Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 011943 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 343 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/... 18Z...RADAR LOOP INDICATES CONVECTIVE PCPN IS STARTING TO INCREASE IN CVRG OVER THE LAST 30 MINUTES OVER THE SRN 1/3 OF THE CWA WHERE THE RAP SHOWS THE HIGHEST CAPE IN PA. EVEN BETTER INSTABILITY CAN BE FOUND SOUTH OF THE MASON DIXON LINE NEAR THE I95 CORRIDOR WHERE THE FIRST LTG STRIKE OF THE AFTN HAS BEEN DETECTED. HIGHEST POPS /30-40%/ HAVE BEEN PAINTED OVER THE SRN TIER ZONES THRU THE EARLY EVENING HOURS. FURTHER TO THE NORTH...WEAK LG SCALE FORCING COUPLED WITH MARGINAL INSTABILITY /HINDERED BY CLOUD COVER/ AND VERY MOIST/HUMID AIRMASS CONTINUES TO SUPPORT IDEA OF MAINLY ISOLD SHOWERS. MESO MDL GUIDANCE SHOWS EVE STORMS EVENTUALLY DISSIPATING AFTER DARK WITH THE LOSS OF HEATING. UPSTREAM STORMS OVER THE GRT LWR MI/OH VLY SHOULD ALSO EXHIBIT A CONSIDERABLE WEAKENING TREND AS THE EVOLVE EWD AND MAY SURVIVE INTO WRN PA LATE TNGT. MAIN FOCUS WILL SHIFT TO THE WEST TONIGHT AS A WELL-DEFINED COLD FRONT APPROACHES THE AREA FROM THE N/W. HIGHEST POPS /40-50%/ WILL BE OVER THE FAR NW MTNS BASED ON MULTI-MODEL ENSEMBLE CONSENSUS QPF. IT WILL BE MUGGY WITH LOWS 65-70F. LGT WINDS AND HI DEWPOINTS ALONG WITH SOME PARTIAL CLEARING FAVORS SOME LOW CLOUDS/FOG. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... A RELATIVELY LOW AMPLITUDE SHORTWAVE TROUGH WILL SLIDE EWD FROM THE GREAT LAKES/MIDWEST INTO NRN NEW ENGLAND BY THE END OF THE PERIOD. THIS FEATURE WILL DRIVE A WELL-DEFINED COLD FRONT /WITH SHARP MSTR-PW GRADIENT/ SEWD FROM THE LWR LKS/OH VLY ACRS THE N-CNTRL APPALACHIANS. 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/...
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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.
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&& .AVIATION /19Z 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...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...RXR AVIATION...STEINBUGL

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