Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 010018 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 818 PM EDT TUE SEP 30 2014 .SYNOPSIS... A SLOW MOVING UPPER LOW AND WEAKENING COLD FRONT WILL DROP SOUTHEAST ACROSS THE REGION TONIGHT...BRINGING A LIKELIHOOD OF SHOWERS AND THUNDERSTORMS...ESPECIALLY ACROSS THE EASTERN HALF OF PENN. UNSETTLED CONDITIONS WILL MOVE EAST OF THE REGION LATER WEDNESDAY...WITH DRY WEATHER EXPECTED THROUGH THE END OF THE WEEK. A STRONGER COLD FRONT WILL PUSH EAST INTO THE COMMONWEALTH LATE FRIDAY NIGHT AND SATURDAY. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... SLOW MOVING BROKEN LINE OF THUNDERSTORMS HAS BEEN IMPACTING MUCH OF CENTRAL PENN AND THE AREA RIGHT ALONG THE ALLEGHENY FRONT OVER THE PAST SEVERAL HOURS...AS A RESULT OF A REGION OF ENHANCED/DEEP UVVEL AT THE NOSE OF AN APPROACHING 80 KT CYCLONICALLY CURVED UPPER JET. THE FORCING ASSOCIATED WITH THIS JET MAX WILL SLIDE TO THE SUSQ VALLEY AND POINTS EAST AFTER 03Z AS THE CENTERED OF A 568 DAM 500 MB LOW BECOMES CENTERED NEAR KPIT. THIS CONVECTION HAS BEGUN TO SLOWLY WEAKEN OVER THE PAST HOUR AS BOUNDARY LAYER HEATING WANES WITH THE ONSET OF NIGHTFALL. EXPECT THIS AREA OF CONVECTION TO CONTINUE TO WEAKEN GRADUALLY THROUGH THE LATE EVENING HOURS AS IT DRIFTS EAST TOWARD THE SUSQ MAINSTEM. RAINFALL RATES AND 1-3 HOUR TOTALS HAVE BEEN CONTAMINATED GREATLY /PERHAPS BY 50 PERCENT OR SE/ BY NUMEROUS OCCURRENCES OF PEA...TO DIME- SIZE HAIL IN THE STRONGEST CORES THAT HAVE HAD TROUBLE PENETRATING THE -20C LEVEL UP AROUND 23 KFT. STILL...SOME OF THE STORMS HAVE DROPPED 0.50 TO 1.00 INCH OF RAIN IN LESS THAN AN HOUR. WILL HAVE TO MONITOR THE REGION NEAR AND TO THE NORTH OF HARRISBURG /TO KIPT AND KAVP/ OVERNIGHT AS THIS UPPER LOW SLOWLY PROGRESSES EAST ACROSS SCENT PENN AND MAINTAINS A CONCENTRATED AREA OF STRONG UPPER LEVEL DIVERGENCE AND DEEP...LOW TO MID LEVEL FRONTOGENESIS. A BLEND OF THE LATEST HRRR/S PRECIP...AND THE LOCATION OF THE BEST FGEN FORCING VIA THE 18Z NAM WILL LEAD US TO INCREASE POPS TO AT LEAST THE HIGH LIKELY CATEGORY LATE TONIGHT ACROSS MUCH OF THE CENTRAL AND LOWER SUSQ VALLEY. THE MAIN THREAT TONIGHT WILL BE AREAS OF 1.00 INCH RAINFALL...WHILE THE CHC OF HAIL GREATLY DIMINISHES BY 01Z. AS THE UPPER LOW NEARLY GRINDS TO A HALT ACROSS SCENT PENN TONIGHT...SCATTERED SHOWERS WILL CONTINUE OVERNIGHT...BUT NOT A CONTINUOUS OR WIDESPREAD RAIN BY ANY MEANS. LOWS GENERALLY IN THE 50S WILL AVERAGE ABOUT 5-10 DEG ABOVE NORMAL FOR THE LAST DAY OF SEPTEMBER. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... SLOWLY FILLING UPPER LOW WILL MOVE SLOWLY EASTWARD ACROSS THE COMMONWEALTH ON WEDNESDAY...BRINGING A STEADY DECLINE IN THE FORCING FOR THE SCATTERED SHOWERS. IT LOOKS QUITE CLOUDY BUT MAINLY DRY WITH ONLY SLGT CHC POPS UNDER THE "COOL" CORE ALOFT. TEMPS ON WED WILL BE COOLER THAN RECENT DAYS. EXPECT HIGHS TO RANGE FROM THE UPPER 60S NORTH TO THE LOWER 70S SOUTH. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... PROGRESSIVE UPPER LOW/COMPACT TROF AXIS FORECAST TO BE LIFTING NE INTO NEW ENGLAND AT THE START OF THE PERIOD WILL BE REPLACED BY A SHORT PERIOD OF RISING HEIGHTS LATE IN THE WEEK. 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. WARMER WEATHER MAKES A BRIEF RETURN THUR...FRI AND EARLY SAT AS THE UPPER RIDGE TEMPORARILY REBUILDS....WITH MOST MAXES AND MINS AT LEAST SEVERAL DEGREES ABOVE CLIMO NORMALS. MAX TEMPS SAT WILL BE BELOW NORMAL. 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 THAN WITH THE FIRST FRONT. PASSAGE OF THE FRONT WILL ALSO BRING NOTICEABLY COOLER TEMPS TO THE REGION STARTING SATURDAY AFTERNOON INTO MONDAY. SEVERAL SHORT WAVES DROPPING INTO THE UPPER TROF / EXPECTED CYCLONIC FLOW OVER THE REGION WILL KEEP THE WEATHER COOL AND UNSETTLED INTO EARLY NEXT WEEK. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
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SLOW MOVING BROKEN LINE OF THUNDERSTORMS HAS BEEN IMPACTING MUCH OF CENTRAL PENN OVER THE PAST SEVERAL HOURS...AS A RESULT OF A REGION OF ENHANCED/DEEP UVVEL AT THE NOSE OF AN APPROACHING 80 KT CYCLONICALLY CURVED UPPER JET. THE FORCING ASSOCIATED WITH THIS JET MAX WILL SLIDE TO THE SUSQ VALLEY AND POINTS EAST THIS MID EVE AS THE CENTERED OF A 568 DAM 500 MB LOW BECOMES CENTERED NEAR KPIT. THOUGH THIS CONVECTION HAS BEEN OVERALL SLOWLY WEAKENING SINCE SUNSET...JUST ABOUT EVERY CELL PRODUCING SOME LIGHTNING. THIS AREA OF CONVECTION SHOULD CONTINUE TO GRADUALLY WEAKEN/DIMINISH THROUGH THE LATE EVENING HOURS AS IT DRIFTS EAST TOWARD THE SUSQ MAINSTEM...THOUGH ISOLATED STRONGER CELLS STILL POSS IN VICINITY OF TERMINALS FROM KSEG TO KMDT-KLNS THROUGH 06Z. AS THE UPPER LOW NEARLY GRINDS TO A HALT ACROSS SCENT PENN TONIGHT...SCATTERED SHOWERS WILL LINGER OVERNIGHT. FOG/LOW CLOUDS WILL DEVELOP AS WELL WITH INCREASED LOW LEVEL MOISTURE ALONG WITH LIGHT WINDS AND MID CLOUD DECK MOVING OUT. EXPECT IFR FOG/CIGS TO DEVELOP AFTER 04Z ACROSS THE WEST/CENTRAL AND A BIT LATER AFTER SHOWER ACTIVITY TAPERS OFF IN THE EAST...WITH IFR LINGERING TO THE MID MORNING HOURS. FOG/LOWER CIGS START THE DAY WED...WITH SLOW IMPROVEMENT THROUGH MID/LATE MORNING BEFORE FINALLY ARRIVING AT VFR CONDITIONS FOR LATE MORNING AND AFTERNOON. WINDS WILL BE LIGHT. OUTLOOK... THU...LOW CIGS LIKELY EARLY...AND COULD PERSIST THRU MUCH OF THE DAY DUE TO HIGH PRESSURE FUELING A MOIST MARITIME FLOW E OF THE APPLCHNS. FRI...SHOWERS AND THUNDERSTORMS LKLY ASSOC WITH A STRONG COLD FRONT. LLWS LKLY DUE TO STG SLY WINDS AHEAD OF THE COLD FRONT. SAT...AM SHOWERS ERN AREAS. BREEZY WITH IMPROVING CONDITIONS E OF THE MTNS. ISOLD SHOWERS AND LOCAL MVFR POSSIBLE OVER N/WRN AREAS. SUN...NO SIG WX.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE/LAMBERT NEAR TERM...LA CORTE/LAMBERT SHORT TERM...LA CORTE LONG TERM...GARTNER AVIATION...RXR

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