textproduct: State College

WHAT HAS CHANGED

* Cancelled all Winter Weather Advisories. Any additional accumulation will be minor, temperatures continue to warm.

KEY MESSAGES

1) Quick-hitting minor to plowable snow accumulation for later tonight into the Wednesday morning commute

2) Increased uncertainty with snow/mixed precip potential Thursday

3) Mild end to February/meteorological winter -- but does March come in like a lion with another wintry system early next week?

DISCUSSION

KEY MESSAGE 1: Quick-hitting minor to plowable snow accumulation for later tonight into the Wednesday morning commute

A clipper system tracking across the Upper Great Lakes will bring a quick-hitting shot of snow primarily across the western and northern Alleghenies late tonight through Wednesday morning. Warm advection ahead of the surface low will combine with left exit region jet dynamics into favorable DGZ to produce 1-3" totals over the higher terrain with C-1" southeast of I99/I80. Bulk of the accumulating snowfall will likely fall within a 4-8 hour window with light snow/flurries after 12Z Wed across the Allegheny Plateau and Laurel Highlands. The snow and slippery road conditions will impact the Wednesday morning commute in some areas and may result in travel/school delays.

KEY MESSAGE 2: Increased uncertainty with snow/mixed precip potential Thursday

Overall, the 2/24 00Z & 12Z model trends have been bearish on the margin concerning snow/mixed precip potential for Thursday. A southeastward QPF shift in the deterministic GFS, NAM, and ECMWF is quite evident in the 12Z runs with NBM QPF matching closer with AIGFS and WPC to AIGEFS. The uncertainty is likely tied to shortwave differences in the fast quasi-zonal flow and strong temperature gradient across the northern half of the CONUS. POPs and snowfall were reduced via baseline foundational NBM which accounts for the bearish trends and implies lower forecaster confidence. It's not out of the question the southeastward shift reverses in future cycles, but for now the signal is considerably weaker than this time yesterday. KEY MESSAGE 3: Mild end to February/meteorological winter -- but does March come in like a lion with another wintry system early next week?

Regardless of the outcome on Thursday, Friday and Saturday continue to shape up quite well as we close out the month of February/meteorological winter on a nice warming trend. Saturday looks like the warmest day with max temps in the low 40s to mid 50s running +5-10 degrees above the historical average.

But does March come in like a lion? Uncertainty exists regarding the potential for overrunning winter precip early next week as Pacific energy/moisture catches up to retreating arctic high pressure. Stay tuned.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

MVFR/Fuel-alt ceilings are expected to continue over the next few hours, before clouds scatter out and conditions improve to VFR levels this afternoon. However, a shortwave moving across the Great Lakes later this afternoon/evening might refuel snow showers over KBFD bringing the return of at least MVFR restrictions for a time. Confidence is lower in spotty snow showers and restrictions around KIPT, KJST and KUNV, but can't be ruled out.

Winds will be becoming westerly this afternoon and west to northwesterly later in the TAF period. Wind gusts of 20 to 25 knots are expected through the afternoon before starting to ease later this evening.

Outlook...

Thu...Low potential (~20-30%) for snow showers across southern Pennsylvania. Elsewhere, dry with VFR conditions probable.

Fri-Sat...Dry conditions with VFR probable.

Sun...Low potential (~30%) for snow showers across NW PA. Elsewhere, dry with VFR conditions probable.

Monday...Low potential (~20-30%) for snow showers across the area, may cause restrictions.

CTP WATCHES/WARNINGS/ADVISORIES

None.