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 patchy valley fog in Northern PA early, otherwise abundant sunshine and low daytime 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 patchy valley fog in Northern PA early, otherwise abundant sunshine and low daytime humidity.

Clear skies, light wind and chilly temps with a near zero T/Td spread across the northern 2/3rds of the state has led to valley fog across the deeper valleys of North Central and NW PA early this AM.

Unseasonably chilly temps to start the day with 37F being the lowest readings noted in McKean and Elk County and upper 30s speckled elsewhere as far south as portions of rural Centre County.

A developing 5-10 kt swrly breeze and abundant morning sunshine will lead to notably warmer afternoon temps (5-8 deg F higher compared to Monday - across the bulk of the CWA). The exception will be across the Lower Susq Valley where the DOD temp change will likely be 2-3 deg F.

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 potentialfor 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 bulk of the convection and severe weather threat with a high shear/low CAPE setup will shift to the SE half of the CWA Thursday.

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 /12Z TUESDAY THROUGH SATURDAY/

VFR conditions continue through 06Z Wednesday with very high (> 80%) confidence, with light winds under the influence of high pressure. Winds increase slightly tomorrow with isolated gusts over 10 knots; however, confidence in stronger wind gusts remain too low to include in the TAFs before decreasing Tuesday night into Wednesday morning.

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...Chance of showers and storms later in the day across the north and west.

CTP WATCHES/WARNINGS/ADVISORIES

None.