671
FXUS61 KCTP 190429
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1129 PM EST WED DEC 18 2024
SYNOPSIS
RAIN AND SNOW ARE EXITING. A LITTLE LAKE EFFECT (AND EVEN SOME
PATCHY FREEZING DRIZZLE OVER THE HIGHER TERRAIN OF CAMBRIA AND
SOMERSET COUNTIES) WILL LAST THROUGH ABOUT SUNRISE. A CLIPPER
WILL BRING LIGHT SNOW TO MOST OF THE AREA ON FRIDAY, FOLLOWED BY
CONSIDERABLY COLDER CONDITIONS FOR THE WEEKEND.
NEAR TERM /UNTIL 7 AM THURSDAY MORNING/
LOW PRESSURE SHOULD BE JUST TO THE EAST OF THE CWA, NOW.
PRECIP IS EXITING TO THE EAST, AND IS BEHAVING AS EXPECTED.
JUST AN INCH OR TWO OF SNOW HAS FALLEN ACROSS THE NRN MTNS EVEN
THOUGH THEY HAD AIR TEMPS JUST ABOVE FREEZING IN MOST PLACES.
TEMPS ARE DOWN TO 32F IN SPOTS, NOW.
THE LOSS OF THICKER CLOUDS WILL TAKE AWAY THE ICE CRYSTALS FROM
THE UPSLOPE PRECIP IN THE LAURELS EARLY TONIGHT. THIS WILL
CREATE AREAS OF FREEZING DRIZZLE STARTING ABOUT NOW (SOMERSET
AWOS IS AT 32F). THE CONDITIONS REMAIN TOO COLD NORTH OF ABOUT
RTE 22, AND SHOULD REMAIN MOSTLY SNOW. NOT MUCH ADDITIONAL SNOW
ACCUMS ARE EXPECTED. BY 08-09Z, EVEN THE PRECIP OVER SOMERSET CO
SHOULD BE JUST FLURRIES. BUT, ANY ICE ACCRETION WILL STILL BE
UNDERNEATH THE SNOW THAT MIGHT FALL AFTER THE DRIZZLE HAS ENDED.
MIN TEMPS THERE WILL RANGE FROM 25-29F, SO THAT COULD KEEP IT
SLIPPERY INTO THE MORNING ON UNTREATED SURFACES. AFTER
COLLABORATION WITH PBZ/LWX, WE'VE SETTLED ON ISSUING A WINTER
WX ADVY FOR THE NIGHT FOR THE LAURELS.
THE LAKE EFFECT WILL BE OF LITTLE CONCERN, WITH JUST ANOTHER
DUSTING IN PLACES ACROSS THE NRN ALLEGHENIES. THE SNOW WILL BE A
DIFFERENT CHARACTER THAN HAS JUST FALLEN. IT SHOULD GET
LIGHTER/FLUFFIER AS TEMPS COOL AND THE TOPS OF THE CLOUDS DIP
INTO THE GOOD DGZ FOR A SHORT TIME BEFORE THE INVERSION DROPS
LOW ENOUGH TO END THE LAKE EFFECT (AROUND SUNRISE OR MID-MORNING
AT THE LATEST).
THE WIND DOES PICK UP FOR TONIGHT AS THE LOW GOES TO OUR EAST
WITH GUSTS INTO THE 20S IN THE LAURELS, BUT LOWER GUSTS ELSEWHERE.
SHORT TERM /7 AM THURSDAY MORNING THROUGH SATURDAY/
TYPICAL NORTHWEST FLOW PATTERN ON THURSDAY WITH BREAKS IN THE
CLOUDS IN SE PA DURING THE AFTERNOON AND PERSISTENT
STRATOCUMULUS FARTHER NORTHWEST. HIGHS ON THURSDAY WILL TREND
CLOSE TO NORMAL WITH HIGHS IN THE LOW 30S TO LOW 40S. AN
APPROACHING CLIPPER SYSTEM WILL TURN WINDS EASTERLY THURSDAY
NIGHT, SUPPORTING A DRY BUT DREARY NIGHT WITH PLENTY OF LOW
CLOUDS AND PERHAPS SOME REDUCED VISIBILITY. LOWS IN THE MID 20S
WILL COOL THE GROUND ENOUGH TO ALLOW ANY SNOW THAT FALLS ON
FRIDAY TO STICK TO UNTREATED/ELEVATED SURFACES.
THAT CLIPPER SYSTEM COMING IN FOR FRIDAY IS MORE CERTAIN, NOW,
BUT AMOUNTS STILL LOOK LIGHT WITH A WIDESPREAD 1-2" N & W, AND
LESS THAN THAT FOR THE S. ONE WILDCARD IS IF A TROUGH LINGERS
ACROSS ERN PA. THAT WOULD SERVE TO INCREASE SNOW (REALLY THE
DURATION OF SNOW) THERE. CONFIDENCE IS TOO LOW TO BUMP SF
NUMBERS UP THERE JUST YET. SOMETHING TO WATCH OUT FOR.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
NORTHWESTERLY FLOW CONTINUES INTO THE BEGINNING STAGES OF THE
LONG-TERM WITH LINGERING LAKE EFFECT SNOW SHOWERS INTO PORTIONS
OF NW PA THROUGH SUNDAY MORNING. NBM POPS DURING THIS TIME SEEM
UNDERDONE, SO HAVE UPPED POPS COMPARED TO PREVIOUS FORECAST
CYCLES WITH A MULTITUDE OF ENSEMBLE GUIDANCE INDICATING SOME
SNOW SHOWERS ACROSS WARREN/MCKEAN/POTTER COUNTIES. NW'LY FLOW
ACROSS PORTIONS OF THE LAUREL HIGHLANDS WILL SUPPORT SOME
MENTIONS OF SNOW SHOWERS; HOWEVER, MUCH LESS CONFIDENCE ON
COVERAGE THIS FAR SOUTH, SO HAVE CAPPED MENTIONS TO A SCHC
MAINLY AHEAD OF SUNRISE SUNDAY. MODEL GUIDANCE DOES CONTINUE TO
INDICATE TEMPERATURES WELL BELOW SEASONAL AVERAGES WITH THE
COLDEST WIND CHILLS ACROSS NE PA BY DAYBREAK SUNDAY. THIS
FORECAST CYCLE CONTINUES TO OUTLINE -5 TO -10 DEGREE WIND CHILLS
ACROSS PORTIONS OF POTTER/TIOGA/SULLIVAN COUNTIES WITH SOME
SIGNALS FOR WIND CHILLS DIPPING BELOW THE -10 DEGREE MARK AT
HIGHER ELEVATIONS OF POTTER COUNTY. NO PLANS ON ANY HEADLINES AT
THIS TIME DUE TO LOWER CONFIDENCE IN TEMPERATURES REACHING
BELOW THRESHOLDS; HOWEVER, WANT TO STRESS THAT IT WILL BE COLD
ACROSS PORTIONS OF NE PA SUNDAY MORNING.
SURFACE HIGH PRESSURE WILL KEEP CONDITIONS DRY WITH
TEMPERATURES SLOWLY MODERATING INTO MONDAY EVENING. MODEL
GUIDANCE BEGINS TO DIVERGE ON TUESDAY WITH RESPECT TO THE NEXT
WEATHER SYSTEM, WITH ECMWF TRENDING DRY THROUGH THE END OF THE
LONG-TERM PERIOD OUTSIDE OF SOME SNOWFALL CHANCES ACROSS THE
NORTHERN TIER WITH THE GFS OUTLINING A MORE ACTIVE PERIOD WITH
RAIN/SNOW ACROSS THE FORECAST AREA ON WEDNESDAY WITH SOME
POTENTIAL FOR DRIER CONDITIONS INTO THURSDAY/FRIDAY. THIS
FORECAST CYCLE STICKS FAIRLY CLOSE TO NBM GUIDANCE GIVEN THIS
SPREAD; HOWEVER, HAVE TAKEN OUT ANY MENTIONS OF FREEZING RAIN AS
CONFIDENCE REMAINS TOO LOW ON TIMING/TRACK TO MENTION ANYTHING
OUTSIDE OF A RAIN/SNOW MIX.
AVIATION /04Z THURSDAY THROUGH MONDAY/
RAIN OVER THE LOWER SUSQ VALLEY IS ENDING LATE THIS EVENING, AS
LOW PRESSURE PASSES EAST OF THE STATE. THE MAIN FOCUS FOR THE
REST OF THE NIGHT WILL BE THE ALLEGHENY PLATEAU, WHERE RESIDUAL
LOW LEVEL MOISTURE ASCENDING THE HIGH TERRAIN WILL RESULT IN
IFR/LIFR CIGS, AS WELL AS SPOTTY VERY LIGHT SNOW OR
-FZDZ THROUGH LATE EVENING.
AN INCREASINGLY DRY NORTHWEST FLOW LATE TONIGHT, SHOULD RESULT
IN IMPROVING CONDITIONS AREAWIDE. MODEL SOUNDINGS AND ENSEMBLE
PLUMES INDICATE IFR CIGS ARE LIKELY TO PERSIST THROUGH DAWN OVER
THE LAUREL HIGHLANDS (JST). HOWEVER, A RETURN TO MVFR CIGS IS
LIKELY OVER THE REST OF THE ALLEGHENY PLATEAU AND A RETURN TO
VFR IS LIKELY DOWNWIND (EAST) OF THE ALLEGHENY PLATEAU.
FLYING CONDITIONS SHOULD CONTINUE TO IMPROVE THURSDAY WITH A
DIMINISHING NORTHWEST BREEZE, AS HIGH PRESSURE BUILDS INTO THE
STATE. FORECAST SOUNDINGS INDICATE LINGERING MVFR CIGS OVER THE
ALLEGHENY PLATEAU WILL GIVE WAY TO VFR CONDITIONS DURING THE
AFTERNOON.
OUTLOOK...
FRI...SPOTTY PM LIGHT SNOW/LOW CIGS LIKELY, MAINLY N AND W MTNS.
SAT...NW WINDS GUSTING TO AROUND 25KTS. AM SNOW SHOWERS
POSSIBLE N AND W MTNS.
SUN-MON...NO SIG WX EXPECTED.
CLIMATE
ASTRONOMICAL WINTER (SOLSTICE) BEGINS ON SATURDAY, DECEMBER 21ST
AT 4:19 A.M. EST.
CTP WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL 8 AM EST THURSDAY FOR PAZ024-033.
SYNOPSIS...DEVOIR/BANGHOFF
NEAR TERM...DANGELO
SHORT TERM...DEVOIR/FITZGERALD/BANGHOFF
LONG TERM...NPB
AVIATION...FITZGERALD
CLIMATE...STEINBUGL
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