textproduct: State College

WHAT HAS CHANGED

* The threat of severe weather has ended. * Expanded discussion about frost/freeze potential through the weekend.

KEY MESSAGES

1) Band of showers to continue to move eastward overnight.

2) Chilly pattern for the end of April with frost/freeze risk through the first weekend of May.

DISCUSSION

KEY MESSAGE 1: Band of showers to continue to move eastward overnight.

At 9 PM, the cold front was over the western portion of central PA, with a few showers. Main band of showers and isolated thunder at times was over eastern PA. Both bands will continue to move eastward overnight.

The rain is heavy at times, but the activity is moving along. Also areas to the east and southeast have been much drier than northwestern PA this Spring. Thus not seeing any issues with the rain.

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KEY MESSAGE 2: Chilly pattern for the end of April with frost/freeze risk through the first weekend of May

Several disturbances rotating around a persistent upper level closed low centered over Ontario and Quebec will help to reinforce broadly deep troughing across the eastern U.S. into next week. This pattern will keep conditions cool and unsettled with temperatures below seasonal norms. Chilly nighttime lows will also lead to frost and freeze concerns Thursday-Saturday night, particularly now that the growing season is now active across all CPA zones. Patchy frost may also develop across our far-northern counties tonight, but higher uncertainty exists given milder temperatures and mostly cloudy skies. For Thursday & Friday nights, frost/freeze chances are primarily north and west of I-80/I-99, with limiting factors being 850 mb temperatures a couple degrees warmer on those days + cloud cover Friday night limiting radiational cooling. Frost/freeze potential is highest Saturday night, with high pressure nosing in from the Tennessee Valley helping skies to clear and winds to lighten, with the greatest potential for frost/freeze north and west of I-78/I-81.

AVIATION /06Z THURSDAY THROUGH MONDAY/

Two areas of showers will bring brief reductions to CIGS and VSBYS early today as a weak cold front pushes east across the Susquehanna Valley during the predawn hours and a mid/upper level cool pool approaches from the Ohio Valley. KIPT and KMDT will be the targets for a few showers very early this morning, while the best chance for showers and KBFD will be broader period from the mid morning through mid afternoon hours today.

As the transition to the deepening, cool NW flow occurs today, we'll see the typical lower conditions (IFR to low end MVFR) at KBFD and KJST while mainly MVFR CIGS and VFR Vsbys will be found at KAOO, KUNV and KIPT. IFR and MVFR conditions at KMDT and KLNS respectively at 06Z will gradually improve through MVFR this morning and reach VFR conditions between 15-17Z today as downsloping NW low-level flow of drier air lifts the cloud bases.

Winds will become moderately gusty (high teens to low 20s (KTS)) late this morning and this afternoon as high pressure builds east town the area in the wake of the departing low. Rain chances return for the midday and afternoon hours Friday.

Outlook...

Fri-Sat...Mainly VFR with brief restrictions possible in showers.

Sun...Restrictions possible northwest in -RA and possibly some -SN.

Mon... Models hinting at another low pressure wave to our west, precip may lead to restrictions, particularly in the west.

CTP WATCHES/WARNINGS/ADVISORIES

Frost Advisory from midnight tonight to 8 AM EDT Friday for PAZ004>006-010-011-017-024-033.