Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 200910 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 510 AM EDT SAT SEP 20 2014 .SYNOPSIS...
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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 AND A FEW THUNDERSTORMS TO THE REGION ON SUNDAY. A LARGE AREA OF HIGH PRESSURE AND A BLOCKING UPPER- LEVEL RIDGE OVER CENTRAL CANADA WILL LEAD TO GENERALLY FAIR AND COOL WEATHER FOR MOST OF NEXT WEEK.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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CLOUDS CERTAINLY COVERING THE AREA EXPECTED WITH THE DOWNSLOPE OFF THE ALLEGHENY PLATEAU THE LIMITING FEATURE AT THIS TIME. SEE SOME BREAKS FORMING IN THE CLOUDS ALREADY TO OUR SOUTH AS THE WINDS COME MORE FROM THE SOUTH AND NOT SO MUCH FROM THE OCEAN. THIS COMBINED WITH THE LACK OF LOW/IFR CIGS - ALL OBS AOA 1KFT - WILL PULL MENTIONS OF FOG/DRIZZLE. WHILE THERE MAY STILL BE VERY SPOTTY PLACES ON THE HIGHER SE-FACES OF THE HILLS BETWEEN UNV/IPT/AOO AND MDT...THERE IS ALREADY DRYING STARTING. THE CONTINUED EASTWARD MOVEMENT OF THE OFF-SHORE LOW WILL CONTINUE THE IMPROVEMENT THROUGH THE DAYTIME. MDLS DO POOL SOME 8H MSTR OVER THE NW AND WILL SHADE A FEW CLOUDS THERE IN THE AFTN...BUT IN GENERAL...IT SHOULD BE BRIGHTENING UP THROUGH THE MORNING AND TURN OUT PRETTY NICE IN THE AFTN. MAXES IN THE 70S OVERALL AND PERHAPS AN 80F TEMP ALONG THE LOWER SUSQ RIVER...STAYING THE COOLEST IN THE SPINE OF THE MTNS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
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CLEARING MAY ALMOST COMPLETE THIS EVENING...IF IT WERE NOT FOR SOME HIGHER CLOUDS MOVING IN FROM THE WEST. THEN THE DIGGING TROUGH TO THE WEST WILL PULL MOISTURE UP FROM THE MIDWEST AND AN ADVANCE TROUGH WILL TRY TO MAKE SHOWERS IN THE NWRN COS BY DAYBREAK ON SUNDAY. THE MAIN LOW AND UPPER TROUGH WILL BE OFFSET ENOUGH THAT THE PATTERN SHOULD REMAIN PROGRESSIVE AND THE MAIN COLD FRONT WILL PASS THROUGH SUNDAY EVENING. THE DEEP LAYER SHEAR AND SOME DECENT INSTABILITY IN THE LOW LEVELS COULD PRODUCE A FEW STRONGER STORMS AS THE FRONT MOVES THROUGH. QPF SEEMS RATHER PALTRY WITH PWATS BRIEFLY PEAKING AROUND 1.5 INCHES. ALL THE SHOWERS/STORMS SHOULD BE MOVING ALONG STEADILY. THE NAM CRANKS UP MORE SHOWERS IN THE POST- FRONTAL AIR...AND HAVE EXTENDED SCT POPS THROUGH THE NIGHT AND INTO MONDAY MORNING FOR THE WESTERN HIGHLANDS. THE 8H TEMPS DIP INTO THE +1-2C RANGE FOR A BRIEF TIME ON MONDAY OVER THE NW. MAX TEMPS WILL THEREFORE TAKE A TUMBLE ROM THE MID70S-L80S ON SUNDAY TO THE M50S- 70F ON MONDAY. THE FLOW DOES NOT REALLY RELAX UNTIL MONDAY EVENING AS THE HIGH SLIDES INTO THE OHIO VALLEY.
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&& .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
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THE RAIN EVENT IN THE SHORT TERM WILL LIKELY BE THE ONLY ONE THAT SHOULD AFFECT THE REGION IN THE NEXT 7-12 DAYS AS A BLOCKING 500HPA RIDGE WITH OVER 2 SIGMA HEIGHT ANOMALIES SHOULD PROVIDE A PROLONGED PERIOD OF DRY WEATHER. HIGH PRESSURE BUILDS IN AS THE LONG TERM IS BEGINNING AND IT 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. DID NOT YET DRAW THE DIURNAL VALLEY FOG AND LOW CLOUDS LIKELY TO AFFECT THE REGION EACH MORNING ONCE THE BIG HIGH TAKES HOLD.
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&& .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... 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. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO NEAR TERM...DANGELO SHORT TERM...DANGELO LONG TERM...GRUMM AVIATION...FITZGERALD/LAMBERT

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