textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Lowered dewpoints on Monday and Tuesday afternoon compared to the previous forecast, to account for stronger and deeper mixing depicted in recent model guidance.

Tweaked Monday's high temperature forecast based on current trends.

Updated the aviation forecast to reflect the recent 18Z TAF issuance.

KEY MESSAGES

1. Low-end fire danger conditions expected Monday and Tuesday afternoons. A Fire Danger Statement remains in effect through 7 PM Monday evening for northeast Georgia. 2. Clear skies and seasonable temperatures persist into next weekend.

DISCUSSION

Key message 1: Low-end fire danger conditions expected Monday and Tuesday afternoons. A Fire Danger Statement remains in effect through 7 PM Monday evening for northeast Georgia.

A dry and seasonably cold cP air mass remains in place across the Carolinas today, stoking expectations of another beautiful day. With sustained low-level CAA continuing beneath an upper low positioned well off the Atlantic coast, winds should remain elevated today, with deep mixing providing the impetus for gusts of 15-20mph during the afternoon hours, mainly across the low terrain.

That same mixing is already allowing dewpoints to drop dramatically across much of the forecast area, and is expected to result in RH values bottoming out below 30% across much of the area. Overlap between critical RHs and gusty winds will be intermittent at best, but will nonetheless provide conditions favorable for rapid spread of outdoor fires. As a result, a Fire Danger Statement remains in place for northeast Georgia, and even zones across NC and SC should expect low-end fire concerns this afternoon.

Daytime mixing should be a little less pronounced tomorrow, as the low pressure center pulls farther northeast and low-level flow weakens in response. Forecast soundings also exhibit more prominent subsidence atop the PBL, which should further inhibit deep mixing. Some degree of a dewpoint drop and another breezy afternoon are nonetheless expected, but RH values should crash less than on Monday, and wind gusts should be lower, and less frequent. By Wednesday, the complete loss of strong low-level CAA and an even stronger subsidence inversion should reduce fire danger concerns even further.

Key message 2: Clear skies and seasonable temperatures persist into next weekend.

The synoptic pattern still looks like it will evolve into an omega- like blocking pattern through the middle of the week. As an upper low off the Atlantic coast retreats northeastward on Tuesday and Wednesday and heights build over the central CONUS, stationary upper troughing will become established east of the area, before the ridge slowly builds into the Carolinas over the weekend.

For our part, we can expect mostly-clear skies, with temperatures slowly but steadily trending warmer through the week. Highs may be a solid category above normal by Thursday (which for this time of year, is still in the mid 70s!). Long-range ensembles have begun to form an unsteady consensus for a weak reinforcing cold front to arrive Friday or Friday night, driving temperatures back below normal going into the weekend. As usual at this timescale, confidence is only moderate.

AVIATION /18Z MONDAY THROUGH SATURDAY/

At KCLT and elsewhere: VFR expected at all six TAF sites through the period. Dry and breezy conditions continue today, with a N/NE wind of 5-10kts at all sites except AVL, where terrain will keep winds more NNW and a little lighter. SKC should persist through the period, though brief FEW/SCT low clouds may develop at AVL around dawn on Tuesday. Light and variable winds expected overnight. N/NE winds continue on Tuesday, but lighter, and currently with no mentionable gusts.

Outlook: Dry, VFR conditions persist through the week, and into next weekend. Mountain valley fog and low stratus will be possible each morning.

GSP WATCHES/WARNINGS/ADVISORIES

GA...INCREASED FIRE DANGER until 7 PM EDT this evening for GAZ010- 017-018-026-028-029. NC...None. SC...None.