Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 240337 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1137 PM EDT WED JUL 23 2014 .SYNOPSIS... A COLD FRONT WILL PUSH SOUTHEAST OF THE COMMONWEALTH OVERNIGHT. A REFRESHING...COOLER AND LESS HUMID AIRMASS WILL OVERSPREAD THE COMMONWEALTH FOR THE END OF THE WEEK INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... SFC FRONT PUSHING OUT OF THE LOWER SUSQ RIVER VALLEY AT THIS HOUR WITH DEEP CONVECTION HAVING PUSHED WELL EAST OF THE AREA. SOME ISOLATED SEVERE REPORTS WERE RECEIVED BY THE OFFICE ON A HANDFUL OF WARNINGS THIS EVENING...BASICALLY A LOW END EVENT WITH SLOW MOVING PULSING CELLS IN WEAK SHEAR AND VERY WARM AIR ALOFT. DEEP LAYER DRYING TAKES PLACE FROM NORTHWEST TO SOUTHEAST OVERNIGHT WITH CYCLONICALLY SHEARED FLOW PERSISTING ACROSS THE EASTERN GREAT LAKES AND NORTHERN MID ATLANTIC. THERE COULD STILL BE BE A LIGHT SHOWER OR TWO THROUGH LATE THIS EVENING AS A POCKET OF COOLER AIR ALOFT MOVES THROUGH NY STATE AND BRUSHES THE NRN TIER INTO THE POCONO PLATEAU REGION. ISOLATED SHOWERS MAY ALSO BRUSH THE LAUREL HIGHLANDS THROUGH MIDNIGHT. ELSEWHERE SHOULD BE MAINLY DRY FOR THE REMAINDER OF THIS EVENING WITH VARYING AMOUNTS OF CLOUDS...AVERAGING OUT MOSTLY CLOUDY. CONDITIONS DRY OUT OVERNIGHT WITH ANY LINGERING SHOWER ACTIVITY DROPPING SOUTH OF THE MASON DIXON LINE BY 12Z THU. THE GUIDANCE TEMPS TONIGHT DO DROP NICELY OVER THE NORTH - BUT WILL TEMPER THAT FALL DUE TO THE ANTICIPATED LOWER CLOUD DECK THERE. MID 50S SHOULD BE LOW ENOUGH EXCEPT FOR THE MOST RURAL VALLEYS. THUS...THERE COULD BE A BIT OF VALLEY FOG TONIGHT...BUT THE AIR IS VERY DRY. WILL THEREFORE NOT MENTION FOG FOR TONIGHT IN THE GRIDS. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... THURSDAY SEEMS LIKE A GREAT DAY FOR ANY OUTDOOR ACTIVITY WITH ANY LOW CLOUDS BURNING AWAY IN THE MORNING. HIGHER CLOUDS ALONG THE SRN BORDER MAY LINGER FOR A BIT LONGER...BUT NOT ENOUGH TO WARRANT A MOSTLY CLOUDY FCST. DESPITE THE 8H TEMPS AS LOW AS +10C IN THE MORNING ACROSS THE NORTHERN TIER...EVEN THEY SHOULD WARM BACK INTO THE LOWER/MID 70S. 80F AND MAYBE A LITTLE WARMER IS EXPECTED IN THE SOUTH. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... OVERALL SCENARIO REMAINS UNCHANGED IN THE LONG TERM PERIOD AS A LARGE UPPER RIDGE BUILDING OVER THE FOUR CORNERS REGION IS FORECAST TO EXPAND NORTH AND EAST INTO THE ROCKIES AND PLAINS DURING THE PERIOD. DOWNSTREAM...THIS WILL LEAD TO MODERATE TO STRONG LONG WAVE TROFFING OVER THE EASTERN THIRD OF THE COUNTRY. UPPER LOW TO THE EAST OF HUDSON BAY WILL BE STRENGTHENED AT TIMES BY SHORTWAVE ENERGY IN THE STRONGER JET STREAM FLOW ACROSS CANADA. SOUTHWARD EXTENSION OF THIS LOW/TROF WILL AT TIMES DURING THE PERIOD STRENGTHENING THE TROFFING ACROSS THE NORTHEASTERN U.S./OUR REGION. THE TREND OF MEDIUM RANGE MODEL GUIDANCE IS FOR STRONGER/DEEPER TROFFING DOWNSTREAM ACROSS THE EASTERN U.S...DEVELOPING AN ALMOST FULL LATITUDE TROF EXTENDING FROM THE EASTERN CANADA LOW SWD TO FLORIDA. THIS WILL LIKELY SERVE TO EXPAND AND PROLONG THE CHANCES FOR PCPN THIS WEEKEND. CONDS WILL BE IMPROVING AT THE START OF THE PERIOD AS COLD FRONT EXITS. A SECOND...POTENTIALLY STRONGER SYSTEM WILL AFFECT THE REGION LATE NEXT WEEKEND. THE TREND OF STRONGER TROUGHING MENTIONED ABOVE HAS LEAD TO SLOWER ARRIVAL AND DEPARTURE OF THE FRONTAL SYSTEM IN THE DAILY PROGS. THE ECMWF IN LATEST RUN HAS SLOWED UP THE PROGRESSION OF THIS UPPER LEVEL LOW...WHERE THE GFS OPERATIONAL AND ENSEMBLES HAVE SPED UP ITS PROGRESSION THROUGH THE GREAT LAKES REGION. A WARM FRONT WILL BE ON THE DOORSTEP OF PA SUNDAY...AS THE EC CONTINUES TO SLOW ITS PROGRESSION SO EXPECT THE WARM FRONT TO MOVE IN CLOSER TO MIDDAY SUNDAY. HAVE THUS ADJUSTED POPS/TIME. ASSOCIATED COLD FRONT DOES NOT CROSS THE STATE TIL MONDAY...WHERE SURPRISINGLY AT THIS POINT...THE EC AND GFS COME CLOSELY IN PHASE. THIS LARGE UPPER LEVEL LOW COULD BECOME QUASI STATIONARY OVER SOUTHERN CANADA...GREAT LAKES REGION WHICH COULD LEAD TO A POTENTIAL PROLONGED PERIOD OF SHOWERS AND THUNDERSTORM THROUGH THE MIDDLE OF NEXT WEEK. && .AVIATION /04Z THURSDAY THROUGH MONDAY/... PRECIPITATION HAS MOVED OUT OF THE AREA...AND FOG BEGINNING TO DEVELOP ACROSS THE REGION. IN ADDITION...DECK OF LOWER STRATUS MOVING INTO THE WESTERN MOUNTAINS...WITH TYPICAL UPSLOPE MOIST FLOW BRINGING IN IFR CIGS INTO KJST. EXPECT IFR CONDITIONS OVERNIGHT IN KJST AND KBFD...AND GENERALLY MVFR CONDITIONS ELSEWHERE. HIGH PRESSURE TO PROVIDE GENERALLY VFR CONDITIONS THROUGH SATURDAY...BEFORE SHRA/TSRA MOVE INTO THE WEST LATER SATURDAY...WITH THE RISK OF SHRA/TSRA SUN/MON. OUTLOOK... FRI...PATCHY AM FOG...OTHERWISE VFR. SAT...PATCHY AM FOG...OTHERWISE MAINLY VFR. PM TSRA/MVFR POSS W. SUN...SHRA/TSRA WITH WARM FRONT PASSAGE MON...MORE WIDESPREAD SHRA/TSRA WITH COLD FRONT PASSAGE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO/DEVOIR NEAR TERM...DANGELO/DEVOIR SHORT TERM...DANGELO/DEVOIR LONG TERM...LAMBERT/GARTNER AVIATION...JUNG

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