Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 220458 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1158 PM EST FRI NOV 21 2014 .SYNOPSIS... HIGH PRESSURE WILL BRING TRANQUIL CONDITIONS OVERNIGHT. A PLUME OF MOISTURE STREAMING NORTHEAST FROM THE OHIO VALLEY...IN ASSOCIATION WITH A WARM FRONT...WILL BRING CLOUDS AND SOME LIGHT FREEZING RAIN TO THE NORTHWEST MOUNTAINS SATURDAY MORNING AND EARLY SATURDAY AFTERNOON...WHILE THE REST OF CENTRAL AND SOUTHERN PENNSYLVANIA STAYS MAINLY DRY. AN APPROACHING STORM SYSTEM WILL BRING RAIN TO THE AREA SUNDAY NIGHT INTO MONDAY. TEMPERATURES WILL BE ON A ROLLER COASTER RIDE OVER THE NEXT SEVERAL DAYS...CLIMBING WELL ABOVE NORMAL ON MONDAY BEFORE TRENDING COLDER BY THANKSGIVING DAY. && .NEAR TERM /UNTIL 8 AM SATURDAY MORNING/... CLEAR SKIES EXPECTED ACROSS THE REGION FOR MOST /OR ALL OF THE NIGHT IN SOME LOCATIONS/ AS THE CENTER OF HIGH PRESSURE SLIDES BY JUST TO THE SOUTH OF THE MASON/DIXON LINE. THE LEADING EDGE OF LAYERED CLOUDS A ALONG AND TO THE NORTHEAST OF A DEVELOPING WARM FRONT WILL OVERSPREAD THE NORTHWEST HALF OF THE STATE DURING THE MID TO LATE MORNING HOURS. UNTIL THE CLOUDS MOVE IN FROM THE OHIO VALLEY...THE CLEAR SKIES...LIGHT WIND AND LOW DEWPOINTS WILL ALLOW TEMPS TO PLUMMET TO THE SINGLE DIGITS ACROSS THE NRN MTNS...AND LOW-MID TEENS IN MOST OTHER LOCATIONS. && .SHORT TERM /8 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... MOISTURE SPREADING NE FROM THE TENN AND OHIO RIVER VALLEY WILL PUSH A DECK OF LAYERED CLOUDS INTO THE REGION EARLY ON...WITH A FEW PERIODS OF VERY LIGHT FREEZING FROM KDUJ AND KBFD...EAST ACROSS THE NORTH-CENTRAL MTNS BY THE LATE MORNING HOURS. COORDINATED WITH SURROUNDING WFOS TO ARRIVE AT THE PRIMARY TARGET ARE OVER NWRN PENN FOR LIGHT ICE ACCUMS OF AROUND 0.05 INCH ICE ACCUM...OR LESS. ALL 18Z MODELS...AND THE LATEST 21Z ENSEMBLES INDICATE A FEW TO SVRL HOUR PERIOD OF LIGHT FREEZING RAIN BETWEEN ABOUT 13-19Z SATURDAY. WE HAVE NEARLY PERFECT TIMING OF THE CLOUDS AROUND DAYBREAK SATURDAY TO ALLOW FOR MAXIMUM RADIATIONAL COOLING...FOLLOWED BY A STUBBORN AND STRONG SFC-BASED INVERSION. INCREASED POPS TO AROUND...OR MORE THAN CATEGORICAL AMTS. BY THE MID AFTERNOON SATURDAY...MOST IF NOT ALL OF THE AREA WILL BE ABOVE FREEZING /WHICH WILL END THE THREAT FOR LIGHT ICING/. LITTLE OR NO MEASURABLE PRECIP IS EXPECTED TO THE SOUTHEAST OF A LINE FROM KJST...TO KUNV AND KIPT /THOUGH PLENTY OF CLOUDS SHOULD BE AROUND FOR THE LATE MORNING AND AFTERNOON HOURS. TEMPS WILL STILL BE NEARLY 10F BELOW NORMAL SAT AFTERNOON...WITH MUCH GREATER DEPARTURES DURING THE MORNING. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... MODELS CONTINUE TO SHOW SPOTTY/LIGHT PCPN OVER THE NRN TIER SAT NGT INTO EARLY SUNDAY WITHIN ZONE OF RELATIVELY STRONG H85 MSTR FLUX AND LOW-MID LVL WAA ASSOCD WITH 40-50KT WSW LLJ ON THE NW PERIPHERY OF SFC HIGH PRESSURE MOVG OFF THE MID ATLC COAST. A FEW WEAK SHORTWAVES CROSSING THE ERN GREAT LAKES MAY PROVIDE ADDNL LIFT. PTYPES ARE FCST TO BE PLAIN RAIN OVER THE NW ZONES WITH LOW CONFIDENCE IN -ZR OVER THE NERN 1/2 OF THE CWA WHERE 2M TEMPS SHOULD BE AROUND 32F PER MULTI-MODEL/MOS BLEND. ALTHOUGH IT WILL BE CLOUDY...MOST LOCATIONS EXPERIENCE A GOOD DEAL OF DRY WX ON SUNDAY WITH TEMPS MODERATING INTO THE MID 40S TO LOW 50S. THE LATEST MODEL AND ENSEMBLE GUIDANCE CONTINUES TO INDICATE A HIGHLY AMPLIFIED UPPER AIR PATTERN DEVELOPING NEXT WEEK. THE 500MB CONFIGURATION WILL FEATURE ANOMALOUS RIDGING ALONG THE WEST COAST AND IN THE WESTERN ATLANTIC WITH A FULL-LATITUDE TROUGH CARVING OUT OVER THE CENTRAL AND ERN U.S. PHASING OF SPLIT-STREAM ENERGY WILL YIELD A DEEP 980MB LOW /-3 TO -4 STD MSLP/ LIFTING NWD THROUGH GREAT LAKES INTO SERN CANADA ON MONDAY. STRONG SLY FLOW AHEAD OF THE TRAILING COLD FRONT WILL BRING A SURGE OF HIGH PWAT AIR INTO THE REGION WHICH WILL SUPPORT WIDESPREAD LIGHT TO MODERATE RAINFALL SUN NGT. RAISED POPS INTO THE CATEGORICAL RANGE ABOVE WPC AND IN-LINE WITH THE MEAN ECENS MOS. TEMPERATURES SHOULD PEAK ON MONDAY 10-20F ABOVE NORMAL /NEAR RECORD HIGHS/ BEFORE THE FROPA MONDAY NIGHT USHERS IN COLDER AIR. CONFIDENCE IS INCREASING IN COLDER TO BELOW AVG TEMPERATURES HEADING INTO THANKSGIVING AS THE GLOBAL MODELS AND ENSEMBLES ARE SUGGESTING PERSISTENCE OF THE ERN CONUS MEAN TROUGH. FINALLY...THERE IS UNCERTAINTY/LOW CONFIDENCE IN POTENTIAL IMPACTS ASSOCIATED WITH ONE OR MORE WAVES DEVELOPING IN THE WRN ATLC DURING THE MIDDLE TO SECOND HALF OF NEXT WEEK. THIS SITUATION WILL NEED TO BE WATCHED AS THE WRN PERIPHERY OF THE MSTR SHIELD MAY CONTAIN SNOW. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... VFR CONDS AND LIGHT EXPECTED OVERNIGHT AS HIGH PRESSURE MOVE OVER THE AREA. A WARM FRONT WILL LIFT NORTH ACROSS THE STATE ON SAT. MOISTURE ALONG THE FRONT WILL LEAD TO VFR CONDS AND SOME PCPN LATER SAT MORNING INTO SAT AFTN MAIN ACROSS THE NRN SECTIONS...KBFD. WITH COLD SFC TEMPS IN PLACE A PERIOD OF FREEZING DRIZZLE/FREEZING RAIN POSSIBLE BEFORE TURNING TO RAIN SAT AFTN. MOST OTHER SITES SHOULD REMAIN PRIMARILY VFR. ALSO INCLUDED LLWS FOR AIRFIELDS IN THE THE NWRN HALF OF THE STATE AS WINDS ALOFT WILL BE INCREASING ABOVE SFC WINDS STARTING THE DAY LIGHT AND VARIABLE THEN SWITCHING TO LIGHT S TO SWRLY. OUTLOOK... SUN...MAINLY VFR WITH A CHANCE OF RAIN SHOWERS NORTH. MON...MVFR WITH RAIN SHOWERS. TUE...MVFR WITH SNOW SHOWERS OVER WESTERN HIGH TERRAIN. VFR ELSEWHERE. WED...MVFR WITH SNOW SHOWERS OVER NORTHWESTERN HIGH TERRAIN. VFR ELSEWHERE. && .CTP WATCHES/WARNINGS/ADVISORIES... FREEZING RAIN ADVISORY FROM 8 AM TO 2 PM EST SATURDAY FOR PAZ004>006-010-011-017. && $$ SYNOPSIS...LA CORTE/LAMBERT NEAR TERM...LAMBERT SHORT TERM...LA CORTE/LAMBERT LONG TERM...STEINBUGL AVIATION...LA CORTE/GARTNER

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