textproduct: State College

WHAT HAS CHANGED

* Frost Advisory issued tonight for the western and northern Alleghenies

KEY MESSAGES

1) Seasonably cool and mainly dry end to the week with areas of frost tonight into early Friday morning

2) Wet weather - but not a total washout - for Mother's Day weekend; monitoring frost freeze risk Monday night/AM Tuesday

DISCUSSION

KEY MESSAGE 1: Seasonably cool and mainly dry end to the week with areas of frost tonight into early Friday morning

Most locations stay dry through the end of the week with a couple of passing showers or sprinkles over the northern portion of the forecast area. Daytime highs Thu/Fri are 5-10F below the historical average for early May. Diurnal/instability cu field should fade this evening and give way to initial clearing before some clouds try to return by the predawn hours Friday. The cloud coverage could limit areas of frost which are most likely to be found across the western and northern Alleghenies where min temps are fcst in the low-mid 30s. Patchy frost is also possible farther to the east/downwind of the Allegheny Front especially in the usually colder sheltered rural valleys between I99/US220 and I81.

KEY MESSAGE 2: Wet weather - but not a total washout - for Mother's Day weekend; monitoring frost freeze risk Monday night/AM Tuesday

Model signals point toward a wet start to Mother's Day weekend with zone of steady light rain early Saturday tapering to showers by Saturday night. Hires output suggests a WSW-ENE oriented band of rain focusing over the northern half of the CWA Saturday morning. Additional showers are likely Sunday into Sunday night although the exact timing is still unclear. Initial read favors late Sunday through Sunday night/early Monday with more rain breaks or intermittent periods of rain/showers for the second half of Mother's Day weekend. Daytime highs this weekend are projected to warmup a bit into the 60-75F range Sunday afternoon. While we have high confidence for rain at times this weekend, we don't expect a total washout. Total rainfall amounts through Sunday evening are generally 0.25" or less in most places. A dry-out period likely follows as rain exits CPA by Monday night with another frost/freeze risk to manage into early Tuesday morning.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

Southwest flow aloft will shift more to the northest for the first part of Friday.

Most locations will remain VFR into Friday, with some high base bands of SC and CU clouds. Main chance for a shower will be at BFD around sunrise, perhaps JST. BFD CIG could drop to MVFR during this time with any showers, but the rest of the area should remain VFR. Earlier shift had a shower in for IPT, left this in the 18Z TAF package, but less chance there.

Winds will weaken after sunset. Winds on Friday will likely pick up, as winds aloft shift more to the northwest and are more likely to mix down.

Weekend looks wet, with lower conditions expected.

Outlook...

Sat...Restrictions possible in rain and fog.

Sun...VFR favored early, with restrictions becoming more likely in the afternoon as another cold front moves SE. SHRA with isolated TSRA possible as cold front passes through.

Mon-Tue...VFR conditions expected to prevail.

CTP WATCHES/WARNINGS/ADVISORIES

Frost Advisory from 11 PM this evening to 8 AM EDT Friday for PAZ004>006-010>012-017-018-024-033-037-041-042.