textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Highs trending cooler Sunday into Monday with cold air damming expected to develop.

KEY MESSAGES

1. Hot and humid east of the mountains through Saturday before cooler and less humid conditions return Sunday into early next week. Those with outdoor plans should stay hydrated and take frequent breaks in air-conditioned or shaded areas. Never leave children or pets in unattended vehicles. 2. Scattered diurnal showers and thunderstorms are expected across mainly western North Carolina through Friday before a cold front brings better shower and thunderstorm chances back area-wide this weekend into Monday. A few strong to possibly severe storms are possible during peak heating hours each day through Friday, with damaging wind gusts being the main hazard with any severe storms that manage to develop.

DISCUSSION

Key message 1: Hot and humid east of the mountains through Saturday before cooler and less humid conditions return Sunday into early next week. Those with outdoor plans should stay hydrated and take frequent breaks in air-conditioned or shaded areas. Never leave children or pets in unattended vehicles.

Hot and humid conditions linger through Saturday east of the mountains as the western periphery of the Bermuda High lingers over the western Atlantic. Despite highs east of the mountains climbing into the low to mid 90s each day, dewpoints are expected to mix out each afternoon keeping heat indices below advisory criteria (<105 degrees). Breezy SW/W winds will develop each afternoon/early evening east of the mountains with gusts expected to remain well below advisory criteria, ranging from 15-25 mph. Breezy winds will allow for some relief from the humid airmass each day. Temperatures will end up around 4-7 degrees above normal area wide through Saturday thanks to low-level flow being mainly W/SW'ly.

The Bermuda High gets nudged farther south as a cold front tracks across the region this weekend, bringing a cooler and less humid airmass behind it Sunday into early next week. Cold air damming looks to develop in the wake of the front late this weekend into early next week as surface high pressure builds over the Northeast and Mid-Atlantic. CAD may allow highs to actually fall below normal on both Sunday and Monday, which we won't complain about for mid- July and could definitely use after the last week.

Key message 2: Scattered diurnal showers and thunderstorms are expected across mainly western North Carolina through Friday before a cold front brings better shower and thunderstorm chances back area- wide this weekend into Monday. A few strong to possibly severe storms are possible during peak heating hours each day through Friday, with damaging wind gusts being the main hazard with any severe storms that manage to develop.

Daily chances for afternoon and evening showers and thunderstorms will continue across mainly western North Carolina through Friday. Some activity could develop across the South Carolina Upstate and northeast Georgia depending on how outflow boundaries propagate the next few afternoons. Per usual, a few strong, sub-severe storms are possible during peak heating hours with the severe storm potential expected to remain isolated. The main hazard with any severe storms that manage to develop is damaging wind gusts from microbursts thanks to weak deep layer shear and decent destabilization expected each afternoon.

Better shower and thunderstorm chances return area-wide this weekend into Monday ahead of and along a cold front. Although deep layer shear will be slightly better, cloud cover along with cooler temperatures (especially on Sunday and Monday due to CAD developing) could limit destabilization. Thus, confidence on the severe weather potential with this front is low. Drier conditions should return by Tuesday as surface high pressure builds into the region behind the departing front.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

At KCLT and elsewhere: Dry and VFR outside of morning fog/stratus and afternoon/evening TSRA. Fog and stratus have already developed across portions of the mountain valleys this morning and will continue to spread and thicken through daybreak. KHKY could also see fog and stratus develop through daybreak but confidence is lower compared to KAVL. Any fog/stratus that develops will lift around or shortly after sunrise. TSRA should remain more isolated this afternoon and evening, with the NC terminals have the best chance to see activity develop. Thus, went with PROB30s for TSRA and associated restrictions late this afternoon into early this evening at KAVL, KHKY, and KCLT. The SC terminals should remain dry today. Calm to light and VRB winds will linger through the early morning hours before picking up out of the SW east of the mountains and mainly NW at KAVL. Wind speeds will gradually increase throughout the day across most terminals with speeds ranging from 5-12 kts. However, lighter winds are expected at KAVL and KHKY. Low-end gusts may develop across the SC terminals this afternoon/early evening. Lighter winds return tonight with wind direction turning more WSW east of the mountains.

Outlook: The NC terminals will have the best potential to see TSRA each afternoon and evening through Friday. SHRA/TSRA chances return for all terminals this weekend into Monday. Low stratus and/or fog will be possible each morning in the mountain valleys and in locations that see appreciable rainfall the previous afternoon/evening.

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...None. SC...None.