Area Forecast Discussion
Issued by NWS State College, PA

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489 FXUS61 KCTP 122008 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 308 PM EST FRI FEB 12 2016 .SYNOPSIS...
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AN ARCTIC COLD FRONT WILL MOVE THROUGH NORTHWESTERN PENN EARLY THIS EVENING...AND PUSH ACROSS THE SUSQ VALLEY SHORTLY AROUND OR SHORTLY AFTER MIDNIGHT. THIS FRONT WILL BE FOLLOWED BY THE COLDEST AIR OF THE SEASON JUST IN TIME FOR VALENTINES WEEKEND WITH STRONG/GUSTY NORTHWEST WINDS...DANGEROUSLY COLD WIND CHILLS...AND AREAS OF SIGNIFICANT LAKE EFFECT AND UPSLOPE SNOW ACROSS THE NORTHWEST MOUNTAINS AND LAUREL HIGHLANDS. HIGH PRESSURE WILL SETTLE ACROSS THE STATE LATE IN THE WEEKEND...THEN A STRENGTHENING STORM WILL LIFT UP THE EAST COAST EARLY NEXT WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/...
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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.
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&& .SHORT TERM /SATURDAY/...
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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.
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&& .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
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*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. THE MOST NOTABLE FEATURE DURING THE PERIOD WILL BE A LOW PRESSURE SYSTEM TRACKING UP THE EAST COAST ON TUESDAY. THE LATEST 12/00Z 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. 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. 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 NGT-TUESDAY.
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&& .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
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MOST OF CENTRAL PA WILL CONTINUE TO BE VFR INTO THE MID AFTERNOON. W/SW WINDS WILL BE 10 MPH OR LESS MUCH OF THE DAY. UPPER TROUGH AND WEAK WARM ADVECTION LIGHT SNOW MOVES THROUGH THE REGION LATE THIS AFTERNOON AND EVENING...ACCOMPANIED BY 1-3SM VSBYS AND MVFR TO LOW END VFR CIGS SPREADING NE TO COVER THE SUSQ VALLEY BY DARK. THIS SYNOPTIC LIGHT SNOW WILL BE FOLLOWED BY A BLAST OF ARCTIC AIR. AS ARCTIC AIR ARRIVES /REACHING NW MTNS BY 00Z/... MORE SIG SNOW SHOWERS/SQUALLS WILL BRING PERIODS OF LIFR/VLIFR IN THIS EVENING INTO SATURDAY MORNING - ESP OVER THE NW HALF OF CWA. THESE WILL BE ACCOMPANIED BY GUSTY NORTHWESTERLY WINDS...AND THESE BRISK WINDS WILL CONTINUE INTO SATURDAY. 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 WEEKEND. 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.
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&& .CTP WATCHES/WARNINGS/ADVISORIES...
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WIND CHILL WARNING FROM 4 AM SATURDAY TO 11 AM EST SUNDAY FOR PAZ004>006-037-041-042. WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 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 FROM 7 PM THIS EVENING TO 10 PM EST SATURDAY FOR PAZ005. LAKE EFFECT SNOW WARNING FROM 7 PM THIS EVENING TO 10 PM EST SATURDAY FOR PAZ004.
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&& $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...LAMBERT LONG TERM...FITZGERALD/STEINBUGL AVIATION...LAMBERT

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