Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 310929 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 529 AM EDT MON AUG 31 2015 .SYNOPSIS...
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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 PENNSYLAVNAI 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. IT WILL FEEL MORE LIKE THE MIDDLE OF SUMMER THAN SEPTEMBER.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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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 ATLANIC 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 PORTIONS OF THIS FRONT WILL MOVE STEADILY EAST/SOUTHEAST AND BECOME LOCATED ACROSS CENTRAL PENN THIS EVENING...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 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.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
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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 INTHE MID TO UPPER 60S ELSEWHERE.
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&& .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 MIDWEEK /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 ELSEHERE...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 /09Z MONDAY THROUGH FRIDAY/... REGIONAL RADAR AT 03Z STILL SHOWING A FEW ISOLATED SHOWERS ACROSS SOUTHERN PA. LOSS OF HEATING SHOULD CAUSE THE REMAINING SHOWERS TO DISSIPATE AFTER MIDNIGHT. FOCUS OVERNIGHT WILL SHIFT TOWARD POTENTIAL OF FOG. LIGHT WIND AND PTCLDY SKIES SHOULD PROMOTE LOCALLY DENSE VALLEY FOG AFTER MIDNIGHT ACROSS NORTHERN PA. CLIMATOLOGY AND LATEST SREF/MOS SUGGEST KBFD IS LIKELY TO EXPERIENCE IFR/LIFR VIS REDUCTIONS LATE TONIGHT. ALSO...MAY HAVE TO CONTEND WITH DENSE FOG AT KIPT...WHERE GROUND IS NOW WET FROM A SHOWER EARLIER THIS EVENING. COMPLICATING FACTOR IS MID LVL CLOUDINESS OVERSPREADING THE SOUTHERN PART OF THE STATE. FEEL CONFIDENT THESE MID LVL CLOUDS WILL BE THICK ENOUGH TO DIMINISH THE RADIATIONAL COOLING AND ASSOC DENSE FOG THREAT ACROSS SOUTHERN PA. HOWEVER...NOT AS CONFIDENT AT KIPT. ANY AM VALLEY FOG ACROSS NORTHERN PA SHOULD 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. OUTLOOK... TUE-FRI...PATCHY AM FOG POSS...MAINLY KBFD. ISOLD PM TSRA IMPACTS POSSIBLE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...LAMBERT LONG TERM...LAMBERT/RXR AVIATION...FITZGERALD/CERU

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