Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 260632 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 132 AM EST MON JAN 26 2015 .SYNOPSIS... A VIGOROUS UPPER LEVEL STORM WILL SPREAD LIGHT SNOW OVER PENNSYLVANIA TONIGHT. AN INTENSE SECONDARY COASTAL LOW WILL FORM OFF THE CAROLINA COAST ON MONDAY. THE COASTAL STORM WILL RIDE INTO NEW ENGLAND TUESDAY. HIGH PRESSURE WILL BUILD OVER THE REGION FOR THE MIDDLE OF THE WEEK...FOLLOWED BY AN ALBERTA CLIPPER THURSDAY. && .NEAR TERM /UNTIL 8 AM THIS MORNING/...
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A LIGHT SNOW FALLING ACROSS MOST OF CENTRAL PA AS OF 06Z IN REGION OF ISENTROPIC LIFT AHEAD OF APPROACHING CLIPPER. STILL SOME RAIN NOTED ALONG THE MASON DIXON LINE. HOWEVER...MDL SOUNDINGS IMPLY EVEN THERE IT WILL GO TO SNOW SHORTLY...AS BLYR COOLS. AS OF 06Z...ACCUMS RANGE FROM 2-3 INCHES ACROSS THE SC MTNS...TO NOTHING ALONG THE NY BORDER. RADAR TRENDS AND BLEND OF MDL QPF SUPPORTS AN ADDITIONAL 1-2 INCHES BTWN 06Z-12Z...WITH THE HIGHER AMTS ACROSS THE CENTRAL COUNTIES NR I-80. LATEST 4KM NAM/HRRR/RAP ALL INDICATE SNOW INTENSITY WILL DIMINISH BY DAWN...AS MID LVL SHORTWAVE AND ASSOC LG SCALE FORCING EDGES EAST OF THE AREA. MINOR ADJUSTMENTS MADE TO TEMPS WITH MIN READINGS BY DAWN FROM THE LTEENS N TIER TO THE U20S S TIER.
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&& .SHORT TERM /8 AM THIS MORNING THROUGH 6 PM TUESDAY/... 945 PM UPDATE... PRECIP MAY BE A LITTLE LIGHTER...ESP IN THE EAST...THAN WHAT IS GOING IN THE FCST...SO HAVE MADE A SLIGHT DOWNWARD MOVE TO THE EAST...BUT IT IS ONLY A HALF INCH OR SO FOR THE DAYTIME ON MONDAY. PREV... WEAKENING PRIMARY CLIPPER LOW OVER THE CENTRAL APPALACHIANS TRACKS SOUTH OF PA MONDAY MORNING WHILE IMPRESSIVE SECONDARY DEVELOPMENT TAKES PLACE OFF OF THE VA/NC COAST AND RACES NE LATER MONDAY. STILL CONCERNED FOR WESTERN EDGE OF HEAVY SNOW FALL TO BRUSH MY FAR SOUTHEAST COUNTIES...WE MAINTAIN A WINTER STORM WATCH FOR YORK LANCASTER AND LEBANON COUNTIES AS A RESULT FOR AN ADDITIONAL 4-6"+ LATER MONDAY INTO TUESDAY. BUT DURING MONDAY...PERIODS OF LIGHT SNOW AND SNOW SHOWERS WILL PERSIST THROUGH MOST OF THE DAY. DEEP EAST FETCH AND UPSLOPE INTO THE LAURELS KEEPS THE SNOWFALL GOING THROUGH THE AFTERNOON HOURS...WITH DEFORMATION BANDING LIKELY SETTING UP OVER THE SOUTHEAST LATE IN THE DAY. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... 945 PM UPDATE... AS WITH MONDAY...THE NEWEST RUN OF THE NAM AND THE 21Z SREF MEAN QPFS ARE PRACTICALLY DRY FOR THE ERN THIRD OF THE AREA FOR MON NIGHT AND TUESDAY. IF THESE ARE PERFECT PROGS...LOL...PERHAPS AN ADVY MAY EVEN BE OVER-DOING IT. HOWEVER...NOT ENOUGH NEW INFO AT HAND TO CHANGE THE WATCH...WHICH IS GOING TO STAND FOR THE TIME BEING. MORE 00Z STUFF /GFS AND ECMWF/ WILL COME IN IN A BIT FOR THE MID SHIFT TO LEARN FROM. HAVE NUDGED QPF AND SNOW DOWN SLIGHTLY IN THE EAST FOR MON NIGHT AND TUES. PREV... HELD ONTO THE WATCH FOR THE FAR SE. OUR EASTERN AREAS WILL BE CLOSE TO THE HEAVIER SNOW FROM THE COASTAL STORM MONDAY NIGHT AND TUESDAY MORNING. STRONGEST WINDS WILL BE EAST OF OUR AREA...BUT GUSTY WINDS WILL BE LIKELY BY TUESDAY MORNING. AS NOTED YESTERDAY...THERE WILL BE A LARGE TEMPERATURE GRADIENT FROM NY TO MD INTO TUE. FRONTAL ZONE RIGHT OVER THE STATE COLLEGE AREA MUCH OF THE MORNING HERE. FIRST CONCERN IS THE INVERTED TROUGH TO THE WEST THAT LINGERS INTO MONDAY NIGHT. DID UP POPS SOME ACROSS THE NW. SECOND CONCERN IS THE DEEP COASTAL THAT FORMS LATE MONDAY AND TRACKS NE. WATCH POSTED FOR THE FAR SE. DID EDGE QPF AND SNOWFALL AMTS UP SOME ACROSS THE FAR EAST AND SE FOR MONDAY NIGHT AND EARLY TUE. WINDS A LITTLE HIGH ON TUE...DID EDGE WIND GUSTS DOWN SOME. WIND CHILLS MAY REACH ADVISORY LEVELS AT TIMES THIS WEEK...BUT REAL CONCERN MAINLY STAYS NE OF OUR AREA. WED STILL LOOKING MAINLY DRY. ANOTHER FRONT FOR LATE THU INTO EARLY FRIDAY. SECONDARY LOW FORMS...BUT SITUATION AT THIS POINT NOT LIKE WHAT WE HAVE AT THE CURRENT TIME. MORE DETAIL BELOW... 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. 12Z GFS MAY BE A LITTLE OFF...FROM 12P CHAT ROOM DISC. ANYWAY...MOST OF THE DATA 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. ACROSS THE REST OF CENTRAL PA...LIGHT SNOW EXPECTED 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. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS THE SYSTEM CONTINUES TO OVERSPREAD THE REGION...TAF SITES CONTINUE TO DROP. ALL TAF SITES OUTSIDE OF BFD ARE MVFR AND LOWER WITH KJST...THV AND AOO SOCKED IN WITH VERY LOW CIG/VSBY AND LIGHT TO MODERATE PRECIP. AN ALBERTA CLIPPER WILL TRACK JUST SOUTH OF PENNSYLVANIA TONIGHT INTO MONDAY...BRINGING ANOTHER ROUND OF SNOW WITH IFR CONDS. THESE CIGS AND VSBYS WILL REDUCE ALL TAF SITES OVERNIGHT...INTO TOMORROW MORNING AS SNOW RAPIDLY OVERSPREADING FROM SW TO NE...BRINGING IFR CONDS TO THE ENTIRE REGION OVERNIGHT. SNOW/SNSH CONTINUES MONDAY INTO TUES. NW WINDS PICK UP MON NIGHT INTO TUES AS LOW PRES SPINS UP OFF NEW ENGLAND COAST. QUIET WX WEDNESDAY BETWEEN SYSTEMS...BEFORE ANOTHER CLIPPER DROPS ACROSS THE AREA LATE THU INTO FRI. OUTLOOK... MON-MON NIGHT...WIDESPREAD IFR/MVFR IN SNOW/SNSH. TUE...AREAS MVFR IN SHSN WEST...AND POSS LINGERING SNOW IN THE EAST. WED...VFR WITH NO SIG WEATHER EXPECTED. THU...VFR TO START...WITH LATE DAY RESTRICTIONS SPREADING IN FROM THE WEST. THU NIGHT- FRI...WIDESPREAD IFR/MVFR IN SNOW. && .CTP WATCHES/WARNINGS/ADVISORIES...
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WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ004>006-010>012-017>019-024>028-033>036-041-045-046-049>053- 056>058-063-064. WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR PAZ059-065-066. WINTER STORM WATCH FROM 1 PM EST THIS AFTERNOON THROUGH TUESDAY MORNING FOR PAZ059-065-066.
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&& $$ SYNOPSIS...DANGELO NEAR TERM...DANGELO/FITZGERALD SHORT TERM...DANGELO/DEVOIR/FITZGERALD LONG TERM...DANGELO/FITZGERALD/MARTIN AVIATION...CERU/EVANEGO

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