Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 251310 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 810 AM EST SUN JAN 25 2015 .SYNOPSIS...
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AN ALBERTA CLIPPER WILL TRACK JUST SOUTH OF PENNSYLVANIA TONIGHT AND EARLY MONDAY...THEN REDEVELOP AND EXPLOSIVELY INTENSIFY OFF THE MID ATLANTIC COAST MONDAY NIGHT AND TUESDAY. HIGH PRESSURE WILL BUILD OVER THE REGION MID WEEK...FOLLOWED BY ANOTHER CLIPPER LATE THURSDAY.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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COLD FRONT WORKING ITS WAY SOUTH ACROSS THE NORTHWEST AND NORTH CENTRAL MOUNTAINS. REGIONAL RADAR MOSAIC DETECTING A BAND OF -SHSN/FLURRIES. MUCH DRIER AIR WORKING IN BEHIND THIS BOUNDARY WILL SHUT OFF THE SNOW SHOWERS ACROSS THE NW MTNS LATER THIS MORNING AND COULD EVEN BRING SOME PARTIAL CLEARING TO THE N TIER COUNTIES TODAY. FURTHER SOUTH...DEEPENING LYR OF MOISTURE ASCENDING THE LAURELS COULD PRODUCE SOME LIGHT OROGRAPHIC SNOW ACROSS THE LAUREL HIGHLANDS THRU EARLY AFTN. HOWEVER...FOCUS REMAINS ON THE APPROACHING POTENT CLIPPER DIVING INTO THE OHIO...WHICH PROMISES TO SPREAD A STEADIER...MORE SIGNIFICANT SNOW INTO SOUTHWEST PA TOWARD EVENING. OVERCAST SKIES...COMBINED WITH LOW LVL CAA...SHOULD BALANCE THE DIURNAL TREND AND RESULT IN NEARLY STEADY TEMPS TODAY WITH HIGHS FROM THE M20S ACROSS THE N MTNS...TO THE U30S ACROSS THE LOWER SUSQ VALLEY.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... BLEND OF MDL QPF SUPPORTS SEVERAL INCHES OF ACCUM...MEETING ADVISORY CRITERIA...ACROSS MUCH OF SOUTH CENTRAL PA TONIGHT AND MONDAY. SNOW/WATER RATIOS BTWN 12/1 AND 15/1 USED BASED ON WPC GUIDANCE AND MDL CROSS SECTIONS OF OMEGA AND TEMP...WHICH SHOW GREATEST UPWARD MOTION OCCURRING ARND -12C...BUT WARMER TEMPS IN THE LOWER CLOUDS...IMPLYING RIMING AND A SLIGHTLY DIMINISHED SLR. WEAKENING SFC LOW OVR THE CENTRAL APPALACHIANS EXPECTED MONDAY...WITH SECONDARY COASTAL DEVELOPMENT TAKING SHAPE E OF THE DELMARVA. ALTHOUGH LG SCALE FORCING MAY NOT BE VERY IMPRESSIVE IN BTWN SYSTEMS ACROSS CENTRAL PA...EASTERLY WIND ANOMALIES BTWN LOW TO THE SOUTH AND HIGH PRES OVR S QUEBEC WILL TRANSPORT ABUNDANT MOISTURE INTO CENTRAL PA...LIKELY SUPPORTING OCNL LIGHT SNOW THRU THE DAY. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
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MAIN FOCUS IN THE EXTENDED FCST WILL BE EVOLUTION OF RAPIDLY DEVELOPING COASTAL LOW EAST OF PA MON NITE AND TUESDAY. MDL DATA SHOWING A FAIRLY TIGHT RANGE OF SOLUTIONS...NEARLY ALL OF WHICH PLACE OUR EXTREME EASTERN COUNTIES FROM LANCASTER NORTH THRU SCHUYLKILL CO ON THE WESTERN PERIPHERY OF THE SIGNIFICANT DEFORMATION BAND SNOW. MDL 7H FGEN FIELDS SEEM TO IMPLY THE HEAVY SNOW WILL REMAIN JUST EAST OF THE CWA. HOWEVER...GIVEN COMPLEXITY OF CRITERIA DIFFERENCES ACROSS OUR BORDERS...AND 40% CONFIDENCE OF AN ADDITIONAL 6 INCHES OR MORE OVER LEBANON/LANCASTER/E YORK COUNTIES WITH THE SECONDARY LOW...OPTED TO ISSUE WINTER STORM WATCH FOR THESE THREE COUNTIES FOR MONDAY AFTERNOON THROUGH TUESDAY MORNING. THE MORE LKLY SCENARIO ATTM APPEARS TO BE ONCL LIGHT SNOW CONTINUING ACROSS THE REST OF CENTRAL PA MONDAY NIGHT AND TUESDAY ASSOC WITH NEXT SHORTWAVE DIVING INTO DEEPENING UPPER TROF AXIS OVR PA. TIGHT PRES GRADIENT WEST OF COASTAL LOW SHOULD RESULT IN A BLUSTERY DAY TUESDAY...BLOWING/DRIFTING SNOW A POSSIBILITY. BUFKIT SOUNDINGS INDICATE GUSTS TO ARND 30KTS LIKELY. FAIR AND CHILLY WED EXPECTED WED...AS HIGH PRES BUILDS OVR THE AREA. MED RANGE GUIDANCE STILL INDICATES NEXT CHANCE OF SNOW THURS/THU NIGHT WITH NEXT IN SERIES OF CLIPPERS. ECENS SHOWS A DEEPENING UPPER LVL TROF OVR THE EASTERN CONUS BY NEXT WEEKEND...OFFERING NO RESPITE FROM THE COLD WX.
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&& .AVIATION /13Z SUNDAY THROUGH THURSDAY/... DECK OF LOWER STRATUS /ASSOCIATED WITH NOW EXITING SHORTWAVE TROF AND COLD FRONT SAGGING SOUTHWARD ACROSS THE STATE/ PERSISTING ACROSS MUCH OF THE REGION...BRINGING GENERALLY MVFR CONDITIONS TO WESTERN AND CENTRAL TERMINALS...EXCEPT KJST WHERE LIFR PERSISTING WITH SNOW /POSS STILL MIXING WITH LIGHT FREEZING DRIZZLE THROUGH 14Z/. DOWNSLOPING SHOULD BE ENOUGH TO KEEP EASTERN AIRFIELDS IN VFR CONDITIONS. WINDS HAVE KICKED UP IN THE WEST AND CENTRAL MTNS AS FLOW INCREASES...WITH SURFACE SPEEDS OF 10-15 MPH WITH GUSTS TO 25 MPH...BUT THESE WILL DIMINISH THROUGH THE LATE MORNING. SOME IMPROVEMENT LIKELY STARTING MID/LATE MORNING FOR SEVERAL HOURS...WITH CIGS RISING TO VFR IN THE NORTH. BUT RESTRICTIONS WILL PERSIST AT KJST-KAOO THROUGH THE DAY. AN ALBERTA CLIPPER WILL TRACK JUST SOUTH OF PENNSYLVANIA TONIGHT INTO MONDAY...BRINGING ANOTHER ROUND OF SNOW WITH IFR CONDITIONS TO THE REGION. THIS WILL IMPACT TERMINALS AFTER 00Z MONDAY...BUT SOME AFFECTS POSSIBLE KJST AND KAOO BEFORE THIS TIME. EXPECT A PROLONGED PERIOD OF RESTRICTIONS INTO MON NIGHT. OUTLOOK... SUN NIGHT...SNOW RAPIDLY OVERSPREADING FROM SW TO NE...BRINGING IFR CONDITIONS TO THE ENTIRE REGION OVERNIGHT. MON...WIDESPREAD IFR/MVFR IN SNOW...GRADUAL IMPROVEMENT OVERNIGHT. TUE...AREAS MVFR IN SHSN WEST...AND ANY LINGERING SNOW IN THE EAST. WED...NO SIG WEATHER EXPECTED. THU...VFR TO START...WITH LATE DAY RESTRICTIONS SPREADING IN FROM THE WEST. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 PM EST MONDAY FOR PAZ017>019-024>028-033>036-050-056-057-063-064. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 1 PM EST MONDAY FOR PAZ059-065-066. WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY MORNING FOR PAZ059-065-066. && $$ SYNOPSIS...FITZGERALD NEAR TERM...DEVOIR/FITZGERALD SHORT TERM...FITZGERALD LONG TERM...DEVOIR/FITZGERALD/MARTIN AVIATION...RXR

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