textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Frost Advisory issued for all of our NC counties except the northern mountains and adjacent Blue Ridge area.

KEY MESSAGES

1. Frost Advisory for all of our NC counties, except the northern mountains and adjacent Blue Ridge area where the growing season hasn't officially begun. Patchy from possible over the Upstate and NE GA. 2. Fire weather concerns continue through this weekend, with relative humidity falling to near-critical levels each afternoon. A Fire Danger Statement remains in effect until 8 PM this evening for Northeast Georgia.

DISCUSSION

Key message 1: Frost Advisory for all of our NC counties, except the northern mountains and adjacent Blue Ridge area where the growing season hasn't officially begun. Patchy from possible over the Upstate and NE GA.

Surface high pressure moves off the New England coast tonight but a ridge remains over the area through Thursday night. Some light wind will linger across portions of the area, along with some cirrus, preventing the best radiational conditions. Still, many locations will decouple. In addition, even though the air mass is dry, there will be enough moisture recovery overnight for frost to form where temps are low enough and winds are light enough. Expect the most favorable conditions will be over our NC counties where the growing season is officially underway. Have issued a Frost Advisory for these locations. That said, the frost could remain more patchy in the normally warmer thermal belt areas of the southern NC foothills, but chance is high enough to have the advisory there. Frost will likely be more patchy across the Upstate and NE GA, but rural areas of York, Chester, and Cherokee Counties could see more in the way of frost.

The air mass continues to modify Thursday and Thursday night even as the surface ridge remains in place. Some of the guidance breaks off a chunk of the sfc high over the area Thursday night, so radiational cooling conditions could become more favorable. Patchy frost is possible, but right now looks more likely in the mountain valleys. Will have to keep an eye on trends to see of another advisory will be needed.

Key message 2: Fire weather concerns continue through this weekend, with relative humidity falling to near-critical levels each afternoon. A Fire Danger Statement remains in effect until 8 PM this evening for Northeast Georgia.

Surface high pressure currently centered off the coast of Maine will continue to ridge down the Eastern Seaboard for the next few days, resulting in steady dry advection in the low-levels. Forecast profiles for this afternoon, Thursday afternoon, and Friday afternoon all feature a robust dry layer above 850mb...enough to permit diurnal mixing and RHs in the 25-30% range for most of the area. Some locations could see RH <25%. Gusty winds of 15-20mph today support a Fire Danger Statement for Northeast Georgia...which remains in effect through 8 PM. For the remainder of the week, winds should be quieter than today...likely not getting gusty enough for a slam dunk Fire Danger Statement...but low RHs alone should be enough for at least isolated fire weather issues.

Dewpoints will begin to climb again on Monday, as surface high pressure retreats into the Atlantic, and southwesterly winds begin to usher in some Gulf moisture.

The South Carolina Forestry Commission's Red Flag Fire Alert remains in effect until further notice.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

At KCLT and elsewhere: Low end gusty NE wind, lighter SSE wind at KAVL, and cirrus will continue through the afternoon. Winds become light by evening into the overnight, then pick back up from the NE, SSE at KAVL, during the day Thursday. A brief period of low end gusts is possible as mixing begins during the mid-morning, but overall speeds should be lower. Mainly cirrus overnight and Thursday as well, but can't rule out some VFR stratocu with heating on Thursday.

Outlook: VFR thru the late part of the week courtesy of high pressure. A developing easterly low level flow could eventually bring a return of low clouds over the weekend. VFR with a more southwesterly flow Monday.

GSP WATCHES/WARNINGS/ADVISORIES

GA...INCREASED FIRE DANGER until 8 PM EDT this evening for GAZ010- 017-018-026-028-029. NC...Frost Advisory from 2 AM to 9 AM EDT Thursday for NCZ035>037- 048-051>053-056>059-062>065-068>072-082-502-504-506>510. SC...None.