Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 220844 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 444 AM EDT FRI AUG 22 2014 .SYNOPSIS... A WEAK UPPER LOW OVER THE CATSKILL REGION OF NEW YORK WILL DRIFT TO THE SOUTHEAST AS AN EXTENSIVE UPPER RIDGE BUILDS FROM THE MISSISSIPPI VALLEY INTO EASTERN CANADA. THE EFFECT OF THESE WEATHER FEATURES WILL BE TO CREATE ENOUGH RIDGING AT THE SURFACE TO PUSH A BACKDOOR FRONT GRADUALLY WESTWARD TO THE ALLEGHENY FRONT BY SATURDAY MORNING. SCATTERED SHOWERS AND THUNDERSTORMS WILL OVER THE REGION TODAY INTO TONIGHT. AFTER A CLOUDY AND COOL START TO THE WEEKEND WITH AREAS OF DRIZZLE AND FOG...CONDITIONS WILL DRY OUT SUNDAY AND EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MOSTLY CLOUDY TO CLOUDY SKIES BLANKETED MUCH OF THE REGION EARLY TODAY...EXCEPT FOR THE SCENT COUNTIES WHERE AN AREA OF CLEAR SKIES AND NEAR CALM AIR WAS LEADING TO PATCHY DENSE FOG /ESP IN PLACES THAT RECEIVED RAINFALL YESTERDAY/. POPS WILL BE MINIMAL THROUGH ABOUT 14-15Z. AFTERWARD...ONE OR TWO WEAK SHORT WAVES EMBEDDED IN THE WNW FLOW ALOFT WILL RIDE OVER THE PAIR OF SLOW MOVING SFC BOUNDARIES /ONE NEAR THE NEW YORK...PA BORDER AND THE OTHER BACKDOOR FRONT NEAR THE SUSQ VALLEY/. THE FAIRLY JUICY...APPROX 1.5 INCH PWAT AIR WILL COMBINE WITH DEVELOPING BREAKS OF SUNSHINE DURING THE MIDDAY HOURS TO QUICKLY INCREASE SFC-BASED CAPES TO BETWEEN 1000-1500 J/KG THIS AFTERNOON. BEST JET DYNAMICS AND LLVL THETA-E CONVERGENCE APPEARS TO FIRST TARGET THE WRN MTNS /PARTICULARLY THE LAUREL HIGHLANDS DURING THE LATE MORNING AND EARLY AFTERNOON/...BEFORE SPREADING EAST AND BECOMING FOCUSED ACROSS SCENT PENN AND THE SUSQ VALLEY LATER THIS AFTERNOON AND EARLY EVENING. BASIN AVERAGE RAINFALL SHOULD BE AROUND 3 OR 4 TENTHS OF AN INCH OVER THE UPCOMING 15 HOURS...THOUGH SHARP DIFFERENCES WILL OBVIOUSLY OCCUR INVOF SMALL CLUSTERS OF SHRA/TSRA THAT ARE EXPECTED TO TRACK ESE ACROSS THE CWA. HIGHEST POPS THROUGH 00Z SAT WILL BE IN THE LIKELY CATEGORY AND EXTEND FROM NEAR KJST...NE TO KAOO...KIPT AND KSEG. LOWEST POPS OF AROUND 30 PERCENT WILL BE ACROSS THE FAR NW ZONES...TO THE WEST OF KBFD. MAX TEMPS TODAY WILL VARY FROM THE MID 70S ACROSS THE NW...TO THE LOWER 80S THROUGHOUT THE LOWER SUSQ VALLEY. THESE READINGS WILL BE CLOSE TO NORMAL FOR LATE AUGUST. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... SCTD TO NUMEROUS SHOWERS WILL BE FOUND MAINLY ACROSS OUR CENTRAL AND SWRN ZONES EARLY TONIGHT. AS THE AFOREMENTIONED BACKDOOR PUSHES WWD TO THE ALLEGHENY FRONT...CONVECTIVE PRECIP WILL WANE WITH STRATUS THICKENING UP/SPREADING WEST LATER TONIGHT. AREAS OF DRIZZLE AND RIDGE-SHROUDING FOG ARE LIKELY LATE TONIGHT THROUGH SATURDAY MORNING...WITH ANY LOW PROB FOR THUNDER LIMITED TO THE AREA WEST OF ROUTE 219. LOW TEMPS TONIGHT UNDER WIDESPREAD CLOUDS AND A LIGHT/MOIST EASTERLY LLVL FLOW WILL BE 60-65F. THE MOIST/ANOMALOUS EASTERLY SFC-850 MB FLOW ASCENDING THE APPALACHIANS SHOULD LEAD TO WIDESPREAD LOW CLOUDS AND PATCHY DRIZZLE/MTN TOP FOG PERSISTING THROUGH MOST OR ALL OF SATURDAY. THIS WILL HELP TO KEEP TEMPS WELL BELOW NORMAL /PERHAPS BY A SOLID 8-10F DURING THE DAY SATURDAY/. PORTIONS OF THE CENTRAL/NRN MTNS MAY STRUGGLE TO CLIMB OUT OF THE UPPER 60S...WITH LOCATIONS ACROSS THE SUSQ VALLEY...AND WEST OF RT 219 LIKELY REACHING THE LOWER TO MID 70S. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A WEAK UPPER LOW MOVING UNDERNEATH THE RIDGE SHOULD ALLOW FOR A SLIGHT CHANCE FOR SHOWERS SATURDAY NIGHT. AFTERWARD...THE BUILDING RIDGE WILL BE THE PRIMARY DRIVER OF OUR WX THRU MOST OF THE EXTENDED FCST. MED RANGE GUIDANCE INDICATES HIGH PRES AND ASSOC DRY AIR MASS WILL DRIFT SOUTH LATE THIS WEEKEND...BRINGING FAIR AND BRIGHTER WX TO CENTRAL PA. PTSUNNY SKIES SHOULD HELP TEMPS REBOUND A BIT ON SUNDAY...BUT STILL REMAIN BLW NORMAL. LARGE SCALE SUBSIDENCE AND DRY AIR SHOULD PERSIST...AS THE MID RANGE MODELS ARE IN FAIR AGREEMENT OF A BUILDING RIDGE OVER THE REGION THROUGH EARLY NEXT WEEK. BY MID NEXT WEEK THE FCST CONFIDENCE BEGINS TO LOWER. BY THE MIDDLE OF NEXT WEEK...WHEN MED RANGE MODELS BEGIN TO DIVERGE. GEFS KEEPS RIDGE AND FAIR WX GOING THRU WED...WHILE ECMWF ENSEMBLE DATA INDICATES A WEAK COLD FRONT COULD PUSH SE INTO THE REGION...THE MODELS SEEM TO BE OFF WITH THEIR TIMING. HAVE KEPT A LOW CHC OF TSRA WED INTO THURSDAY. WHAT APPEARS CERTAIN IS THAT THE COOL TEMPS OF THIS WEEKEND WILL GIVE WAY TO A SLOW WARMING TREND THRU THE FIRST HALF OF NEXT WEEK...AS COOL AIR MASS MODIFIES UNDER STILL STRONG AUGUST SUN. GEFS AND EC ENS 850 TEMPS SUPPORT HIGH RETURNING TO ABV NORMAL BY WED. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... VERY MOIST LLVL ATM WITH SFC DEWPOINTS 65F+ COMBINED WITH LGT WINDS SHOULD SUPPORT WDSPRD REDUCED CIGS AND VSBYS EARLY THIS MORNING. EXPECT GRADUAL IMPROVEMENT THROUGH LATE MORNING WITH VFR CONDS BY THE AFTN. CONCERNING THE CONVECTIVE OUTLOOK...OVERALL CONFIDENCE IS LOW AND COVERAGE SHOULD BE GENERALLY SPARSE - AT IT APPEARS THE MAIN PCPN AXIS WILL BE SHIFTED SWD CLOSER TO WAVY QSTNRY FRONTAL BOUNDARY EXTENDING FROM OH SEWD INTO WV/VA. HOWEVER BRIEF TSTM IMPACTS ARE POSSIBLE BUT ARE BEYOND THE PREDICTABILITY HORIZON AT THIS RANGE. THEREFORE WILL ONLY INCLUDE VCTS AND ALLOW SUBSEQUENT TAF PACKAGES TO REFINE FCST AS NECESSARY. A LARGE AREA OF HIGH PRES WILL BUILD SWWD FROM ERN CANADA INTO THE NORTHEAST AND DOWN THE EAST SIDE OF THE APPLCHNS THIS WEEKEND. EASTERLY FLOW TO THE SOUTH OF THE HIGH SHOULD LEAD TO LOW CLOUDS AND LIGHT RA/DZ FOR THE FIRST PART OF THE WEEKEND BEFORE CONDS IMPROVE INTO EARLY NEXT WEEK. OUTLOOK... SAT...AM LOW CIGS/FOG/DZ/LGT RAIN. SUN...AM LOW CIGS PSBL..BCMG VFR. MON-TUE...VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...LAMBERT LONG TERM...LAMBERT/CERU AVIATION...DEVOIR/STEINBUGL

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