textproduct: State College

WHAT HAS CHANGED

* Special Weather Statement in effect for locations south of I-80 through 6PM for an elevated risk of rapid wildfire spread. * Increased wind gusts each of the next several afternoons as a series of upper level disturbance move across New York.

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 continues to drift off the East Coast this afternoon as upper level ridging builds in and surface pressure decreases ahead of an approaching surface low drifting across the Upper Midwest. Clouds will continue to increase 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 as low as the upper 30s and the persistently dry fine fuels across the southern third to half of the state to create an elevated threat for wildfire spread. A Special Weather Statement remains in effect until 6PM Sunday for locations south of I-80 in Central PA.

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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). Sufficient uncertainty exists right now such that the details of timing/location/intensity of severe weather remain fuzzy. If you have outdoor plans this week, continue to monitor the forecast - no need to cancel anything yet!

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 /18Z SUNDAY THROUGH FRIDAY/

VFR conditions are expected for all central PA airfields through this evening and overnight 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 25 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 will overspread northwest PA before dawn on Monday and overspread the area through the day. MVFR ceilings are favored at BFD by mid morning and could reach JST/UNV/IPT toward the end of the 18Z TAF package. As rain showers encounter drier air and downsloping winds with southeastward extent, they will weaken/dissipate. Brief MVFR visibilities are possible, but widespread/persistent restrictions from rain are not likely.

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 IPT, MDT and LNS, but confidence remains too low to prevail any restrictions.

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.

Fri...Restrictions possible early, then improving to VFR in the afternoon.

CTP WATCHES/WARNINGS/ADVISORIES

None.