Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 190556 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 156 AM EDT TUE AUG 19 2014 .SYNOPSIS... RECENT DRY WEATHER WILL GIVE WAY TO UNSETTLED CONDITIONS THIS WEEK AS A SLOW MOVING FRONTAL SYSTEM HANGS CLOSE TO THE LOCAL AREA. DRIER AIR IS LIKELY TO REBUILD OVER THE COMMONWEALTH THIS WEEKEND AS HIGH PRESSURE REESTABLISHES ITSELF FROM NEW ENGLAND TO THE NORTHERN MID ATLANTIC COAST. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... UPPER RIDGE BUILDING OVER THE AREA...COMBINED WITH COOLING/STABILIZING BLYR...SHOULD ENSURE DRY WX THE REST OF THE NIGHT OVER NEARLY ALL OF CENTRAL PA. HOWEVER...MOIST SERLY FLOW COMBINED WITH RAD COOLING IS ALREADY YIELDING PATCHY STRATUS ACROSS SOUTHERN PA. LATEST MDL DATA SUPPORTS MCLDY SKIES BY DAWN OVER ALL BY PERHAPS THE NW MTNS. WHERE SKIES REMAIN MCLEAR...PATCHY DENSE FOG IS POSSIBLE IN THE DEEP VALLEYS OF THE NW MTNS. FOG IS ALSO POSSIBLE ALONG THE RIDGETOPS OF THE LAUREL HIGHLANDS. THE INCREASED DWPTS WILL RESULT IN MIN TEMPS MILDER THAN RECENT MORNINGS WITH LOW FROM THE L50S NORTH...TO L60S SOUTH. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TODAY/... UPPER LOW WILL REMAIN WELL WEST OF PA ON TUESDAY. HOWEVER...LEAD SHORTWAVE...SEEN OVER ILLINOIS AT 05Z IN THE WATER VAPOR IMAGERY...WILL PUSH INTO CENTRAL PA DURING THE AFTN HOURS. LARGE SCALE FORCING AHEAD OF THIS FEATURE SHOULD SUPPORT SCT CONVECTION DURING TIME OF MAX HEATING ACROSS THE ALLEGHENY PLATEAU. LATEST GEFS OUTPUT INDICATES THE BEST CHC OF SHOWERS AND POSS TSRA WILL BE ALONG LOW LVL CONVERGENCE AND THTE AXIS OVR THE SPINE OF THE ALLEGHENIES. 00Z GEFS OUTPUT SUPPORTS POPS OVR 50 PCT ACROSS THE LAUREL HIGHLANDS. MEANWHILE...LINGERING SFC RIDGE ACROSS SE PA WILL LIKELY SHIELD THAT AREA FROM PRECIP TODAY. MDL SOUNDINGS INDICATE TODAY WILL AVERAGE MCLDY WITH GREATEST AMTS OF SUNSHINE FOUND NORTH AND LESS BREAKS ACROSS THE SOUTH. GEFS 925 TEMPS IMPLY HIGHS WILL BE FAIRLY UNIFORM ACROSS THE AREA...IN THE U70S TO L80S. && .LONG TERM /TONIGHT THROUGH MONDAY/... MID TO LATE WEEK CONTINUES TO LOOK LIKE A TUMULTUOUS TIMEFRAME FOR WEATHER...GEFS/CMC...LOOK FOR SLIGHTLY ANOMALOUS PWATS WEDNESDAY INTO THURSDAY...HOWEVER OPERATIONAL RUNS FROM THE GFS/EC/CANADIAN CONTINUE THE TREND OF SLOWING THE SYSTEMS EASTWARD PROGRESSION. AS THE UPPER LEVEL CURRENTLY OFF THE NEW ENGLAND COAST SLOWLY MOVES TO THE NORTHEAST...THE RIDGE SHOULD TILT NEGATIVELY AND SLOWLY FLATTEN. THIS SHOULD ALLOW FOR THE TROUGH CURRENTLY STRADDLING THE CANADIAN...MINNESOTA BORDER...BEFORE ENTERING THE GREAT LAKES ON WEDNESDAY. THIS LOW...MOVING BELOW HIGH BUILDING INTO NORTHERN CANADA AND SPECIFICALLY HUDSON BAY...HAS WEAK FLOW ALOFT. THIS SHOULD ALLOW IT TO SLOWLY MEANDER EASTWARD. CONSIDERING IT IS CUTOFF FROM MAJOR MOISTURE SOURCES...PRECIPITATION WILL BE GENERALLY LIGHT WITH SLIGHTLY HIGHER AMOUNTS POSSIBLE IN THUNDERSTORMS. THIS PROGRESSION SHOULD DELAY FRONTAL PASSAGE AND ANY ORGANIZED PRECIPITATION TO LATE WEDNESDAY NIGHT INTO THURSDAY. GFS IS THE FASTEST WITH THE CANADIAN/EC FURTHER WEAKENING AND SLOWING EASTWARD PROGRESSION OF THE SYSTEM. BROAD MODEL AND ENSEMBLE SUPPORT FOR LIKELY POPS BY THURSDAY ...AS THE SFC FRONTAL BOUNDARY ASSOCIATED WITH UPPER LEVEL ENERGY DRIFTING EASTWARD THRU THE CENTRAL GREAT LAKES PUSHES SLOWLY EASTWARD ACROSS THE CWA. USED A BLEND OF MODELS LEADING TOWARD THE EC AND MOS GUIDANCE. BY FRIDAY THE CONFIDENCE IN THE MEDIUM RANGE FORECAST DROPS OFF AS ENSEMBLES SHOW GREAT VARIABILITY IN TIMING AND PLACEMENT.THOUGH THE WEEKEND IS TRENDING TOWARDS A DRIER SOLUTION. THE UPPER LEVEL LOW THAT MOVES THROUGH MID WEEK COULD BECOME QUASI-STATIONARY JUST OFF THE COAST. DEPENDING ON ITS POSITION COULD ALLOW FOR WEAK SHORT WAVES THROUGH THE REGION THAT COULD ALLOW FOR CHANCE POPS. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... SCATTERED SHOWERS WHICH WERE MAINLY SOUTH AND WEST OF KJST EARLIER THIS EVENING HAVE DISSIPATED. VFR CONDITIONS WILL GIVE WAY TO FOG AND LOWERING VSBYS OVERNIGHT. EXPECT WIDESPREAD MVFR TO IFR VSBYS AND CIGS TO DEVELOP OVERNIGHT AT MOST CENTRAL AND NORTHERN AIRFIELDS. HOWEVER...HAVE NOT INCLUDED FOG IN THE LOWER SUSQUEHANNA TAFS OF KMDT AND KLNS...AS CONFIDENCE OF FORMATION IS LOWER. IF FOG DOES DEVELOP...LIKELY TO BE IN THE MVFR RANGE AT THESE LOCATIONS. CURRENT TIMING OF FOG IS FOR DEVELOPMENT AROUND 07Z IN MOST LOCATIONS...WITH THE DENSEST FOG BETWEEN 09Z AND 12Z. FOR TOMORROW...AFTER MORNING FOG...EXPECT GENERALLY VFR CONDITIONS. THERE IS A THREAT FOR SHRA/TSRA...MOST LIKELY IN THE SOUTHWEST AND LEAST LIKELY IN THE NORTHEAST. A VERY SLOW APPROACHING UPPER LOW WILL SLOWLY INCREASE CHANCES FOR DAILY SHOWERS AND POTENTIAL AFTERNOON TSRA FOR THE BALANCE OF THE WEEK. CURRENTLY...LATER WEDNESDAY AND THURSDAY LOOK LIKE THE HIGHEST LIKELIHOOD OF PRECIPITATION...WITH SURFACE FRONT CROSSING THE REGION. OUTLOOK... TUE...MORNING FOG...THEN MAINLY VFR...WITH SHRA/TSRA POSSIBLE. WED-FRI...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT INCREASING CHANCES OF MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED RESTRICTIONS. SAT...MAINLY VFR. STILL CHANCE OF SHRA...BUT DECREASING CHANCES. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE NEAR TERM...FITZGERALD SHORT TERM...DEVOIR/FITZGERALD LONG TERM...CERU/STEINBUGL AVIATION...JUNG

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