textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

No major changes.

KEY MESSAGES

1. Much cooler today with below normal highs expected. Showers will continue to blossom through daybreak, mainly along and north of I-85 and west of I-77. A low-end flood threat will persist through at least daybreak with this activity. 2. Drier conditions return Monday night, persisting through mid-week. A cold front will bring rain chances back towards the end of the week. Above normal temperatures return for the rest of the week.

DISCUSSION

Key message 1: Much cooler today with below normal highs expected. Showers will continue to blossom through daybreak, mainly along and north of I-85 and west of I-77. A low-end flood threat will persist through at least daybreak with this activity.

A wedge-like pattern will remain in place today thanks to high pressure building in from the northeast. Easterly 850 mb flow has allowed showers to develop mainly along and north of the I-40 corridor this morning. Shower activity will continue to blossom through daybreak as it progresses W/SW, mainly along and north of I- 85 and west of I-77. With weak shear in place, shower activity has been slow moving. Slow shower movement combined with impressive rainfall rates will lead to a low-end flood threat through at least daybreak. Mainly isolated nuisance to minor flooding is possible but cannot entirely rule out the potential for localized flash flooding for locations that receive multiple rounds of heavy rainfall. Drier conditions should gradually return from east to west throughout the day. NE'ly flow combined with cloud cover sticking around will lead to below normal highs today. Finally some much needed relief from the heat and humidity!

Key message 2: Drier conditions return Monday night, persisting through mid-week. A cold front will bring rain chances back towards the end of the week. Above normal temperatures return for the rest of the week.

Unfortunately, below normal highs will be short-lived as an upper anticyclone builds into the Southeast Monday night into Tuesday night, lingering over the region through Wednesday. This will, however, allow dry conditions to return Monday night through Wednesday night. The anticyclone gradually breaks down Wednesday night as weak upper troughing tracks eastward and attempts to dig as far south as the Carolinas and northern Georgia Thursday into Friday. This will drag a surface cold front across the GSP forecast area late Thursday night into Friday before stalling over the Southeast over the weekend. As a result, shower and thunderstorm chances should return Thursday into Friday ahead of the front and may linger through the weekend behind the front. Above normal highs can be expected the rest of the week, although some locations may end up near normal Tuesday afternoon.

AVIATION /06Z MONDAY THROUGH FRIDAY/

At KCLT and elsewhere: SHRA should gradually expand in coverage through daybreak, mainly impacting KAVL and the SC Upstate terminals. KAND may not see SHRA develop until closer to daybreak. Although some SHRA is floating around near KHKY, the bulk of activity has pushed south of the terminal so went with dry conditions. KCLT should remain dry through the period. Should see drier conditions return by mid to late morning. MVFR cig restrictions have already developed everywhere but KCLT as of 05Z. Conditions will gradually deteriorate through daybreak with mainly IFR cigs and IFR to MVFR vsbys expected. Any SHRA that develops should improve cigs and vsbys slightly so have this accounted for in the morning TEMPOs. Restrictions will be slow to lift, especially cigs, throughout the day. Should see cigs lift to VFR at KCLT shortly after daybreak with the rest of the terminals not seeing VFR return until early to mid-afternoon. Wind direction will remain NE east of the mountains and E/SE at KAVL through the period. Low-end gusts of ~16-20 kts should develop east of the mountains by late morning or early afternoon before gradually diminishing by late afternoon or early evening.

Outlook: Drier and VFR conditions lingering through mid-week outside of morning mountain valley fog and low stratus. Rain chances and possible restrictions back Thursday into Saturday in association with a cold front.

GSP WATCHES/WARNINGS/ADVISORIES

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