Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 182355 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 755 PM EDT MON AUG 18 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 TUESDAY MORNING/... SOME SMALL SHOWERS FIRED ON THE HIGH TERRAIN OF SOMERSET COUNTY UP INTO NORTHERN BEDFORD COUNTY. THESE SHOULD FADE WITH THE LOSS OF HEATING LEADING TO ANOTHER MAINLY DRY OVERNIGHT FOR THE REGION. MINS WILL BE MILDER THAN RECENT MORNINGS WITH LOW TO MID 50S EXPECTED NORTH AND LOWER 60S ACROSS THE SOUTH. A BIT OF MUGGINESS WILL BE FELT IN THE AIR AS DEWPOINTS HAVE CREPT SLOWLY UPWARD...AND SOME LCL MVFR/IFR CONDS IN VALLEY FOG ARE EXPECTED ACROSS ESPECIALLY CENTRAL AND NORTH CENTRAL PA. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... MOST AREAS WILL SEE A BREAK IN SHOWER ACTIVITY ON TUESDAY... IN BETWEEN THE WEAK FORCING SHIFTING OFF THE COAST AND DEEPER UPPER LOW DRIFTING INTO THE CENTRAL GLAKS. UNDER A SHORTWAVE RIDGE AXIS...MOST AREAS WILL BE DRY...BUT CANNOT RULE OUT A SHOWER ACROSS THE SOUTH IN THE FLATTER SLIGHTLY CYCLONIC UPPER FLOW IN A RICHER AMBIENT MOISTURE ENVIRONMENT (PW ~1.7"). CLOUD COVER SHOULD BE SIMILAR TO TODAY WITH GREATEST AMTS OF SUNSHINE FOUND NORTH...AND LESS BREAKS ACROSS THE SOUTH. MAXES SIMILAR TO...RANGING FROM MID 70S NORTH TO LOWER 80S SOUTH. && .LONG TERM /TUESDAY NIGHT 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 /00Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS EARLY THIS EVENING WILL GIVE WAY TO FOG AND LOWERING VSBYS LATER TONIGHT. EXPECT WIDESPREAD MVFR TO IFR VSBYS AND CIGS TO DEVELOP OVERNIGHT AT MOST CENTRAL AND NORTHERN AIRFIELDS. HOWEVER...ATTM 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. ISOLATED SHOWERS OVER THE FAR SOUTHWEST WILL BE CLOSE ENOUGH TO THE KJST AIRFIELD TO INCLUDE VCSH FOR SEVERAL HOURS THIS EVENING. OTHERWISE...CONDITIONS SHOULD BE DRY OVERNIGHT. 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...DEVOIR/LA CORTE NEAR TERM...DEVOIR/LA CORTE SHORT TERM...DEVOIR LONG TERM...CERU/STEINBUGL AVIATION...JUNG

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