textproduct: State College

WHAT HAS CHANGED

* Increased the probability of precip and amounts of wet snow northward into Central PA and with elevation (especially at elevations AOA 1500 ft MSL) later Sunday afternoon and Sunday night

KEY MESSAGES

1) With a short-term predictability barrier still to be resolved, there are increased chances for wet snow on the margin late Sunday/Sunday night for Central/Southeast PA

2) Welcomed warmup/thaw picks up some steam next week with an active precip pattern Wednesday into the second-to-last weekend of February

DISCUSSION

KEY MESSAGE 1: With a short-term predictability barrier still to be resolved, there are increased chances for wet snow on the margin late Sunday/Sunday night for Central/Southeast PA

12Z Sat operational and EFS/NBM guidance has trended a bit higher, further north and slightly colder leading to a generally nuisance winter weather event with minor impacts throughout the higher population centers in the Lower Susq Region and valleys in southern and central PA.

Based of the Wet bulb Zero will reside between 1-2 kft agl today, before gradually dropping to near or below 1 kft across the bulk of the CWA at the time of precip onset Sunday afternoon/early evening.

This will lead to a highly elevation-dependent mixed rain/wet snow event for the southern half to two thirds of the state, with SLRs generally less than 8:1. Storm total QPF will vary from 0.20 of an inch or slightly less near and just to the south of the I-80 corridor to as much as 0.4 to 0.5 inch near the PA/MD border.

Varied SLRs greatly by elevation Sunday/Sunday night, but storm total snowfall amts still remain below advisory criteria.

This next bout of precip will be associated with a strong southern stream shortwave and associated surface low tracking from the Lower MS Valley to the Outer Banks of NC. This is due to more interaction with a stronger (run/run) northern stream shortwave coming into western PA Sunday night. The eventual northern stream energy is coming onshore the Pacific NW this morning, and once over land should be better assimilated/initialized in subsequent short term and hires model runs.

The other tricky aspects of the fcst include: relatively warm boundary layer/road temps, precip rates/banding, onset timing, elevation, and wet bulb effects. Without going to far into the weeds, the key takeaway for this cycle is that odds have increased on the margin for accumulating wet snowfall across south central and particularly southeast PA Sunday afternoon into Sunday night. The largest % chance increase is for areas to the east of I-81 with WPC, RRFS, and NBM showing low to moderate chances (30-50%) of snowfall totals >1 inch. The official NDFD fcst initialized off of the 14/01Z NBM is likely a bit too low at this point and would anticipate/front-run an uptick in POPs and snow amounts to be more in the C-1" range with the next cycle. There is the potential for additional changes to this forecast in the next 12-24 hours so continue to monitor especially for possible early Monday morning commute impacts. KEY MESSAGE 2: Welcomed warmup/thaw picks up some steam next week with an active precip pattern Wednesday into the second-to- last weekend of February

Max/min temperatures over the next 7 days (2/14-2/20) are forecast to be above the historical average for mid/late February. To better contextualize the welcomed warmup/thaw: in some areas, a 7-day run of positive temp departures from normal has not happened since late September 2025!

Surface low over the western High Plains by Tuesday should track eastward across the Dakotas/Upper Midwest into the Great Lakes by Thursday. A broad area of stratiform precip is fcst to the north and east of the low track near a low level baroclinic zone or temperature gradient with cold air closer to the Canadian border. There may be southward flex of strong arctic high that sends a weak backdoor front into PA; but outside of that scenario (increasing the odds for mixed precip especially over northern PA) the dominant ptype from midweek into the weekend looks like rain. An organized low pressure system is expected to develop across the Midwest and Ohio Valley to close out the work week. 12-24hr precip signals are maximized on Wednesday and Friday next week.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Mainly VFR conditions for the rest of today and tonight.

Westerly winds with some minor gusts into the mid teens will occur this afternoon before diminishing by sunset, as a weak area of high pressure builds into the area.

Outlook...

Sun...Low clouds with scattered rain/snow mix over the area.

Mon...Low clouds linger much of the day. IFR expected NW.

Tue...Mainly VFR.

Wed...IFR -RA/cigs N, MVFR -RA/cigs elsewhere.

CTP WATCHES/WARNINGS/ADVISORIES

Air Quality Alert until midnight EST tonight for PAZ057-059- 063-065-066.