Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 280029 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 729 PM EST THU NOV 27 2014 .SYNOPSIS... A WEAK UPPER AIR DISTURBANCE WILL KEEP CLOUDS AND THE CHANCE OF A FEW LIGHT SNOW SHOWERS IN THE FORECAST TONIGHT AND FRIDAY. TEMPERATURES WILL BEGIN TO MODERATE THIS WEEKEND AS HIGH PRESSURE MOVES OFF THE SE COAST. THE NEXT DISTURBANCE WILL BRING LIGHT RAIN SHOWERS EARLY NEXT WEEK BEFORE A QUICK SHOT OF COOLER AIR FOR MIDWEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... A BATCH OF SNOW SHOWERS MOVED ACROSS THE AREA EARLIER THIS AFT. ANOTHER BAND OF SNOW SHOWERS JUST TO THE WEST OF THE OFFICE. WHILE THESE SHOULD WEAKEN AS THEY CROSS THE MTS...SOME ARE ON THE HEAVIER SIDE. ALSO MORE BANDING TO THE WEST...WITH COLDER TOPS NOTED ON THE IR SATELLITE LOOP OVER NE OH NORTHWARD. THUS DID UP POPS AND QPF A LITTLE INTO FRIDAY MORNING. DID ADJUST WORDING IN HWO A SHORT TIME AGO. REST OF PACKAGE LOOKS GOOD FOR NOW. EARLY DISCUSSION BELOW. LATEST SFC ANALYSIS SHOWS A WEAK SFC LOW NEAR CAPE HATTERS AND ALONG THE WEST COAST OF LAKE ONTARIO...SUPPORTED BY SEVERAL SHORTWAVES SWINGING EAST FROM THE TENNESSEE VALLEY. THIS ENERGY AND RESULTING SFC CONVERGENCE/UPSLOPE FLOW IS FORCING AN AREA OF LIGHT SNOW ACROSS THE NRN AND CENTRAL MTNS THAT WILL AFFECT PARTS OF CENTRAL PA INTO THE EVENING HOURS INTO THE CENTRAL COUNTIES. AT THIS POINT STILL DO NOT EXPECT SIGNIFICANT SNOW ACCUMS WITH BUT COULD BE ENOUGH TO COAT ROADS AND CAUSE SOME SLICK SPOTS...SO HAVE UPDATED PHLHWOCTP TO GIVE THE PUBLIC/CUSTOMERS A HEADS UP. BIGGEST QUESTION FOR THE OVERNIGHT WILL BE WHETHER A PERIOD OF MORE ORGANIZED LAKE EFFECT CAN GATHER ITSELF OVER NWRN AREAS. DEEP LAYER FLOW DOES LOOK FAVORABLE FOR A TIME TONIGHT...BUT RELATIVELY SHORT OVER-LAKE TRAJECTORIES SHOULD LIMIT SNOWFALL TO MAINLY SUB ADVISORY LEVELS. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... INVERSION HEIGHTS ARE EXPECTED TO LOWER FRIDAY WHICH SHOULD PUT A DAMPER ON ANY OF THE BEST DEVELOPED LAKE EFFECT BANDS...BUT CLOUDS AND PERHAPS A FEW SNOW SHOWERS WILL REMAIN POSSIBLE OVER THE NORMAL WESTERN AND NORTHERN LOCATIONS. THE BEST CHANCES WILL BE IN THE MORNING...WITH BRIGHTENING SKIES LIKELY IN THE AFTERNOON. HIGHS WILL BE A FEW DEG COOLER THAN TODAY AS THE CORE OF THE POST FRONTAL COLD AIR SETTLES OVERHEAD. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... BROAD ZONAL FLOW DEVELOPS DURING THE WEEKEND. THIS WILL PROMPT A WARM-UP AS LOW LEVEL FLOW VEERS TO THE SW AS HIGH PRESSURE SLIPS OFF FURTHER TO OUR SOUTHEAST. AFTER A CHILLY NIGHT FRI NIGHT WITH LOWS INVOF 20F...THE AIRMASS WILL BEGIN MODERATING ON SATURDAY...WITH READINGS REACHING THE MID 40S TO MID 50S BY SUNDAY. MAY SEE SCT LIGHT SHSN ACROSS NW MTNS IN WEAK NW/W FLOW. MODELS SEEM TO BE BACK IN BETTER AGREEMENT ON APPROACH OF A FRONT FOR MONDAY...THOUGH GFS/GEFS CONTINUE TO BE 6 TO MAYBE 12 HRS FASTER WITH FROPA. AHEAD OF THAT...ONE AREA OF POSSIBLE CONCERN COULD BE THE EXPECTED DEVELOPMENT OF SOME LIGHT WARM ADVECTION PRECIP SATURDAY NIGHT INTO SUNDAY MORNING MAINLY ACROSS WESTERN SECTIONS. TEMPS ALOFT WARM RAPIDLY...AND I KEPT FORECAST SURFACE MINS MAINLY ABOVE FREEZING. BUT IF WE END UP A FEW DEG COOLER...WE COULD SEE A PERIOD OF SOME LIGHT ICING UNTIL TEMPERATURES CAN RECOVER SUNDAY. POST FRONT WILL BRING COOLER TEMPS BACK IN FOR MIDWEEK AS LARGE SURFACE HIGH SLIDES ACROSS S CANADA...BUT NOTABLE MODEL DIFFS BEGIN TO DEVELOP AROUND THEN WITH ECMWF MUCH FLATTER THAN GFS. EC SOLUTION BRINGS HIGH PRESSURE OVER THE REGION BY LATE WEEK WITH SLOWLY MODERATING TEMPS...WHILE THE GFS/GEFS SPINS UP A SURFACE LOW OVER THE MIDWEST WHICH WOULD PUSH EVEN WARMER TEMPS OUR WAY. FOR NOW...TEMPERED WARMUP A BIT AS MUCH UNCERTAINTY IN LATER TIME PERIODS. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/...
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AN UPPER LEVEL TROUGH WILL CROSS THE REGION TONIGHT AND EARLY FRIDAY...DRIVING A NEW SURGE OF COLD AIR OVER THE RELATIVELY WARM LAKES. A SUFFICIENT NORTHWESTERLY FETCH WILL BE IN PLACE FOR NUMEROUS SNOW SHOWERS MAINLY OVER THE WRN 1/3 OF THE AIRSPACE - WITH IFR IMPACTS FELT PRIMARILY AT THE HIGHER ELEVATION TERMINALS IN ZOB SECTOR. PERIODS OF IFR ARE A GOOD BET AT JST/BFD WITH GREATER CONFIDENCE AT JST. DOWNSLOPE TO THE EAST SHOULD KEEP MVFR TO VFR CONDS IN PLACE THRU FRIDAY. THE SHSN ACTIVITY SHOULD TAPER DOWN OVER THE WRN SXNS BY LATER FRIDAY AFTERNOON WITH IMPROVING CONDS EXPECTED AT BFD AND JST. OUTLOOK... FRI...IFR-MVFR/-SHSN WEST...IMPROVING. MVFR TO VFR ELSEWHERE. SAT...VFR/MVFR. ISOLD -SHRASN PSBL. SUN...MVFR/IFR. OCNL -SHRA NW 1/2. MON...MVFR WITH OCNL IFR. SCT -SHRA. COLD FROPA/WND SHFT 250-300. TUE...VFR/MVFR CIGS. NO SIG WX.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE/GARTNER NEAR TERM...GARTNER/MARTIN SHORT TERM...LA CORTE LONG TERM...RXR AVIATION...STEINBUGL

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