textproduct: State College

WHAT HAS CHANGED

* Increased max wind gusts for Thursday, mainly over the Laurels

KEY MESSAGES

1) No change to marginal severe/heavy rain risk overnight through Thursday afternoon

2) Unusually windy by June standards Thursday

DISCUSSION

KEY MESSAGE 1: No change to marginal severe/heavy rain risk overnight through Thursday afternoon

HREF and REFS 3hr PMMs both indicate upstream convective activity in the Ohio Valley will likely weaken as it reaches NW PA late tonight. This suggests a rather low potential for severe wx and/or heavy rain impacting CPA.

Early day/leftover convection sliding to the southeast brings a reduced severe wx risk to much of CPA on Thursday with the strongest activity most likely to develop along a cold front between midday and late afternoon across the lower Susquehanna Valley or to the southeast of I-81. Very strong low level wind fields for this time of year will promote a isolated to scattered damaging wind threat. SPC made no changes to the convective outlook for Thursday with the 1730UTC update.

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KEY MESSAGE 2: Unusually windy by June standards Thursday

After further consideration and collaboration with LWX and PBZ, we've posted a wind advisory for the daylight hours over the Laurel Highlands. BUFKIT profiles from 18Z runs over JST bring 50KT winds down to just 3500ft AGL. Peak winds on the hill tops and through the gaps will be up to 50 MPH.

Prev... Anomalously strong -4SD (near record low MSLP) surface low- pressure tracking through the Lower Great Lakes will result in very windy day by June standards on Thursday with widespread gradient/non-thunderstorm wind gusts between 35-45 mph. Max wind gusts could approach advisory criteria in some areas. Fully leafed trees may also lead to a higher impact vs. more typical cold season wind events. We will continue to highlight wind impacts in the HWO with some considerations given to a NPW headline for this cycle.

AVIATION /06Z THURSDAY THROUGH MONDAY/

Not a lot of change from the 00Z TAF package.

Very deep low and strong shear today, but instability is limited so far, given that dewpoints not real high. Have seen many cases where weaker warm advection can bring in the higher dewpoint air faster.

Thus the main concern early today is still LLWS, followed by gusty winds this afternoon, as the sfc flow becomes more westerly.

Main change to the package was to add more detail late this evening.

Earlier information below.

Clouds are continuing to build in from the west as the deep center of low pressure approaches from the Great Lakes. Mid and high clouds increase overnight ahead of a warm front lifting northward through the region, and light rain will overspread Central PA from west to east after 00Z. This will be the first of two rounds of rain. A very strong low- level jet for this time of year will move through tonight, leading to a period of LLWS at nearly all TAF sites into the morning.

A weakening line of showers and thunderstorms is then expected to move through along a cold front, first reaching BFD and JST in the 08-09Z timeframe. This will be the second round of rain. This line should be east of all TAF sites by 15-18Z. PROB30s have been included at all TAF sites to provide some more specific timing for heavier showers and thunderstorms, but the timing may have to be adjusted as confidence increases. There is some potential for these showers and storms to mix down some of the very strong winds aloft, but confidence is low on this occurring.

Scattered showers will continue through the rest of the morning behind the front, but widespread rainfall is unlikely after 15Z. The bigger concern for Thursday will be strong westerly winds. Gusts to 30 knots appear possible at all TAF sites, with BFD, JST, AOO, and UNV, potentially seeing gusts as high as 40 knots.

Outlook...

Fri-Sat...VFR with no significant weather.

Sun...Showers and thunderstorms developing in the afternoon across the far west.

Mon...Restrictions possible with widespread showers and thunderstorms.

CTP WATCHES/WARNINGS/ADVISORIES

Wind Advisory from 7 AM this morning to 6 PM EDT this evening for PAZ024-033-034.