textproduct: State College

WHAT HAS CHANGED

* New details about the next chance for storms & gusty synoptic scale winds Wednesday night into Thursday.

KEY MESSAGES

1) A nice end to the Labor Day weekend.

2) Uptick in heat and humidity for mid midweek.

3) Showers, storms, and gusty winds Wednesday night into Thursday.

DISCUSSION

KEY MESSAGE 1: A nice end to the Labor Day weekend.

A refreshingly low dewpoint airmass has settled in across Pennsylvania and will ensure comfortably cool temperatures tonight and pleasant conditions for Labor Day outdoor activities.

High pressure will build over the region tonight leading to clear skies, calm wind and quite cool temperatures.

A large temperature difference between the air, and still warm waters of the rivers and lakes, will support widespread valley fog development by early Monday morning.

Lows will range from the mid 40s in the northwest mountains to mid 50s in the southeast. No doubt a perfect night to open the windows!

After morning valley fog mixes out, Labor Day will feature weather conditions be about as good as it gets. A few wispy cirrus clouds will accentuate bright blue skies with abundant sunshine, passing fair weather cumulus clouds, and seasonable temperatures.

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KEY MESSAGE 2: Uptick in heat and humidity for midweek.

As high pressure drifts southeast of PA by Wednesday, a southwesterly flow will usher in warmer and a bit more humid airmass for later Wednesday. Most of the day will be dry.

Wind fields will be on the strong side, but dewpoints stay below 70 degrees, and frontal timing is late Wednesday night early Thursday, thus the risk of severe storms limited at this point.

While temperatures will be above normal on Wednesday, nothing like what we just had last week.

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KEY MESSAGE 3: Showers, storms, and gusty winds Wednesday night into Thursday.

By Wednesday night, a low pressure system will be moving across northern Ontario with a cold front extending south through the Great Lakes and Ohio Valley region. The pressure gradient will support a notable uptick in synoptic scale winds Wednesday night into Thursday. It's been awhile since we've had widespread gusty winds, but we're getting into the time of year where such a weather pattern becomes more common.

Gusty winds will ramp up Wednesday during the day out of the southwest ahead of an approaching cold front, and continue through Thursday afternoon shifting to a westerly direction after the front passes. Wind gusts of 25 to 35 mph seem realistic at this point, with the highest readings occurring at higher elevations in the Laurel Highlands.

Highest POPS for showers and storms will be on Thursday, as front moves into southern PA.

High pressure builds behind the cold front and the end of the week/start of the weekend looks sunny and dry with low humidity.

AVIATION /00Z MONDAY THROUGH FRIDAY/

VFR conditions will persist through at least the first half of tonight with a very light north to northeast breeze going calm at most airfields by shortly after midnight.

A strong signal for fog continues in much of model guidance this evening; thus, increasing confidence in fog impacting some subset of airfields across the region.

Best chance for fog and a 2-3 hour period of LIFR/VLIFR conditions will be at BFD/UNV/IPT while a briefer period of fog is expected at AOO.

The lowest confidence of any fog formation will be at LNS with current thinking that JST/MDT remain VFR by Monday morning. That being said about all of the fog mentions, there is a solution where dry air wins out and fog potential across the area remains minimal but that appears to be a lower confidence solution at this time.

Widespread VFR will return to the area by 13-14Z Monday with those conditions continuing through the end of the 00Z TAF package.

Outlook...

Tue...AM valley fog possible; otherwise predominantly VFR.

Wed...Primarily VFR, although late-day SHRA/TSRA possible across the northern tier.

Thu...Cold FROPA could bring scattered SHRA/TSRA areawide.

Fri...Primarily VFR conditions, some potential for afternoon SHRA/TSRA but uncertainty remains high.

CTP WATCHES/WARNINGS/ADVISORIES

None.