textproduct: State College

WHAT HAS CHANGED

* Added frost in the Susquehanna Valley late Thursday night into early Friday morning

KEY MESSAGES

1) Frost/freeze conditions and marginal uptick in wildfire spread risk into late week

2) Little to no precipitation forecast through the upcoming weekend with temperatures trending above the historical average into next week

DISCUSSION

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

Cold start this morning with clear skies/light winds allowing min temps to bottom in the 10-25F range or 10 to 15 degrees below early April climo. This may very well be the coldest morning until later in the Fall. A few of the usually colder sites in the northern tier could print a single digit low temp!

Freeze warning is verifying in the recently activated growing season zones and remains in effect until 9AM. The freeze watch for late tonight into early Thursday morning will be upgraded later today.

A marginal uptick in wildfire spread risk is probable into late week as fuel moisture levels cure/drop closer to or below the key 10% threshold (per DCNR fire weather partner coordination).

KEY MESSAGE 2: Little to no precipitation forecast through the upcoming weekend with temperatures trending above the historical average into next week

An increasingly milder south to southwest flow will transport warmer air back into CPA through the end of the week. Forecast max temps on Friday are +15-20 degrees higher than today (4/8). Following a minor (5-10F) setback on Saturday, another warm surge is projected into early next week.

A pair of weak cold fronts should bring some limited rainfall largely confined to the NW Alleghenies Thursday night through Friday night. Total QPF range is 0.10-0.50 inches. Little to no rainfall is expected across the southeastern half of CPA in the D0-D2 drought areas.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

VFR is expected to prevail across all central PA terminals through the 12Z TAF period as a high pressure slides across the Northeast. Southerly return flow will develop across the Commonwealth this afternoon due to a light pressure gradient on the western periphery of the high pressure, with sustained winds between 5-10 kts at our terminals, as well as gusts to 15-20 kts during the afternoon (18Z-22Z) at KBFD/KJST where the pressure gradient will be slightly tighter.

Fog chances look low (10-20%) again for tonight as a light pressure gradient keeps southerly winds of around 5 kts over most of the state, with some high clouds moving over our western terminals (KBFD/KJST/KAOO) overnight. Winds will be lower across the Lower Susquehanna Valley (KMDT/KLNS) where the high pressure center is closer by, with some mesoscale model guidance (e.g. the HRRR and 3km NAM) suggesting at least some localized fog development in that area.

Moreover, wind shear looks to approach LLWS criteria at KBFD between 03Z-12Z Thursday, but is below LLWS thresholds by around 5 kts at this time. The evolution of potential fog development across portions of the Lower Susquehanna Valley & of potential LLWS at KBFD after 03Z Thursday will continue to be evaluated for the next TAF package.

Outlook...

Wed-Thu...VFR.

Fri...Chance of -SHRA especially in the N/W.

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

Sun...Chance of afternoon -SHRA in the NW.

CTP WATCHES/WARNINGS/ADVISORIES

Freeze Warning until 9 AM EDT this morning for PAZ026>028-035- 036-049>052-056-057-059-063>066. Freeze Watch from late tonight through Thursday morning for PAZ026>028-035-036-049>052-056-057-059-063>066.