textproduct: State College

WHAT HAS CHANGED

* Extreme Cold Warning has been expanded into Cambria County for tonight into midday Sunday

KEY MESSAGES

1) Prolonged dangerous cold weather continues through tonight, with wind exacerbating the cold Sunday into Sunday night.

2) Light accumulating snow possible late Monday night and early Tuesday and again late Tuesday night into Wed (mainly southern PA)

3) Light accumulating snow is possible again Fri-Sat, followed by gusty winds and another shot of Arctic air for next weekend.

DISCUSSION

KEY MESSAGE 1: Prolonged dangerous cold weather continues through tonight, with wind exacerbating the cold Sunday into Sunday night.

Limited moisture streaming southeast from the Glakes and trapped beneath the low subsidence inversion with temps occupying the entire prime DGZ zone producing some light flurries across mainly the nrn and wrn mtns of PA.

NW edge of a higher cloud deck was edging into our far SE zones, while SKC to SCT stratus occupied much of the Central Ridge and Valley Region early today.

For today, NW wind gusts increase to 25-35 mph across the area thanks to a tightening llvl pressure gradient on the back side of an intensifying coastal storm east of the NC's Outer Banks.

The increasing winds and cloud cover will limit the extent to which temperatures fall early today, but we'll still see wind chill values near 10 below zero for most locations and potentially colder than 20 below zero in the Laurel Highlands. Given this threat, an Extreme Cold Warning continues for Somerset and Cambria Counties into early this Sunday afternoon. Elsewhere, Cold Weather Advisories are in effect. Warren County remains out of the Advisory with winds not expected to be quite as strong there.

Temperatures will begin to moderate by Groundhog Day (Monday), but it will still be cold for this time of year with highs remaining below the freezing mark in most of central PA.

Be on the lookout for icicles and other large chunks snow and ice that might fall off rooftops as winds pick up today and temperatures rise gradually through the upcoming work week.

KEY MESSAGE 2: Accumulating snow possible for the midweek period (Tuesday night into Wed), mainly across southern PA.

NBM/NBMv5 are signaling the chance for a stripe of light snow accumulation (trending down in amounts to C-2") Tuesday night Feb 3 into Wednesday Feb 4 with a clipper system. There is considerable spread in model guidance with the placement of this stripe of snow, with some solutions keeping central PA dry. The highest probabilities of greater than 1 inch of snow are south of I-76 at this time.

KEY MESSAGE 3: Accumulating snow is possible again Fri-Sat, followed by gusty winds and another shot of Arctic air for next weekend.

By the end of the week, a low pressure system will ride along the top of the western US ridge and race southeast across the Great Lakes. This storm will have a strong ridge of high pressure behind it, ensuring a tight pressure gradient, reinforcing Arctic air, and strong winds in its wake. Accumulating snowfall is likely for much of the area, with highest totals favored in the typical lake effect/upslope regions of Central PA. Snowfall amounts should remain manageable based on the anticipated fast forward speed of the storm system, and ice coverage on the Great Lakes. The bigger story will be the wind and cold to follow. The Climate Prediction Center has highlighted a High Risk for Below Normal Temperatures (Saturday- Sunday) and a Moderate Risk of High Winds across Pennsylvania. Single digit (above and below zero) temperatures and below zero wind chills across much of the region are favored.

AVIATION /08Z SUNDAY THROUGH THURSDAY/

Ceilings at BFD and JST should dip to IFR overnight, while they will likely hold at MVFR at AOO. Some guidance, particularly the HREF, suggests the potential for a few hours of VFR ceilings at AOO between 00Z and 06Z as some breaks in the clouds develop, but with continued northwest flow, MVFR appears more likely. Expect MVFR ceilings to eventually reach IPT and UNV as well. The Lower Susquehanna Valley should remain VFR.

An increasingly breezy northerly wind will develop overnight in response to deepening low pressure off the East Coast, with gusts of 20 to 30 knots expected for Sunday. Ceilings will rise to MVFR across the western highlands, and should gradually become VFR elsewhere through the morning and early afternoon. There is some guidance suggesting JST will see little improvement and even a dip into LIFR ceiling conditions Sunday morning. Precipitation from the offshore storm should remain south/east of the region. As has been the case for the past week, cold north- northwesterly flow could support a few flurries at BFD and JST during the day, but the probability is too low to include any snow in the TAFs.

Outlook...

Mon...Dry conditions expected area wide.

Mon night-Tue...Light snow across N/W PA, with restrictions possible.

Tue night-Wed AM...Light snow possible areawide, restrictions possible.

Wed PM-Thu...Lingering -SHSN possible across nrn PA.

CLIMATE

State College tied the second longest run (7) of consecutive days with max temp staying <= 20F for the period 1/25 through 1/31). The last time this occurred was post-Christmas 2017 (12-28-2017 to 01-03-2018). Based on multi-model consensus, it looks like this string will come to an end today with the max temp fcst to reach the low 20s. The longest run of 10 days occurred in January 1893 from the 11th-20th.

It will be a top 3 coldest last week/7 days of January (mean temp 1/24-1/31) for State College

CTP WATCHES/WARNINGS/ADVISORIES

Cold Weather Advisory until 10 AM EST this morning for PAZ005- 006-010>012-017>019-025>028-034>037-041-042-045-046-049>053- 056>059-063>066. Extreme Cold Warning until 1 PM EST this afternoon for PAZ024- 033.