Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 221951 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 351 PM EDT FRI MAY 22 2015 .SYNOPSIS... A COLD FRONT WILL PUSH THROUGH THE SOUTHERN HALF OF PENNSYLVANIA THROUGH EARLY THIS EVENING...ACCOMPANIED BY ISOLATED TO SCATTERED BRIEF RAIN SHOWERS. A LARGE AREA OF HIGH PRESSURE WILL LIKELY BRING US THE COLDEST NIGHT WE`LL SEE UNTIL OCTOBER...ALONG WITH NEAR OR SLIGHTLY BELOW RECORD LOW TEMPERATURES MAINLY IN THE 20S AND 30S. A GRADUAL WARMING TREND IS FORECAST TO BEGIN SUNDAY...WITH WARM AND MODERATELY HUMID CONDITIONS IN STORE WITH A CHANCE OF A SHOWER OR THUNDERSTORM EACH AFTERNOON DURING THE TUESDAY THROUGH FRIDAY PERIOD. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... SFC COLD FRONT NEAR A KAVP TO KDUJ LINE AT 1845Z...AND WILL BE SAGGING SOUTH ACROSS THE SOUTHERN HALF OF THE STATE THROUGH 23Z. SIGNIFICANT BREAKS OF SUNSHINE AHEAD OF THE FRONT AND COOLING ALOFT WAS HELPING TO FORM AN AREA OF 850-500 MB LAPSE RATES BETWEEN 6 AND 7C/KM. THIS WAS LEADING TO ISOLATED TO SCATTERED SHOWERS NEAR AND SOUTH OF THE I-80 CORRIDOR. RAINFALL AMOUNTS SHOULD BE BELOW 0.05 OF AN INCH IN PRACTICALLY ALL LOCATIONS THAT SEE ONE OR TWO OF THESE BRIEF SHOWERS. A GUSTY WEST TO NW WIND /UP TO 25 KTS AT TIMES/ WILL PRECEDE AND IMMEDIATELY FOLLOW THE CFRONT THROUGH 22Z. THE FRONT WILL DROP SOUTH OF THE PENN/MD BORDER THIS EVENING FOLLOWED BY DIMINISHING WIND AND CLEARING SKIES. A LARGE...COLD HIGH WILL SETTLE INTO THE REGION LATE TONIGHT INTO SATURDAY BRINGING WIDESPREAD FROST TO THE CENTRAL RIDGE AND VALLEY REGION WITH LOW TEMPS OF 33 TO 36F. A HARD FREEZE IS EXPECTED ACROSS MUCH OF THE NRN MTNS...WHERE TEMPS WILL BOTTOM OUT IN THE MID TO UPPER 20S IN MANY LOCATIONS. WOULDN`T BE SURPRISED TO SEE A FEW COOP OBSERVERS AND MESO OB SITES COME IN AROUND 20F ACROSS PORTIONS OF MCKEAN...ELK AND POTTER COUNTIES. THE LAUREL HIGHLANDS WILL TEETER AROUND THE 32F MARK AT SUNRISE SATURDAY...BUT MOST OF THE POPULATION THERE SHOULD SEE LOWS OF 33 OR 34F WITH FROST ALMOST A CERTAINTY. THESE COLD TEMPS WILL APPROACH OR DROP BELOW RECORD LOWS IN MANY LOCATIONS. THE MOST LIKELY AREA TO JUST ESCAPE A RECORD LOW BY 1-3 DEG F WOULD BE THE LOWER SUSQ VALLEY...WHERE A LIGHT NW BREEZE COULD PERSIST UNTIL WELL AFTER MIDNIGHT. LOWS ACROSS THE LOWER SUSQ REGION WILL BE IN THE U30S TO LOWER 40S. SOME RURAL LOCATIONS COULD SEE PATCHY FROST WITH A SAT MORNING MIN OF 35 OR 36F. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... HIGH PRESSURE OVER THE COMMONWEALTH SAT MORNING WILL DRIFT SE TO THE DELMARVA COAST BY SAT EVENING. VERY LOW PWAT AIR OF ONLY AROUND 0.25 INCH AND LARGE SCALE SUBSIDENCE WILL LEAD TO ABUNDANT SUNSHINE WITH LIGHT WIND. MAX TEMPS IN THE MID 60S NORTH...TO AROUND 70F IN THE SOUTH WILL STILL BE A FEW TO SVRL DEG F BELOW NORMAL. SOME THIN HIGH CLOUDS WILL DRIFT IN FROM THE WEST LATE SAT NIGHT WITH A LIGHT SOUTHWEST WIND. TEMPS WILL BE QUITE COOL AGAIN SAT NIGHT WITH LOWS IN THE MID 30S TO LOWER 40S. A FEW PLACES IN NRN PENN COULD SEE A PATCHY LIGHT FROST TWD DAYBREAK SUNDAY...BUT NOTHING CLOSE TO WHAT/S IN STORE FOR EARLY SATURDAY. && .LONG TERM /SUNDAY THROUGH FRIDAY/... AFTER A COOL START...SUNDAY MARKS THE BEGINNING OF A ROBUST WARM- UP THAT WILL CONTINUE THROUGH NEXT WEEK. ALL GUIDANCE SIGNALS THIS WARMING TREND...WITH HIGH CONFIDENCE IN ABOVE NORMAL TEMPERATURES BY MEMORIAL DAY AS ANOMALOUS 500MB RIDGE BUILDS OVER THE EASTERN U.S. SOME DIFFERENCES ON PLACEMENT OF A WARM FRONTAL ZONE LIFTING NWD FROM THE SRN PLAINS/LWR MS VLY WHICH WILL HAVE IMPACTS ON PCPN RISK EARLY NEXT WEEK...THOUGH BEST DAILY POPS WILL BE OVER THE NW. DEWPOINTS ON SUNDAY WILL BE STILL IN THE 40S. HARD TO SEE MUCH CHANCE OF ANY SHOWERS. BETTER CHANCE OF SHOWERS NORTH OF PA...IN AREA OF BETTER WARM ADVECTION. DEWPOINTS WILL BE MAINLY IN THE 50S THE FIRST PART OF NEXT WEEK FOR MOST OF THE AREA. SE PA WILL LIKELY SEE DEWPOINTS IN THE 60 TO 65 DEGREE RANGE...BUT NOT REALLY THAT HIGH FOR LATE MAY. AT THE SAME TIME...500 MB HEIGHTS COME UP...AS THE UPPER LVL RIDGE BUILDS. WARM FRONT ALSO FCST TO LIFT WELL NORTH OF THE AREA ON TUE. THUS BASED ON THESE FACTORS AND OTHER FACTORS...DID LOWER POPS SOME...AND EDGE TEMPS UP A DEGREE OR SO. OVERALL...NOT LOOKING AT TEMPERATURES OR DEWPOINTS AS HIGH AS RECENT EVENTS. THUS A NICE HOLIDAY WEEKEND IN STORE FOR THE AREA...AND NOT A BAD PERIOD OF LATE SPRING WEATHER NEXT WEEK...ENJOY THE HOLIDAY WEEKEND. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... A COLD FRONT EXTENDING FROM NEAR KAVP TO KDUJ AT 1845Z WILL DROP SOUTH TO THE MASON/DIXON LINE BY THIS EVENING. ISOLATED TO SCATTERED SHOWERS ALONG AND JUST AHEAD OF THE FRONT WILL BE GENERALLY LIGHT...BRIEF AND CAUSE MAINLY VFR CIGS AND VSBYS. VERY BRIEF HIGH-END MVFR VSBYS ARE POSSIBLE. HIGH PRESSURE BUILDS SE ACROSS THE STATE LATE TONIGHT AND SAT MORNING...THEN DRIFTS TO THE DELMARVA COAST SAT NIGHT. THIS FEATURE WILL BRING WIDESPREAD VFR CONDITIONS AND LIGHT/VARIABLE WIND THROUGH SUNDAY MORNING...WITH A LIGHT SWRLY FLOW DEVELOPING DURING THE DAY SUNDAY. OUTLOOK... SUN-MON...NO SIG WX EXPECTED. TUE-THU...ISOLD PM TSRA IMPACTS POSSIBLE. && .FIRE WEATHER... LIGHT RAIN OVER MOST OF THE AREA THURSDAY AND THE GREEN-UP HAVE MOST LIKELY LOWERED THE RISK FOR RAPID WILDFIRE SPREAD AND GROWTH. HOWEVER...WEST-SOUTHWEST TO WNW WINDS WILL STAY GUSTY AS THE DRY COLD FRONT DROPS THROUGH CENTRAL AND SRN PENN LATE TODAY. RH/S WILL BE THE 30S. PEAK WIND GUSTS OF 25-30 MPH ARE LIKELY FOR THE REST OF THIS AFTERNOON. && .CTP WATCHES/WARNINGS/ADVISORIES... FREEZE WARNING FROM MIDNIGHT TONIGHT TO 8 AM EDT SATURDAY FOR PAZ004>006-010>012-017-018-037-041-042. FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EDT SATURDAY FOR PAZ019-024>028-033-034-045-046-049>053-058. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...LAMBERT LONG TERM...MARTIN AVIATION...LAMBERT FIRE WEATHER...LAMBERT

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