Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 200656 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 256 AM EDT SAT SEP 20 2014 .SYNOPSIS... AFTER A BRIEF PERIOD OF CLOUDS AND PATCHY DRIZZLE THIS MORNING...FAIR WEATHER IS EXPECTED FOR THE SECOND HALF OF THE DAY. A FRONTAL SYSTEM WILL BRING SCATTERED SHOWERS TO THE REGION ON SUNDAY. ANOTHER LARGE AREA OF HIGH PRESSURE AND A BLOCKING UPPER- LEVEL RIDGE OVER CENTRAL CANADA WILL BRING ADDITIONAL FAIR AND COOL WEATHER FOR MOST OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... CLOUDS CONTINUE TO EXPAND ON SCHEDULE AND IN LINE WITH CURRENT FCSTS. EXPECT THESE CLOUDS TO CONTINUE TO LOWER AND BECOME MORE WIDESPREAD OVERNIGHT AS THE LONG FETCH OFF THE ATLANTIC ASCENDS THE MOUNTAINS OF CENTRAL PA. WHILE THE DRIZZLE/FOG MAY NOT BE QUITE AS BAD AS ADVERTISED...THE RIDGES WILL STILL BE SHROUDED AND MISTY AND CARE WILL NEED TO BE TAKEN WHEN TRAVELING OVER THE MOUNTAINS. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/... THE WINDS SHOULD CONTINUE TO VEER TODAY AND HELP THE TEMPERATURES WARM AND ALLOW THE LOW CLOUDS TO BREAK UP THROUGH THE MORNING AND EARLY AFTERNOON. AFTER THE CLOUDY START...TEMPS WILL REBOUND NICELY IN THE AFTERNOON WITH MAXES RISING INTO THE 70S FOR MOST PLACES - ESP IN THE VALLEYS OF THE SE WHERE THERE SHOULD BE LESS CLOUD COVER. WILL HOLD THE TEMPS AROUND 70F ALONG THE SPINE OF THE MOUNTAINS WHERE THE CLOUDS WILL TAKE LONGEST TO BREAK. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... ALL OF THE GUIDANCE SHOWS A FRONTAL SYSTEM MOVING NORTHWEST TO SOUTHEAST ACROSS THE STATE OVERNIGHT SATURDAY INTO SUNDAY EVENING. THIS IS MOST LIKELY THE ONLY RAIN EVENT THAT SHOULD AFFECT THE REGION OF THE NEXT 7-12 DAYS AS A BLOCKING 500 HPA RIDGE WITH OVER 2 SIGMA HEIGHT ANOMALIES SHOULD PROVIDE A PROLONGED PERIOD OF DRY WEATHER. AT THIS TIME THE MODELS AND ENSEMBLES ALL IMPLY AN INCREASE IN SHOWER ACTIVITY AFTER MIDNIGHT NORTHWESTERN PENNSYLVANIA AND TOWARD SUNRISE IN CENTRAL AREAS EARLY MORNING. THE GEFS AND SREF BOTH IMPLY THE 12 HOUR PERIOD FOR THE BEST RAINFALL WILL BE BETWEEN ABOUT 8 AM AND 8 PM SUNDAY. THE RAINFALL LINGERS IN THE ENSEMBLE PDF UNTIL BETWEEN 8 AND 2 AM SUNDAY NIGHT INTO MONDAY IN THE EAST. THE RAPIDLY LOWERING PW FIELD IMPLIES ALL RAIN GONE IN EAST AFTER MIDNIGHT SUNDAY. AT THIS TIME THE HIGHER POPS AND HIGHER QPFS SHOULD BE IN THE NORTHERN AREAS. FEW MEMBERS OF ANY EFS SHOW MUCH MORE THAN 0.25 INCHES WITH PERHAPS 40 PERCENT SHOWING 0.50 INCHES IN THE NORTHERN AREAS. MOST QPFS IMPLY A 0.10 TO 0.20 INCH RAINFALL EVENT. KIND OF ANEMIC. DID MENTION THUNDERSTORMS AS THERE IS A WARM SURGE AND SOME HINTS OF MODEST CAPE IN THE HIGHER RESOLUTION MODELS AND EFS PERHAPS 600 TO 800JKG-1. LOWER IN THE GEFS. A FEW THUNDERSTORMS COULD BOOST QPFS UP A BIT IF THEY APPEAR. HIGH PRESSURE BUILDS IN MONDAY BEHIND THE FRONT AND SORT OF PARKS ITSELF OVER NEW YORK AND NEW ENGLAND WITH +2 TO +3 SIGMA ABOVE NORMAL MSLP ANOMALIES BY WEDNESDAY-THURSDAY. HIGH CONFIDENCE IN THIS FORECAST AS THE MODELS ALL SHOW A BLOCKING 500 HPA ANTICYCLONE TO THE NORTHWEST AS A MASSIVE 500 HPA POSITIVE HEIGHT ANOMALY OF +2 TO +3 SIGMA DEVELOPS OVER CENTRAL CANADA BY THURSDAY AND INTO FRIDAY. OUR MODELS AND EFS DO WELL FORECASTING ANTICYCLONES. SO I AM HIGH ON THE FAIR WEATHER FORECAST NEXT WEEK. ONLY FUN ISSUES ARE HOW MUCH RAIN SUNDAY AND HOW SUNNY WILL IT GET BEHIND THE FRONT MONDAY. DID NOT ATTEMPT TO DRAW THE DIURNAL FOG AND LOW CLOUDS LIKELY TO AFFECT THE REGION ONCE THE BIG HIGH TAKES HOLD. THIS WILL BE A NEARLY IDEAL DIURNAL FOG PATTERN WED-SUNDAY. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
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SFC HIGH PRESSURE EXITING WELL EAST OF THE NEW ENGLAND COAST...AND A COLD FRONT MOVING ACROSS THE UPPER GLAKES TODAY WILL CREATE A LIGHT TO MODERATE SOUTHERLY BREEZE OF 8-10 KTS TODAY WITH SOME GUSTS INTO THE LOWER 20 KTS RANGE THIS MORNING AS THE AXIS OF A 35-40 KT SOUTHERLY 850 MB JET SHIFTS EAST ACROSS THE REGION. EARLY MORNING 11-3.9 MICRON SATL LOOP SHOWS AN EXTENSIVE AREA OF MVFR STRATUS ENTRENCED ACROSS THE CENTRAL RIDGE AND VALLEY REGION OF PENN...ALONG WITH THE NORTHERN MTNS OF THE STATE. KBFD AND JST HAVE RECENTLY ENTERED INTO THIS MVFR REALM AS THE LLVL MOISTURE IS PUSHED NORTHWESTWARD ACROSS THE ALLEGHENY FRONT. EXPECT THE POTENTIAL FOR FLUCTUATION BETWEEN MVFR AND VFR NEAR THE RT 219 CORRIDOR FROM KBFD...SOUTH TO KFIG AND KJST THROUGH 13Z...WHILE ALL OTHER CENTRAL AND ERN PENN TAF SITES STAY STUCK WELL INTO THE MVFR CIG RANGE. PERIODS OF MVFR VSBYS WILL ALL OCCUR...MAINLY IMPACTING THE SUSQ VALLEY AIRFIELDS. PATCHY LIGHT DRIZZLE IS POSSIBLE THROUGH THE MID MORNING HOURS...PRIMARILY ON THE UPSLOPE...SE FACES OF THE RIDGES. LLWS WILL BE LIKELY OVER ALL CENTRAL PENN AND SUSQ VALLEY AIRFIELDS EARLY THIS MORNING. THE BASE AND BULK OF THIS SHEARED LAYER WILL OCCUR WITHIN THE UPPER HALF OF THE STRATUS CLOUD DECK. SOUTHERLY WINDS IN THE 1500-2000 FT AGL LAYER WILL BE BLOWING AT 30-35 KTS THROUGH ABOUT 13Z. AFTER 13Z TODAY CONDITIONS WILL STEADILY IMPROVE AND BECOME VFR IN ALL LOCATIONS BY 15Z...WITH BKN STRATO CU BASED AROUND 4500-5000 FT AGL. VFR EXPECTED TO CONTINUE FOR MOST OF THE NIGHT FOLLOWED BY AREAS OF MVFR CIGS /AND VSBYS IN LIGHT FOG/ AFTER 07Z SUNDAY. OUTLOOK... SUN...AM FOG POSSIBLE EASTERN PA. SLIGHT CHC OF PM TSRA IMPACTS W MTNS. MON...AM LOW CIGS POSS W MTNS. TUE-WED...NO SIG WX EXPECTED.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO/LA CORTE NEAR TERM...DANGELO/LA CORTE SHORT TERM...DANGELO/GARTNER LONG TERM...GRUMM AVIATION...LAMBERT/FITZGERALD

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