414
FXUS61 KCTP 191051
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
551 AM EST SUN JAN 19 2025
SYNOPSIS
*QUICK-HITTING, PLOWABLE/LOCALLY HEAVY SNOWFALL EXPECTED TODAY
*ARCTIC BLAST DELIVERS BITTER TO EXTREME COLD TONIGHT-WEDNESDAY
*DEEP FREEZE ENDS LATE WEEK WITH TEMPERATURES MODERATING CLOSER
TO THE HISTORICAL AVERAGE FOR LATE JANUARY BY NEXT WEEKEND
NEAR TERM /THROUGH TONIGHT/
ARCTIC AIR IS SPILLING INTO THE NORTHERN TIER OF CPA EARLY THIS
MORNING WHILE MUCH OF SOUTH CENTRAL AND SOUTHEASTERN PA IS STILL
HOVERING AOA THE FREEZING MARK AT 10Z. VERY SHALLOW MOISTURE
PROFILES COMBINED WITH NNW UPSLOPE FLOW HAS SUSTAINED FZDZ/FZFG
IN THE LAUREL HIGHLANDS SO WATCH OUT FOR SLICK SPOTS HEADING
OVER THE SOUTHWEST MTNS EARLY THIS MORNING.
RADAR TRENDS ARE STARTING TO SHOW SNOW BREAKING OUT FROM
EASTERN KY INTO WV ALONG MAX UPPER LEVEL DIVERGENCE ZONE/LEFT
EXIT JET REGION ASSOCIATED WITH SHORTWAVE TROUGH EXPECTED TO
PIVOT NORTHEASTWARD THROUGH THE TN VALLEY INTO THE MID ATLANTIC
BY THIS EVENING.
HIRES MODEL GUIDANCE CONTINUES TREND TOWARD A BETTER OVERALL
CONSENSUS THE HEAVIEST SWATH OF SNOWFALL SETTING UP EARLY TODAY
ACROSS SOUTH CENTRAL PA THEN QUICKLY MOVING TO THE NORTHEAST
THROUGH THE MID/LOWER SUSQUEHANNA VALLEY INTO THE LEHIGH VALLEY
LATER THIS AFTERNOON AND EVENING. A SLIGHTLY COLDER SOLUTION WAS
PREFERRED THIS CYCLE WITH SLRS INCREASED A BIT IN THE SOUTHEAST.
HOWEVER, UPDATED STORM TOTAL SNOWFALL AMOUNTS REMAINED VERY
CLOSE TO THE PREVIOUS FORECAST WITH MAX TOTALS STILL IN THE 3-6"
RANGE OVER THE SOUTHERN HALF OF THE FORECAST AREA. THE ONLY
CHANGE TO THE WINTER HEADLINES WAS TO ADD A FEW ZONES TO SQUARE
OFF THE NORTHERN EDGE OF THE ADVISORY AND TREND MORE IN LINE
WITH SNOW ACCUMULATION IN THE 2-3" RANGE.
THE PERIOD OF HEAVIEST SNOW IS PROJECTED TO BE IN THE 12-6PM
TIMEFRAME MAXIMIZED ACROSS PORTIONS OF THE LOWER SUSQUEHANNA
VALLEY WHERE RATES COULD EXCEED 1"/HR IN THE 2-5PM WINDOW BASED
ON THE 00Z HREF. A MORE PROLONGED PERIOD OF THE HEAVIER RATES
WITHIN A BANDING FGEN SNOW FEATURE COULD DELIVER A BOOM
SCENARIO OF UP TO 7-8" LOCALLY.
SNOW IS PROJECTED TO TAPER OFF AND END BTWN 00-03Z AS DRY ARCTIC
AIR IS DIRECTED INTO THE AREA. SOME LAKE ENHANCED/UPSLOPE SNOW
SHOWERS SHOULD LINGER OVER THE NW ALLEGHENIES AND LAUREL
HIGHLANDS WITH LITTLE ADDITIONAL ACCUMULATION THROUGH 12Z MON.
MIN TEMPS DIP INTO THE +SINGLE DIGITS TO MID TEENS WITH MIN WIND
CHILLS RANGING FROM -10F IN THE LAURELS TO +SINGLE DIGITS INT
THE LOWER SUSQUEHANNA VALLEY.
SHORT TERM /MONDAY THROUGH MONDAY NIGHT/
BITTER COLD AND FRIGID MLK DAY WITH HIGHS 15 TO 30 DEGREES BELOW
THE HISTORICAL AVERAGE. SNOW SHOWERS AND FLURRIES ARE EXPECTED
TO CONTINUE ACROSS THE ALLEGHENY PLATEAU WITH VERY LIGHT ACCUM.
BASED ON MINIMUM WIND CHILLS AND COLLABORATION WITH NEIGHBORING
OFFICES, WE TRANSITIONED TO A LONGER DURATION COLD WX ADVISORY
MONDAY NIGHT FOR MOST OF THE AREA WITH HIGH ENOUGH CONFIDENCE
FOR AN EXTREME COLD WARNING FOR THE LAUREL HIGHLANDS FOR WCS AS
LOW AS 20 BELOW ZERO. LATER SHIFTS COULD CONSIDER EXPANDING THE
COLD WX ADVISORY TO INCLUDE THE REMAINDER OF THE CWA WITH THE
COLDEST PERIOD OF WCS NOW LOOKING LIKE TUESDAY NIGHT-WED.
LONG TERM /TUESDAY THROUGH SATURDAY/
THE MAIN STORY FOR THE LONG TERM WILL BE THE BITTER COLD THAT WE
WILL EXPERIENCE THROUGH THE MIDDLE OF THE WEEK. PERSISTENT
UPPER LEVEL TROUGHING WILL KEEP IT QUITE COLD ACROSS MUCH OF THE
EASTERN UNITED STATES.
FOR CENTRAL PA, HIGH TEMPERATURES TUE-WED WILL RUN 20-30
DEGREES BELOW AVERAGE. CONSIDERING THAT LATE JANUARY IS
CLIMATOLOGICALLY THE COLDEST TIME OF THE YEAR, THIS WILL BE A
SIGNIFICANT ARCTIC OUTBREAK.
A WAVE OF LOW PRESSURE PASSING WELL TO OUR SOUTH COULD BRUSH
SOUTHEASTERN PA WITH SOME LIGHT SNOW TUES EVE/NIGHT. AFTER A
VERY COLD WED, TEMPERATURES WILL MODERATE A BIT THURS INTO FRI.
A REINFORCING SHOT OF COLD AIR (NOT QUITE AS COLD AS EARLIER IN
THE WEEK) COULD BE ACCOMPANIED BY SOME SNOW SHOWERS ACROSS N/W
PA LATE FRIDAY OR EARLY SATURDAY.
AVIATION /10Z SUNDAY THROUGH THURSDAY/
SNOW SHOWERS CONTINUE TO PRODUCE LIFR CONDITIONS AT JST AS OF
05Z. ELSEWHERE, IFR CEILINGS ARE BEING OBSERVED AT BFD WHILE
MVFR/VFR CEILINGS CAN BE FOUND AT THE OTHER TAF SITES. SOME
PATCHY FOG HAS DEVELOPED ACROSS THE LOWER SUSQUEHANNA VALLEY AND
WILL CONTINUE TO PRODUCE MVFR VISIBILITIES THROUGH MUCH OF THE
NIGHT BEFORE GRADUALLY IMPROVING INTO THE MORNING.
A COASTAL LOW WILL BRING A ROUND OF SNOW INTO THE AREA ON
SUNDAY. THE SNOW WILL OVERSPREAD THE AREA FROM SOUTH TO NORTH
THROUGH THE MORNING AND EARLY AFTERNOON HOURS. ONCE THE SNOW
BEGINS, CONDS SHOULD QUICKLY DROP TO IFR. MOST GUIDANCE SUGGESTS
THAT A PERIOD OF HEAVY SNOW IS LIKELY AT MDT AND LNS IN THE
18Z-00Z TIMEFRAME AND VISIBILITIES AS LOW AS 1/4SM WILL BE
POSSIBLE FOR THOSE AIRFIELDS.
THE STEADY SNOW WILL PULL EAST OF THE REGION SUNDAY EVENING
INTO SUNDAY NIGHT, ALTHOUGH LINGERING LIGHT UPSLOPE
PRECIPITATION REMAINS POSSIBLE ACROSS THE WESTERN HIGHLANDS
SUNDAY NIGHT. AS THE SNOW EXITS THE REGION, CEILINGS GRADUALLY
RISE TO VFR EAST OF UNV, WHILE MVFR CEILINGS PERSIST TO THE
WEST.
OUTLOOK...
MON...MVFR TO IFR CONDS IN SNOW SHOWERS ACROSS MAINLY
NORTHWESTERN PA; COLDER AREAWIDE WITH GUSTY WEST WINDS.
TUE...NO SIG WX EXPECTED; VERY COLD.
TUES NIGHT-WED...SCATTERED SNOW SHOWERS POSSIBLE, BRINGING
LOCALIZED RESTRICTIONS; VERY COLD.
THU...NO SIG WX EXPECTED; CONTINUED COLD.
CTP WATCHES/WARNINGS/ADVISORIES
COLD WEATHER ADVISORY FROM 4 AM MONDAY TO NOON EST WEDNESDAY
FOR PAZ004>006-010>012-017-018-037-041-042.
WINTER WEATHER ADVISORY FROM 8 AM THIS MORNING TO 8 PM EST
THIS EVENING FOR PAZ012-017-018-041.
WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
PAZ019-024>028-033>035-042-045-046-049>052.
COLD WEATHER ADVISORY FROM 7 PM MONDAY TO NOON EST WEDNESDAY
FOR PAZ019-025>028-034-035-045-046-049>053.
COLD WEATHER ADVISORY FROM 4 AM MONDAY TO 1 AM EST TUESDAY FOR
PAZ024-033.
EXTREME COLD WARNING FROM 1 AM TUESDAY TO NOON EST WEDNESDAY
FOR PAZ024-033.
WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR PAZ036-
053-056>059-063>066.
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...MARTIN/EVANEGO
AVIATION...EVANEGO/BAUCO
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