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000
FXUS61 KCTP 310056
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
756 PM EST FRI JAN 30 2015

.SYNOPSIS...
ARCTIC AIR WILL BRING BITTER COLD TEMPERATURES AND SUB-ZERO WIND
CHILLS TO MUCH OF CENTRAL PENNSYLVANIA TONIGHT INTO EARLY SATURDAY.
CONFIDENCE IS INCREASING FOR A HIGH IMPACT WINTER WEATHER EVENT
SUNDAY INTO MONDAY WITH THE POTENTIAL FOR SIGNIFICANT SNOW
ACCUMULATION AND SOME MIXED WINTRY PRECIPITATION. ANOTHER SHOT
OF ARCTIC AIR SHOULD FOLLOW FOR TUESDAY.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
THE SUBSIDENCE INVERSION BASE WILL BE CRASHING BY 3-4 KFT OVER
THE NEXT SEVERAL HOURS AS HIGH PRESSURE NEAR KORD BUILDS EAST AND
THE MEAN...850-700MB THERMAL TROUGH DRIFTS TWD EASTERN PENN.

PRIOR TO THAT...NARROW BANDS OF LIGHT TO MODERATE SHSN WILL AFFECT
THE NRN AND WRN MTNS OF PENN THROUGH 02Z WITH ADDITIONAL LIGHT
ACCUMS OF AROUND 1/2 INCH IN A FEW LOCATIONS. ELSEWHERE ACROSS THE
CENTRAL RIDGE AND VALLEY REGION..SCATTERED FLURRIES WILL OCCUR.

WIND CHILLS WILL RANGE FROM 10 TO 20 BELOW ZERO OVER WESTERN
HIGHER ELEVATIONS...AND FROM ZERO TO 10 BELOW THROUGHOUT THE
CENTRAL RIDGE AND VALLEY REGION.

SKIES WILL CLEAR ACROSS MOST OF THE REGION LATER TONIGHT. WESTERN
UPSLOPE AREAS AND MY FAR NORTHEASTERN ZONES MAY KEEP CLOUDS AND
LINGERING FLURRIES THE LONGEST...BUT FORECAST SOUNDINGS SHOW THE
INVERSION HEIGHTS COMING DOWN SO THE CHANCES FOR ACTUAL MEASURABLE
SNOW WILL BE DWINDLING QUICKLY. WINDS REMAINING IN THE 10-15 MPH
RANGE LATE TONIGHT...WITH HIGHER GUSTS WILL KEEP WIND CHILLS IN
THE 10-20 BELOW ZERO RANGE OVER MUCH OF THE REGION.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
SATURDAY WILL START BRIGHT IN MOST AREAS AS THE HIGH CRESTS JUST
TO OUR SOUTH. HIGH CLOUDS MAY BEGIN TO INVADE FOR THE LAST HALF OF
THE AFTERNOON...BUT THEY SHOULD DO LITTLE TO MAR AN OTHERWISE FAIR
ALBEIT COLD MID WINTER`S DAY.

HIGHS FROM THE MID TEENS TO MID 20S NORTH TO SOUTH WILL BE ABOUT
15 DEG BELOW NORMAL ON AVERAGE.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
*SIGNIFICANT WINTER WEATHER/SNOW EVENT POSSIBLE SUNDAY-MONDAY
*BITTER COLD TEMPERATURES AND DANGEROUS WIND CHILLS POSSIBLE
 MONDAY NIGHT INTO TUESDAY

A POTENTIALLY WIDESPREAD HIGH IMPACT WINTER WX EVENT APPEARS TO
BE SHAPING UP ACROSS CENTRAL PENNSYLVANIA FOR SUNDAY INTO MONDAY.
A WINTER STORM WATCH HAS BEEN ISSUED FOR ALL CENTRAL PA COUNTIES
AND IS VALID FROM 12PM SUNDAY THROUGH 12 PM MONDAY. CONFIDENCE IN
THE EVENT OCCURRING IS AVERAGE WITH SLIGHTLY LOWER CONFIDENCE IN
THE DETAILS SUCH AS LOCATION AND SNOW ACCUM NUMBERS GIVEN THE
UNCERTAINTY IN THE TRACK OF THE SYSTEM...AND POTENTIAL FOR MIXED
PCPN/WARMER TEMPS IN THE SRN 1/3 OF THE AREA.

A SHORTWAVE NOW ENTERING CENTRAL BRITISH COLUMBIA WILL BE DIGGING
SOUTHEAST DOWN INTO THE NORTHERN/CENTRAL PLAINS LATER SAT AND INTO
SUN. THIS ENERGY COUPLED WITH A MORE SUBTLE SHORTWAVE ON ITS HEELS
DROPPING DOWN FROM THE NORTHWEST TERRITORIES WILL PLAY A KEY ROLE
IN THE EVOLUTION OF SURFACE LOW PRESSURE THAT IS CURRENTLY
FORECAST TO DEVELOP OVER THE LOWER MO AND MID MS VALLEY REGION BY
EARLY SUN BEFORE THEN AIMING EAST TOWARD THE OH VALLEY AND MID-
ATLANTIC STATES SUN NIGHT AND MON. AS THIS STORM DEVELOPS...MUCH
COLDER AIR WILL BUILD NOT ONLY BEHIND THE SYSTEM AS A LARGE ARCTIC
ANTICYCLONE HEADS SOUTHWARD INTO THE NORTHERN PLAINS...BUT COLDER
AIR WILL ALSO BLEED EASTWARD AS PRESSURES RISE OVER SOUTHEASTERN
CANADA AND NORTHERN NEW ENGLAND IN ASSOCIATION WITH A PRONOUNCED
UPPER CONFLUENCE ZONE. THE COMBINATION OF THESE TWO SYSTEMS WILL
HELP GENERATE A INCREASINGLY TIGHT BAROCLINIC ZONE UPON WHICH THE
DEVELOPING SURFACE LOW WILL MOVE ALONG.

THE PREVAILING SHIFT IN THE 12Z MODELS WAS TO CONTINUE A MORE
NORTHERLY TRACK WITH THIS SYSTEM...WHICH IS REFLECTED IN THE WPC
FORECAST WHICH WAS WEIGHTED HEAVILY IN THE FINAL GRIDDED SNOW/ICE
ACCUMULATIONS. HOWEVER FORECAST CONFIDENCE IS TEMPERED BY THE RUN-
TO- RUN INCONSISTENCIES THE MODELS HAVE SHOWN ALONG THE WITH
DISTINCT POSSIBILITY THAT THE MODELS MAY REVERSE TRENDS IN
SUBSEQUENT RUNS. WITH SEVERAL FORECAST CYCLES COMING UP ANTICIPATE
SOME CHANGES REGARDING NUMBERS AND LOCATIONS OF SNOWFALL TOTALS.

A SHOT OF ARCTIC AIR IS FORECAST TO SURGE INTO THE AREA BEHIND THE
EARLY WEEK STORM WITH POTENTIAL FOR DANGEROUS WIND CHILLS MONDAY
NIGHT INTO TUESDAY. THIS COULD ADD TO STORM-RELATED IMPACTS. HIGH
PRESSURE SHOULD BRING COLD BUT QUIET WEATHER INTO MIDWEEK. MODELS
AND ENSEMBLES SHOW A COASTAL TYPE SYSTEM SOMETIME NEXT WED-FRI BUT
IT IS WAY TOO EARLY TO SPECULATE ON THIS SYSTEM.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
PREDOMINANTLY IFR AT BFD AND JST WILL CONTINUE INTO THE AFTERNOON
AS POST FRONTAL SNOW SHOWERS CONTINUE TO FAVOR THE HIGH TERRAIN
TERMINALS OF THE WEST AND NORTH. THROUGH THE CENTRAL AREAS THE
CONDITIONS WILL SLOWLY IMPROVE AS THE DAY CONTINUES BEFORE
BECOMING VFR BY MID TO LATE AFTERNOON. EASTERN AND SOUTHEASTERN
TERMINALS WILL BE MAINLY VFR WITH PERHAPS A BRIEF REDUCTION IN A
PASSING SNOW SHOWER.

GUSTY WINDS WILL CONTINUE INTO THE OVERNIGHT BUT DIMINISHING
SOMEWHAT TO BETWEEN 15-20KT.

OUTLOOK...

SAT...VFR.

SUN...WIDESPREAD IFR/MVFR DEVELOPING ASSOCIATED WITH A STORM
MOVING TOWARD THE REGION.

MON...REDUCED CONDS EARLY...IMPROVING AS THE STORM MOVES AWAY FROM
THE AREA.

TUE-WED...NO SIG WX.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY
MORNING FOR PAZ004>006-010>012-017>019-024>028-033>037-041-042-
045-046-049>053-056>059-063>066.
WIND CHILL ADVISORY UNTIL 11 AM EST SATURDAY FOR PAZ004>006-
010>012-017>019-024-033-037-041-042-045-046-049-051>053-058.

&&

$$
SYNOPSIS...LA CORTE/LAMBERT
NEAR TERM...LA CORTE/LAMBERT
SHORT TERM...LA CORTE
LONG TERM...STEINBUGL
AVIATION...LA CORTE/GARTNER