Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 081256
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
756 AM EST MON FEB 8 2016

.SYNOPSIS...
A SLOW MOVING AND DEEPENING UPPER TROUGH WILL SLIDE SOUTHEAST
FROM THE UPPER GREAT LAKES...TO PENNSYLVANIA EARLY WEDNESDAY. A
LONG- DURATION PERIOD OF SNOW WILL LIKELY RESULT IN A WIDESPREAD
LIGHT TO MODERATE ACCUMULATION FOR MUCH OF CENTRAL PA LATE MONDAY
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. A MUCH
COLDER WEATHER PATTERN IS EXPECTED BY LATER IN THE WEEK WITH A
BLAST OF ARCTIC AIR FOR VALENTINES WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE SQUEEZE PLAY IS ON TODAY ACROSS THE REGION...AS A DEEP LOW
OFF THE COAST MOVES NE...WHILE A SLOW-MOVING AND AMPLIFYING UPPER
TROUGH TAKES ON A NEGATIVE TILT ACROSS THE MID ATLANTIC REGION
LATE TONIGHT.

MADE MINOR ADJUSTMENTS TO THE GRIDS TODAY. TIMING WAS QUITE GOOD.
EXPECT SOME LIGHT SNOW INTO THE WESTERN AREAS BY EARLY TO MID
AFT...AND EASTERN AREAS AFTER DARK.

LOOKS LIKE HIGHEST AMTS LATE TODAY AND EARLY TONIGHT WOULD BE
ACROSS SOMERSET AND CAMBRIA COUNTIES. POSTED AN WINTER WEATHER
ADVISORY FOR THIS AREA.

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 AFTERNOON/EVENING...EXCEPT FOR PERHAPS THE
SUSQ VALLEY AT OR BELOW 900 FT MSL.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY 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.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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 LATER ON WED.

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

AS THE BROAD UPPER LEVEL CIRCULATION DEPARTS OVER THE NORTHEAST
TOWARD THE END OF THE WEEK...THE GLOBAL MODELS SHOW IT BEING
REPLACED BY A POLAR VORTEX DROPPING SOUTH FROM THE ARCTIC. COLD
AIR WILL BEGIN SPILLING SOUTHWARD FROM CANADA LATER IN THE WEEK
REINFORCED INITIALLY BY A SECONDARY FRONT ON THURSDAY...FOLLOWED
BY A SIGNIFICANT ARCTIC AIR INTRUSION FOR VALENTINE`S WEEKEND.

RESIDUAL SNOWS ASSOCIATED WITH THE UPPER TROUGH ON WED SHOULD
TRANSITION TOWARD LAKE EFFECT/UPSLOPE FOR SEVERAL DAYS THU-SAT
WITH ADDITIONAL ACCUMULATION LKLY OVER THE FAVORED AREAS DOWNWIND
OF LAKE ERIE AND IN THE HIGHER TERRAIN OF THE ALLEGHENIES/LAURELS.

CONFIDENCE IS HIGH IN THE FCST COLD PATTERN WHICH SHOULD PEAK
OVER THE WEEKEND. MAX/MIN TEMPERATURE DEPARTURES OF 20 DEGREES
BELOW CLIMO ARE PROBABLE SAT-SUN. WIDESPREAD SUB ZERO WIND CHILLS
APPEAR LIKELY SATURDAY NIGHT INTO EARLY SUNDAY...WITH PROJECTED
MINIMUM WC VALUES BETWEEN -10 TO -25 DEGREES BELOW ZERO.

&&

.AVIATION /13Z MONDAY THROUGH FRIDAY/...
A FADING NARROW RIDGE OF HIGH PRESSURE BETWEEN TWO WEATHER
SYSTEMS IS BRINGING VFR CONDITIONS TO CENTRAL PA THIS MORNING.
HIGH CLOUDS WILL THICKEN OVERHEAD TODAY AS AN UPPER LEVEL TROUGH
AND WEAK COLD FRONT APPROACH.

THE UPPER LEVEL TROF WILL DROP DOWN OVER THE AREA THIS
AFTERNOON...SPREADING SNOW INTO WESTERN AREAS BY MID AFTERNOON
THEN SPREADING EASTWARD THIS EVENING. 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-FRI...MVFR IN -SHSN W MTNS. VFR ELSEWHERE.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO MIDNIGHT
EST TONIGHT FOR PAZ024-033.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE TUESDAY
NIGHT FOR PAZ064>066.

&&

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


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