Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 251756
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1256 PM EST SUN JAN 25 2015

.SYNOPSIS...
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.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
COLD FRONT WORKING ITS WAY SOUTH ACROSS THE WEST CENTRAL AND
CENTRAL MOUNTAINS. REGIONAL RADAR MOSAIC CONTINUES TO DETECT
A BAND OF -SHSN/FLURRIES...ALTHOUGH UPSTREAM ACTIVITY OVER OHIO IS
INCREASING AS WARM ADVECTION FROM MID MISSISSIPPI VALLEY LOW
PRESSURE HAS COMMENCED.

MUCH DRIER AIR HAS WORKED INTO NORTHERN AREAS AS
EXPECTED...SHUTTING OFF MOST OF THE SNOW SHOWER ACTIVITY THERE FOR
THE TIME BEING. FURTHER SOUTH...DEEPENING LYR OF MOISTURE
ASCENDING THE LAURELS SHOULD CONTINUE TO 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.

&&

.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/...
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.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
COLD FRONT SAGGING SOUTHWARD ACROSS PA. NRN PA SEEING SOME
IMPROVEMENT NORTH OF THE FRONT...WHILE LOWS CIGS AND LIGHT PRECIP
PERSIST ALONG AND SOUTH OF THE FNT ACROSS SRN PA.

KJST SOCKED IN WITH VERY LOW CIG/VSBY AND LIGHT PRECIP.
DOWNSLOPING FARTHER TO THE EAST SHOULD BE ENOUGH TO KEEP SERN
AIRFIELDS /KMDT AND KLNS/ IN VFR/HIGH MVFR CONDS.

AN ALBERTA CLIPPER WILL TRACK JUST SOUTH OF PENNSYLVANIA TONIGHT
INTO MONDAY...BRINGING ANOTHER ROUND OF SNOW WITH IFR CONDS. THIS
WILL IMPACT MOST TERMINALS AFTER 00Z MONDAY...BUT SOME AFFECTS
POSSIBLE EARLIER AT KJST.

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...

SUN NIGHT...SNOW RAPIDLY OVERSPREADING FROM SW TO NE...BRINGING
IFR CONDS TO THE ENTIRE REGION OVERNIGHT.
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 FROM 6 PM THIS EVENING TO 7 PM EST
MONDAY FOR PAZ010>012-017>019-024>028-033>036-041-045-046-
049>053-056>058-063-064.
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...FITZGERALD/MARTIN
AVIATION...EVANEGO


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