Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 262135 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 535 PM EDT THU MAR 26 2015 .SYNOPSIS...
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A STRONG COLD FRONT WILL PUSH SOUTHEAST ACROSS THE REGION THIS EVENING. A LARGE HIGH PRESSURE SYSTEM WITH COLD AIR WILL DOMINATE OUR REGION INTO THE WEEKEND. THE UPPER LEVEL FLOW BECOMES MORE ZONAL NEXT WEEK SO TEMPERATURES SHOULD REBOUND TOWARD NORMAL.
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&& .NEAR TERM /UNTIL 10 PM THIS EVENING/...
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RADAR SHOWING A DEVELOPING LINE OF CONVECTION ALONG COLD FRONT AT 21Z...AS IT ENTERS THE LOWER SUSQ VALLEY. MARGINAL INSTABILITY FROM HARRISBURG SOUTH AND EASTWARD...COMBINED WITH MODERATELY STRONG MID LVL FLOW...COULD RESULT IN LOCALLY STRONG WGUSTS ACCOMPANYING SHRA/TSRA AS THEY MOVE THRU BTWN 21Z-00Z. LATEST HRRR HAS LINE OF CONVECTION EXITING LANCASTER CO ARND 00Z. ACROSS THE NW MTNS...BACK EDGE OF PRECIP WILL CHANGE TO LGT SNOW FOR A TIME THIS EVENING. HOWEVER...LIGHT QPF AND MARGINAL SFC TEMPS SHOULD LIMIT ACCUMS TO JUST A COATING IN SPOTS. POPS DROP BEHIND FRONT THIS EVENING AND ARRIVAL OF COLD AIR TURNS ANY LINGERING SHRA TO SHSN OVR THE ALLEGHENIES. AGAIN...LGT PRECIP RTS AND MARGINAL SFC TEMPS SHOULD LIMIT ANY MINOR ACCUMS TO THE HIGHER TERRAIN OF THE ALLEGHENIES.
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&& .SHORT TERM /10 PM THIS EVENING THROUGH 6 PM FRIDAY/...
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THE COLD AIR AND GUSTY WINDS PUSH ACROSS OUR ENTIRE REGION OVERNIGHT. ANY RESIDUAL SHOWERS WILL TURN TO SNOW SHOWERS OR FLURRIES. BEST CHANCE OF A DUSTING OR LIGHT SNOW ACCUMULATIONS WOULD BE OVERNIGHT IN NORTHWESTERN AREAS. BY MIDNIGHT TEMPERATURES WILL RANGE 40S IN SOUTHEAST TO AROUND 30 IN NORTHWEST. SOME SNOW SHOWER ACTIVITY POSSIBLE IN THE WEST FRIDAY. MORNING LOWS MAINLY UPPER 20S IN NORTH TO LOW TO MID 30S IN SOUTHEAST. STRONG COLD ADVECTION AND 850 HPA TEMPERATURES FORECAST TO FALL WELL BELOW LATE FRIDAY INTO FRIDAY NIGHT...WILL BE UNSEASONABLY COLD DAY FOR LATE MARCH. TEMPERATURES JUST ABOVE FREEZING IN MOUNTAINS TO MID 40S IN LOWER SUSQUEHANNA VALLEY. THE COLDEST AIR AT 850 HPA WITH -2 TO -2.5 STANDARD DEVIATION ANOMALIES COMES BY FRIDAY EVENING INTO SATURDAY.
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&& .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... UPPER TROF DEEPENING OVER THE EASTERN U.S. AT THE START OF THE PERIOD WILL AFFECT THE WEATHER THROUGH AT LEAST THE EARLY PART OF THE WEEKEND. SIGNIFICANT PRECIPITATION ASSOCIATED WITH THIS TROF SHOULD HAVE CONCLUDED BY DAYTIME FRIDAY...BUT SEVERAL SHORTWAVES ROTATING AROUND THE UPPER TROF WILL SLOW THE ADVANCE OF THE OTHERWISE PROGRESSIVE TROF/ASSOCIATED SFC LOW...CAUSING LINGERING SHOWERS INTO SATURDAY. AREA OF HIGH PRESSURE SHOULD EVENTUALLY MOVE INTO THE REGION FOR SUNDAY INTO EARLY NEXT WEEK. BEHIND THE DEEP UPPER TROF WILL BRING ANOTHER SHOT UNSEASONABLY COLD AIR INTO THE REGION...ESPECIALLY NOTICEABLE AFTER A COUPLE DAYS OF MORE SPRING LIKE CONDS TODAY. TEMPERATURES WILL BE 10 TO 20 DEGREES BELOW NORMAL OVER THE WEEKEND. A COMPARATIVELY WEAKER NRN STREAM WAVE WILL MOVE ACROSS THE UPPER GREAT LAKES REGION AND TOWARDS THE NORTHEAST ON MONDAY. THIS WILL CONTINUE THE CHILLY TEMPS AS WELL AS BRING THE CHANCE FOR MORE SNOW SHOWERS. WEATHER WILL DRY OUT BUT REMAIN COOL FOR THE MIDDLE OF NEXT WEEK AS ANOTHER AREA OF HIGH PRESSURE ARRIVES BEHIND FRONT. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... KEY ISSUE OVER THE NEXT 24 HOURS IS THE TIMING OF THE FRONT AND THE FRONTAL RAIN AND ISOLATED THUNDERSTORMS. THERE WILL ALSO BE SOME ISSUES WITH RAIN TO SNOW IN NORTHWESTERN PA THIS EVENING. THE BEST CHANCE FOR MODEST THUNDERSTORMS IS INT THE 20Z TO 00Z TIMEFRAME MAINLY IN CENTRAL AND SOUTHEASTERN AREAS. THERE COULD BE A WEAK LINE OF SHOWERS AND THUNDERSTORMS IN SOUTHEASTERN AREAS THIS EVENING. THE RAIN....SNOW....AND LINE OF SHOWERS WILL PRODUCE AREAS OF MVFR AND IFR. BEHIND THE FRONTAL SYSTEM MOISTURE COULD PRODUCE SOME AREAS OF PATCHY FOG AND AREAS OF SNOW SHOWERS IN THE NORTHWEST...AREAS OF IFR AND MVFR. THE COLD AIR COMES IN AND COULD CHANGE THE RAIN TO SNOW OVER THE ENTIRE REGION BY FRIDAY. MAINLY VFR AND SOME AREAS MVFR IN SNOW SHOWERS IN MOUNTAINS. FRIDAY WILL BE A MOSTLY VFR AREAS MVFR IN SNSH. WINDY DAY WITH SOME GUST SPREAD ISSUES. OUTLOOK... FRI-SAT...MVFR/IFR WITH SNOW SHOWERS NORTH/WEST. VFR TO MVFR CENTRAL AND EAST WITH SCHC OF -SHRA. SUN...NO SIG WX/VFR. MON...CHANCE OF LIGHT RAIN /LIGHT SNOW EARLY/ ACROSS NW HALF WITH MVFR REDUCTIONS. VFR SE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...GRUMM/FITZGERALD NEAR TERM...GRUMM/FITZGERALD SHORT TERM...GRUMM LONG TERM...DEVOIR/GARTNER AVIATION...GRUMM

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