Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 261758 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 158 PM EDT THU MAR 26 2015 .SYNOPSIS... SHOWERS AND ISOLATED THUNDERSTORMS WILL OCCUR AHEAD OF A STRONG COLD FRONTAL SYSTEM 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. && .NEAR TERM /UNTIL 10 PM THIS EVENING/... THE TONGUE OF WARM AIR HAS PUSHED 60F READINGS WELL INTO CENTRAL PENNSYLVANIA WHILE COLD AIR REMAINS ENTRENCHED ALONG THE NY BORDER WHERE IT IS STILL IN THE 30S. SNOW IS OCCURRING NOT TOO FAR TO THE NORTH AND WEST. THE MODELS AND RADAR INDICATED SHOWERS AND ISOLATE THUNDERSTORMS WILL MOVE ACROSS THE STATE TODAY. BEST CHANCE OF THUNDER IN THE WARM AIR FROM CENTRAL PA TO THE SOUTHEAST. THE HRRR CONTINUES TO SHOW A CONVECTIVE LINE DEVELOPING IN CENTRAL PA IN THE 3-4 PM TIME FRAME THEN THIS LINE MOVING EASTWARD CLEARING LANCASTER COUNTY BY 7-8 PM. THERE IS A CHANCE OF THUNDER OVER SOUTHEASTERN PA THIS EVENING. TOTAL QPF IS RELATIVELY LIGHT IN THE 0.05 TO 0.25 RANGE WITH HINTS OF PERHAPS 0.25 TO 0.40 INCHES IN MORE INTENSE SHOWERS. ENSEMBLE GUIDANCE IMPLIES RELATIVE TO HRRR/RAP IS ABOUT 0.10 TO 0.20 INCHES. NOT A BIG EVENT. MOST AREAS WILL LIKELY BE LUCKY TO SEE ABOUT 0.10. POPS DROP BEHIND THIS LINE AND THIS EVENING COLD AIR TURNS ANY SHOWERS TO SNOW IN THE NORTHWEST. ALL NORTHERN AND WESTERN MOUNTAIN AREAS SHOULD BE SNOW BY 10 PM. SNOW CHANGE OVER IS SLOWER TO EAST AND IN NEXT PERIOD AND AFTER THE BULK OF THE FORECAST QPF. && .SHORT TERM /10 PM THIS EVENING THROUGH 6 PM FRIDAY/.... THE COLD AIR AND GUSTY WINDS PUSH ACROSS OUR ENTIRE REGION THIS OVERNIGHT. SOME PATCHY FOG IN SOUTHEAST. 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 POSSBILE 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. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... DEEPENING BUT PROGRESSIVE UPPER TROF WILL BE MOVING EAST ACROSS THE MID ATLANTIC STATES EARLY IN THE LONG TERM PERIOD. SIGNIFICANT PRECIPITATION ASSOCIATED WITH THIS TROF SHOULD HAVE CONCLUDED BY DAYTIME FRIDAY...BUT LINGERING SHOWERS ARE POSSIBLE INTO THE DAY AS THE PUSH OF THE UPPER TROF HAS SLOWED A BIT IN RECENT GUIDANCE. AT THE SFC...EXPANSIVE AREA OF HIGH PRESSURE WILL BUILD INTO THE REGION STARTING LATER FRIDAY WITH SEVERAL DRY DAYS INTO THE WEEKEND. THE DEEPNESS OF THIS UPPER TROF WILL BRING ANOTHER SHOT UNSEASONABLY COLD AIR INTO THE REGION...ESPECIALLY NOTICEABLE AFTER A COUPLE DAYS OF MORE SPRING LIKE CONDS WED AND THUR. 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 LATE SUNDAY INTO MONDAY. THIS WILL CONTINUE THE CHILLY TEMPS AS WELL AS BRING THE CHANCE FOR MORE SNOW SHOWERS. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... ISOLATED SHOWERS MOVING INTO WESTERN SECTIONS. SOME AREAS STILL NEAR FREEZING. WILL CONTINUE TO MONITOR ABD UPDATE AS NEEDED. 12Z TAFS WILL BE OUT SHORTLY. UPDATED THE TAFS TO REFLECT THE SURGE OF WARM AIR AND THE POTENTIAL SHOWERS AND MENTION OF VCTS IN SOUTHEASTERN AREAS THIS AFTERNOON AND EVENING. MVFR WILL LIKELY HOLD NEAR NY BORDER AND PERIODS OF VFR LIKELY IN SOUTH-CENTRAL PA AS THE WARM AIR HAS SCOURED OUT THE LOW-LEVEL COLD AIR. BUT THE FAST APPROACHING FRONT WILL BRING SHOWERS AND MVFR/IFR TO THE REGION THIS AFTERNOON AND EVENING. BEHIND THE FRONT MOST AREAS WILL GO UP OVERNIGHT MAINLY TO VFR AND PATCHY MVFR. BUT IN THE SOUTHEAST COULD SEE SOME AREAS IFR/MVFR BEFORE SUNRISE WITH PATCHY FOGGY DEVELOPING. 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/LAMBERT NEAR TERM...GRUMM SHORT TERM...GRUMM LONG TERM...DEVOIR/GARTNER AVIATION...GRUMM

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