ WILL RESULT IN AREAS OF BKN-OVC STRATO CU DRIFTING ESE FOR THE NEXT 3-5 HOURS. THE HIGH WILL BE ACCOMPANIED BY BELOW NORMAL PWATS OF LESS THAN 0.75 OF AN INCH...LIGHT SFC-925 MB WINDS /GRADUALLY VEERING AROUND TO THE N-E/...AND BELOW NORMAL TEMPS AT 850 MB. EXPECTING THAT WE SEE A GRADUAL DECREASE IN THE STRATO CU FOR SEVERAL HOURS EARLY MONDAY MORNING...THIS HIGH AND ITS ASSOCIATED COOL AIRMASS WILL BRING CONDITIONS FAVORABLE FOR THE FIRST WIDESPREAD FROST OF THE SEASON ACROSS NRN PENN...WHERE TEMPS OF 33-37 ARE LIKELY LATE TONIGHT THROUGH EARLY MONDAY. A FROST ADVISORY REMAINS IN EFFECT ACROSS 4 OF OUR TYPICALLY COLDEST NRN MTN COUNTIES - FROM 08-13Z MONDAY. ELSEWHERE...PATCHY STRATO CU AND THIN STREAKS OF CIRRUS WILL HAVE MINIMAL EFFECT ON TEMPS OVERNIGHT...WITH THE MERCURY FALLING STEADILY TO CHILLY READINGS BY DAYBREAK MONDAY IN THE 30S NORTH...TO MID 40S SOUTH. LARGE AIR/WATER TEMP SPREAD...AND SFC DEWPOINTS BETWEEN 43-47F WILL LEAD TO PATCHY DENSE RIVER VALLEY FOG...ESPECIALLY THROUGHOUT THE DEEPER VALLEYS OF CENTRAL AND NRN PENN. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... ANY LOWER CLOUDS IN THE SC/SE IN THE MORNING SHOULD SLIDE TO THE EAST AND DISSIPATE AS WE SAW WHAT HAPPENED SUN MORNING. GOOD SHORT WAVE MOVING W-E OVER THE GREAT LAKES WILL PULL ENOUGH MOISTURE INTO THE AREA TO CREATE A FEW TENTHS OF AN INCH OF RAIN MON NIGHT. THE POPS SHOULD BE HIGH IN THE N AND NOT QUITE AS HIGH IN THE SW...BUT SHOWERS ALSO LIKELY OR BETTER IN THE SE. THE FAST MOVEMENT OF THE SYSTEM SHOULD PUSH ALL OF THE PRECIP TO THE EAST OF THE AREA AT OR JUST AFTER SUNRISE ON TUESDAY MORNING. MAXES MONDAY WILL GET PRETTY CLOSE TO NORMALS...AND THE CLOUDS AND HIGHER DEWPOINTS SHOULD HOLD TEMPS UP IN THE 50S IN MOST PLACES TUESDAY MORNING. THE COOLING EFFECTS OF THE RAIN AND EARLY PASSAGE OF THE COLD FRONT WILL HELP THE NRN TIER DIP INTO THE 40S. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... SHORTWAVE LIFTING INTO NEW ENGLAND BY TUE...BUT SCT LINGERING LIGHT SHOWERS MAY PERSIST THROUGH MIDDAY BEFORE COOLER...DRIER AIR FILTERS IN WITH INCREASING AMOUNTS OF SUNSHINE. NORTHWEST FLOW AND SURFACE HIGH PRESSURE WILL BRING QUIET WEATHER FOR LATER TUE THROUGH FRI...WITH JUST A WEAK FRONTAL BOUNDARY WASHING OUT AS IT MOVES THROUGH MIDWEEK...FOLLOWED BY A REINFORCING SHOT OF COOLER AIR. EXPECT CHILLY MORNINGS /POSS BOTTOMING OUT IN THE 30S IN PORTIONS OF NORTHERN MOUNTAINS/ AND DAILY HIGHS RUNNING ABOUT 5F BELOW NORMAL. GFS/ECMWF STILL DIFFER ON STRENGTH OF A SHORTWAVE TROUGH HEADED OUR WAY FOR NEXT WEEKEND...BUT OVERALL TREND WILL BE FLOW TURNING AROUND TO THE SOUTHWEST WITH A MODERATION OF TEMPS STARTING SAT...AND RAIN CHANCES INCREASING FOR SUNDAY. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... A WEAK SHORTWAVE ALOFT IS HELPING TO PRODUCE SOME STRATOCU OVER THE NW AND CENTRAL MTNS. MVFR CONDITIONS ARE POSSIBLE FROM THE STRATUS SLIDING IN FROM THE SOUTH AFTER MIDNIGHT. THE LAYER IS CURRENTLY HUNG UP OVER NRN WV AND IS NOT ENTIRELY LIKELY TO MAKE IT INTO CENTRAL PA. TRAPPED MOISTURE HAS ALLOWED FOR IFR CIGS AT IPT...WHICH SHOULD VARY OVERNIGHT. EXPECT MVFR POSSIBLE THROUGH THE LOWER SUSQ WHERE PATCHY FOG IS EXPECTED IN THE MORE- CLEAR AREAS IN THE MORNING. IFR POSSIBLE IN THE DEEPER VALLEYS AROUND SUNRISE. A HEALTHY SHORT WAVE WILL MOVE W-E THRU THE GREAT LAKES AND DRAG COLD FRONT THROUGH MONDAY NIGHT AND VERY EARLY TUESDAY. SHOWERS ARE EXPECTED TO CREATE REDUCTIONS IN THE FLYING CONDITIONS MONDAY NIGHT...BUT SHOULD BE OFF TO THE EAST BY 12Z TUES. LINGERING LOWER CLOUDS AND SOME FOG WILL LAST INTO THE DAY ON TUESDAY BEFORE CLEARING STARTS. OUTLOOK... TUE NIGHT-FRI...AM FOG POSS...OTHERWISE NO SIG WX. && .CTP WATCHES/WARNINGS/ADVISORIES... FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR PAZ005-006-010- 037. && $$ SYNOPSIS...DANGELO/LAMBERT NEAR TERM...DEVOIR/LAMBERT SHORT TERM...DANGELO LONG TERM...RXR AVIATION...CERU/GARTNER

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