169
FXUS61 KCTP 182030
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
330 PM EST WED DEC 18 2024
SYNOPSIS
RAIN AND SNOW EXIT THIS EVENING, WITH RESIDUAL LAKE EFFECT AND
UPSLOPE SNOW SHOWERS AND FLURRIES OVER THE NORTHWEST MOUNTAINS
AND LAUREL HIGHLANDS, AND EVEN SOME PATCHY FREEZING DRIZZLE OVER
THE HIGHER TERRAIN OF CAMBRIA AND SOMERSET COUNTIES. A CLIPPER
WILL BRING LIGHT SNOW TO MOST OF THE AREA ON FRIDAY, FOLLOWED BY
CONSIDERABLY COLDER CONDITIONS FOR THE WEEKEND.
NEAR TERM /UNTIL 6 PM THIS EVENING/
AREAS OF RAIN COVER THE SOUTHERN 2/3 OF CENTRAL PA, WHILE SNOW
FALLS OVER THE NW MOUNTAINS. RAIN/SNOW LINE LIES BETWEEN KFIG
AND KDUJ AT MIDAFTERNOON, WITH KDUJ REPORTING A SFC TEMP OF 35F.
NORTH OF I-80, SLUSHY COATINGS TO LOCALLY 1-2"+ ARE EXPECTED
WITH HIGHEST AMOUNTS OVER THE NW MOUNTAINS, THANKS TO WAA AND
CONVERGENCE ALONG A 34-45KT 850 MB JET, WHICH CONTINUES TO
SUPPORT CATEGORICAL POPS THIS AFTERNOON INTO THIS EVENING.
ENSEMBLE MEAN QPF BY THIS EVENING RANGES FROM 0.15 TO 0.40
INCHES, WITH THE HEAVIEST AMOUNTS OVER SOMERSET AND SCHUYLKILL
COUNTIES, WHERE OROGRAPHIC ENHANCEMENT IS MAXIMIZED.
SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/
PRECIPITATION TAPERS OFF QUICKLY FROM WEST TO EAST THIS
EVENING, AS THE WAVE OF LOW PRESSURE SLIDES EAST OF PA.
RESIDUAL LOW LEVEL MOISTURE ASCENDING THE ALLEGHENIES SHOULD
RESULT IN LINGERING LIGHT RAIN/SNOW SHOWERS OVER THE WESTERN
COUNTIES EARLY THIS EVENING, WHILE A DOWNSLOPING NORTHWEST FLOW
RESULTS IN DEVELOPING BREAKS IN THE OVERCAST FURTHER EAST. THE
AIRMASS CROSSING THE GRT LKS THEN BECOMES COLD ENOUGH TO SUPPORT
SCATTERED, OROGRAPHICALLY- ENHANCED, LAKE EFFECT SNOW SHOWERS
OVER THE W MTNS LATE WED NIGHT. LOW INVERSION HEIGHTS INDICATE
ANY ACCUMULATIONS WILL BE VERY LIGHT (<0.5 INCHES). MAIN
QUESTION GIVEN MODEL SOUNDINGS LOSING CLOUD SEEDERS IS THAT
SHALLOW CLOUD DEPTHS MAY SUPPORT PATCHY -FZDZ IN SPOTS RATHER
THAN -SHSN OVER THE RIDGES OF THE LAUREL HIGHLANDS. CONFIDENCE
NOT HIGH ENOUGH FOR WIDESPREAD GLAZING, BUT WILL CONTINUE TO
MENTION PATCHY FZDZ AND EVENING SHIFT MAY CONSIDER HEADLINES OR
SPS FOR OVERNIGHT.
THE WINDOW FOR LAKE EFFECT SNOW SHOWERS OVER NW PA EXTENDS INTO
MIDDAY THURSDAY WITH GENERALLY LIGHT ACCUMS EXPECTED. 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.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
THIS WEEKEND WILL BE VERY COLD WITH FORECAST MAXES ONLY IN THE
20S-L30S SATURDAY AND MIDTEENS- MID20S SUNDAY. OVERNIGHT LOWS
LIKELY CHALLENGE 0F IN THE N (SUN AM). ALMOST EVERYONE WILL DROP
INTO THE SINGLE DIGITS MON AM. WIND CHILLS DO GET NEAR -10F SUN
AM IN THE NE, BUT NOT ON MON AM WHEN THE WIND IS LIGHTER/CALM
UNDER THE SFC HIGH DESPITE THE COLDER AIR TEMPS.
SPRAWLING HIGH PRESSURE WILL MAKE FOR DRY WEATHER INTO EARLY
TUESDAY WITH MODERATING BUT STILL SEASONABLY CHILLY TEMPS.
SEVERAL SHORTWAVES WILL BRING A WEATHER SYSTEM TOWARD THE STATE
CHRISTMAS EVE INTO CHRISTMAS DAY. PCPN AMOUNTS DO NOT APPEAR TO
BE SIGNIFICANT, BUT TIMING AND P-TYPE MAY POSE SOME TRAVEL
ISSUES OVER THE HOLIDAY.
AVIATION /20Z WEDNESDAY THROUGH MONDAY/
PRECIP SHIELD WORKING ITS WAY EAST ACROSS THE AIRSPACE HAS AND
WILL CONTINUE TO LEAD TO DETERIORATING CONDS, MAINLY LOW CIGS
THAT WILL PERSIST INTO THIS EVENING.
AS PRECIP EXITS THE EASTERN TERMINALS 04-06Z, A WINDSHIFT TO
280-320 DEGREES WILL FAVOR CONTINUED IFR/LIFR AT KBFD/KJST WHILE
SITES TO THE EAST OF THE MTNS BEGIN TO IMPROVE TO MVFR OR LOW
END VFR. SNOW SHOWERS AND PATCHY FREEZING DRIZZLE WILL LIKELY
IMPACT KBFD AND KJST OVERNIGHT INTO EARLY THURSDAY MORNING.
OUTLOOK...
THU...SNOW SHOWERS AND FLURRIES ENDING BY THURSDAY NIGHT.
MVFR/IFR WEST TO LOW VFR EAST.
FRI...IFR LIKELY IN LIGHT SNOW.
SAT-SUN...IFR/MVFR IN SNOW SHOWERS AT BFD/JST. MVFR TO LOW END
VFR ELSEWHERE WITH FLURRIES.
MON...PRIMARILY VFR.
CLIMATE
ASTRONOMICAL WINTER (SOLSTICE) BEGINS ON SATURDAY, DECEMBER 21ST
AT 4:19 A.M. EST.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...DEVOIR/BANGHOFF
NEAR TERM...DEVOIR/FITZGERALD/BANGHOFF
SHORT TERM...DEVOIR/FITZGERALD/BANGHOFF
LONG TERM...GARTNER/BAUCO
AVIATION...STEINBUGL/GARTNER
CLIMATE...STEINBUGL
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