Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 272242 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 642 PM EDT MON JUL 27 2015 .SYNOPSIS... A FRONT LINGERING OVER SOUTHEASTERN PENNSYLVANIA WILL DISSIPATE AND SLOWLY SAG TO THE SOUTH. HIGH PRESSURE WILL BUILD 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 MIDNIGHT TONIGHT/... ONLY WEAK SHOWERS ABLE TO GROW OVER PA AS OF 18Z...BUT PEAK HEATING STILL TO COME. MANY MORE SHRA/TSRA JUST TO THE S OF PA/MD BORDER. THE FRONT APPEARS ON SFC PRES AND WIND ANALYSIS TO BE OVER KMDT AND KHGR AND THEN GO WEST TO KMGW. THUS...MORE STORMS ARE EXPECTED NEAR AND TO THE SOUTH OF THE FRONT. BUT THE ELEVATED HEATING SFCS OF THE RIDGETOPS ALONG THE ALLEGHENIES AND RIDGE AND VALLEY REGION ARE ALSO PROVIDING JUST ENOUGH LIFT TO BRING CLOUDS UP JUST ENOUGH TO PRODUCE SOME RAIN. MORE HEAT AND BETTER CONVERGENCE WILL ADD TO THE MIX AND COVG SHOULD INCREASE THROUGH 5-7 PM THEN WANE AFTER SUNSET. PWATS STILL UP TO 1.6 INCHES IN THE SRN TIER AND 8H-3H MEAN WIND ONLY 10-15 KTS FROM THE NW. SFC-BASED CAPES RUNNING ABOVE 1000 AND 200 JOULES ACROSS THE SOUTH. THUS...SOME PLACES COULD PICK UP A BRIEF HEAVY DOWNPOUR. BUT ONLY A FEW HOT SPOTS WHERE STORMS REGENERATE WILL HAVE A RISK FOR RAIN HEAVY ENOUGH TO DO MORE THAN MAKE BIG PUDDLES. && .SHORT TERM /MIDNIGHT THROUGH 6 PM TUESDAY/... HIGH PRESSURE TAKES OVER THROUGH THE LATE EVENING AND CAUSES SKIES TO CLEAR OUT. THE SUMMERY DEWPOINTS...CLEAR SKIES AND STILL AIR WILL ALLOW FOG TO FORM IN AT LEAST THE VALLEYS OF THE N/C COS BUT ALSO ACROSS THE SOUTH - ESP WHERE ANY RAIN HAD FALLEN EARLIER. MINS WILL DIP INTO THE 50S IN THE NRN VALLEYS...AND SHOULD HIT THE CROSSOVER TEMPS IN ALMOST ALL LOCATIONS AS EVEN THE SRN TIER SHOULD FALL INTO THE 60S. TUESDAY LOOKS VERY NICE IF YOU LIKE THE HOT AND HUMID STUFF. MAXES WILL RUN AT 90F IN THE SOUTH WITH 575 THICKNESSES AND 8H TEMPS OF 18-20C. M80S ELSEWHERE. ONLY THE LAURELS MAY STAY IN THE L80S. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... 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 LASTS 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 /00Z TUESDAY THROUGH SATURDAY/... SURFACE COLD FRONT THAT TRIGGERED THE NUMEROUS THUNDERSTORMS SUNDAY EVENING HAS WASHED OUT FROM THE LOWER SUSQ VALLEY... WESTWARD ALONG THE MASON-DIXON LINE. A RIBBON OF HIGHER AMTS OF MOISTURE EXTENDS ABOVE THIS BOUNDARY FROM THE LAUREL HIGHLANDS AND ARCS NORTH AND EAST ALONG THE ALLEGHENY FRONT...HELPING TO ENHANCE THE VERTICAL DVLPMT OF THE CU FIELD AND SUPPORT A FEW...HIGHLY ISOLATED RAIN SHOWERS THAT WERE DRIFTING SSE. DRIEST AIR WAS OVER THE LOWER SUSQ VALLEY AND NRN TIER OF PENN. WILL BE REMOVING MENTION OF ANY SHOWERS FROM THE KMDT AND KLNS TAFS BASED ON THE RELATIVELY DRIER LOW-MID LEVEL AIR IN THAT AREA. THE CU AND TCU WILL FIZZLE OUT OVER THE NEXT SEVERAL HOURS...AND SKIES WILL BECOME CLEAR IN ALL AREAS BY LATE THIS EVENING. FOG WILL BECOME A PROBLEM FOR MANY SITES OVERNIGHT. MANY LOCATIONS COULD GO IFR OR EVEN LIFR AS TEMPS SHOULD DROP BELOW CROSSOVER TEMPS. AFTER ANY FOG/STRATUS BRNS AWAY TUES...THERE SHOULD NOT BE MUCH IN THE WAY OF CLOUDS AS UPSTREAM RIDGING GETS NEARER. OUTLOOK... WED...MAINLY VFR. THU...CFROPA W/VERY BRIEF REDUCTIONS DUE TO TSRA. FRI...MAINLY VFR. SAT...MAINLY VFR AM...SHRA/TSRA POSS NW. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO NEAR TERM...DANGELO SHORT TERM...DANGELO LONG TERM...RXR AVIATION...LAMBERT/DANGELO

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