Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 012220 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 620 PM EDT MON SEP 1 2014 .SYNOPSIS... WARM AND HUMID CONDITIONS WILL CONTINUE INTO TUESDAY UNTIL A COLD FRONTAL PASSAGE BRINGS DRIER AND SLIGHTLY COOLER AIR TO CENTRAL PENNSYLVANIA THROUGH MID WEEK. HUMIDITY WILL RETURN TOWARD THE END OF THE WEEK AHEAD OF THE NEXT FRONTAL SYSTEM THAT WILL BRING THE CHANCE OF RAIN FOR THE UPCOMING WEEKEND. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... FAIRLY TRANQUIL LATE SUMMER EVENING TO CLOSE LABOR DAY HOLIDAY WEEKEND OVER CENTRAL PA...AFTER SOME EARLIER HEAVY DOWNPOURS TRACKED ACROSS SOME PORTIONS OF THE CENTRAL AND SOUTH CENTRAL MOUNTAINS. THESE WERE ASSOCIATED WITH A SHORTWAVE TROF WHICH TRACKED INTO THE CATSKILLS THIS EVENING. FARTHER SOUTH...ANOTHER SHORTWAVE TROF TRACKING FROM THE WV PANHANLDE TO SOUTHERN MD TOUCHED OFF ISOLATED COVERAGE OF SHOWERS AND A FEW THUNDERSTORMS FROM SOUTHEAST PA THROUGH CENTRAL NJ. A THIRD UPPER TROF IS APPROACHING SOUTHWEST PA FROM NRN KY AND EXTREME SOUTHERN OH...INITIATING ISOLATED TO SCATTERED SHOWER ACTIVITY ACROSS SOUTHWEST PA AND EXTENDING INTO THE WEST CENTRAL MOUNTAINS AT THIS HOUR. MAIN CONVECTIVE ACTIVITY IS FAR WEST OF CENTRAL PA...OCCURRING WITH THE SFC COLD FRONT EXTENDING FROM SOUTHEAST MICHIGAN INTO NORTHWEST OHIO AND EASTERN INDIANA THIS EVENING. UPSTREAM STORMS SHOULD WEAKEN POST SUNSET...WITH FOCUS FOR CONVECTION SHIFTING WESTWARD TOWARDS THE APPROACHING COLD FRONT... EXPECTED TO CROSS CENTRAL PA TUESDAY AFTERNOON AND EVENING. AREAS OF FOG AND LOW CLOUDS WILL FORM ONCE AGAIN LATE TONIGHT WITH WINDS REMAINING LIGHT AND LLVL MOISTURE ABUNDANT. IT WILL BE MUGGY WITH LOWS 65-70F. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... A WELL-DEFINED COLD FRONT /WITH SHARP MSTR- PW GRADIENT/ WILL DROP ACROSS THE REGION TUESDAY AFTERNOON AND EVENING. A CONDITIONAL RISK FOR STRONG TO ISOLATED SEVERE STORMS WILL EXIST FROM LATE TUE MORNING THROUGH THE AFTERNOON WITH THE PRIMARY POTNL TSTM HAZARD BEING DAMAGING WINDS. CLOUD COVER FROM UPSTREAM CONVECTION LKLY ONGOING AT 12Z ALONG WITH RESIDUAL OVERNIGHT LOW STRATUS/FOG SHOULD ACT TO LIMIT DESTABILIZATION EARLY TOMORROW. ALTHOUGH 700-500MB LAPSE RATES WILL GENERALLY REMAIN WEAK TO POOR...THE MODELS SHOW A BELT OF STRONGER WESTERLY MID-LVL FLOW AND DEEP LYR SHEAR. THIS SHOULD HELP TO SUPPORT AN INCREASE IN CONVECTIVE PCPN/INTENSITY AS RENEWED DEVELOPMENT OCCURS ALONG OUTFLOWS/DIFFERENTIAL HEATING ZONES BY LATE MORNING INTO THE AFTERNOON...WITH SOME ORGANIZATION INTO LINE SEGMENTS/CLUSTERS. THIS SHOULD YIELD AT LEAST AN ISOLD DMGG WIND THREAT...WARRANTING AN UPGRADE BY SPC TO A CATEGORICAL /SLGT/ RISK DESIGNATION. THIS HAS BEEN REFLECTED IN AN UPDATED HWO. EARLY CLOUDS SHOULD BREAK FOR A WARM AND HUMID DAY WITH FCST HIGHS EXPECTED TO RANGE FROM THE MID 70S OVER THE NW TO NEAR 90 OVER THE LOWER SUSQ VLY. THE SECOND HALF OF THE PERIOD ESPECIALLY AFTER MIDNIGHT SHOULD FEATURE A COOLER/DRYING TREND BEHIND THE FRONT WITH PWS FALLING AOB NORMAL BY 12Z WED. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... COLD FRONT EXITING TO THE EAST TUE NIGHT ALONG WITH NORTHWEST FLOW AROUND BUILDING HIGH PRESSURE AREA OVER OHIO VALLEY WILL BRING A TRANSITION TO A NOTICABLY DRIER AIRMASS FOR MIDWEEK. DAYTIME HIGHS WILL REMAIN SLIGHTLY ABOVE NORMAL...BUT LOWER DEWPOINTS WILL MAKE IT FEEL MORE COMFORTABLE. OVERNIGHT LOWS WED NIGHT WILL DIP TO NEAR 50F IN THE NORTHERN MTNS TO AROUND 60F IN THE SE. THE HIGH WILL MOVE OFF THE EAST COAST THU INTO FRI...ALLOWING MORE HUMID AIR TO BEGIN RETURNING TO THE REGION. A SURFACE LOW SLIDES FROM THE NORTHERN PLAINS ACROSS THE GREAT LAKES AND LIFTING INTO S CANADA ON FRI...DRAGGING A COLD FRONT ALONG BEHIND. AS THIS FRONT APPROACHES...AN AREA OF HIGHER PWATS /1-2"/ SURGES INTO THE OHIO VALLEY...AND THEN INTO PA FRI NIGHT INTO SAT. AT SAME TIME A BROAD UPPER TROUGH SAGS SOUTHWARD. THIS WILL BRING ELEVATED CHANCES FOR SHOWERS/TSTMS STARTING FRI NIGHT IN THE NW AND SPREADING AREAWIDE ON SAT. BEHIND THE FRONT...AIRMASS CHANGE WILL USHER IN MUCH COOLER AND DRIER AIR FOR LATE WEEKEND INTO EARLY NEXT WEEK. HIGHS WILL FALL BACK ABOUT 10F...RANGING FROM THE UPPER 60S TO MID 70S. AS LARGE HIGH PRESSURE AREA TRACKS ACROSS NEW ENGLAND...MORNING LOWS SHOULD DIP WELL INTO THE 40S ACROSS THE NORTHERN MTNS...AND IN THE LOWER TO MID 50S ACROSS THE SOUTH. && .AVIATION /22Z MONDAY THROUGH SATURDAY/... 18Z...CIGS/VISBYS HAVE IMPROVED TO VFR OR MVFR AS EXPECTED. HOWEVER DESPITE A GENERAL INCREASE IN SHOWER ACTIVITY THERE IS STILL LOW CONFIDENCE IN POINT TERMINAL IMPACTS. EVOLUTION OF CONVECTIVE ACTIVITY AND COLLOCATION OF BEST INSTABILITY SUGGESTS THE SRN TAFS HAVE THE BEST CHC TO SEE SCT SHOWERS OR A BRIEF TSRA DOWNPOUR. HAVE ADDED SOME 1HR TEMPS THRU 19Z WITH SHOWERS MOVG THRU AOO/UNV. OTHER CONCERN WILL BE CLOUD TRENDS OVERNIGHT WITH MOIST AIRMASS LKLY PROMOTING ANOTHER PERIOD OF LOW CIGS/FOG INTO TUE MORNING. A COLD FRONT MOVG EWD THRU THE MIDWEST WILL ALSO BRING THE CHC FOR SOME SHOWERS TO REACH THE NW 1/4 TO 1/3 OF THE AIRSPACE BY EARLY TUE MORNING. THIS FRONT WILL BE A FOCUS FOR SCT-NMRS SHWRS/TSTMS TUES AFTN-EVE AS IT MOVES SEWD ACRS CENTRAL PA. THE RECENT GUIDANCE SUGGESTS A SLIGHTLY HIGHER PROBABILITY FOR LCL SVR STORMS AND AT LEAST AN ISOLD THREAT FOR DAMAGING TSTM WIND GUSTS. OUTLOOK... WED-THU...PATCHY AM FOG...OTHERWISE VFR. FRI...MAINLY VFR. CHC OF PM TSTMS WEST. SAT...VFR/MVFR WITH SCT SHWRS/TSTMS ASSOCD WITH COLD FROPA. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DEVOIR/STEINBUGL NEAR TERM...DEVOIR/STEINBUGL SHORT TERM...DEVOIR/STEINBUGL LONG TERM...RXR AVIATION...STEINBUGL

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