Area Forecast Discussion
Issued by NWS State College, PA

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421
FXUS61 KCTP 110500
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1200 AM EST THU FEB 11 2016

.SYNOPSIS...
A PERSISTENT NORTHWEST FLOW WILL BRING A PROLONGED PERIOD OF LAKE
EFFECT AND UPSLOPE SNOW SHOWERS THROUGHOUT THE NORTHWEST SNOWBELT
AND ACROSS THE LAUREL HIGHLANDS. AN ARCTIC BLAST WILL DELIVER THE
COLDEST AIR OF THE SEASON FOR VALENTINES WEEKEND WITH DANGEROUS
COLD AND WIND CHILLS EXPECTED TO IMPACT THE AREA SATURDAY INTO
SUNDAY.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
IN THE NEAR TERM...OUR LINE OF SNOW SHOWERS AND SQUALLS HAS BEGUN
TO WEAKEN AND BECOME MORE DISORGANIZED...MORE OR LESS ALONG THE
LINES OF THE HIGH RES MESO MODELS. STILL LOOKING AT THE
POSSIBILITY OF A QUICK COATING OF SNOW IN A FEW LOCATIONS AS THIS
FEATURE SLIDES OFF TO THE SOUTHEAST.

FOR THE LARGER PICTURE...PERSISTENT UPSLOPE SNOW SHOWERS AND
FREQUENT LES FROM MEANDERING SNOW BANDS ACROSS THE FAR NW ZONES
WILL BRING AN ADDITIONAL 1 TO 2 INCHES EVERY 4 TO 6 HOURS THROUGH
TONIGHT...THOUGH PORTIONS OF NW WARREN COUNTY COULD SEE NEARLY
DOUBLE THOSE SNOWFALL RATES.

THE WELL-ALIGNED SFC-800 MB FLOW FROM ABOUT 270 DEGREES...WILL
VEER TO ABOUT 295 DEG OVERNIGHT AS A SECONDARY COLD FRONT SWINGS
SE THROUGH THE AREA.

BASED ON THE MODERATELY STRONG...WELL ALIGNED...AND PERSISTENT 280-290
DEG FLOW THROUGH ABOUT 04Z FRIDAY...WE EXTENDED THE WINTER WX AND
LES ADVISORIES AND WARNINGS OUT IN TIME THROUGH 03Z FRIDAY...AND
EXPANDED THE WINT WX ADVIS NORTH TO COVER ELK AND CLEARFIELD
COUNTIES.

LATER TONIGHT...LOOK FOR VARIABLE AMOUNTS OF CLOUDS WITH SCATTERED
FLURRIES ACROSS THE SUSQ VALLEY AND SOUTHERN TIER...WHILE A FEW
BRIEF SNOW SHOWERS IN NARROW NW-SE STREAMERS OFF LAKE ERIE COULD
ADD AN ADDITIONAL LIGHT COATING FROM KAOO TO KUNV.

LOWS TONIGHT WILL VARY FROM 5-10F ACROSS THE NORTHERN AND WESTERN
MTNS...TO THE UPPER TEENS IN THE SUSQ VALLEY. WIND CHILLS COULD
DIP TO NEAR -10F AT TIMES LATE TONIGHT ACROSS THE NRN AND WRN
MTNS...AND IN THE ZERO TO 10 ABOVE RANGE ACROSS THE CENTRAL AND SE
ZONES...BUT WILL BE A GOOD 5 TO 10 DEG F ABOVE WIND CHILL ADVISORY
CRITERIA IN ANY OF THESE LOCATIONS.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
PERSISTENT...MEAN BLYR FLOW FROM 280-290 DEGREES WILL LEAD TO
WIDESPREAD STRATO CU WITH CLOUD TEMPS ACROSS MUCH OF CENTRAL PENN
FALLING WITHIN THE FAVORABLE DGZ OF -12 TO -18C.

THIS WILL LEAD TO WIDESPREAD FLURRIES AND BRIEF SNOW SHOWERS FROM
NARROW...AND SLOWLY MEANDERING BANDS. MESOSCALE MODELS SUCH AS
THE HRRR AND 3 KM NCAR ENSEMBLE WILL PLAY AN IMPORTANT ROLE IN
FORECASTING THE LOCATION...MVMT...AND SNOW FROM THESE FAIRLY WELL-
ORGANIZED BUT NARROW SNOW BANDS THAT WILL REACH INTO THE CENTRAL
RIDGE AND VALLEY REGION AT TIMES.

ADDITIONAL SNOW ACCUMS OF A FEW TO SEVERAL INCHES WILL OCCUR
DURING THE DAYLIGHT HOURS THURSDAY ACROSS THE NW MTNS AND LAUREL
HIGHLANDS WHERE THE WINT WX AND LES ADVISORIES...AND LES WARNINGS
WILL CONTINUE.

MAX TEMPS THURSDAY WILL BE ONLY 12-25F WHICH IS AROUND 15 DEG F
BELOW NORMAL FOR THIS TIME OF YEAR.

THE BULK OF THE MORE SIGNIFICANT SNOW SHOWERS/LES SHOULD TAPER
OFF/LIFT TO THE NORTH...CLOSELY HUGGING THE I-90 CORRIDOR AS MEAN
BLYR WINDS BACK MORE TO THE WSW AFTER MIDNIGHT.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
*IMPACT WEATHER HIGHLIGHTS: SNOW SQUALLS LIKELY WITH ARCTIC FRONT
 FRIDAY NIGHT-SATURDAY. FRIGID TEMPERATURES AND DANGEROUS WIND
 CHILLS FOR VALENTINES WEEKEND.

POLAR VORTEX DIVES FROM HUDSON BAY SOUTHEAST ACROSS QUEBEC AND
NORTHERN NEW ENGLAND THURSDAY-SUNDAY. THE GLOBAL MODELS AND
ENSEMBLE MEANS KEEP A `MILDER` TROUGH PATTERN IN PLACE OVER THE
EASTERN US INTO NEXT WEEK. EMERGENCE OF SOUTHERN STREAM SHORTWAVE
AND ITS INTERACTION WITH THE NORTHERN STREAM FLOW CREATES THE
POTENTIAL FOR WINTER PRECIPITATION MON-WED BUT WITH A HIGH DEGREE
OF UNCERTAINTY/LOW CONFIDENCE. A PATTERN SHIFT TO PACIFIC ZONAL-TO
SOUTHWEST FLOW ALOFT WITH RISING/ABOVE NORMAL HEIGHTS IS FCST BY
THE END OF NEXT WEEK. THIS FAVORS A RETURN TO MILDER WEATHER.

LAKE EFFECT AND UPSLOPE SNOW SHOWERS CONTINUE INTO THE WEEKEND
BEFORE TAPERING OFF ON SUNDAY...AS ARCTIC HIGH BUILDS OVER THE
REGION. ADDITIONAL LIGHT SNOW ACCUMULATIONS ARE LIKELY IN THE
FAVORED NORTHWEST SNOWBELT AND HIGHER TERRAIN ALONG THE
ALLEGHENIES/LAUREL HIGHLANDS.

THE COLDEST AIRMASS OF THE 2015-16 WINTER SEASON REMAINS POISED
TO ARRIVE THIS WEEKEND...AS A BLAST OF ARCTIC AIR DELIVERS A SHORT
DURATION COLD OUTBREAK TO CENTRAL PENNSYLVANIA. SNOW SQUALLS ARE
LIKELY WITH THE ARCTIC FRONTAL PASSAGE FRIDAY NIGHT INTO SATURDAY.

MAX/MIN TEMPERATURE DEPARTURES OF -20 TO -25 DEGREES BELOW CLIMO
ARE FCST SATURDAY AND SUNDAY. MINIMUM TEMPERATURES SATURDAY NIGHT
INTO EARLY SUNDAY MORNING RANGE FROM 0F IN THE LOWER SUSQ. VALLEY
TO -10F IN THE NORTHWEST ALLEGHENIES. THE FRIGID TEMPERATURES
COMBINED WITH DANGEROUS WIND CHILLS /-10 TO -25 BELOW ZERO/ WILL
RESULT IN AN INCREASED RISK FOR FROSTBITE AND HYPOTHERMIA. WIND
CHILL HEADLINES ARE A GOOD BET AND PRECAUTIONS SHOULD BE MADE NOW
TO PROTECT/PREPARE FOR THE UPCOMING COLD SNAP.

A MODERATION (WARMING TREND) IS EXPECTED INTO EARLY NEXT WEEK.
THERE IS STILL A LOT OF SPREAD CONCERNING A POTENTIAL STORM SYSTEM
IMPACTING THE NORTHEAST EARLY NEXT WEEK. THE OPERATIONAL EC
REMAINS MORE BULLISH THAN THE GFS IN DEVELOPING A SIGNIFICANT
CYCLONE AND HAS TRENDED EVEN FURTHER TO THE WEST WITH IS 10/12Z
RUN. CONFIDENCE REMAINS LOW BUT THE SYSTEM WILL NEED TO BE MONITORED.

&&

.AVIATION /04Z THURSDAY THROUGH MONDAY/...

OVERALL VFR CIGS AND VBSYS WILL BEGIN TO DOMINATE OVERNIGHT. THE
SNOW CONVECTION SWITCHED FROM A WAVE TO A LINEAR BAND FEATURE. THE
HRRR DID A DECENT JOB OF SHOWING THE SWITCH...HOWEVER FAILED TO
SHOW THE INTENSITY. THE BIGGEST ISSUE WILL BE THE GUSTY WINDS
INTERACTION WITH ANY SNOW...WHICH COULD THEN BRING MVFR OR LOWER
VSBYS. THE BAND SHOULD BRIEFLY MOVE OVER UNV...BETWEEN 05 TO 07Z.
OTHERWISE VFR SHOULD DOMINATE THROUGH THE CENTRAL AND WESTERN TAF
SITES. BFD AND JST SHOULD REMAIN MAINLY MVFR WITH PERIODS OF IFR
POSSIBLE THROUGH THE FIRST HALF OF TOMORROW MORNING AND WILL
SLOWLY FADE BY TOMORROW EVENING.


OUTLOOK...

THU/THU NIGHT...MVFR WITH PERIODS OF IFR IN -SHSN ACROSS THE WRN
PENN MTNS. MAINLY VFR ELSEWHERE.

FRI...MVFR IN -SHSN...MAINLY LATE WITH STRONG COLD FRONT.

SAT...MVFR IN -SHSN W MTNS. VFR OTHERWISE. WINDY.

SUN...MVFR IN -SHSN IN W MTNS EARLY...OTHERWISE VFR.

MON...VFR POSSIBLE EARLY ACROSS THE EASTERN HALF OF PENN...THEN
LOWERING AND THICKENING CLOUDS LIKELY WITH A FEW PERIODS OF SNOW
POSSIBLE...YIELDING MVFR TO IFR VSBYS AND CIGS.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST THURSDAY FOR PAZ005.
LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THURSDAY FOR PAZ004.
WINTER WEATHER ADVISORY UNTIL 10 PM EST THURSDAY FOR PAZ010-
017-024-033.

&&

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



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