textproduct: State College

WHAT HAS CHANGED

* Increased odds for rain across the far northwest Alleghenies this evening into tonight

KEY MESSAGES

1) Frost/freeze conditions and marginal uptick in wildfire spread risk today and Friday

2) Above normal temperatures and little to no rainfall forecast into next week

DISCUSSION

KEY MESSAGE 1: Frost/freeze conditions and marginal uptick in wildfire spread risk today into Friday

Not as cold as yesterday morning, but several locations across the south central ridge and valley region will start the day chilly to frosty with daybreak temps in the upper 20s to low 30s. Freeze warning remains in effect for the recently activated growing season zones until 9AM.

A marginal uptick in wildfire spread risk is expected today and Friday as fine fuel moisture continues to cure/trend lower toward 10%. We plan to issue a statement (SPS) to highlight the elevated wildfire spread risk that closely matches the latest PA DCNR fire danger map (for context: fire danger of moderate to high is pretty typical for central PA in April). KEY MESSAGE 2: Above normal temperatures and little to no rainfall forecast into next week

An increasingly milder south to southwest flow will transport warmer air back into CPA through the end of the week. Temps briefly cool down over the weekend before surging +20 degrees above the historical average early next week.

A pair of weak cold fronts bring limited rainfall the NW portion of the forecast area this evening through Friday night. Total QPF range is 0.10-0.50 inches near and to the north/west of I99/US220. Little to no rainfall is expected across the southeastern half of CPA providing no relief or improvement in the abnormally dry (D0) to moderate/severe drought conditions (D1-D2 intensity).

AVIATION /12Z THURSDAY THROUGH MONDAY/

VFR prevails across central PA as of 12Z, with high confidence (>90%) for VFR with mainly mid/high level clouds to continue at most terminals through 12Z Friday, with an exception at KLNS where a marine layer will bring MVFR restrictions through 13-14Z, as well as at KBFD where MVFR visibility restrictions are possible in gusty showers primarily between 23Z-01Z. Otherwise, southerly flow prevails on the western side of a high pressure draped across the East Coast, with winds of around 10 kts gusting to 15-20 kts expected this afternoon as the pressure gradient tightens in response to a low pressure crossing over the northern Great Lakes and southern Canada.

VFR is highly likely (>90%) to return at KLNS by 14Z as the maritime air mass is scoured out by diurnal mixing. Nighttime Microphysics imagery shows that the low cloud deck that developed is already pushing north of KLNS and thinning out, which is likely to continue given we're past sunrise.

At KBFD, low pressure passing to the north is moderately likely (60-70% chance) to bring sufficient lift for scattered showers after 23Z, with a PROB30 for 4SM -SHRA with 20 kt gusts between 23Z-01Z to signal at the potential for gusty showers. Driving this decision is an inverted-V profile with LCLs around 5000 ft, where evaporative cooling within the drier air beneath the cloud base could enhance downdrafts. The gust potential is expected to diminish after 01Z as the boundary layer stabilizes, with regular scattered showers expected through the end of the TAF package. Limited instability (HREF mean CAPE between 50-100 J/kg) precludes thunder mentions at this time.

Outlook...

Fri...Generally VFR, with MVFR possible primarily N/W due to -SHRA and lowering cloud ceilings.

Sat...Restrictions poss early, then trending VFR.

Sun...Mainly dry. Maybe a shower near the NY border.

Mon...Chance of showers, mainly N/W later in the day.

CTP WATCHES/WARNINGS/ADVISORIES

Freeze Warning until 9 AM EDT this morning for PAZ026>028-035- 036-049>052-056-057-059-063>066.