Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 270804 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 404 AM EDT MON JUL 27 2015 .SYNOPSIS... A WEAKENING COLD FRONT OVER SOUTHERN PENNSYLVANIA WILL CONTINUE TO SLOWLY SAG TO THE SOUTH OVERNIGHT. THEN...HIGH PRESSURE BUILDS INTO THE REGION THROUGH MIDWEEK AS THE TEMPERATURE AND HUMIDITY INCREASE. THE NEXT FRONT WILL BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS WEDNESDAY NIGHT AND THURSDAY...BEFORE SEASONABLY WARM CONDITIONS RETURN. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... WEAK COLD FRONT SAGGING ACROSS SOUTHEAST PA CONTINUES TO PRODUCE HIGH INTENSITY RAINFALL RATES FROM EASTERN PORTIONS OF THE SOUTH CENTRAL MOUNTAINS THROUGH THE LOWER SUSQ RIVER VALLEY. WIDESPREAD ONE TO TWO INCHES WITH POCKETS OF 3" + KEEPING US BUSY INTO THE PRE DAWN HOURS. EXPECT THE MOST ACTIVE CONVECTION TO EXIT MY AREA BY 400 AM. IT APPEARS SHOWERS WILL LAST ALL NIGHT OVER SOUTHERN PORTIONS OF YORK AND LANCASTER COUNTIES. FOR THE REST OF THE NIGHT...POPS WERE PREVIOUSLY TRIMMED TO 10 PERCENT OR LESS ACROSS THE NW MTNS. BUMPED UP POPS TO LIKELY AND CATEGORICAL OVER THE LOWER SUSQ THROUGH 09Z. SOME CLEARING IS POSSIBLE OVER THE NW. PATCHY DENSE FOG IS ALSO LIKELY FOR LATE TONIGHT/EARLY MONDAY...ESPECIALLY IN THOSE AREAS WHERE RAIN FELL AND THE SKY CLEARS OUT. MIN TEMPS EARLY MONDAY WILL BE IN THE UPPER 50S NORTH...TO UPPER 60S ACROSS THE SOUTH. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... FRONT NOT IN A HURRY AND FOCUS MAY REMAIN TO THE EAST OF THE SUSQ. ALL DAY. FORCING IN THE FORM OF A SHORT WAVE ALOFT WILL MAKE IT ALMOST LIKELY TO SHOWER/STORM. THERE...BUT WILL KEEP CONTINUITY AND WITHIN COLLABORATION TO CALL IT SCT COVERAGE. PWATS STILL RUN IN THE 1.5-INCH RANGE MONDAY. SO THAT COULD STILL RESULT IN SOME SLOW MOVING HEAVY RAINERS IN THE SE. MAXES SHOULD BE RATHER HOMOGENEOUS IN THE L-M80S...WITH THE NW IN MORE SUNSHINE AND HIGHER 8H TEMPS/MIXING POTENTIAL OVER THE SE. AIR BEGINS TO DRY OUT IN THE SE MON NIGHT. WILL SLIDE POPS TO NILS AFTER MIDNIGHT. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... RIDGE OVER CENTRAL U.S. WILL EXPAND INTO THE GREAT LAKES AND MID ATLANTIC REGION THROUGH MIDWEEK. THEN RIDGING WILL BE REPLACED BY BROAD TROUGH OVER EASTERN U.S. AS MAIN LARGE BUBBLE OF HIGH PRESSURE RETROGRADES WESTWARD TO THE FOUR CORNERS REGION LATER IN THE WEEK. DRY PERIOD STILL IN STORE FOR TUESDAY INTO WEDNESDAY WITH HIGH PRESSURE IN CONTROL AT THE SFC AND ALOFT. NEXT CHC FOR RAIN/TSTMS WILL ARRIVE WED NIGHT INTO THURSDAY AS NEXT TROUGH AND ITS ASSOCD COLD FRONT REACHES THE APPALACHIANS. BEHIND THAT SYSTEM...MAINLY DRY WEATHER RETURNS FOR FRI AND SAT. ANOTHER WAVE SLIDES IN FROM THE WEST SUN INTO MON RE-ESTABLISHING THE TROUGH. ECMWF/GFS STILL LOOK TO BE LATCHING ONTO AT LEAST A WEAK WAVE ORIGINATING OVER THE SOUTHEAST U.S. AND LIFTING IT NORTHWARD ALONG THE APPALACHIANS BY MON...WHICH COULD HAVE IMPACTS ON THAT FORECAST PERIOD. BUT FOR NOW WILL BROADBRUSH IN GENERALLY UNSETTLED WEATHER FOR LATE NEXT WEEKEND INTO START OF NEXT WEEK. TEMPS WILL BE GENERALLY ABOVE NORMAL FOR MUCH OF THE WEEK...WITH A PEAK IN THE HEAT OCCURRING AROUND WED IN THE NORTH AND WED-THU ACROSS THE SOUTH...WITH HIGHS PEAKING FROM THE MID 80S TO LOWER/MID 90S. DEWPOINTS WILL ALSO INCREASE MIDWEEK...AS HEAT INDEX VALUES MAY APPROACH 100F IN THE LWR SUSQ VLY. COOLER AND LESS HUMID WEATHER RETURNS AS WE HEAD INTO NEXT WEEKEND. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... SHOWERS HAVE EXITED THE REGION AFTER COLD FRONTAL PASSAGE. SLOWLY CLEARING SKIES...AND COPIOUS AMOUNTS OF LOW LEVEL MOISTURE WILL ALLOW FOR PERIODS OF PATCHY DENSE FOG OVERNIGHT AND THROUGH SUNRISE. AREAS THAT RECEIVED THE HEAVIEST PRECIPITATION...UNV...AOO...IPT SHOULD EXPECT TO SEE IFR CIGS AND VSBYS BETWEEN 08Z TO 14Z. EXPECT FOG TO LIFT/DISSIPATE SLOWLY AFTER SUNRISE...AND TO BE GONE BY 15Z AT THE LATEST. ANOTHER ROUND OF SHOWERS WILL BE POSSIBLE TOMORROW AFTERNOON WHERE SCATTERED TSRA/SHRA COULD BRING MVFR TO IFR CIGS AND VSBYS TO CENTRAL AND SOUTHERN TAF SITES AFTER 21Z. HIGH PRESSURE FINALLY PUSHES THE MOISTURE OUT OF THE ENTIRE AREA LATER MONDAY NIGHT. VALLEY FOG POSS IN THE NRN MTNS TUES AM. OUTLOOK... TUE...VALLEY FOG POSS AM...OTHERWISE NO SIG WX. WED...MAINLY VFR WITH ISO PM SHRA/TSRA. THU...CFROPA W/VERY BRIEF REDUCTIONS DUE TO TSRA. FRI...MAINLY VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...DEVOIR/LAMBERT SHORT TERM...DANGELO LONG TERM...RXR AVIATION...CERU/GARTNER

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