Area Forecast Discussion
Issued by NWS State College, PA

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000
FXUS61 KCTP 112317
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
617 PM EST THU FEB 11 2016

.SYNOPSIS...

AN ARCTIC COLD FRONT WILL DELIVER THE COLDEST AIR OF THE SEASON
FOR VALENTINES WEEKEND. THE ARCTIC FRONTAL BOUNDARY WILL BE
ACCOMPANIED BY A ROUND OF BLINDING SNOW SQUALLS LATE FRIDAY AND
FRIDAY NIGHT...FOLLOWED BY DANGEROUS COLD AND VERY LOW WIND CHILLS
THAT ARE EXPECTED TO IMPACT THE AREA SATURDAY INTO SUNDAY.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...

NUMEROUS...NARROW BANDS OF SNOW SHOWERS AND BRIEF SQUALLS
CONTINUE TO STREAM SE AND WELL INLAND FROM THE GLAKES...WITH THE
LATEST RADAR TRENDS STARTING TO HINT AT A LITTLE WEAKENING.

LATEST HRRR REALLY DRIES THINGS UP FAST OVER THE NEXT FEW HOURS.
BUFKIT INDICATES INVERSION HEIGHTS DROPPING FAST SO THIS SOLUTION
LOOKS REASONABLE.

WILL MAINTAIN CURRENT WINTER WEATHER HEADLINES WHICH WRAP UP AT
03Z/10 PM. UNLESS THINGS WIND DOWN EVEN MORE RAPIDLY THAN EXPECTED...WE
WILL LET THINGS RUN UNTIL THE CURRENT EXPIRATION TIMES.

THE WIND WILL MAKE IT FEEL MUCH COLDER WITH WIND CHILLS BETWEEN
-10 AND +10 ACROSS THE ENTIRE AREA. THE BLUSTERY CONDITIONS WILL
JUST BE A TASTE OF WHAT IT IS ON THE HORIZON FOR LATER FRIDAY
NIGHT RIGHT INTO SUNDAY.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
SFC HIGH PRESSURE WILL SLIDE SOUTH OF THE STATE LATE TONIGHT
BRINGING GRADUAL CLEARING. FLURRIES AND SCATTERED SNOW SHOWERS
WILL LIFT NORTH EARLY TONIGHT AND BE CONFINED MAINLY TO THE
NORTHERN TIER BY AROUND MIDNIGHT.

TEMPS DROP INTO THE SINGLE DIGITS TONIGHT AS SOME CLEARING TAKES
PLACE IN THE NW...BUT THE CALM AIR IN THE SE COULD CAUSE THE TEMPS
THERE TO BECOME COLDER IN A FEW OF THE PERENNIAL COLD RURAL
AREAS...SUCH AS SEG AND THV - MAKING THEM 3-5F COLDER THAN THE
SURROUNDING LOCALES.

THE FIRST PART OF FRIDAY SHOULD BE QUIET WITH PARTLY TO MOSTLY
SUNNY SKIES AND RELATIVELY LIGHT WSW WIND. CLOUDS WILL QUICKLY
INCREASE FROM THE SW AS SOME MEAGER WARM ADVECTION KICKS IN AHEAD
OF THE WELL- ADVERTISED ARCTIC FRONT. SOME LIGHT SNOW/SNOW
SHOWERS WILL DEVELOP DURING THE AFTN...BUT ACCUMS SHOULD BE MEAGER
/GENERALLY UNDER 1/2 INCH. TEMPS WILL TRY TO GET INTO THE 20S ALL
OVER BUT THE PERSISTENT CLOUD COVER IN THE NW WILL LIKELY LIMIT
THEM TO THE UPPER TEENS.

ARCTIC FRONT AND AN EXPANSIVE AREA OF STEEP 850-700 MB LAPSE
RATES GREATER THAN 8C/KM WILL PLOW ACROSS THE STATE LATE
FRIDAY IN THE NW...AND AFTER DARK - FRIDAY NIGHT ELSEWHERE. THIS
SHOULD BE ONE OF THOSE ONCE IN A YEAR /OR SEVERAL YEAR/ EVENTS
COMPLETE WITH DANGEROUS BLINDING SNOW SQUALLS CREATING WIDESPREAD
TRAFFIC/TRAVEL PROBLEMS...FROM THE COMBINED EFFECT OF HEAVY
FALLING AND BLOWING SNOW - AMOUNTING TO BETWEEN 1-3 INCHES IN A
SHORT 30 TO 60 MINUTE PERIOD. THUNDER WAS ALSO MENTIONED IN THE
GRIDDED WEATHER FIELDS...ESP ACROSS THE NW HALF OF THE STATE BASED
ON THE LATE DAY/EVENING TIMING OF THE ARCTIC FROPA.

WIND CHILLS DIP TO UNDER ADVISORY CRITERIA /-15F/ EARLY SAT
MORNING ACROSS THE NRN MTNS...AND DROP TO NEAR OR SEVERAL DEG F
BELOW ZERO ELSEWHERE BY THEN.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
*IMPACT WEATHER HIGHLIGHTS: FRIGID TEMPERATURES AND DANGEROUS WIND
 CHILLS FOR VALENTINES WEEKEND. POTENTIAL WINTER STORM EARLY NEXT
 WEEK.

POLAR VORTEX DIVING INTO NORTHERN NEW ENGLAND WILL DELIVER THE
COLDEST AIR OF THE SEASON WITH ARCTIC BLAST INTO CENTRAL PA SAT-
SUN. THE GLOBAL MODELS AND ENSEMBLES KEEP A MEAN TROUGH IN PLACE
OVER THE EASTERN US INTO THE MIDDLE OF NEXT WEEK. THE MOST NOTABLE
FEATURE DURING THE PERIOD WILL BE A LOW PRESSURE SYSTEM TRACKING
UP THE EAST COAST ON TUESDAY. THE LATEST 11/12Z MODEL GUIDANCE
HAS TRENDED WEST WITH THE LOW TRACK...BUT THERE IS STILL A DECENT
SPREAD. AT THIS TIME PRECIPITATION WITH THIS SYSTEM APPEARS LIKELY
MON-TUE BUT THE TRACK WILL ULTIMATELY DETERMINE PRECIPITATION
TYPE. NEXT WEEK SHOULD END ON A MILDER NOTE.

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. A WIND
CHILL WATCH WAS ISSUED FOR NORTHERN PA WHERE CONFIDENCE IS HIGH IN
REACHING -25F WIND CHILLS. WIND CHILL HEADLINES ARE A GOOD BET
IN LATER SHIFTS FOR THE REMAINDER OF THE AREA AND PRECAUTIONS
SHOULD BE MADE NOW TO PROTECT/PREPARE FOR THE UPCOMING COLD SNAP.

A MODERATION (WARMING TREND) IS EXPECTED INTO EARLY NEXT WEEK.
THE MODEL SPREAD HAS NARROWED A BIT CONCERNING A POTENTIAL WINTER
STORM SYSTEM IMPACTING THE MID ATLC/NORTHEAST NEXT MON-TUE. THE
11/12Z OPERATIONAL EC REMAINS ON THE WWD EDGE OF THE ENVELOPE
FOLLOWED BY THE CANADIAN GEM AND GFS/GEFS. THE GFS/GEFS HAVE BOTH
TRENDED WWD FROM THE PREVIOUS RUN. CONFIDENCE REMAINS LOW ON
PTYPES BUT ALL THE MODELS ARE SIGNALING A SIGNIFICANT QPF
EVENT...AND THEREFORE HAVE INCREASED POPS IN THE THE LKLY RANGE
FOR DAY 5.5-6 /MON NGT-TUESDAY/.

&&

.AVIATION /23Z THURSDAY THROUGH TUESDAY/...
LAKE ENHANCED OROGRAPHIC SNOW WILL RESULT IN MAINLY IFR VSBYS AT
KBFD/KJST AND POSSIBLY MVFR AT AOO...THROUGH THE FIRST HALF OF THE
EVENING. THESE CONDITIONS WILL GRADUALLY IMPROVE WHEN THE MEAN
LLVL WIND BACKS FROM THE NW...TO A MORE WESTERLY DIRECTION AS HIGH
PRESSURE SLIDES BY JUST TO OUR SOUTH ACROSS THE MIDDLE OHIO RIVER
VALLEY...BY 06Z.

THROUGHOUT THE CENTRAL RIDGE...THE VALLEY REGION...AND OVER THE
SUSQ VALLEY AIRFIELDS...EXPECT MAINLY VFR CONDITIONS. THE SNOW
BANDS COULD POSSIBLY BRING IPT AT UNV TO MFR CIGS THROUGH 03Z...WITH
EVEN SOME VERY BRIEF IFR IN THE HEAVIER SNOW SHOWERS AND SQUALLS.

A TIGHT PRES GRADIENT WILL BRING GUSTY WINDS UP TO 35KTS FOR THE
REST OF THIS AFTERNOON AND EARLY EVENING AS DIURNAL
HEATING/MIXING WITHIN THE RATHER DEEP BOUNDARY LAYER ALLOWS
STRONGER WINDS ALOFT TO MIX TO GROUND LEVEL.

ARRIVAL OF SFC RIDGE SHOULD BRING WIDESPREAD VFR CONDS AND
DIMINISHING WIND TO CENTRAL PA THIS EVENING...AND CONTINUING
THROUGH AT LEAST THE FIRST HALF OF FRIDAY.

OUTLOOK...

FRI...PM SHSN/VIS REDUCTIONS LIKELY...ESP W MTNS. PERIODS OF
LIFR/VLIFR IN INTENSE SNOW SQUALLS LATE FRIDAY /NW/ AND FRIDAY
NIGHT EARLY SAT MORNING CENTRAL AND SE.

SAT...WINDY. SHSN/REDUCED VIS POSS W MTNS...MAINLY AM.

SUN...NO SIG WX EXPECTED.

MON...PM SNOW POSSIBLE.

MON NIGHT AND TUE...SNOW LIKELY NW HALF OF PENN...WITH RAIN OR
SNOW IN THE SE.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST THIS EVENING FOR
PAZ005.
WIND CHILL WATCH FROM LATE FRIDAY NIGHT THROUGH SUNDAY MORNING
FOR PAZ004>006-037-041-042.
LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR
PAZ004.
WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
PAZ010-017-024-033.

&&

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


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