Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 311154 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 754 AM EDT MON AUG 31 2015 .SYNOPSIS... A MODERATELY HIGH AMOUNT OF MOISTURE STREAMING EAST FROM THE OHIO VALLEY WILL EXTEND ACROSS PENN THROUGH MUCH OF THIS WEEK. THE CLOSE PROXIMITY OF A NEARLY EAST-WEST FRONTAL BOUNDARY ACROSS PENNSYLVANIA WILL LEAD TO ISOLATED MAINLY AFTERNOON AND EARLY EVENING SHRA/TSRA TODAY THROUGH THURSDAY. HIGH PRESSURE OFF THE EAST COAST WILL RIDGE NORTHWEST INTO PENNSYLVANIA AND LEAD TO TEMPERATURES WELL ABOVE NORMAL THIS ENTIRE WEEK. IT WILL FEEL MORE LIKE THE MIDDLE OF SUMMER THAN SEPTEMBER. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 730 AM UPDATE... RADAR RETURNS ACROSS THE SRN TIER ARE VERY LIGHT AND MAY STILL BE ALOFT. PATCH HEADED FOR KTHV SHOULD TELL THE TALE. BUT IT IS ALSO THE AREA OF HIGHEST RETURNS AS WELL. THUS...THE 30 POPS ACROSS THE SRN TIER STILL LOOK STELLAR AND SFC CONVERGENCE AND HEATING UNDER LESS CLOUDS IN THE NORTH WILL POP A FEW CELLS THIS AFTN. PREV... SFC HIGH PRESSURE LOCATED JUST OFF THE SE U.S. COAST WILL SLOWLY BUILD NORTHWEST...AS AN UPPER RIDGE LOCATED OVER THE UPPER GLAKES AND MISS VALLEY MOVES EAST TO THE OHIO RIVER VALLEY AND MID ATLANTIC REGION BY 12Z TUES. 925-850 MB THETA-E RIDGE EXTENDS FROM THE OHIO VALLEY...ENE THROUGH PENN EARLY TODAY...WITH A WEAK/STALLED-OUT SFC FRONT EXTENDING FROM DETROIT...SW TO ST LOUIS. THE NORTHERN PART OF THIS FRONT WILL MOVE STEADILY EAST/SOUTHEAST AND BECOME LOCATED ACROSS CENTRAL PENN THIS EVENING...AND STAY THERE THROUGH MUCH OF TUESDAY. A BIT OF DRYING WILL BE SEEN ACROSS THE REGION NEAR AND TO THE NORTH OF INTERSTATE 80. 03Z SREF PROB OF CAPE EXCEEDING 1000 J/KG CLIMBS TO THE 60-80 PERCENT RANGE THIS AFTERNOON...HOWEVER THE PROB OF 2000 J/KG IS VERY LOW AT 10 PERCENT OR LESS TODAY THROUGH THURSDAY...THUS THE LOW DIURNAL POP/CVRG FOR CONVECTION. 07Z HRRR CONFIRMS THIS THINKING AS IT PLACES GENERALLY ISOLATED- SCATTERED/POPCORN LIKE COVERAGE BETWEEN 17Z-22Z TODAY. PLENTY OF BKN-OVC ALTO CU /TOPPED BY SOME CIRRUS/ BLANKETED THE SE HALF TO TWO-THIRDS OF PENN EARLY TODAY...WHILE MOSTLY CLEAR SKIES AND THE COOLEST TEMPS IN THE L60S WERE FOUND INVOF KBFD. ELSEWHERE...TEMPS RANGED FROM THE MID 60S TO MID 70S - A RATHER MUGGY EARLY MORNING FOR THE FINAL DAY OF METEOROLOGICAL SUMMER. ASIDE FROM A HIGHLY ISOLATED AND BRIEF LIGHT SHOWER OR TWO ON THE RADAR SCOPE EARLY TODAY...CONDITIONS ACROSS MUCH OF CENTRAL AND NORTHERN PENN WILL BE DRY WITH A VERY LIGHT AND VARIABLE WIND THROUGH THE MID MORNING HOURS. FARTHER SOUTH...WEAK UPPER LOW OVER THE WESTERN CAROLINAS WILL LIFT NORTHWARD OVERNIGHT ON THE WESTERN PERIPHERY OF THE SPRAWLING WESTERN ATLANTIC UPPER HIGH CIRCULATION. THIS WILL MAINTAIN THE FOCUS FOR POOLING MOISTURE AND FORCING FOR SHOWER ACTIVITY THROUGH THE PRE DAWN HOURS ACROSS MY FAR SOUTH. AGAIN...AREAS TO THE NORTH SHOULD BE DRY AFTER 06Z AS DEFORMATION LESSENS AND FORCING FOCUS SHIFTS TO AREAS ALONG AND SOUTH OF MY SOUTHERN TIER. SOME FOG HAS FORMED...BUT VSBYS ARE HOLDING UP AOA 1 SM MINS AROUND SUNRISE TODAY WILL RUN IN THE 60S IN PRACTICALLY ALL LOCATIONS AS DEWPOINTS SHOULD NOT GO ANY LOWER THAN 60F. A FEW OF THE NORMALLY COLD SPOTS NEAR...AND THE EAST OF KBFD WILL SEE A LOW TEMP IN THE MID 50S. HIGH TEMPS THIS AFTERNOON WILL VARY FROM THE U70S OVER THE HIGHEST ELEVATIONS OF THE NORTH AND WEST...TO THE MID AND UPPER 80S ACROSS OUR SE ZONES. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/... TONIGHT SHOULD BE A NEAR REPEAT OF SUNDAY NIGHT/EARLY MONDAY WITH VARIABLE AMTS OF MAINLY MID AND HIGH CLOUDS AND PERHAPS JUST A COUPLE SMALL SHOWERS ROAMING THE STREETS. CONSALL TEMP BLEND YIELDS LOWS AROUND 60F ACROSS THE NRN MTNS...AND IN THE MID TO UPPER 60S ELSEWHERE. && .LONG TERM /TUESDAY THROUGH SUNDAY/... ANOMALOUS UPPER LEVEL RIDGE WILL DOMINATE THE OHIO VALLEY AND EASTERN UNITED STATES MUCH OF THE UPCOMING WEEK...WITH LATEST GUIDANCE REMAINING FIRM FOR AN EXTENDED RUN OF 850HPA TEMPS PEAKING DAILY AROUND 16-18C. THIS WILL TRANSLATE TO WELL ABOVE- NORMAL SFC TEMPS. THIS WARMTH AND INCREASING HUMIDITY SHOULD ALLOW FOR AT LEAST A SLIGHT CHC FOR DIURNAL CONVECTION EACH DAY...BUT WARM MID-LEVELS WILL KEEP THE PROBABILITY OF WIDESPREAD RAINFALL QUITE LOW. BEST CHANCES FOR PRECIP WILL BE DURING THE MID-LATE WEEK PERIOD /WED-THU-FRI/ WITH A COUPLE SUBTLE FEATURES. FIRST...A WEAK UPPER LEVEL WAVE /BEST PROGGED ON THE ECMWF/ SLIPS OVERHEAD ON WED AS BERMUDA HIGH BRIEFLY RECEDES. AT SAME TIME A WEAK BACKDOOR COLD FRONT SLIPS SOUTHWARD OFF THE EAST COAST. THIS COULD HELP POOL SOME LOW LEVEL MOISTURE OVER THE MID ATLANTIC AND OHIO VALLEY AS MID LEVELS COOL JUST A BIT...BRINGING POTENTIAL FOR SCT TSTMS. RIDGE BUILDS BACK IN FOR FRI...BUT ANOTHER SURFACE BACKDOOR FRONT TRIES TO SLIP ACROSS THE STATE AS SURFACE HIGH EXPANDS IN FROM THE NORTH. THIS BOUNDARY SHOULD BRING SCT CONVECTION FOR FRI. EXTENDED MODELS HINT AT POTENTIAL FOR DAILY CONVECTION CONTINUING INTO THE WEEKEND ALONG SOUTHER BORDER...BUT OVERALL CONDITIONS WILL BE MAINLY RAIN-FREE. TEMPS PEAK MIDWEEK WITH READINGS APPROACHING 90F IN THE SE...AND EVEN GETTING INTO THE 80S ELSE HERE...EASILY WELL ABOVE NORMAL FOR THE FIRST WEEK OF SEPT. LOWS WILL ALSO REMAIN QUITE MILD MID/LATE WEEK AS HIGH HUMIDITY AIR HANGS AROUND. SLIGHTLY COOLER BUT STILL ABOVE AVERAGE TEMPS WILL CONTINUE THROUGH THE WEEKEND. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... EARLY MORNING FOG HAS REMAINED ISOLATED AT IPT AND BFD...WITH IFR AND MVFR RESPECTIVELY. ANY AM VALLEY FOG WILL BURN OFF BY LATE AM. OTHERWISE...WIDESPREAD VFR CONDS AND LIGHT WIND APPEAR VERY LIKELY MONDAY WITH ONLY ISOLD LATE DAY SHRA/TSRA POSSIBLE...AS HIGH PRESSURE BUILDS OFF THE MID ATLANTIC COAST. SHOWERS WILL BE MOST LIKELY THROUGH THE SOUTHERN TAF SITES WITH LNS AND MDT MOST LIKELY...MAINLY BETWEEN NOW AND THROUGH THE EARLY AFTERNOON HOURS. OUTLOOK... TUE-FRI...PATCHY AM FOG POSS...MAINLY KBFD. ISOLD PM TSRA IMPACTS POSSIBLE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...DANGELO/LAMBERT SHORT TERM...LAMBERT LONG TERM...LAMBERT/RXR AVIATION...FITZGERALD/CERU

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