Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 222043 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 343 PM EST THU JAN 22 2015 .SYNOPSIS... A WEAK TROUGH OF LOW PRESSURE COMBINED WITH LOW LEVEL MOISTURE STREAMING SOUTHEAST OFF THE GREAT LAKES WILL MAINTAIN WIDESPREAD STRATUS AND STRATO CU CLOUDS AND AREAS OF LIGHT FOG...ALONG WITH SOME FLURRIES. A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE OHIO VALLEY BY TONIGHT...AND THEN MOVE INTO THE MID ATLANTIC STATES FRIDAY. LOW PRESSURE IS EXPECTED TO DEVELOP OVER THE GULF OF MEXICO FRIDAY AFTERNOON AND MOVE NORTHEAST OFF THE MID ATLANTIC COAST SATURDAY. IT WILL PROBABLY PASS CLOSE ENOUGH TO BRING THE THREAT FOR WINTRY PRECIPITATION TO SOUTHEASTERN AREAS. A CLIPPER SYSTEM WILL ARRIVE LATE SUNDAY OR SUNDAY NIGHT. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... DIFFUSE/WEAK...LLVL TROUGH EXTENDING FROM THE CENTRAL NJ COAST...NWWD TO KIPT AND KELZ AT 18Z WAS RESPONSIBLE FOR A DWINDLING AREA OF VERY LIGHT SNOW ACROSS THE NCENT MTNS AND MIDDLE SUSQ VALLEY. NOTHING MORE THAN A DUSTING OF SNOW WILL OCCUR THIS AFTERNOON...LIMITED TO THE NRN AND ERN MTNS OF PENN /AND PERHAPS THE RIDGES WEST OF RT 219/. A FEW BREAKS IN THE CLOUD COVER ACROSS THE NCENT...AND SCENT MTNS WILL ALLOW TEMPS THIS AFTERNOON TO NOSE UP TO SLIGHTLY ABOVE NORMAL. INCREASED VERTICAL MIXING TAPPING NWRLY WIND OF 10-15KT PRESENT IN THE 1-2KFT AGL LAYER HAS HELPED TO DISSOLVE THE LOW STRATUS AND THICKER FOG ACROSS THE LOWER SUSQ VALLEY AND RAISE THE STRATO CU CLOUD BASES TO AOA 3 KFT AGL. AGAIN...TEMPS THIS AFTERNOON WILL BE NEAR NORMAL ACROSS THE CENTRAL AND WESTERN MTNS...AND SLIGHTLY BELOW NORMAL THROUGHOUT THE MID AND LOWER SUSQ VALLEY. VERY SHALLOW MOISTURE TONIGHT...AND THE CONTINUED WELL-ALIGNED LIGHT TO MODERATE LLVL NWRLY FLOW...SHOULD ALLOW FOR SOME DECENT BREAKS TO DEVELOP IN THE STRATO CU DECK IN THE FAVORED DOWNSLOPE REGION OF THE SUSQ VALLEY AND CENTRAL MTNS. MSTLY CLOUDY TO CLOUDY SKIES WILL LIKELY PERSIST OVER THE WRN MTNS OF PENN. LOW TEMPS EARLY FRIDAY WILL VARY FROM THE TEENS ACROSS THE NORTH TO LOWER 20S IN THE SOUTH. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... SFC HIGH PRESSURE AND A PROGRESSIVE/FLAT RIDGE ALOFT BUILDS OVER THE REGION FRIDAY BRINGING PERIODS OF SUNSHINE DURING THE MORNING AND MIDDAY HOURS...WITH A FAIRLY QUICK INCREASE IN MID AND HIGH CLOUDS ACROSS THE SOUTHWEST HALF OF THE STATE IN THE AFTERNOON. MAX TEMPS FRIDAY SHOULD BE 3-4F BELOW NORMAL FOR THE DATE. THICKENING CLOUDS WILL OVERSPREAD THE REGION FRIDAY NIGHT WITH THE NRN EDGE OF LIGHT SNOW MOVING INTO SOUTH-CENTRAL PENN AROUND MIDNIGHT...BEFORE BECOMING FOCUSED ACROSS THE SERN THIRD...TO HALF OF THE STATE BY 12Z SATURDAY. A GENERAL 1-3 INCHES SHOULD BE ON THE GROUND ACROSS THE SE HALF OF THE CWA BY DAYBREAK SATURDAY...WITH THE HEAVIEST AMTS TO THE SE OF INTERSTATE 81. && .LONG TERM /SATURDAY THROUGH THURSDAY/...
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SATURDAY WILL SEE THE PRECIPITATION MOVING NORTHEAST AWAY FROM THE FORECAST AREA. NORTHWEST WINDS WILL KEEP CLOUDS ACROSS THE NORTHWEST AND LAURELS WITH A FEW LAKE ENHANCED AND UPSLOPE SNOW SHOWERS. JUST AS THE SNOW SHOWERS DIMINISH ON SUNDAY...CLOUDS WILL INCREASE FROM THE NORTHWEST AS A CLIPPER DROPS THROUGH WISCONSIN TOWARD PENNSYLVANIA. AS FAR AS CLIPPERS GO...THIS ONE LOOKS TO HAVE A STRONGER PUNCH THAN THE PREVIOUS ON THIS PAST WEEK. THE SYSTEM DEEPENS AS IT CROSSES PENNSYLVANIA...THEN CONTINUES TO DEVELOP OFF THE ATLANTIC COAST ON MONDAY. GEFS PLUMES BEGINNING TO SHOW A CLUSTER OF QPF SOLUTIONS IN THE 0.30 TO 0.40 INCH RANGE WITH THE TYPICAL OUTLIER BOOKENDS. PLENTY OF COLD AIR AVAILABLE AND EXPECT NO PRECIP TYPE ISSUES WITH THIS EVENT. AS THE LOW INTENSIFIES OFF THE THE ATLANTIC COAST ON MONDAY...WE COULD SEE LIGHT SNOW/SHOWERS CONTINUING THROUGH THE DAY WITH TEMPERATURES REMAINING STEADY OR SLOWLY FALLING THROUGH THE 20S. COLDEST AIR OF THE WEEK DIVES IN BEHIND THE DEPARTING SYSTEM ON TUESDAY WITH STATEWIDE HIGHS A FEW DEGREES EITHER SIDE OF 20F. A GRADUAL WARMING IS IN STORE FOR THE MID TO LATE WEEK AS THE DEEP TROUGH MOVES OVER THE GULF STREAM AND RIDGING...BOTH AT THE SURFACE AND ALOFT MOVES INTO THE OHIO VALLEY.
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&& .AVIATION /21Z THURSDAY THROUGH TUESDAY/... WIDESPREAD...MAINLY MVFR CIGS AND MVFR TO VFR VSBYS WILL CONTINUE INTO TONIGHT WITH JUST SOME AREAS OF VERY LIGHT SNOW ACROSS THE NRN AND WRN MTNS. CIGS WILL LIKELY DIP BACK INTO THE IFR RANGE OVERNIGHT ACROSS THE WESTERN MTNS KBFD AND KJST/. HIGH PRES BUILDING IN FROM THE OHIO VALLEY WILL LIKELY CAUSE SKIES TO AT LEAST PARTIALLY CLEAR ACROSS EASTERN PA TONIGHT. HOWEVER...LOW LVL MOISTURE TRAPPED BENEATH INVERSION AND FORCED OVR THE ALLEGHENY MTNS VIA A LIGHT TO MDT NWRLY FLOW MAY PRODUCE PERSISTENT IFR CIGS AT KBFD AND KJST THRU FRIDAY MORNING. OUTLOOK... FRI...AM LOW CIGS POSS AT KBFD AND KJST. OTHERWISE...MAINLY VFR. FRIDAY NIGHT AND SAT...SNOW SPREADING INTO FAR SOUTHERN PENN AROUND MIDNIGHT...THEN FOCUSING ACROSS THE SE THIRD TO HALF OF THE STATE SATURDAY MORNING WITH MVFR TO IFR IN THOSE AREAS. MAINLY VFR IN THE NORTH AND WEST THROUGH THE MIDDAY HOURS SAT. THEN...PM LGT SNOW LIKELY W MTNS WITH AREAS OF MVFR TO IFR POSSIBLE. SUN...VFR INTO THE AFTERNOON...THEN SNOW DEVELOPING ACROSS THE WEST IN THE AFTERNOON OR EVENING...AND OVERSPREADING ALL OF CENTRAL PENN AND THE SUSQ VALLEY AT NIGHT. MON...AM SNOW WITH WIDESPREAD MVFR TO IFR LIKELY. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...LAMBERT LONG TERM...TYBURSKI AVIATION...LAMBERT

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