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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1003 PM EST FRI FEB 12 2016

.SYNOPSIS...
AN ARCTIC COLD FRONT WILL MOVING THROUGH NOW WILL BE FOLLOWED BY
THE COLDEST AIR OF THE SEASON AND RESULT IN STRONG/GUSTY
NORTHWEST WINDS WHICH WILL MAKE DANGEROUSLY COLD WIND CHILLS.
AREAS OF SIGNIFICANT LAKE EFFECT AND UPSLOPE SNOW ARE ALSO
EXPECTED FOR THE NORTHWEST MOUNTAINS AND LAUREL HIGHLANDS DURING
THE FIRST PART OF THE WEEKEND. HIGH PRESSURE WILL SETTLE ACROSS
THE STATE LATE IN THE WEEKEND...THEN A STRENGTHENING STORM WILL
LIFT UP THE EAST COAST EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 7 AM SATURDAY MORNING/...
10 PM UPDATE...
SQUALL LINE HAS INDEED BROKEN APART...BUT STILL NASTY SQUALLS OUT
THERE - ESP IN SWRN/WCENT PA HEADED FOR THE LAURELS.
INSTABILITY/CAPE OUT AHEAD OF THE FRONT WILL LIKELY MAKE IT
NASTIER THERE THAN UP THE NORTH. SHSN IN WAVES OUT HEAD OF THE
MAIN AREA OF SHSN COULD BE INDICATIVE OF INSTABILITY. RAP/HRRR
HINT THIS...TOO. HAVE BEEFED UP SNOW TOTALS IN THE SW - AND SE
WHERE THE STEADY LIGHT SNOW IS STARTING TO MOVE TO THE EAST...BUT
NOT YET. LAKE EFFECT BANDS HAVE BEGUN. FLOW SHOULD BECOME BETTER-
ALIGNED IN A BIT. THIS SHOULD HELP THEM WITH
ORGANIZATION/COHESION. 

530 PM UPDATE...
TWEAKS MADE TO TIMING OF SHSN /SLOWER BY A FEW HRS/ AND MENTIONED
A COATING POSS IN THE SERN HALF OF THE AREA THIS EVENING. TAILED
OFF THE MENTIONS OF SQUALLS AS THEY WOULD MOVE THROUGH THE AREA
BASED ON LATEST SNOW SQUALL PARAMETERS AND LOSS OF
HEATING/INCREASING STABILITY.

PREV...
LOWERING AND THICKENING ALTOSTRATUS AND NS DECK IS NOW PRODUCING
STEADY LIGHT SNOW ACROSS THE WESTERN HALF OF PENN WITH VSBYS
GENERALLY IN THE 1-3SM RANGE AS WAA. THE LIGHT PRECIP IS THE
RESULT OF WEAK WAA OVERSPREADING THE AREA IN ADVANCE OF UPPER LOW
/POLAR VORTEX/ PLUNGING SOUTH FROM JAMES BAY. 

NEAR TERM...HIGH RES MODELS REMAIN PRETTY CONSISTENT ON THE
TIMING OF THE ARCTIC FROPA /ACROSS THE FAR NW IN THE 23-01Z
WINDOW...AND NEAR THE I-99/RT 22 CORRIDOR IN SW AND CENTRAL PENN
BETWEEN 03-05Z...WITH THE SUSQ VALLEY TO BE IMPACTED BY SCATTERED
SHSN/BRIEF ISOLATED SQUALLS MAINLY AFTER MIDNIGHT.

THE LIGHT WARM ADVECTION SNOWS LATE TODAY AND EARLY TONIGHT WILL
BRING A GENERAL COATING TO ONE INCH WITH SOME SLICK TRAVEL ON AREA
ROADS. 

THE SQUALLS LATER TONIGHT WILL BRING AN ADDITIONAL COATING TO 2
INCHES OF FLUFFY...WIND WHIPPED SNOW...THOUGH SOME LOCALIZED 3
INCH AMOUNTS AREN/T OUT OF THE QUESTION WHERE THE INITIAL NE/SW
BAND OR TWO OF SQUALLS IS FOLLOWED-UP BY MORE BOUNDARY LAYER WIND
PARALLEL...NARROW SQUALLS LATER TONIGHT/SAT MORNING. 

WILL HIGHLIGHT/TRACK THE TIMING OF THIS SQUALL BAND VIA SPECIAL
WEATHER STATEMENTS AS NEEDED THIS EVENING AND OVERNIGHT.

WE PEPPERED THE FCST AREA WITH A HOST OF WARNINGS AND ADVISORIES
FOR SNOW/LES...WIND CHILLS...AND STRONG WIND GUSTS SATURDAY. THESE
FLAGS ARE STAGGERED IN TIME TONIGHT...RIGHT THROUGH SUNDAY
MORNING. SEE PHLWSWCTP AND PHLNPWCTP /OR OUR VARIOUS SOCIAL MEDIA
OUTLETS - FB AND TWITTER - FOR DETAILS.

LOW TEMPS AT DAYBREAK SAT WILL VARY FROM SLIGHTLY UNDER ZERO
F ACROSS THE NW MTNS...TO THE LOWER AND MID TEENS IN THE SUSQ
VALLEY.

&&

.SHORT TERM /7 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
ARCTIC AIR MASS WILL POUR INTO THE REGION EARLY SATURDAY...ACCOMPANIED
BY GUSTY NW WINDS...WHICH WILL PRODUCE DANGEROUS WIND CHILLS
ACROSS AT LEAST THE NORTHERN AND WESTERN MTNS. ISSUED A WIND
ADVISORY OUTSIDE OF THE PREVIOUS WIND CHILL FLAGGED AREAS WHERE
CHILLS WON/T MEET CRITERIA...BUT WINDS WILL GUSTS AROUND 40KT AT
TIMES THROUGHOUT THE DAY. 

WE'LL SEE THE COLDEST DAYTIME TEMPS SINCE LAST WINTER
TOMORROW. GEFS MEAN 8H TEMPS BTWN -22F AND -25F SHOULD SUPPORT
HIGH TEMPS SATURDAY ONLY AROUND ZERO ACROSS THE NW MTNS...TO THE
LOWER AND MID TEENS IN THE SE.

LK HURON CONNECTION SHOULD SHOULD FOCUS THE MOST PERSISTENT SNOW
SHOWERS ACROSS THE NW WARREN CO AND THE LAUREL HIGHLANDS...WHERE
AN ADDITIONAL INCH OR SO SEEMS LIKELY BASED ON NCAR MESOSCALE
ENSEMBLE.

AN ADDITIONAL FEW...TO SVRL INCHES OF LES AND UPSLOPE SNOW LIKELY
SAT ACROSS THE NW SNOWBELT AND LAURELS...AND ADVISORIES/WARNINGS
FOR SNOW/LES ARE IN EFFECT UNTIL 03Z SUNDAY. 

ELSEWHERE...DRY ARCTIC AIR MASS SHOULD PRECLUDE SIG LAKE EFFECT
SNOW ACROSS CENTRAL PA SATURDAY.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
*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 
LATE SAT-SUN. THE GLOBAL MODELS AND ENSEMBLES KEEP A MEAN TROUGH
IN PLACE OVER THE EASTERN US INTO THE MIDDLE OF NEXT WEEK
WITH SEVERAL REINFORCING SHOTS OF COLD AIR MOVING THROUGH THE MEAN
TROF POSITION. 

THE MOST NOTABLE FEATURE DURING THE PERIOD WILL BE A LOW PRESSURE
SYSTEM TRACKING UP THE EAST COAST ON TUESDAY. THE LATEST 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 TEMPS/WCHILLS EXPECTED SAT NIGHT OVR THE AREA...AS
8H TEMP ANOMALIES OF NEAR 3SD BLW CLIMO GRAZE THE AREA. MINIMUM
TEMPERATURES SATURDAY NIGHT INTO EARLY SUNDAY MORNING EXPECTED TO
RANGE FROM ARND ZERO IN THE LOWER SUSQ VALLEY TO -10F IN THE
NORTHWEST MTNS. THE FRIGID TEMPERATURES COMBINED WITH DANGEROUS
WIND CHILLS /-10 TO -25 BELOW ZERO/ WILL RESULT IN AN INCREASED
RISK FOR FROSTBITE AND HYPOTHERMIA. 

THE MODEL SPREAD HAS NARROWED A BIT CONCERNING A POTENTIAL WINTER
STORM SYSTEM IMPACTING THE MID ATLC/NORTHEAST NEXT MON-TUE. LATEST
GEFS AND ECENS INDICATING A SFC LOW TRACK ACROSS EASTERN PA IS
MOST LIKELY...WHICH WOULD FAVOR RAIN ACROSS ALL BUT PERHAPS THE W
MTNS. CONFIDENCE REMAINS LOW ON PTYPES ACROSS WESTERN PA...BUT NOW
DEFINITELY FAVORS RAIN ACROSS THE EAST. ALL THE MODELS ARE
SIGNALING A SIGNIFICANT QPF EVENT...AND THEREFORE HAVE INCREASED
POPS IN THE LKLY RANGE FOR MON NIGHT THROUGH TUESDAY.

A MODERATING TREND IS EXPECTED LATER NEXT WEEK...AS HEIGHTS ARE
FORECAST TO RISE AND A PSBL LOW PRESSURE SYSTEM LIFTS THROUGH THE
GREAT LAKES TO THE WEST OF PA.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
THE SQUALL LINE IS COMING ONSHORE...HOWEVER THE LATEST MODELS AND
ANALYSIS SHOWS IT IS SPLINTERING AND WEAKENING AS IT MAKES ITS WAY
INLAND. HAVE IMPROVED FORECAST FOR ALL TAF SITES EXCEPT BFD AND
JST...DOWNSLOPE FLOW KICKS IN LATE TONIGHT...BRINGING
IMPROVEMENT TO VFR IN MOST PLACES THROUGHOUT THE CENTRAL RIDGE AND
VALLEY REGION. THE WESTERN HIGHER TERRAIN WILL CONTINUE TO SEE
RESTRICTIONS IN SNOW SHOWERS/BLOWING SNOW/UPSLOPE FLOW INTO THE
WEEKE

OUTLOOK...

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...
WIND CHILL WARNING FROM 4 AM SATURDAY TO 11 AM EST SUNDAY FOR 
PAZ004>006-037-041-042.
WINTER WEATHER ADVISORY UNTIL 10 PM EST SATURDAY FOR PAZ010-
017-024-033.
WIND CHILL ADVISORY FROM 4 AM SATURDAY TO 11 AM EST SUNDAY FOR 
PAZ010>012-017-018-024-033.
WIND ADVISORY FROM 4 AM TO 5 PM EST SATURDAY FOR PAZ019-
025>028-034>036-045-046-049>053-056>059-063>066.
WIND CHILL ADVISORY FROM 5 PM SATURDAY TO 11 AM EST SUNDAY FOR 
PAZ019-025>028-034>036-045-046-049>053-056>059-063>066.
LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST SATURDAY FOR PAZ005.
LAKE EFFECT SNOW WARNING UNTIL 10 PM EST SATURDAY FOR PAZ004.

&&

$$
SYNOPSIS...DANGELO/LAMBERT
NEAR TERM...DANGELO/LAMBERT
SHORT TERM...LAMBERT
LONG TERM...FITZGERALD/GARTNER
AVIATION...LAMBERT/CERU

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