Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 102108
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
408 PM EST WED FEB 10 2016

.SYNOPSIS...
A FEW COMPACT DISTURBANCES WILL SLIDE SOUTHEAST OVER THE NEXT
SEVERAL DAYS THROUGH A DEEP UPPER TROUGH OVER THE NORTHEASTERN
U.S.. 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/...
MOSTLY CLOUDY SKIES AND BLUSTERY CONDITIONS WITH FLURRIES AND A
FEW BRIEF SNOW SHOWERS WILL BE FOUND ACROSS MUCH OF THE CENTRAL
RIDGE AND VALLEY REGION LATE THIS AFTERNOON INTO THIS EVENING
WITH WEAK LLVL RIDGING IN PLACE.

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.

18Z HRRR HAS BEEN FAIRLY CONSISTENT WITH ITS PAST SEVERAL RUNS IN
DISPLAYING SIMILAR TIMING OF A NARROW NE-SW ORIENTED BAND OF
BRIEFLY HEAVY SNOW SHOWERS AND POSSIBLE SQUALLS...THAT WILL
ACCOMPANY A SECONDARY CFRONT ACROSS THE NW MTNS LATE TODAY BEFORE
REACHING A KELM TO KFIG LINE AROUND 00Z THURSDAY.

ONCE THIS SNOW BAND SLIDES OFF THE HIGHER TERRAIN OF THE
ALLEGHENY PLATEAU LATER THIS EVENING...AND LLVL INSTABILITY WANES
A BIT...THE HRRR IS PROBABLY ON TRACK WITH WEAKENING IT BY 02Z
NEAR A KAVP...TO KSEG AND KUNV LINE.

THE WELL-ALIGNED SFC-800 MB FLOW FROM ABOUT 270 DEGREES...WILL
VEER TO ABOUT 295 DEG LATE TODAY/EARLY TONIGHT AS THE
AFOREMENTIONED SECONDARY COLD FRONT SWINGS SE THROUGH THE AREA.
THE FRONT COULD BRING A QUICK 1/2 INCH ALONG AND EAST OF THE
INTERSTATE 99/RT 22 CORRIDOR...WITH UP TO ONE INCH ON THE HIGH
TERRAIN TO THE NORTH AND WEST.

BASED ON THE MODERATELY STRONG...WELL ALIGNED...AND PERSISTENT 280-290
DEG FLOW LATE TODAY 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.

TEMPS ARE RIGHT AROUND THEIR FCST MAXES OF AROUND 20F ACROSS THE
LAUREL HIGHLANDS...AND IN THE U20S TO LOWER 30S HEADING FROM THE
CENTRAL MTNS TO THE MIDDLE AND LOWER SUSQ VALLEY.

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 /21Z WEDNESDAY THROUGH MONDAY/...
MAINLY VFR CIGS AND VSBYS WILL PREVAIL ACROSS THE SUSQ VALLEY TAF
SITES /KIPT...KMDT AND KLNS/ WITH HIGH END MVFR CIGS AND VFR TO
MVFR VSBYS AT KUNV AND KAOO.

THE POOREST FLYING CONDITIONS WILL CONTINUE TO BE AT KJST AND
KBFD FOR THE NEXT SEVERAL DAYS...WHERE CIGS AND VSBYS WILL BE
MAINLY IN THE MVFR TO UPPER IFR RANGE...WITH OCNL DIPS TO
LIFR/VLIFR IN LAKE EFFECT SNOW BANDS AND AREAS OF ENHANCED UPSLOPE
SNOWS.

FOR KUNV...KAOO...AND PERHAPS KIPT...EXPECT UP TO A FEW HOUR
PERIOD OF MORE FREQUENT SNOW SHOWERS LATE TODAY AND AFTER
SUNSET...AS A SECONDARY COLD FRONT PUSHES THROUGH THE AREA.

GUSTY WEST TO WNW WINDS WILL PREVAIL THIS AFTERNOON...TONIGHT AND
AND THURSDAY...AVERAGING 12-15 KTS WITH GUSTS IN THE LOW-MID 20
KT RANGE.

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...LAMBERT/STEINBUGL
NEAR TERM...LAMBERT
SHORT TERM...LAMBERT
LONG TERM...STEINBUGL
AVIATION...LAMBERT


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