textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

No major changes.

KEY MESSAGES

1. Dry and quiet through at least Friday. Near to just below normal highs develop briefly today before above normal highs return for the rest of the workweek. 2. A more active pattern brings rain chances back this weekend, potentially lingering into early next week. Confidence on timing and details remains low at this time.

DISCUSSION

Key message 1: Dry and quiet through at least Friday. Near to just below normal highs develop briefly today before above normal highs return for the rest of the workweek.

Troughing will be the dominate upper feature across the northern and eastern United States through Friday. At the surface, dry high pressure will be the main feature for the central and much of the eastern United States through at least Friday. Near to just below normal highs briefly develop today before above normal highs return for the rest of the workweek. Highs peak on Thursday, ending up around 10 degrees above normal.

Key message 2: A more active pattern brings rain chances back this weekend, potentially lingering into early next week. Confidence on timing and details remains low at this time.

The western periphery of an upper ridge over the western Atlantic builds northwestward towards the Southeast Friday night into Sunday before shifting south and west into the Gulf early next week. Meanwhile, an upper low attempts to develop somewhere over Texas before lifting northeast toward the Tennessee Valley/ Midwest over the weekend and the Northeast early next week. This will allow rich gulf moisture to stream into the Southeast over the weekend, of which there will be plenty thanks to a both a stationary boundary and a tropical disturbance creeping northward towards the Gulf Coast.

The tropical disturbance is currently located in the southwestern Gulf and will eventually lift northward sometime Friday or over the weekend while interacting with the stationary boundary. Per the NHC this disturbance is expected to develop into a Tropical Depression by mid-week, depicting the system as having a high chance of tropical formation through 48 hours. Global models are not in agreement regarding the strength, timing, or exact track of this system which is to be expected as the system currently remains a disorganized cluster of shower and thunderstorms. Guidance should come into better agreement once the system becomes more organized. For now, the disturbance appears to track northward and just west of the GSP forecast area. However, rain chances still look likely for locations east of the disturbance but confidence on exact arrival time and departure time of rain remains low. The GFS is the fastest solution, showing rain returning to the GSP forecast area by Saturday morning/early afternoon while the Canadian is the slowest solution with rain not arriving until Sunday afternoon/evening. The Euro is caught in the middle, showing rain arriving Saturday evening/night. The GFS has drier conditions returning by early next week due to it being the faster solution, while the Canadian and Euro have rain lingering through early next week with these two models being the slower solutions.

For now it looks like this system will bring mainly beneficial rain to the GSP forecast area. There is still plenty of time for the forecast to change between now and the weekend so make sure to stay up to date with the latest forecast information regarding this system.

AVIATION /06Z TUESDAY THROUGH SATURDAY/

At KCLT and elsewhere: Derived satellite imagery reveals fog/low stratus is gradually expanding across the mountain valleys and some foothills rivers/lakes early this morning...and is gradually encroaching upon KAVL and KHKY. Nevertheless, it remains somewhat debatable as to whether restrictions will develop at those sites this morning in light of slow near-surface drying, and in the case of KHKY, light NE winds. The best course of action at this point seems to be inclusion of tempos for MVFR visby as well as FEW/SCT clouds at the LIFR level. The other sites should see VFR conditions persist through sunrise, although a brief restriction can't be ruled out at KAND.

After sunrise, attention turns to an area of enhanced low level moisture currently moving steadily SSW across southeast Virginia and north-central NC, while expanding to the west. Several guidance sources bring some of this moisture to the KCLT area by daybreak...yielding cig restrictions. While there is hardly a consensus on this, there's enough of a signal in observational and guidance sources to introduce a tempo for MVFR cigs between 12-15Z at KCLT. Late AM cigs are less likely farther west, but there should be enough moisture trapped beneath a stable layer aloft to yield FEW/SCT stratocu/cumulus in the 020-040 range at most sites during the late morning into the afternoon, with cloud bases steadily lifting through the afternoon. NE winds are forecast to steadily increase to 8-12 kts through the morning before weakening again during the afternoon/evening.

Outlook: VFR conditions prevail through the end of the week. Mountain valley fog and low stratus are possible each night.

GSP WATCHES/WARNINGS/ADVISORIES

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