textproduct: State College

WHAT HAS CHANGED

* Kept max temperatures on Friday a bit cooler than model guidance, especially across eastern zones, due to the expected presence of a backdoor cold front.

KEY MESSAGES

1) Periods of beneficial rainfall expected into this weekend.

2) Warmest temperatures since late last Fall poised to arrive areawide by Saturday.

DISCUSSION

KEY MESSAGE 1: Periods of beneficial rainfall expected into this weekend.

On the heels of one of the driest winters on record, periods of beneficial rain are expected into this weekend. Patchy light rain will linger across southern PA today, before a more robust moisture surge spreads widespread steadier rain into central PA overnight through Thursday. Rainfall of 0.75-1.25" is expected through Thursday evening.

PoPs and QPF for Friday look comparatively low. The next good chance for widespread rainfall will arrive Saturday into Saturday night, ahead of and accompanying a cold frontal passage.

KEY MESSAGE 2: Warmest temperatures since late last Fall poised to arrive areawide by Saturday.

Cold air damming will delay the arrival of the warm air for much of central PA until Saturday. However, the persistent and amplified upper level ridging over the Southeast U.S./Western Atlantic will (eventually) provide a significant springtime warming trend by Saturday. Fcst max and min temperatures will be 15-30 degrees above average on Saturday.

Even with a cold frontal passage Sat night, it should remain unseasonably mild into early next week.

AVIATION /00Z THURSDAY THROUGH MONDAY/

IFR to LIFR ceilings and visibilities are underway across most of our sites this evening as mild, saturated air aloft overruns cool, moist air at the surface, forming an area of persistent low clouds and fog. This will expand into the Northern Tier as moisture flows into the region ahead of an approaching low pressure system, with a deterioration to LIFR conditions expected overnight.

Rounds of rain and showers associated with the approaching system will move west to east across Pennsylvania through tomorrow evening, with the HREF depicting a wave of steadier rain during the overnight and early morning hours, and another wave of steadier rain in the afternoon and through the evening. Pockets of weak elevated instability embedded within these waves could result in rumbles of thunder, though MUCAPE values look too meager (0 to 200 J/kg) for prevailing thunderstorms at any one site. A relative lull is expected between these waves during the late morning and early afternoon, though scattered rain showers are still expected.

Outlook...

Fri...Stationary front across the region. Restrictions possible, especially across central/eastern airfields.

Sat...Restrictions remain possible, especially in the north and east. VFR most likely from KJST south and west, where winds could get gusty in the warm sector. Afternoon/evening showers and thunderstorms likely with cold FROPA.

Sun...Trending towards VFR.

Mon...Restrictions possible as low-level moisture increases.

CTP WATCHES/WARNINGS/ADVISORIES

None.