textproduct: State College

WHAT HAS CHANGED

*Minor changes for the upcoming 3 days, but will closely monitor the potential for a potential MCS moving across the NW third of PA late Wed night and early Thursday.

KEY MESSAGES

1) Another dry day with scattered clouds and low humidity.

2) Severe thunderstorm risk for Wed night/Thursday 6/17-18, with a gusty westerly gradient wind of 30-35 mph in the afternoon across the NW half of the state.

DISCUSSION

KEY MESSAGE 1: Another dry day with scattered clouds and low humidity.

Mainly clear to partly cloudy skies are expected through the rest of the afternoon with a light south wind. Temperatures will max out around 70 degrees across the north and west, while areas to the south and east will see high temperatures in the mid to upper 70s.

Developing southerly breeze tonight and Wednesday, combined with the passage of a weak sfc and upper level trough, will bring some deeper layered clouds over mainly the NW half of the CWA. A period of showers and maybe a brief TSRA looks likely late tonight and early Wednesday, followed by another dry and warm day for the midday and afternoon hours Wed.

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KEY MESSAGE 2: Severe thunderstorm risk for Wed night/Thursday 6/17-18, with a gusty westerly gradient wind of 30-35 mph in the afternoon across the NW half of the state.

Latest model guidance is a bit concerning regarding the potential for an Eastward/SEWD moving MCS late Wed night and Thursday AM. The area most prone to seeing this will be the NW Mtns of PA where a surge of llvl moisture and warmer temps will lead to at least several hundred J/kg of MU CAPE - mainly across the NW half of PA.

We'll be monitoring the potential timing for severe weather closely. It could be one of those rare nights where the number and timing of storms makes it a rather noisy night to sleep undisturbed.

The severe threat shifts to the southeastern half of the CWA for Thursday, though there still remains some uncertainty regarding how much the airmass will be able to recover behind any morning convection and cloud cover.

The nose of a very strong, 40-50 KT swrly 850 mb jet 50+ KT at 700 mb (both being 3-4 sigma on the standardized anomaly scale), the the left exit region of a 100 KT 250 mb jet and PWATS around 1.5 inches (with the potential for a narrow tongue of an EML surging east ahead of a strong sfc cold front) will create a favorable synoptic setup for severe weather (High Cape Low shear Environment).

Another notable weather factor for the bulk of the daylight hours Thursday will be the likelihood of 30-35 kt gradient, westerly wind gusts focused mainly across the NW half of the CWA.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

VFR conditions are expected through the 18Z TAF period with scattered clouds around 5000 feet likely sticking around through the rest of the afternoon. Winds will be light out of the south-southwest into the evening, before becoming variable at less than 5 knots for tonight. Mid and high clouds increase from west to east overnight ahead of a low pressure system that will track well to our north. This system will bring a few showers and possibly even a thunderstorm to northern PA into the morning. The best chance for rain will be at BFD and IPT, though a few showers may make it as far south as JST, AOO, and UNV. Some guidance shows additional showers developing around MDT and LNS, though confidence is too low to introduce any mentions of rain in the TAF for now.

Scattered to broken clouds between 5000 and 10000 feet will stick around through Wednesday morning, though rain becomes less likely after 14Z. Winds will be out of the southwest around 10 knots with gusts of 15 to 20 knots possible by late morning. Additional widely scattered showers may develop during the afternoon, but most TAF sites are expected to remain dry at this point.

Outlook...

Wed...Higher chances for -SHRA/-TSRA, restrictions more likely late. High probability (90+ percent) for LLWS Wed night into Thursday morning as the axis of an anomalously strong south/southwesterly LLJ slides east across the Commonwealth.

Thu...Restrictions possible in -SHRA/-TSRA.

Fri...Showers ending.

Sat-Sun...Chance of afternoon showers and thunderstorms over the north and west.

CTP WATCHES/WARNINGS/ADVISORIES

None.