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/...
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.

&&

.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...
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.

&&

$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO/FITZGERALD
SHORT TERM...DANGELO/DEVOIR/FITZGERALD
LONG TERM...DANGELO/FITZGERALD/MARTIN
AVIATION...CERU/EVANEGO



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