textproduct: State College

WHAT HAS CHANGED

* No significant changes.

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 pleasant conditions for Labor Day outdoor activities.

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

As the center of high pressure drifts southeast of PA on Tuesday and Wednesday, return southwesterly flow will usher in an uptick and heat and humidity. The never ending ridge of high pressure centered over the Central US will also begin to nudge into the Mid Atlantic as upper troughing over the Northeast retreats and the amplified upper level pattern begins to flatten out a bit.

Highs on Tuesday will range from the mid 70s to mid 80s and Wednesday will trend about 5 degrees warmer areawide. Combined with dewpoints back in the mid to upper 60s, heat index values may crest the 90F mark in the south central mountains on Wednesday. Dry conditions will prevail and we'll continue to enjoy a break from very active stretch of severe weather we've dealt with this summer.

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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 afternoon 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.

The cold front will also bring a chance for showers and storms ahead of and along the front. The risk for severe weather will depend on the magnitude of a shortwave trough racing through the region and any associated jet dynamics in play.

Vertical wind profiles look unidirectional, so the primary hazard would be from damaging winds. Timing of the cold front and dewpoints largely staying out of the upper 60s to lower 70s range are the 2 main reasons to think storms will not get too crazy, unlike recent events. Timing of the cold front has been similar the last few days.

Rain arrives in northwest PA late Wednesday night and will sag south across the Commonwealth during the day on Thursday.

High pressure builds behind the cold front, giving way to a dry and sunny Friday. There could be a few isolated PM showers and a storm or two on Saturday or Sunday, but most locations will stay dry.

AVIATION /18Z MONDAY THROUGH SATURDAY/

VFR conditions are virtually certain to continue this afternoon and evening with plentiful sunshine and light winds. There will be some fair weather stratocumulus clouds across the region this afternoon before dissipating this evening; however, any decks will likely stay between 3,000-4,000 ft AGL. Guidance outlines another round of patchy fog will be possible into Tuesday morning, though it may not be as extensive as it is this morning. BFD/UNV/IPT will be the main airfields of concern; however, drier low-level dry air in recent observations allows for slightly higher confidence in less restrictions overnight into Tuesday morning. Any fog Tuesday morning likely mixes out quickly with VFR conditions likely (> 90% chance) by 14Z and into the end of the 18Z TAF package.

Outlook...

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

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

Fri...VFR prevails with drier conditions across all of central Pennsylvania.

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

CTP WATCHES/WARNINGS/ADVISORIES

None.