684
FXUS61 KCTP 201611
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1111 AM EST THU FEB 20 2025
SYNOPSIS
AN UPPER LEVEL LOW WILL TRACK ACROSS PENNSYLVANIA TODAY, THEN A
MORE ZONAL PATTERN WILL DEVELOP OVER THE CONUS THIS WEEKEND. A
WEAK SHORTWAVE AND ASSOCIATED COLD FRONT IS LIKELY TO PUSH
THROUGH THE REGION TUESDAY OF NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
SNOW HAS BEEN VERY LIGHT ACROSS ALL OF THE AREA. HIDDEN VALLEY
DID HAVE ALMOST AN INCH (0.9") OF SNOWFALL BY THEIR CO-OPERATIVE
OBSERVATION THIS MORNING. JST HAS DIPPED AS LOW AS 1/2SM VISBY
THIS AM. SO, THOSE HILLS ARE PRODUCING WHAT THEY SHOULD. SEE NO
REASONS TO MODIFY THE FORECAST BEYOND TEMP/DEW TWEAKS FOR THE
NEAR TERM. WILL CONTINUE TO MENTION 0.1" ACCUMS ACROSS THE
ENTIRE CWA, AS IT HAS STARTED TO SNOW OVER THE SE AND MAY
CONTINUE THROUGH THE MIDDLE OF THE AFTN. WHILE IT HAS BARELY
STARTED TO MAKE THE TOPS OF THE CARS SLUSHY IN THE PARKING LOT,
WE STILL HAVE A COUPLE MORE HOURS OF LIGHT SNOW TO GO.
PREV...
A DEEPENING UPPER LOW OVER OHIO WILL PASS OVER PA LATER TODAY.
STRONG LARGE SCALE FORCING/UPPER LEVEL DIFFLUENCE AHEAD OF THIS
FEATURE SHOULD SUPPORT A PERIOD OF LIGHT SNOW OVER MOST OF
CENTRAL PA. HOWEVER, A LACK OF MOISTURE WITH THIS SYSTEM SHOULD
KEEP ACCUMULATIONS VERY LIGHT. ENSEMBLE MEAN QPF SUPPORTS SNOW
TOTALS RANGING FROM <1 INCH SOUTHEAST OF THE ALLEGHENY PLATEAU,
TO AS MUCH AS 3-4 INCHES ALONG LAUREL RIDGE IN SOMERSET COUNTY,
WHERE LINGERING LAKE-ENHANCED UPSLOPE SNOW WILL LAST THROUGH
TONIGHT. MODEL TIME/HEIGHT PROFILES INDICATE MUCH OF THE CLOUD
LAYER WILL FALL WITHIN THE DGZ, SUPPORTING SNOW/WATER RATIOS
CLOSE TO 20/1.
AS THE UPPER LOW EXITS THE REGION LATE TODAY, EXPECT THE LIGHT
SNOW TO TAPER OFF OVER MUCH OF CENTRAL PA. HOWEVER, A COLD
NORTHWEST FLOW WILL GENERATE LINGERING LIGHT SNOW SHOWERS OVER
THE ALLEGHENIES THAT WILL LAST THROUGH TONIGHT. A TIGHT
PRESSURE GRADIENT, AIDED BY SUBSIDENCE FORCED BY DIFFERENTIAL
ANTICYCLONIC VORTICITY ADVECTION, WILL RESULT IN GUSTY NORTHWEST
WINDS LATE THIS AFTERNOON INTO TONIGHT. BUFKIT SOUNDINGS SUPPORT
HIGHER WINDS THAN NBM GUIDANCE, WITH GUSTS LATE TODAY AND THIS
EVENING IN THE 25-35KT RANGE, WITH THE HIGHEST GUSTS OVER THE
LAURELS/SC MTNS. THESE WINDS, COMBINED WITH AN INCH OR TWO OF
DRY, FLUFFY SNOW, SHOULD CAUSE SOME BLOWING/DRIFTING OVER THE
LAURELS LATE TODAY/EVENING
MAINLY OVERCAST SKIES AND A POOL OF ANOMALOUSLY COLD AIR ALOFT
WILL RESULT IN MAX TEMPS WELL BELOW SEASONAL NORMALS TODAY. SEE
NO REASON TO DEVIATED FROM TODAY'S NBM MAX TEMPS, WHICH RANGE
FROM THE UPPER TEENS OVER THE ALLEGHENIES, TO THE UPPER 20S OVER
THE LOWER SUSQ VALLEY. THE UPPER LOW AND ASSOCIATED CORE OF
COLDEST AIR ALOFT WILL BE EXITING THE STATE TONIGHT, SO DON'T
ANTICIPATE TEMPS FALLING MUCH OVERNIGHT. READINGS BY DAWN
SHOULD RANGE FROM THE TEENS OVER MOST OF CENTRAL PA.
SHORT TERM /FRIDAY THROUGH SATURDAY/
FALLING INVERSION HEIGHTS SHOULD CAUSE LINGERING LAKE EFFECT
SNOW SHOWERS/FLURRIES TO TAPER OFF FRIDAY OVER THE NW
MTNS/LAURELS, WITH INCREASING SUNSHINE TO THE LEE OF THE
ALLEGHENIES. GEFS 2M TEMP ANOMALIES INDICATE HIGHS FRIDAY WILL
BE 7-12F BELOW AVERAGE, TRANSLATING TO HIGHS FROM AROUND 20F
OVER THE N MTNS, TO MID 30S IN THE LOWER SUSQ VALLEY. A GUSTY
NORTHWEST WIND WILL ADD TO THE CHILL. MODEL SOUNDING SUPPORT
FREQUENT GUSTS TO AROUND 25KTS.
SURFACE RIDGING WILL BUILD INTO THE REGION FRIDAY NIGHT AND
SATURDAY, SUPPLYING FAIR AND MILDER WEATHER TO PA. LOW LEVEL
MOISTURE TRAPPED BENEATH A SUBSIDENCE INVERSION MAY YIELD
LINGERING LOW CLOUDS ACROSS THE NW MTNS INTO EARLY SATURDAY.
OTHERWISE, MODEL RH PROFILES SUPPORT A GOOD DEAL OF SUNSHINE,
HELPING TO PUSH SAT AFTERNOON READINGS TO NEAR SEASONABLE
LEVELS.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
LATE EVENING UPDATE.
NOT A LOT OF CHANGE TO THIS SECTION. AS NOTED BELOW, HIGH
PRESSURE WILL RESULT IN A DRY WEEKEND, WITH MODERATING
TEMPERATURES.
SEVERAL WEAK SYSTEMS WILL BRING SOME PRECIPITATION TO THE
AREA NEXT WEEK, BUT NO REAL EXTREME EVENTS, THAT WE HAVE
SEEN LATELY.
EARLIER DISCUSSION BELOW.
HIGH PRESSURE AT THE SURFACE WILL PROVIDE DRY WEATHER THROUGH
THE WEEKEND. A COUPLE OF SHORTWAVES PASSING THROUGH WILL LEAD TO
NOTHING MORE THAN INCREASED CLOUD COVER, ESPECIALLY ACROSS THE
NORTHERN AND WESTERN MOUNTAINS. THE MOST NOTICEABLE THING THIS
WEEKEND WILL BE THE WARMER TEMPERATURES. HIGH TEMPS BY SUNDAY
WILL BE IN THE 40S IN THE LOWER SUSQUEHANNA VALLEY, WHILE THE
INCREASED CLOUD COVER OVER THE NORTH AND WEST WILL KEEP
TEMPERATURES IN THE 30S.
BY MONDAY NIGHT INTO TUESDAY, ANOTHER MORE POTENT SHORTWAVE IS
PROGGED TO DRIFT ACROSS PENNSYLVANIA AS LOW PRESSURE PASSES
NORTH OF THE STATE. THERE IS STILL SOME DIFFERENCES IN THE
MODELS AS TO HOW THIS SYSTEM EVOLVES, BUT RAIN WITH SOME SNOW
MIXED IN FOR HIGHER ELEVATIONS APPEARS MOST LIKELY AT THIS
POINT. UPSLOPE AND LAKE EFFECT PRECIPITATION WILL LINGER ACROSS
THE WESTERN HALF OF CENTRAL PA INTO WEDNESDAY. MOST GUIDANCE
INDICATES THE POTENTIAL FOR ANOTHER SYSTEM TO IMPACT THE REGION
IN THE THURSDAY/FRIDAY TIMEFRAME, BUT THERE IS TOO MUCH
UNCERTAINTY TO GET INTO ANY SPECIFICS YET.
AVIATION /16Z THURSDAY THROUGH MONDAY/
JUST TEMPORARY DIPS BELOW 1SM AT JST AND BFD, BUT GENERALLY 2SM+
VISBYS AT AOO-UNV-IPT. MDT JUST STARTED SNOWING BUT HAS ALREADY
BOUNCED BACK UP (FROM 3SM) INTO VFR VISBY AND A CIG JUST DOWN
INTO MVFR (FL027) AT 16Z. LNS STILL WAITING FOR THEIR FLAKES TO
START. SHOULD BE THERE SOON.
WIND GUSTS HAVE ALREADY BEGUN TO INCREASE AND SHOULD KEEP
GETTING STRONGER WITH GUST OF 25 TO 35 KNOTS POSSIBLE. STEADY
SNOW EXITS BY EARLY EVENING (EARLIER IN MANY PLACES), BUT
ADDITIONAL UPSLOPE AND LAKE ENHANCED SNOW SHOWERS WILL CONTINUE
INTO THE LAUREL HIGHLANDS AND NW MTNS (KJST AND KBFD), WITH MVFR
TO IFR CIGS HOLDING ON THERE INTO AT LEAST FRIDAY MORNING. BFD
WILL BE THE LAST PLACE TO GO VFR ON FRIDAY WITH THE STRATOCU
HANGING ON LONGEST OVER NRN PA. THE WIND WILL BEGIN TO DIMINISH
FRIDAY MID-DAY, BUT SOME G20KT LINGER INTO FRI EVENING.
OUTLOOK...
FRI NIGHT-SUN...VFR/NO SIG WX.
MON...RAIN AND SNOW SHOWERS DEVELOPING IN THE AFTERNOON NW.
CTP WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL 7 AM EST FRIDAY FOR PAZ033.
SYNOPSIS...FITZGERALD/DANGELO
NEAR TERM...FITZGERALD/DANGELO
SHORT TERM...FITZGERALD
LONG TERM...BANGHOFF/MARTIN/BAUCO
AVIATION...DEVOIR/DANGELO
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