textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 00z TAFs.

KEY MESSAGES

- 1. Increasing chances for widespread rain Friday and Saturday.

DISCUSSION

KEY MESSAGE 1: Increasing chances for widespread rain Friday and Saturday.

Moisture continues to remain relatively low at least in the north and western portion of the forecast, pooling ahead of a weak boundary with PWATs around 2 inches generally south of I-20. While isolated storms remains possible in the south and eastern portions of the area this afternoon, convection will once again be limited. Latest HREF indicates moisture will marginally increase Thursday with additional chances for isolated afternoon storms. Then global ensembles favor a more amplified pattern for Friday and Saturday as a shortwave digs into the Great Lakes region. This favors deep SW flow over the Southeast on Friday and Saturday with a surface low developing along a baroclinic zone near the forecast area. Enhanced surface convergence and increasing PWAT values to near or above 2 inches favors widespread showers and thunderstorms Friday and Saturday. With higher than normal deep layer shear for the season, and a conditionally unstable air mass, organized storms will be possible. Steep lapse rates and height falls could support damaging winds and small hail on Friday afternoon, especially in the eastern Midlands where moisture will be deeper. As the upper trough axis slowly moves through the area Saturday, precipitation will taper off from west to east with drier moving into the area.

Otherwise, it will be warmer than normal today and Thursday but with drier air over the region and weaker ridging no heat thresholds should be met. Isolated thunderstorms will be possible each afternoon through Thursday but any damaging wind threat will be isolated as typical for the season. Cooler weather is likely next week with temperatures closer to normal.

AVIATION /00Z THURSDAY THROUGH MONDAY/

VFR conditions expected to persist through Thursday.

All's quiet here in the midlands of SC and CSRA of GA. PWs are relatively low for this time of year, resulting in a beautiful aviation day with light winds and only a few fair weather cumulus. Any clouds that were out there are diminishing now, and while we can't rule out a rogue thunderstorm similar to what we saw east of OGB last night, it can be safely said that this is unlikely to impact any TAF site if it does go up. Some modest moisture return is expected tonight with some light southeasterlies at 925 hPa and this may result in enough surface moisture to yield ground fog at OGB. As we get into Thursday, more persistent southerly flow should result in a gradual increase in PWs. Guidance is mixed on overall rain chances but those that do show storms developing hold them off until around or after 00z Friday. So only mention an increase in cloud cover tomorrow afternoon but precip remains unlikely until the end of this period, with VFR expected throughout.

EXTENDED AVIATION OUTLOOK...Isolated thunderstorms possible late Thursday evening but rain chances increase Friday and Saturday with scattered to widespread convection expected.

CAE WATCHES/WARNINGS/ADVISORIES

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