Plaincast

What has changed

Increased confidence in the threat of severe weather tomorrow, Tuesday, July 28.

Updated Aviation discussion through Tuesday evening.

Messages

Isolated storms across eastern NC possible this afternoon/evening.

A slight risk (2 of 5) of severe weather on Tuesday. The main hazard will be damaging winds, with large hail and a tornado or two also possible.

Discussion

KEY MESSAGE 1. Isolated storms across eastern NC possible this afternoon/evening.

Isolated thunderstorms are expected across portions of Eastern NC this afternoon, mainly along and east of the I-95 corridor, as daytime heating interacts with the sea breeze and a lingering boundary. Latest ensemble guidance indicates storms will develop along the sea breeze with limited inland progression into the Coastal Plain, though a few isolated strong storms capable of gusty winds cannot be ruled out. Storm activity will rapidly diminish after sunset. Overnight, areas that received rainfall may see low stratus clouds and patchy fog develop where winds become light and calm.

KEY MESSAGE 2. A slight risk (2 of 5) of severe weather on Tuesday. The main hazard will be damaging winds, with large hail and a tornado or two also possible.

Details: Large-scale ascent associated with an approaching mid-level shortwave trough and an attendant cold front will provide sufficient forcing for convective initiation Tuesday afternoon, with storms becoming more widespread through the evening. Ahead of the front, southerly winds will bring warm and moist air to the region, supporting MUCAPE of roughly 1500-3000 J/kg Tuesday afternoon. This will combine with 40-50 knots of 0-8 km shear to support initially supercells with a localized wind and hail threat. Storm interactions in the late afternoon and evening should then favor clustered convection and bowing segments, with the primary hazard being a damaging wind threat. A brief tornado or two will also be possible as the low-level jet strengthens and increases low-level shear and helicity from the Triangle eastward. The threat of flooding should be a lesser threat due to quicker storm propagations expected. High rain rates within the strongest storms may produce localized flooding in urban and poor drainage areas.

Timing: Storms look to start forming and approach the region in the early afternoon, with storms entering the western Piedmont around 2 to 4 PM before progressing eastward across the region. The most likely timing for the severe weather threat currently appears to be between 4 and 10 PM, potentially lasting until midnight.

What could diminish the threat: While confidence is increasing in the threat of severe weather, the primary forecast uncertainty remains how upstream convection currently located in the Great Lakes region will evolve overnight and into tomorrow. If rain/cloud cover is able to persist over the mountains into the morning hours more than currently expected, the destabilization in the Carolinas would be reduced tomorrow afternoon, leading to a lesser severe threat.