Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 171804 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 104 PM EST WED DEC 17 2014 .SYNOPSIS... BRISK WESTERLY WINDS WILL BRING IN COLDER AIR THIS AFTERNOON. SCATTERED...MAINLY MOUNTAIN SNOW SHOWERS ARE EXPECTED THROUGH THE END OF THE WEEK AS CLOUDY AND COLD CONDITIONS PERSIST. A WEAK LOW PRESSURE AREA IS EXPECTED TO MOVE SOUTH OF THE REGION THIS WEEKEND...BUT MOST OF THE PRECIPITATION WILL STAY TO THE SOUTH OF THE STATE. && .NEAR TERM /UNTIL 7 PM THIS EVENING/... GUSTY WESTERLY WINDS WILL ADVECT SEASONABLY COLD AIR INTO THE REGION THIS AFTERNOON. NARROW BANDS OF MAINLY LIGHT SNOW SHOWERS WILL OCCUR ACROSS THE HIGHER TERRAIN OF THE NORTH AND WEST THIS AFTERNOON...WHILE ANY SNOW SHOWERS THROUGHOUT THE CENTRAL RIDGE AND VALLEY REGION FROM THE RELATIVELY SHALLOW STRATOCU DECK WILL BE ISOLATED AND BRIEF /THANKS TO DECREASING LAPSE RATES IN THE 850-700MB LAYER/. THE FAR SOUTHEAST WILL STAND THE BEST CHC FOR SEEING A FEW BREAKS IN THE OTHERWISE EXTENSIVE CLOUD SHIELD COVER. NO REAL ACCUMULATIONS ARE EXPECTED TODAY WITH THE NEAR TO SLIGHTLY ABOVE FREEZING TEMPS THROUGH THE AFTERNOON. HOWEVER...A COATING TO ONE INCH OF SNOW IS POSSIBLE ACROSS THE HIGHER TERRAIN CLOSE TO THE PA/NY BORDER WHERE MORE PERSISTENT/STEEPER LOW-MID LEVEL LAPSE RATES WILL BE FOUND. THE MAIN WEATHER STORY TODAY WILL BE THE WIND WITH 10-20 KTS SUSTAINED AND GUSTS WELL INTO THE 20S. TEMPS WILL BE NEARLY STEADY FOR THE REST OF THE DAYLIGHT HOURS...RANGING FROM 30-32 ACROSS THE NW MTNS AND LAURELS...TO THE MID AND UPPER 40S IN THE LOWER SUSQ VALLEY. && .SHORT TERM /7 PM THIS EVENING THROUGH 6 PM THURSDAY/... COLD AIR FIRMLY IN PLACE FOR THE SHORT TERM. A COMPACT...THOUGH MDTLY STG MID-LEVEL SHORTWAVE WILL TRACK ESE ACROSS THE FCST AREA BETWEEN ABOUT 00-07Z THURSDAY /AT THE NRN EDGE OR LEFT EXIT REGION OF A POTENT 130 KT UPPER JET/ WITH A DISTINCT POCKET OF RELATIVELY STEEP...850-700MB LAPSE RATES IN EXCESS OF 5C/KM. THIS FEATURE SHOULD SUPPORT A FEW HOUR PERIOD OF SCT-NUMEROUS SNOW SHOWERS /THIS EVENING UNTIL SHORTLY AFTER MIDNIGHT/ WITH THE POTENTIAL FOR A QUICK GROUND WHITENING - EVEN ACROSS THE CENTRAL MTNS AND SUSQ VALLEY. MINS TONIGHT WILL FALL INTO THE 20S AND EVEN SOME UPPER TEENS IN THE HIGHEST ELEVS OF THE LAURELS. WIND CHILLS WILL BRUSH THE SINGLE DIGITS THERE. BRISK...WEST TO WNW WINDS WILL CONTINUE THROUGH THE NIGHT. THURSDAY...WINDS MAY VEER JUST SLIGHTLY TO THE NORTHWEST. SPEEDS OF 10-15 MPH AND GUSTS INTO THE L20S ARE POSSIBLE OVER THE MOUNTAINS. CLOUD COVER WILL CONTINUE WITH THE CLASSIC UPSLOPE- POST-FRONTAL CRUD HANGING OVER THE NWRN HALF OF THE CWA. THE FLOW OFF THE LAKE WILL CREATE MORE SHSN. ACCUMULATIONS WILL BE MINOR...AND CONFINED TO THE FAR NW AND VERY HIGHEST ELEVATIONS. NO MORE THAN 2 INCHES EXPECTED IN WARREN COUNTY ON THE HIGH END. SOME SUN MAY GET THE LOWER SUSQ INTO THE LOWER 40S. SUB-FREEZING MAXES IN STORE FOR THE WRN MTS. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... CYCLONIC FLOW ALOFT WILL WEAKEN ON THURSDAY AS UPPER LOW SHIFTS EWD ACROSS THE CANADIAN MARITIME REGION AND RIDGE ALOFT BUILDS OVER JAMES BAY. DESPITE A WELL ALIGNED WNW FLOW AND FAIRLY STRONG LOW LEVEL COLD AIR ADVECTION EARLY IN THE DAY...MODEL SOUNDINGS SHOW RATHER SHALLOW MOISTURE AND CAPPING INVERSION HGTS GENERALLY BELOW 850MB WHICH SHOULD LIMIT SNOW ACCUMS TO AROUND 1 INCH IN MOST AREAS IN THE NW MTNS. LOCALLY HIGHER AMOUNTS ARE POSSIBLE (2-4" MAXIMUM ACCUMULATION POTENTIAL) OVER THE FAVORED PERENNIAL SNOWBELT DURING THE 24 HOUR PERIOD ENDING 12Z FRI. THE PATTERN WILL REMAIN SEASONABLY COLD AND BRISK THROUGH THE END OF THE WEEK. LARGE SCALE SUBSIDENCE ASSOCIATED WITH SURFACE HIGH MIGRATING EAST FROM THE GREAT LAKES/MIDWEST INTO EASTERN CANADA SHOULD BRING AN END TO NUISANCE/MINOR SNOW SHOWER ACTIVITY AND LINGERING FLURRIES OVER THE NW ALLEGHENIES BY FRI NGT. CONCERNING THE WEEKEND SYSTEM... THE MODELS SHOW A SOUTHERN STREAM TROUGH DEVELOPING TOWARD THE SOUTHERN ROCKIES AND PLAINS ON FRIDAY WITH THE ASSOCIATED HEIGHT FALLS INVIGORATING A WAVE OF LOW PRESSURE OVER THE WESTERN GULF COAST STATES BY 00Z SAT. THERE REMAINS A BROAD MODEL CONSENSUS IN TRACKING THE DEVELOPING SFC WAVE EAST-NORTHEAST ACROSS THE SOUTHEAST PIEDMONT BEFORE EXITING THE LOWER 48 INVOF THE CAROLINA COASTAL PLAIN---BETWEEN HATTERAS AND MYRTLE BEACH. WHILE THERE IS MUCH BETTER MODEL AGREEMENT AND CONVERGENCE TOWARD A WEAKER/MORE SUPPRESSED SOLUTION OVER THE LAST 2 MODEL CYCLES...THERE IS STILL ENOUGH SPREAD/UNCERTAINTY IN THE EVOLVING SPLIT-FLOW PATTERN THAT A MORE SIGNIFICANT STORM SYSTEM STILL CANNOT BE RULE OUT. HOWEVER CONFIDENCE IN A MAJOR STORM HAS LARGELY DIMINISHED SINCE YESTERDAY WITH THIS SCENARIO NOW LOOKING LIKE A LOW PROBABILITY OUTCOME. CONFIDENCE REGARDING THE STORM TRACK AND ASSOCIATED WEATHER IMPACTS HAS INCREASED SOMEWHAT (FROM LOW TO AVERAGE) GIVEN THE CONVERGENCE TOWARD A MORE COMMON SOLUTION...WITH A LIGHT RAIN/SNOW EVENT EMERGING AS THE MOST LIKELY AND PROBABLE OUTCOME. HIGH PRESSURE SHOULD PROVIDE A QUIET WEATHER PERIOD EARLY NEXT WEEK BEFORE THE PATTERN TURNS INCREASINGLY UNSETTLED AND POTENTIALLY STORMY HEADING INTO CHRISTMAS EVE/DAY. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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WIDESPREAD STRATO CU AND PERSISTENT MVFR TO IFR CIGS WITH ISOLATED-SCATTERED AND GENERALLY BRIEF MVFR TO IFR VSBYS IN SNOW SHOWERS WILL OCCUR ACROSS THE NW MTNS AND LAUREL HIGHLANDS /INVOF KBFD AND KJST/ THROUGH FRIDAY MORNING. CONDITIONS ACROSS THE CENTRAL MTNS AND SUSQ VALLEY WILL VARY BETWEEN LOW END VFR...AND MVFR CIGS. GUSTY WEST TO WNW WINDS /UP AROUND 25 KTS AT TIMES/ WILL ADD SOME MECHANICAL TURBULENCE DURING TAKEOFF AND FAP TO REGIONAL AIRFIELDS THIS AFTERNOON THROUGH THURSDAY. A SECONDARY COLD FRONT AND COMPACT UPPER AIR DISTURBANCE DROPPING SE ACROSS THE REGION LATE TODAY AND EARLY TONIGHT COULD BRING SOME BRIEFLY HEAVIER SNOW SHOWERS...WITH A COATING TO 1/2 INCH POSSIBLE EVEN ACROSS THE CENTRAL MTN AND SUSQ VALLEY AIRFIELDS. OTHERWISE...NOT A LOT GOING ON TILL MAYBE JUST BEFORE CHRISTMAS. THERE COULD BE WIDESPREAD RAIN SHOWER ACTIVITY AROUND AS A POTENT SFC AND UPPER LOW TRACKS NE TWD THE OHIO RIVER VALLEY. OUTLOOK... THU-FRI...MVFR CIGS POSS NW. OTHERWISE NO SIG WX EXPECTED. SAT-SUN...SNOW/REDUCED VSBY...MAINLY ALONG THE MD BORDER.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO/LAMBERT NEAR TERM...LAMBERT SHORT TERM...DANGELO/LAMBERT LONG TERM...STEINBUGL AVIATION...LAMBERT

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