textproduct: State College

WHAT HAS CHANGED

* Elevated risk of wildfire spread once again today across primarily the Southern third to half of PA. * Nudged wind/gusts (from the SE to S) up by a few KTS today and trimmed dewpoints a bit for late this morning and this afternoon.

KEY MESSAGES

1) Elevated risk of wildfire spread once again today across primarily the Southern third to half of PA.

2) Warm up begins today and continues through the week; near- record warmth on tap for Wednesday and Thursday.

3) Several periods of showers and thunderstorms expected during the upcoming week, especially in the north and west.

DISCUSSION

KEY MESSAGE 1: Elevated risk of wildfire spread once again today across primarily the Southern third to half of PA.

High pressure centered near Albany, NY early today with a ridge extending south into the Delaware Valley of Eastern PA, will lead to mainly clear skies with a light east to southeast wind early today. A Frost Advisory continues through 12Z today across portions of the Lower and Mid Susquehanna Valley with min temps in the mid 30s where the growing season is active.

Look for an increase in cloud cover today as a warm front pushes Northeast from the Ohio Valley.

Southeast to South winds will also increase today with gusts in the low to mid 20s (MPH.) The wind will combine with min RHs in 30s and the persistently dry fine fuels across the southern third to half of the state to create an elevated threat for wildfire spread.

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KEY MESSAGE 2: Warm up begins today and continues through the week; near-record warmth on tap for Wednesday and Thursday.

LLVL warm advection kicks in today with a moderately gusty southerly flow ushering in a prolonged period of warmer than normal temperatures through the upcoming week.

On the large-scale, our ensemble prediction systems are in good agreement showing a mean upper-level trough across the western CONUS, with downstream upper ridging taking hold from the Gulf states up the eastern seaboard.

This will bring a notable warming trend, with daily highs ranging from the 70s-mid 80s across central PA from Tuesday onward.

The latest forecast brings near-record temperatures across the region Wednesday morning through Friday morning, with lows Thursday morning forecast to be warmer than our average highs this time of year. Highs in the 70s and 80s will accompany lows in the 50s and 60s. Dewpoints will start to approach the 60F mark, so it will feel a bit humid but not overly uncomfortable.

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KEY MESSAGE 3: Several periods of showers and thunderstorms expected during the upcoming week, especially in the north and west.

The storm track for the week ahead will run from SW to NE across the Great Lakes, with multiple waves of low pressure drifting into Ontario, CA. A frontal boundary will set up generally west to east across New York and keep unsettled weather in place across northwest PA in particular.

A few shortwaves ejecting from the mean Central/Western US trough will likely bring and increase in the chance for severe weather, which is well supported by some of the NCAR Ensemble guidance that highlights an elevated severe threat Tuesday (NW), Wednesday (all of PA) and Thursday (southeast PA).

The prob for showers/storms will be highest in northwest PA. Locations that have been wet lately will continue to see more rain, while drought- stricken locations across the southeast part of our CWA will see less rainfall.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

VFR conditions are expected for all central PA airfields through the 12Z TAF period under increasing mid and high level clouds. A few showers may develop this afternoon over northern PA ahead of a warm front, but limited moisture and weak forcing should keep them pretty isolated. The best chance for rain (around 20 percent) will be at BFD. Winds will be out of the south at 10 to 15 knots with gusts to 20 knots possible.

A 40 to 50 knot low-level jet will move in from the west after 00Z Monday, bringing a period of LLWS to all TAF sites. This will also usher in better low-level moisture, allowing ceilings to gradually lower through the night. Light rain may begin to enter northwest PA early Monday morning, but likely stays west of all TAF sites until after 12Z.

Recent guidance suggests the potential for low clouds to develop over the Lower Susquehanna Valley tonight as light southeasterly flow develops. This may lead to MVFR ceilings at MDT and LNS, though confidence is low on whether or not this occurs.

Outlook...

Mon...Restrictions possible in rain showers, especially northern and western TAF sites.

Tue-Thu...VFR most of the time, but brief restrictions possible in hit and miss showers and thunderstorms, mainly across the north and west.

CTP WATCHES/WARNINGS/ADVISORIES

Frost Advisory until 8 AM EDT this morning for PAZ027-028- 049>052-056-057-059-066.