Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 300239 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1039 PM EDT MON SEP 29 2014 .SYNOPSIS... A WEAK COLD FRONT AND AN UPPER LEVEL DISTURBANCE WILL MOVE OUT OF THE GREAT LAKES AND BRING AN INCREASE IN CLOUDS ALONG WITH SOME SHOWERS OR THUNDERSTORMS TUESDAY INTO WEDNESDAY. A STRONGER COLD FRONT WILL PUSH EAST INTO THE COMMONWEALTH LATE FRIDAY NIGHT OR SATURDAY. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... A LONE SHOWER COULD AFFECT A FEW SPOTS ALONG THE MASON DIXON LINE IN YORK AND ADAMS CO BTWN 03Z-04Z. SOME MEAGER CAPES NOTED IN THE RAP OUTPUT ACROSS THIS AREA AT 02Z. HOWEVER...COOLING/STABILIZING BLYR AND PASSAGE OF UPPER LVL SHORTWAVE SHOULD BRING AN END THE SHOWER THREAT BY ARND MIDNIGHT. SHIELD OF MID AND HIGH LVL CLOUDS OVER EASTERN PA SHOULD PUSH EAST OF THE AREA BY ARND 06Z...AS SHORTWAVE AND ASSOC WAA ALOFT SHIFT EAST OF THE STATE. CENTRAL PA WILL BE IN BTWN SHORTWAVES TONIGHT...ONE DEPARTING THE E COAST AND NEXT SHORTWAVE DIVING ACROSS THE GRT LKS. LG SCALE SUBSIDENCE BTWN THESE SYSTEMS SHOULD ENSURE A DRY FCST OVERNIGHT. MCLEAR SKIES AND A CALM WIND WILL PROMOTE AREAS OF LATE NIGHT VALLEY FOG. LATEST SREF AND RAP OUTPUT SUGGEST...UNLIKE MANY RECENT NIGHTS...SOME OF THE FOG COULD AFFECT EVEN THE LOWER SUSQ VALLEY. DWPTS IN THE 50S SHOULD TRANSLATE TO ANOTHER MILD NIGHT FOR LATE SEPT...WITH LOWS MOSTLY IN THE L/M 50S. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... A POTENT UPPER SHORTWAVE/LOW OVR THE GRT LKS WILL DIVE SE ACROSS PA ON TUESDAY. DECREASING STABILITY UNDER THE COLD POOL ALOFT WILL HELP SUPPORT THE DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS. ENSEMBLES AND OPERATIONAL GUIDANCE INDICATE THAT CAPE WILL BE MODEST...BUT FORECAST TOTAL-TOTALS IN EXCESS OF 50 ARE USUALLY A GOOD INDICATOR FOR THE POTENTIAL OF SOME LOW TOPPED CONVECTION. BASIN AVERAGE RAINFALL IS EXPECTED TO BE LIGHT...ON THE ORDER OF 0.10 OF AN INCH OR LESS...BUT AMOUNTS COULD BE SLIGHTLY HEAVIER...0.15 TO 0.25 OF AN INCH...ACROSS THE FAR NW TUESDAY AFTERNOON AND EVENING. MAX TEMPS TUESDAY ARE EXPECTED TO BE JUST A FEW DEG COOLER AND IN THE LOWER TO MID 70S. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... PROGRESSIVE UPPER LOW/COMPACT TROF AXIS OVER THE NERN U.S. AT THE START OF THE PERIOD IS FORECAST TO LIFT OUT BY THE END OF THE WEEK...AS UPPER RIDGE REBUILDS ACROSS THE REGION INTO THE EARLY PART OF THE WEEKEND. A SECOND...MUCH STRONGER AND EXPANSIVE UPPER TROF AXIS EXTENDING SWD FROM AN UPPER LOW ANCHORED OVER NRN ONTARIO IS FORECAST TO SWEEP ACROSS THE EASTERN U.S. OVER THE WEEKEND. CLOUDIER AND MORE UNSETTLED WEATHER THAN RECENT DAYS IS EXPECTED TO ACCOMPANY THE FIRST TROF WED...HOWEVER THE SYSTEM IS SOMEWHAT MOISTURE-LIMITED AND SIGNIFICANT PCPN IS NOT EXPECTED. TEMPS ON WED HOWEVER WILL BE COOLER THAN RECENT DAYS. WARMER WEATHER MAKES A BRIEF RETURN THUR...FRI AND EARLY SAT AS THE UPPER RIDGE REBUILDS....WITH MAXES AND MINS AT LEAST SEVERAL DEGREES ABOVE CLIMO NORMALS. THE ARRIVAL OF THE SECOND TROF WILL SUPPORT A STRONG COLD FRONT WITH DEEPER CONNECTIONS TO THE GOMEX AND THE ATLANTIC OCEAN...THUS POTENTIAL FOR MORE WIDESPREAD AND HEAVIER RAINFALL. PASSAGE OF THE FRONT WILL ALSO BRING NOTICEABLY COOLER TEMPS TO THE REGION FOR SUNDAY INTO MONDAY. A SHORT WAVE WITHIN THE THEN EXPECTED CYCLONIC FLOW OVER THE REGION WILL BRING ANOTHER FRONTAL SYSTEM TO THE REGION WITH AN INCREASED CHANCE OF SHOWERS FOR THE END OF THE PERIOD. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... CLOUDS WILL CONTINUE TO THIN OVERNIGHT. DID HIT THE FOG A LITTLE HARDER THAN IN THE 18Z TAF PACKAGE...ESPECIALLY WITH HIGHER DEWPOINTS THIS EVENING THAN IN RECENT DAYS. THERE WAS LITTLE FOG LAST NIGHT...AS MID AND HI CLDS MOVED IN OVERNIGHT. PERHAPS A FEW SHOWERS ACROSS THE WEST ON TUE. WED...AN UPPER TROUGH/LOW DROPPING OUT OF THE GR LAKES INTO THE LOCAL AREA WILL BRING SCT RAIN SHOWERS AND EVEN SOME THUNDERSTORMS. LOW CIGS PROBABLE AT NIGHT. OUTLOOK /THU THROUGH SAT/... THU...LOW CIGS COULD LINGER MUCH OF THE DAY AS HIGH PRESSURE TO THE EAST PROVIDES AN EAST-SOUTHEAST MARITIME FLOW. FRI...SHOWERS AND THUNDERSTORMS PSBL ASSOC WITH GUSTY FROPA. SAT...BREEZY WITH IMPROVING CONDITIONS. SHOWERS AND LOCAL MVFR POSSIBLE OVER NWRN AREAS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD/LA CORTE LONG TERM...LAMBERT/GARTNER AVIATION...MARTIN

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