Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 020030 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 830 PM EDT FRI AUG 1 2014 .SYNOPSIS...
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A PERSISTENT MID-LEVEL TROUGH TO OUR WEST AND A STRONG RIDGE OVER THE WESTERN ATLANTIC WILL ALLOW MOISTURE TO MOVE UP THE EAST COAST. UNTIL THE TROUGH SURGES TO THE EAST AND PUSHES THE MOISTURE OFF TO THE EAST...OUR REGION WILL BE ON THE WESTERN EDGE OF THE MOISTURE PLUME. THE GENERAL TREND OVER THE NEXT SEVERAL DAYS IS FOR THE MOISTURE PLUME TO SLOWLY SLIDE EAST. CHANCES OF ORGANIZED RAIN WILL BE GREATER IN THE EAST AND SHOULD SLOWLY DECREASE SUNDAY INTO TUESDAY.
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&& .NEAR TERM /UNTIL 7 AM SATURDAY MORNING/...
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EARLIER CONVECTION IN THE EAST IS GONE...BUT ADDITIONAL SHRA/TSRA FORMING NOW UP OVER THE NWRN MTS IN A LINE FROM BRADFORD TO TIDIOUTE. THIS IS RIGHT WHERE THE NAM FROM 18Z MADE CONVECTION THIS EVENING. SO...IT HAS MY CONFIDENCE THERE. THE NAM DOES NOT QUITE HAVE ANY CONVECTION OR STRATIFORM RAIN MOVING INTO THE OPPOSITE CORNER OF THE CWA NEAR LANCASTER/YORK COS AT THIS TIME. IT DOES BUBBLE CONVECTION UP FROM THE SE AGAIN LATER TONIGHT...LIKE THE NARRE AS WAS NOTED BY THE PREV SHIFT. THE CURRENT RAP SLIDES THE PRECIP IN THE NW TO THE SOUTH - OR VERY MUCH OPPOSITE THE FLOW AND THE NAM PREDICTION. IT COULD BE THAT CONVECTION DIES IN PLACE AND ADDITIONAL TOWERS POP UP TO THE SOUTH. BUT I AM SUSPICIOUS THAT WILL BE THE CASE. SO WILL ADJUST THE FORECAST TO MATCH THE CURRENT TRENDS AND WEIGHT TOWARD THE NAM SOLUTION FOR THE NEAR TERM. POPS ARE SET TO INCREASE FROM SE TO NW OVER THE SE TONIGHT AND WILL KEEP IT THERE AS IT SEEMS TO MATCH THE CURRENT FLOW AND CONCEPTUAL MODEL. TEMPS AND OTHER PARAMETERS ON TRACK.
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&& .SHORT TERM /7 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
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THE FLOW BETWEEN THE 500 HPA TROUGH TO OUR WEST AND THE 500 HPA RIDGE TO OUR EAST WILL ALLOW MOISTURE PLUME TO SURGE INTO THE MID- ATLANTIC REGION SATURDAY. NAM-GFS-SREF SUGGEST HIGHER POPS IN EAST SATURDAY AM. LOWER POPS TO WEST THOUGH IMPLIED QPF SHIELDS SHOW A SQUEEZE PLAY WITH A ZONE OF VERY LOW POPS EXTENDING FROM NY INTO PA. BUT THIS DRY ZONE/S POSITION VARIES FROM MODEL TO MODEL. THE NAM IS MUCH DRIER IN SW MOUNTAINS THAN GFS. DUE TO DEEP MOISTURE BOUNDARY KEPT POPS RELATIVELY HIGH IN EAST/SOUTHEAST AND SW MOUNTAINS AND LOWER TO NORTH AND WEST. THE 4KM NAM IMPLIES PRETTY QUIET OVER THE REGION AROUND 8 AM AND NOTHING OF NOTE CONVECTIVELY UNTIL AFTERNOON. THEN IT SHOWS LITTLE ORGANIZATION AND MOSTLY SCATTERED SHOWERS...WITH THE HIGHEST CONCENTRATION IN THE WEST-CENTRAL PART OF THE CWA. MESSAGE...LOTS OF UNCERTAINTY SATURDAY BUT A RELATIVELY DRY MORNING AFTER 7-8AM IN THE EAST THEN SCATTERED SHOWERS/TSTMS POP UP AGAIN IN THE AFTERNOON.
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&& .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... THE FORECAST AREA WILL BE NEAR THE NWRN EDGE OF THE EXTENSIVE DEEP MOISTURE PLUME STREAMING NNE FROM THE ERN GOMEX AND WRN ATLANTIC THIS WEEKEND. THE SHORT WAVE TROUGH TO OUR WEST...AND PERIODS OF WEAK-MDT LARGE SCALE UVVEL ASSOCIATED WITH COMPACT WAVES AT THE SFC AND ALOFT RIDING NEWD...WILL SPARK ISOLATED TO SCATTERED NOCTURAL SHOWERS...AND A CHANCE OF A FEW AFTERNOON TSRA BOTH SUNDAY AND MONDAY. THE MID AND UPPER FLOW VEERS AROUND TO THE WEST TUESDAY AHEAD OF SIGNIFICANT UPPER WAVE /AND POTENT SFC CFRONT/ DROPPING SE ACROSS THE GLAKES. A SECONDARY CFRONT WILL MOVE SE THROUGH THE AREA DURING THE DAY WEDNESDAY. PWATS WILL BE DROPPING BACK TO NEAR OR SLIGHTLY BELOW NORMAL /EVEN AHEAD OF THE 2 CFRONTS/. HOWEVER...850-500 MB LAPSE RATES AHEAD OF BOTH FEATURES WILL BE AS MUCH AS 6.5C/KM...WHICH WILL LEAD TO SCATTERED...MAINLY AFTERNOON AND EARLY EVENING TSRA. A FEW OF THE TSRA EACH AFTERNOON COULD BE ON THE STRONG SIDE. 0-3KM BULK SHEAR WILL BE AOB 15 KTS...SO THE CFROPAS BOTH DAYS DON/T APPEAR TO POSE A SIGNIFICANT...CONVECTIVE WIND THREAT ATTM. FOR LATER NEXT WEEK...A LARGE AREA OF HIGH PRESSURE AT THE SFC /BENEATH BROAD WESTERLY CONFLUENT FLOW ALOFT/ WILL BUILD IN FROM THE MIDWEST AND SHOULD BRING AT LEAST A FEW DAY PERIOD OF PARTLY TO MOSTLY SUNNY WEATHER AND LOW HUMIDITY. A BLEND OF GEFS...GFS...AND EC GUIDANCE INDICATES SLIGHTLY RISING HEIGHTS AND A WEAK SHORT WAVE OR TWO EMBEDDED IN THE WESTERLY FLOW ALOFT. THIS WILL BRING AN INCREASE IN PWATS LATE FRIDAY NIGHT AND SATURDAY WITH SCATTERED SHRA/TSRA DEVELOPING AS WE HEAD INTO NEXT WEEKEND. AFTER A NEAR PERFECT MATCH OF MONTHLY AVG HIGH AND LOW TEMPS TO NORMAL AT KMDT AND KIPT IN JULY...MAX AND MIN TEMPS IN THE LONG TERM PERIOD DON/T APPEAR TO STRAY SIGNIFICANTLY FROM NORMAL. THE WARMEST TEMPS APPEAR TO BE TUESDAY AHEAD OF THE INITIAL CFRONT AS A DECENT WESTERLY DOWNSLOPE LLVL COMPONENT KICKS IN. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS ACROSS THE REGION...EXCEPT SOME AREAS LIKELY SEEING ISOLATED MVFR/IFR CONDITIONS IN SHOWERS AND THUNDERSTORM OVER THE MIDDLE/LOWER SUSQUEHANNA REGION. BASED ON LATEST RADAR...HAVE REMOVED VCTS FROM TAFS FOR THE REMAINDER OF THIS AFTERNOON AND EVENING. ONLY TAF SITE WHICH LOOKS IMMINENT TO SEE A SHOWER IN THE NEXT HOUR OR TWO IS KIPT...AND HAVE INCLUDED VCSH IN THEIR TAF. FOR THE MOST PART...DIURNAL SHOWERS SHOULD WANE DURING THE EVENING. HOWEVER...SHORT TERM / HIGH RESOLUTION MODELS HINT AT REGENERATING PRECIPITATION FOR THE SOUTHEASTERN AIRFIELDS OVERNIGHT. OVERALL...LOOK FOR FOG AND HAZE DEVELOPMENT OVERNIGHT...WITH WIDESPREAD MVFR...AND AREAS OF IFR/LIFR. CONDITIONS IMPROVE SATURDAY BUT THE CLOUDS AND MOISTURE TO OUR EAST ARE NOT FORECAST TO MOVE OUT ALL TOO FAST. OUTLOOK... SAT-SUN...AM MVFR/IFR...THEN MAINLY VFR BUT WITH SCATTERED AFTERNOON SHRA/TSRA IMPACTS POSSIBLE. MON...POSSIBLE AM FOG AREAS MVFR/IFR. OTHERWISE MAINLY VFR. TUE...SCATTERED SHRA/TSRA WITH APPROACHING COLD FRONT. WED...SCATTERED SHRA/TSRA. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...GRUMM NEAR TERM...GRUMM/DANGELO SHORT TERM...GRUMM/DANGELO LONG TERM...ROSS/LAMBERT AVIATION...GRUMM/JUNG

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