textproduct: State College

WHAT HAS CHANGED

* Severe storms Tuesday are even more certain. * Smoke today will be mainly over western PA

KEY MESSAGES

1) Severe thunderstorms are near-certain for Tuesday. Widespread severe weather and scattered flash flooding are expected.

2) Thicker wildfire smoke should stay mainly over western PA, with levels barely noticeable in the east.

DISCUSSION

KEY MESSAGE 1: Severe thunderstorms are near-certain for Tuesday. Widespread severe weather and scattered flash flooding are expected.

Severe weather is once again on the docket. Tuesday (Day 2) has been consistently highlighted by SPC for many days as a potentially active and dangerous weather day. The threat for damaging wind is very certain, and could occur anywhere over the CWA Tuesday afternoon and evening. The threat for hail is higher than they were this past Saturday, and the threat for tornadoes is about the same.

A potent upper trough will dig into the Great Lakes tonight and early Tuesday. Warm air will surge northward in the morning hours. Some showers and weaker storms will roll through southern and eastern PA late tonight, perhaps helping to raise dewpoints. It looks like a pre- frontal trough will charge in from the NW and cross the CWA in the afternoon hours. The real cold front will arrive later in the evening/early night. It may arrive too late (some stabilization could already happen) and have little left to work with by the time it gets into the CWA to make much of a severe threat.

There is also a flooding threat, but only if there will be a location or two that gets multiple rounds of heavy rain. There should be a good movement to the storm cells, limiting the threat somewhat. However, moisture is expected to be very high, PWATs 1.5-2".

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KEY MESSAGE 2: Thicker wildfire smoke should stay mainly over western PA, with levels barely noticeable in the east.

An air quality alert/action day remains in effect for most of southwestern PA where levels are expected to be unhealthy for sensitive groups. HRRR smoke plume progs keep the thicker smoke over western PA with much less over the east. The light wind this morning will turn from easterly to southerly through the day which will help to keep the near-sfc smoke from spreading to the east.

AVIATION /08Z MONDAY THROUGH FRIDAY/

Mostly clear skies and dry conditions means VFR is expected to prevail for the next 24 hours. Winds will remain light, and patchy fog development is possible over the region. Confidence is overall low on any impactful fog reaching the airfields outside of KBFD. The probability of visibility restrictions elsewhere remain less than 30%.

Smoke will once again flow into central PA from the north today and be present through this afternoon. Density of this smoke is expected to be much lighter based on output from the HRRR/RRFS models (which have the ability to model smoke), this smoke will linger through at least tomorrow while still being too light to bring visibility restrictions.

Outlook...

Tue-Wed...Brief restrictions possible in showers/t-storms with cold FROPA expected between Tuesday/Wednesday. T-storms more likely on Tuesday, with lingering showers possible Wednesday.

Thu-Fri...VFR Conditions.

CTP WATCHES/WARNINGS/ADVISORIES

Air Quality Alert until midnight EDT tonight for PAZ024-033.