textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

QPF has trended down Saturday thru Sunday, but still expect decent rain chances.

Updated the aviation discussion for the 06Z TAF issuance.

KEY MESSAGES

1. Dry weather through Thursday with above normal temperatures through Friday. 2. Rain is likely this weekend with the passage of a slow-moving cold front. Locally heavy rainfall will be possible. Temperatures trend slightly cooler Saturday, and much cooler Sunday. Dry weather is expected to return Monday, with below-normal temperatures through the middle of next week.

DISCUSSION

Key message 1: Dry weather through Thursday with above normal temperatures through Friday.

Upper ridge will build over the Southeast thru Thursday, then will slowly flatten, as a series of shortwaves ride thru the prevailing westerlies across the northern US. Sfc high pres will migrate east off the coast, setting up a Bermuda-High-like pattern, with a gradual increase in moisture.

Temperatures will continue to be above normal thru Friday. Friday is expected to be the warmest day of the week, with highs well into the 80s in the lower elevations, and around 90 in portions of the Lakelands and southeast of Charlotte. Enough moisture and weakening of a subsidence inversion will result in some uncapped instability across the western mountains, thus a return of scattered showers possible. Most of the forecast area will likely remain dry thru Friday night.

Key message 2: Rain is likely this weekend with the passage of a slow-moving cold front. Locally heavy rainfall will be possible. Temperatures trend slightly cooler Saturday, and much cooler Sunday. Dry weather is expected to return Monday, with below-normal temperatures through the middle of next week.

A broad upper trough will slowly dig across the Midwest to the Ohio Valley over the weekend, allowing a frontal boundary to sag southeastward across the central Appalachians and Mid-Atlantic by early Saturday. The latest guidance is in pretty good agreement that the front will slide into the area from the north during the day Saturday, and have some instability to trigger widespread showers. The 850 mb flow remains on the weak side, and forcing remains modest. So, there is no strong signal for widespread heavy rainfall, although with PWATs surging to 1.75-2.0" (above the 95th percentile of climo), locally heavy rainfall will be possible Saturday night into Sunday. Instability will be weak, due to moist profiles and weak lapse rates, but isolated thunderstorms will be possible. As the front sags south, a hybrid CAD looks to develop, with a 1028 mb parent high tracking east from the Great Lakes to New England. This will bring temps down, from slightly above normal Saturday to below normal on Sunday.

Upper trough continues to deepen over the eastern CONUS early next week, ushering in a fairly strong Canadian high pressure system. Some chance PoPs linger in the southeast part of the CWFA early Monday, but dry conditions should return by Monday aftn. Dry weather will likely continue thru the middle of next week. Temps look to be near normal Monday, then 5-10 deg below normal under mostly clear skies Tuesday and Wednesday.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

At KCLT and elsewhere: Dry, VFR conditions should continue thru the 06z TAF period with mostly clear skies and light winds. Mtn valley fog/low stratus will likely develop again overnight in the usual locations, however like the past few mornings, it is not expected to reach KAVL. With the light to calm winds and higher dewpts overnight, we could see some patchy fog develop outside the mtns. Confidence is too low for any TAF mention. Winds will pick up marginally out of the S to SW this afternoon in the 3 to 6 kt range. They will go light and VRB to calm again later this evening. Otherwise, expect mostly clear skies with a few fair wx cumulus and high cirrus this afternoon.

Outlook: Dry, VFR conditions should persist through Thursday. Moisture will begin to increase across the area on Friday, with a chance of showers by Friday afternoon over the mtns and more widespread showers and associated restrictions across the area over the weekend. Mtn valley fog/low stratus remains possible each morning.

GSP WATCHES/WARNINGS/ADVISORIES

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