textproduct: Columbia

WHAT HAS CHANGED

Flash Flood Watch in effect starting at Noon today for the Columbia Metro Area and counties to the south and east. Key message updated to reflect latest model guidance. Aviation discussion updated for 06Z TAF Update.

KEY MESSAGES

- 1. Scattered to numerous showers and thunderstorms expected today, resulting in heavy rainfall and localized flash flooding. Rain persists into the Saturday, mainly across the eastern forecast area.

DISCUSSION

Key Message 1: Scattered to numerous showers and thunderstorms expected today, resulting in heavy rainfall and localized flash flooding. Rain persists into the Saturday, mainly across the eastern forecast area.

After many days of anticipation, the backdoor cold front has reached the forecast area and will continue to drift south towards the southern Midlands and CSRA. Now that the boundary has reached South Carolina, the threat for heavy rainfall and flash flooding will be highest today. The WPC has placed the majority of the CWA in a Slight (2/4) risk for excessive rainfall with a Moderate (3/4) risk across the southeastern Midlands. The slow moving front will serve as an axis for rounds of showers and thunderstorms supported by rising PWATs in excess of 2", increasing low to mid level moisture, and decreasing winds aloft. Latest model guidance is particularly concerning, showing the potential for 2 to 4 inches of rainfall, with locally higher amounts in excess of 5 inches. This has prompted the issuance of a Flash Flood Warning for portions of the Midlands with this forecast package. The main concern will be from urban and small stream flooding, especially if training thunderstorms move over areas prone to flash flooding. Regardless of whether you are in the watch itself, everyone should remain weather aware today and remember to turn around, don't drown should you encounter a flooded roadway.

Showers and thunderstorms will remain possible into Saturday, although coverage should become more scattered as the front weakens and eventually dissipates. Model guidance suggests that the eastern forecast area will be more likely to see significant rainfall on Saturday, especially along and east of I-95. The clouds and rain should provide some relief from the heat with forecast highs today mostly in the 80s and a few degrees warmer on Saturday. A more typical late July pattern is expected to return next week, bringing back hot and humid conditions with diurnally driven showers and thunderstorms.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

Restrictions expected throughout the TAF period with lowering cigs and periodic heavy rain-storms.

A slow moving front is draped across the area and will bring IFR cigs through Friday morning along with periodic showers. Cigs will lift later this morning to MVFR across the area but waves of showers and thunderstorms remain expected until the end of the TAF period. Periodic IFR-LIFR restrictions likely at times along with thunder. Confidence is highest in restrictions at CAE, OGB, and CUB from 00z Saturday - 12z Saturday. Winds for CAE and CUB should remain out of the northwest throughout the period while OGB, DNL, and AGS will be slightly more variable closer to the front.

EXTENDED AVIATION OUTLOOK...Periodic restrictions from showers and thunderstorms likely into the weekend for all TAF sites.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Flood Watch from noon EDT today through late tonight for SCZ027-028-031-037-038-041-135>137. GA...None.