Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 291000 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 600 AM EDT WED OCT 29 2014 .SYNOPSIS...
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A COLD FRONT OVER SOUTHEAST PA THIS MORNING WILL PUSH EAST OF THE STATE LATER TODAY. A POTENT SHORTWAVE WILL CARVE OUT A DEEP TROUGH OVER THE NORTHEAST CONUS AS IT DIVES ACROSS THE REGION LATE FRIDAY AND SATURDAY. THE UPPER TROUGH WILL LIFT OUT BY EARLY NEXT WEEK...REPLACED BY A RIDGE BUILDING ALONG THE EAST COAST.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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SFC ANALYSIS SHOWS COLD FRONT PUSHING INTO THE LOWER SUSQ VALLEY AT 09Z. ALL MDL DATA PUSHES THE FRONT EAST OF EVEN LANCASTER CO BY ARND 12Z. HOWEVER...RADAR CONTINUES TO SHOW NARROW BAND OF POST- FRONTAL RAIN FALLING ACROSS THE CENTRAL COUNTIES IN ASSOC WITH FGEN FORCING CAUSED BY THERMALLY DIRECT CIRCULATION BENEATH UPPER JET ENTRANCE REGION. ALL NEAR TERM MDLS SHOWING THIS BAND OF 700-850MB FGEN FORCING SLOWLY SLIDING EASTWARD TODAY...IMPLYING PERSISTENT SHOWERS ACROSS THE SE COUNTIES INTO THIS AFTN. HAVE PAINTED CATEGORICAL POPS SE OF OF KAOO/KUNV/KIPT THIS MORNING...A SCENARIO SUPPORTED BY THE 00Z GEFS. BACK EDGE OF RAIN SHOULD BE EXITING LANCASTER CO BY ARND 21Z. BRIGHTENING SKIES SHOULD EVENTUALLY OVERSPREAD THE CENTRAL AND WESTERN COUNTIES BY LATE AFTN. HOWEVER...LAKE EFFECT STRATOCU WILL ALSO BE FORMING IN THE NW...AS CHILLY AIR FLOWS OVER THE STILL WARM LAKE ERIE. THE CLOUD COVER AND CAA SHOULD TRANSLATE TO LITTLE WARMING FROM AM LOWS TODAY. CONSALL INDICATES HIGHS FROM THE L50S NW TO L60S OVR THE SUSQ VALLEY.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
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CHILLY AIR FLOWING OVR LK ERIE SHOULD SUPPORT SCT LAKE EFFECT -SHRA ACROSS THE NW MTNS TONIGHT. PASSAGE OF MID LVL SHORTWAVE AND FALLING INVERSION HGTS SHOULD CAUSE THOSE -SHRA TO DIMINISH AFTER 06Z. MDL SOUNDINGS BECOME MARGINALLY COLD ENOUGH TO PERHAPS SUPPORT A FEW FLURRIES OVR THE HIGHEST TERRAIN OF THE NW MTNS THURSDAY MORNING. LG SCALE SUBSIDENCE ASSOC WITH RIDGING AT SFC AND ALOFT SHOULD ENSURE A DRY THURSDAY FOR NEARLY ALL OF CENTRAL PA WITH THE EXCEPTION OF A FEW MORNING SPRINKLES OVR THE NW MTNS. HOWEVER...LAKE MOISTURE TRAPPED BENEATH SUBSIDENCE INVERSION WILL LIKELY RESULT IN A GOOD DEAL OF STRATOCU ACROSS THE ALLEGHENY PLATEAU...WHILE DOWNSLOPING NW FLOW YIELDS A BRIGHTER DAY ACROSS THE SUSQ VALLEY. ENS MEAN 925MB TEMPS SUPPORT MAX TEMPS FROM THE M40S ALLEGHENIES...TO M50S SUSQ VALLEY.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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ALL MED RANGE GUIDANCE STILL SHOWING A POTENT SHORTWAVE DIVING SE FROM CANADA AND CARVING OUT A DEEP TROUGH OVR THE NORTHEAST CONUS BY SATURDAY. ASSOC SFC CLIPPER LOW IS PROGGED TO TRACK ACROSS EASTERN OHIO/WESTERN PA LATE FRIDAY AND FRIDAY NIGHT...BRINGING THE BEST CHANCE OF PRECIP TO THAT AREA. BOTH GEFS AND OPER ECMWF/CANADIAN MDLS ALL POINT TOWARD A MAINLY RAIN EVENT. HOWEVER...AS UPPER LOW CUTS OFF SOUTH OF PA EARLY SATURDAY...THERMAL PROFILES MAY BECOME JUST COLD ENOUGH TO PRODUCE A LIGHT COATING OF SNOW ACROSS THE HIGH TERRAIN OF THE ALLEGHENIES. AS ENERGY SHIFTS FROM CLIPPER TO DEVELOPING COASTAL LOW LATER SATURDAY...TIGHTENING PRES GRADIENT AND NW FLOW WILL DRAW MUCH COLDER/DRIER AIR INTO THE REGION. OPER RUNS AND NEARLY ALL ENSEMBLE MEMBERS KEEP COASTAL LOW FAR ENOUGH OUT TO SEA TO NOT DIRECTLY IMPACT CENTRAL PA. HOWEVER...COLD NW FLOW MAY PRODUCE LE SNOW SHOWERS ACROSS THE NW MTNS SAT NIGHT. TEMPS THIS WEEKEND WILL ALMOST CERTAINLY BE THE COLDEST YET THIS SEASON. ENS MEAN 8H TEMPS POINT TOWARD DAYTIME HIGHS FROM THE U30S OVR THE ALLEGHENIES TO THE 40S ELSEWHERE. THE COLDEST NIGHT OF THIS OUTBREAK WILL LIKELY BE SUNDAY NIGHT...WHEN SFC HIGH BUILDS OVR THE REGION. THOSE LOCATIONS THAT HAVE YET TO SEE A FREEZE WILL LIKELY GET IT BY MON AM. HIGH CONFIDENCE IN A PERIOD OF DRY WEATHER SUNDAY/MONDAY...WHEN ALL GUIDANCE BUILDS SFC HIGH AND ASSOC DRY AIR MASS ACROSS PA. AN APPROACHING COLD FRONT WILL BRING THE NEXT CHC OF SHRA BY LATE TUES.
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&& .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... SFC COLD FRONT EXTENDED FROM KBGM TO KIPT AND KAOO AT 07Z. THIS FRONT WAS PRECEDED BY AN AREA OF MAINLY LIGHT RAIN SHOWERS WITH CLOUD BASES MAINLY AOA 7 KFT AGL...AND VSBYS OF 6SM OR GREATER. AREAS OF MVFR CIGS WILL OCCUR ACROSS THE MTNS OF WESTERN PENN TODAY /FROM KJST NORTH TO KBFD/...THANKS TO OROGRAPHIC LIFT OF A COOLER/WESTERLY FLOW CONTAINING LIMITED LLVL MOISTURE. BRIEF...MVFR CIGS AND VSBYS ARE ALSO POSSIBLE THROUGH 15Z TODAY INVOF KMDT AND KLNS AS THE COLD FRONT PUSHES THROUGH ACCOMPANIED BY SHOWERS OF LIGHT TO MODERATE INTENSITY. EXPECT WEST TO WEST-SOUTHWEST WINDS TO PICK UP SOME BY LATE THIS MORNING. VFR CONDITIONS ARE EXPECTED TO PREVAIL ACROSS THE CENTRAL VALLEYS AND SUSQUEHANNA REGION UNDER A BKN HIGH-BASED STRATO CU AND ALTO CU CLOUD DECK. OUTLOOK... THUR...MVFR CIGS WEST EARLY...THEN VFR. VFR EAST. FRI...VFR/MVFR EARLY WITH SHOWERS POSS WEST...BCMG MVFR/IFR FRI NGT WITH NW WIND GUSTS 20-30 MPH AND RA/SN SHOWERS. SAT...MVFR/IFR WITH SCATTERED SNOW SHOWERS WEST. VARYING VFR- MVFR CONDS CENTRAL/EAST WITH OCNL -SHSN AND FLURRIES. NW WIND GUSTS 25-35 MPH. SUN...BECOMING VFR...WINDS DECREASING. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD LONG TERM...FITZGERALD AVIATION...LAMBERT/MARTIN

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