textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Increasing rain chances into next week.

KEY MESSAGES

1. A cool and very dry airmass will be in place today into Sunday, with a Red Flag Warning for our entire forecast area until 11 PM this evening. Conditions will not be as windy on Sunday, however dry air will keep fire danger elevated across the area. 2. Warm temperatures and increased moisture next week with shower and thunderstorm chances increasing.

DISCUSSION

Key message 1: A cool and very dry airmass will be in place today into Sunday, with a Red Flag Warning for our entire forecast area until 11 PM this evening. Conditions will not be as windy on Sunday, however dry air will keep fire danger elevated across the area.

In the wake of a cold frontal passage last night, a cool and very dry airmass has set up. Upper trough remains in place over the East Coast and as it moves east, the best upper confluence will shift east of the Appalachians pulling a surface high with it. In the meantime, the pressure gradient between the departing front and the incoming high will keep gusty surface conditions through the rest of today, weakening briefly overnight as the surface ridge passes through the area, but as the high moves offshore Sunday morning the gradient around especially the western periphery will increase again. Red Flag conditions will continue today though in some areas dewpoints have not quite dropped as quickly as forecast. Dry air aloft should mix down through the afternoon. With the excellent radiational conditions, lows tonight will drop 8-10 degrees below normal, easily below freezing in the mountains and even some across the NW Piedmont.

Surface flow around the western periphery of the high will flip around to the south on Sunday, allowing temperatures especially across the mountains and along the I77 corridor to warm a few degrees from today's highs, though still a few degrees below late March normals. Dewpoints will increase accordingly as well in response to the moist surface flow so RHs should not bottom out to critical levels area-wide. Plenty of areas will drop below 30% and most of our NC counties will likely drop below 25%. Winds will not be quite as high so can see the need for an Increased Fire Danger on Sunday, but will hold off to allow the RFW to remain in place today and provide time for additional coordination with land management agencies.

Key message 2: Warm temperatures and increased moisture next week with shower and thunderstorm chances increasing.

High pressure will slide off the coast early next week leading to warming and an increase in moisture as the week goes along. A cold front will approach from the west on Wednesday, but then nearly stall and only slide through part of the area by Friday. The front will then return north next Saturday. This will act to keep the area in moist flow leading to a chance of showers and a few thunderstorms each day and night for the middle to end of the week. The rainfall amounts are expected to be light to moderate.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

At KCLT and elsewhere: VFR through the period. with only passing high clouds Gusty N/NNE winds at TAF time will continue through the afternoon, though peak gusts will continue to slowly diminish, dropping off after sunset. High pressure passing to the north and moving offshore will veer winds around to S of E around the same time the gusts diminish, current timing for KCLT is 01z. Direction will be VRB for a period of time overnight, but pick up from the SE with mixing on Sunday.

Outlook: Dry, VFR conditions are expected into early next week. Moisture will increase Tuesday into Wednesday, bringing chances for convection and associated restrictions.

GSP WATCHES/WARNINGS/ADVISORIES

GA...Red Flag Warning until 11 PM EDT this evening for GAZ010-017- 018-026-028-029. NC...Red Flag Warning until 11 PM EDT this evening for NCZ033- 035>037-048>053-056>059-062>065-068>072-082-303-501>510. SC...Red Flag Warning until 11 PM EDT this evening for SCZ008>014- 019-101>109.