textproduct: State College

SYNOPSIS

* Heaviest precip exits east tonight as lingering freezing drizzle and patchy freezing fog extends travel impacts. * Freezing rain/rain mix Sunday morning transitions to all rain Sunday night. * Strong cold front brings lake effect snow showers, strong winds, and sharply colder temps/wind chills Monday night into the New Year.

NEAR TERM /UNTIL 6 PM THIS EVENING/

KEY MESSAGES: - Ice Storm Warning was cancelled 4 hours ahead of time, but the Winter Weather advisory will remain intact through 12Z for Central and Eastern parts of the CWA. - Dry conditions and a slight rebound in temperatures for today, but untreated and elevated surfaces will continue to be slick. - A weak cold front over Southern New York will drift south across the Pennsylvania today with increasing sunshine through variable amounts of high clouds.

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Areas of weak high pressure near Chicago and over Southern Ontario will consolidate and drift east across the region tonight.

Widespread and relatively warm/shallow clouds will slowly break up from south to north across the CWA as the llvl nwrly flow increases and advects some dry air SE into the region with enhanced drying/adiabatic warming of the air from downsloping off the higher Allegheny Plateau.

Highs this afternoon will remain below freezing for most locations north of I-80, and perhaps even farther south depending on the extent and durability of cloud cover and cold advection on Saturday. The South Central Mtns and Lower Susquehanna Valley will see the mercury climb to between 35 and 40F.

SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/

A veil of high clouds will spread east and thicken-up tonight, well in advance of the next weather system (an intense sfc low moving from the Western Great Lakes to the St. Lawrence River Valley Sunday afternoon through Monday night).

WAA ramps up a few to several KFT AGL as the wind flow in that layer increases from the southwest. The first mentions of precipitation come near/just after sunrise on Sunday with increasing low-level moisture progged by the bulk of model guidance.

Skies will at least partially clear tonight as a ridge of high pressure at the surface and aloft drifts east over the state. This clearing and light wind will allow temperatures to drop into the teens and low 20s across the Northeast Half of Pennsylvania, and into the upper 20s to low 30s across the Southwest.

Clouds will thicken-up quickly Sunday morning and if a 12 to 18 hour period of rain and drizzle, ahead of a warm/cold front tandem, arrives quicker than currently forecast, areal coverage of morning freezing rain could be greater. For now, we're expecting areas of freezing rain to be confined to the Mountains North and East of Williamsport and points east across the Poconos.

Recent NBM model guidance outlines ice potential north of I-80 with ~40+% members outlining some chances of measurable ice in this timeframe. Further south, lower confidence in any ice accumulation but have retained mentions at this time scale with no thoughts of headlines and relegating any mentions to the HWO with the ongoing system and lack of confidence at this juncture.

LONG TERM /MONDAY THROUGH FRIDAY/

The aforementioned, intense surface low will continue to track east across Southern Ontario and Southern as we head through Monday and Tuesday, allowing for a transition back into a rain/snow mix across the northwestern half of the forecast area with rain prevailing further southeast.

Westerly/northwesterly flow and an approx 25-30 deg F temp plunge during the day Monday/Monday evening behind the cold front promotes a combination of lake effect and upslope snow shower mentions across northwestern Pennsylvania through Thursday.

Recent NBM/LREF model guidance paints an impressive signal for gusty winds on Monday after the cold frontal passage with EC/GFS model guidance in fair agreement in a 850mb 70kt LLJ across the Laurel Highlands. Additionally, BUFKIT GFS Time Sections for KJST show 50 kt isotachs down below 500 ft AGL, and 60 kts at about 800 ft AGL. With the intense SFC low sliding by to our north, there's not a significant 3 hourly pressure rise (i.e., GRTN 5 mb/3 hr) accompanying the 30 deg F temp plunge on Monday.

We topped out winds in the low 50s (KTS) across the highest ridges just west of Interstate 99 and west of RT 219 in the Laurel Highlands. That being said, would like to see another model run or two before hoisting a High Wind Watch as the NAM and other blended guidance indicates solid Advisory Criteria winds.

Previous Disc -

Have bumped up wind and wind gusts to the higher end of the ensemble envelope to convey the threat of strong winds. After a mild high in the 40s and 50s on Monday, wind chills will plummet to the single digits and teens by Tuesday morning in the wake of the front.

Cooler temperatures and wind chills also eek their way into the forecast for New Year's Eve and into the first couple days of 2026, we're talking about late December into early January, after all! Minimum wind chills for any outdoor New Year's Eve celebrations will be pushing into the single digits across northwestern Pennsylvania to the upper teens across the Lower Susquehanna Valley. Minimum temperatures by daybreak on New Year's Day range from 0 (NW) to the mid-teens (SE), with slightly cooler temperatures Thursday night into Friday morning.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

Consensus of all model guidance outlines high (90+%) confidence in LIFR ceilings across the western terminals (BFD/JST) throughout much of the 12Z TAF package with ample low-level moisture outlined in recent RAP/HREF model guidance. GLAMp guidance continues on with this trend with a persistent cloud deck below 500ft AGL as winds begin to decrease this morning and into the afternoon. Low probability solutions exist where brief periods of IFR/MVFR occur at these airfields; however, confidence in observations prevailing over one hour remain low and will likely remain down towards LIFR thresholds.

Recent RAP model soundings continue to suggest all airfields outside of BFD/JST will have some magnitude of improvement through ~00Z Sunday. This TAF package blends in more recent GLAMP/RAP model analyses in order to outline shorter windows of opportunity with longer durations of MVFR ceilings; however, some uncertainty remains with the magnitude of improvement. Lower probability solutions outline more optimistic clearing across the area, with all airfields potentially scattering out between 18-21Z Saturday. Highest probabilities for longer duration of VFR conditions throughout the 12Z TAF package generally remain at MDT/LNS.

Outlook...

Sun...Rain with -FZRA possible across higher elevations early, then becoming windy. Restrictions possible.

Mon...Mild early with widespread rain showers, then colder and windy later in the day with with snow showers across the mountains.

Tue...Windy and cold with snow showers across the mountains. Dry southeast.

Wed...Chance of snow showers across the north and west, dry southeast.

CTP WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until 7 AM EST this morning for PAZ006- 011-012-018-019-025>028-034>037-041-042-045-046-049>053- 056>059-063>066.