Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 081956
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
256 PM EST MON FEB 8 2016

.SYNOPSIS...
A LONG-DURATION PERIOD OF SNOW WILL LIKELY RESULT IN A WIDESPREAD
LIGHT TO MODERATE ACCUMULATION FOR MUCH OF CENTRAL PA TONIGHT INTO
EARLY WEDNESDAY. LAKE EFFECT AND UPSLOPE SNOW SHOWERS WILL FOLLOW
FROM MID WEEK INTO THE FIRST PART OF THE WEEKEND...WITH ADDITIONAL
ACCUMULATION LIKELY IN THE FAVORED NORTHWEST SNOWBELT AND HIGHER
TERRAIN ALONG THE ALLEGHENIES AND LAURELS. THE COLDEST AIRMASS OF
THE WINTER IS POISED TO BRING FRIGID TEMPERATURES AND DANGEROUS
WIND CHILLS FOR VALENTINES WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF MID AFTERNOON...CENTRAL PA REMAINS IN REGION OF NIL
WEATHER...THE CALM BEFORE THE EXTENDED PERIOD OF UNSETTLED
WEATHER. HARD TO CALL IT A STORM PER SE AS A SLOW- MOVING AND
AMPLIFYING UPPER TROUGH TAKES ON A NEGATIVE TILT ACROSS THE MID
ATLANTIC REGION LATE TONIGHT.

WHILE THE SNOW COULD START AS RAIN...WET BULB ZERO ELEVATION
CLOSE TO THE SFC PAINTS A SNOW...RATHER THAN RAIN/SNOW MIX IN MOST
PLACES LATER MONDAY EVENING...EXCEPT FOR PERHAPS THE SUSQ VALLEY
AT OR BELOW 900 FT MSL.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
IT IS FAIRLY CERTAIN CENTRAL PA WILL EXPERIENCE A PROLONGED
PERIOD OF LIGHT...POSSIBLY MODERATE SNOW /IN ONE OR TWO SLOW
MOVING AND RATHER NARROW FGEN BANDS/ DURING THE MONDAY NIGHT
INTO TUESDAY PERIOD.

AFTER DISCUSSION WITH PHI AND LWX...ALONG WITH NEW WPC
GRAPHICS...HAVE ISSUED WINTER STORM WATCH AFTER 05Z TUE FOR
OUR 3 SE COUNTIES.

A WELL-DEFINED UPPER TROUGH/CIRCULATION TO THE WEST...WILL
GRADUALLY PHASE-IN ADDITIONAL SHORTWAVE ENERGY AS IT DIGS
SOUTHEAST THROUGH THE GREAT LAKES...EVOLVING INTO A CLOSED LOW
WITHIN A BROAD/ANOMALOUS MEAN TROUGH MIGRATING SLOWLY FROM THE
OHIO VALLEY INTO THE NORTHEAST STATES THROUGH MIDWEEK. THE COMPLEX
EVOLUTION/AMPLIFICATION OF THE LARGE SCALE TROUGH CHARACTERIZED BY
SEVERAL EMBEDDED SHORTWAVE DISTURBANCES CONTINUES TO RESULT IN A
COMPLICATED/LOWER CONFIDENCE SNOWFALL FORECAST. THUS HAVE WATCH
IN JUST THE HIGHEST AREA OF EXPECTED SNOWFALL. AGAIN...NOT A LOT
TO WORK WITH...BUT USED THE LOCATION OF INVERTED TROUGH AND TREND
OF MODELS ALONG WITH WPC GRAPHICS AND OTHERS TO KEY ON SMALL AREA
OF HIGHEST CONCERN.

WHAT WE DO KNOW IS THAT A PROLONGED PERIOD OF SNOW IS LIKELY FROM
MONDAY NIGHT THROUGH TUESDAY...FOLLOWED BY A TRANSITION TOWARD A
LAKE EFFECT/UPSLOPE SNOW PATTERN WEDNESDAY INTO WEDNESDAY NIGHT.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
*IMPACT WEATHER HIGHLIGHTS INCLUDE ADDITIONAL LAKE EFFECT AND
 UPSLOPE SNOW ACCUMULATIONS THURSDAY-SATURDAY...FOLLOWED BY FRIGID
 TEMPERATURES AND DANGEROUSLY COLD WIND CHILLS FOR VALENTINES
 WEEKEND.

ANOMALOUS WESTERN RIDGE/EASTERN TROUGH PATTERN WILL REMAIN IN
PLACE THROUGH THE WEEKEND. THE GLOBAL ENSEMBLE MEANS GENERALLY
KEEP THIS PATTERN CONFIGURATION INTACT INTO NEXT WEEK BUT AT A
DECREASING AMPLITUDE.

AS THE BROAD UPPER LEVEL CIRCULATION DEPARTS OVER THE NORTHEAST
TOWARD THE END OF THE WEEK...IT WILL BE REPLACED BY A POLAR
VORTEX DROPPING SOUTH ACROSS HUDSON BAY INTO SE CANADA. COLD AIR
WILL BEGIN SPILLING SOUTHWARD LATER IN THE WEEK...REINFORCED
INITIALLY BY A SECONDARY FRONT ON THURSDAY. CONFIDENCE CONTINUES
TO INCREASE IN A SIGNIFICANT ARCTIC AIR INTRUSION/COLD OUTBREAK
FOR VALENTINE`S WEEKEND.

LAKE EFFECT/UPSLOPE SNOWS FOR SEVERAL DAYS THU-SAT WILL BRING
ADDITIONAL LGT-MDT ACCUMULATION OVER THE FAVORED NORTHWEST
SNOWBELT DOWNWIND OF LAKE ERIE AND IN THE HIGHER TERRAIN OF THE
ALLEGHENIES/LAURELS. A NEW ELEMENT IN THE FCST IS DEVELOPING LOW
PRESSURE OFF THE MID-ATLANTIC/NORTHEAST COAST BY EARLY SATURDAY.
AT THIS TIME THE 08/00Z ECMWF LIES ON THE WESTERN EDGE OF THE
GUIDANCE ENVELOPE.

CONFIDENCE IS HIGH IN THE FCST COLD PATTERN/WELL-BELOW NORMAL
TEMPERATURES THROUGH THE PERIOD. THE COLDEST AIRMASS OF THE
WINTER APPEARS POISED TO ARRIVE THIS WEEKEND WITH GFS/EC BOTH
BRINGING -30C AIR AT 850MB INTO PA.

MAX/MIN TEMPERATURE DEPARTURES OF -20 TO -25 DEGREES BELOW CLIMO
ARE PROBABLE SATURDAY AND SUNDAY. WIDESPREAD SINGLE DIGIT
TEMPERATURES +/- ZERO ARE FCST SATURDAY NIGHT INTO EARLY SUNDAY.
A STRONG GRADIENT BETWEEN LOW PRESSURE OFF THE NEW ENGLAND COAST
AND 1040+MB ARCTIC HIGH DROPPING INTO THE UPPER MS VALLEY WILL
PRODUCE GUSTY WINDS AND DANGEROUSLY COLD WIND CHILLS -10F TO -25F
DEGREES BELOW ZERO.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
FLYING CONDS OVER CENTRAL PA AIRSPACE EXPECTED TO REMAIN VFR INTO
THE LATE AFTN/EARLY EVENING HOURS. LOWERING CLOUDS AND LIGHT PCPN
WILL OVERSPREAD THE REGION FROM THE WEST THIS EVENING AS AREA OF
SFC LOW PRESSUR DEVELOPS AND DEEPENDS ACROSS THE REGION.

THE COMPLEX WEATHER PATTERN WILL RESULT IN WIDESPREAD... BUT
MAINLY LIGHT TO OCCASIONALLY MODERATE... SNOW TONIGHT INTO TUESDAY
NIGHT. WHILE THERE MAY BE BREAKS FROM TIME TO TIME...EXPECT FAIRLY
WIDESPREAD SNOW/SNOW SHOWERS AND ASSOCIATED RESTRICTIONS OVER MUCH
OF THE REGION THROUGH THAT PERIOD.

LOOKING AHEAD...SNOW SHOWERS BECOME CONFINED TO WESTERN HIGHER
TERRAIN MID/LATE WEEK AS SHOT OF QUITE COLD AIR ARRIVES ON NW
FLOW.

OUTLOOK...

TONIGHT INTO TUE NIGHT...PERIODS OF LIGHT SNOW. IFR CONDITIONS.
WED...IFR/MVFR IN SHSN WRN AIRSPACE. MVFR-VFR CIGS CENTRAL/EAST.
SFC WIND GUSTS 20+KT FROM 270-300.
THU-SAT...MVFR IN -SHSN W MTNS. VFR ELSEWHERE.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 7 PM EST WEDNESDAY FOR PAZ024-
033.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 5 AM EST
WEDNESDAY FOR PAZ025>028-034>036-056-057-059-063.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 5 AM EST
WEDNESDAY FOR PAZ064>066.

&&

$$
SYNOPSIS...STEINBUGL
NEAR TERM...GARTNER
SHORT TERM...GARTNER/STEINBUGL
LONG TERM...STEINBUGL
AVIATION...GARTNER/RXR


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