textproduct: Columbia

WHAT HAS CHANGED

Removed key message that discussed severe and flooding threat for Saturday. Updated discussion for the daily chances of showers and storms. Aviation discussion updated for 06z TAF.

KEY MESSAGES

- 1. Daily shower and thunderstorm chances continue into the upcoming week, with localized flash flooding possible for the next few days.

DISCUSSION

Key Message 1: Daily shower and thunderstorm chances continue into the upcoming week, with localized flash flooding possible for the next few days.

The overall pattern is forecast to remain relatively similar the next few days as an upper ridge off shore and an upper low over the lower Mississippi Valley keeps persistent southwest flow over the region. At the surface, a Bermuda high is anticipated to remain generally in place for the next several days while high pressure along the mountains is forecast to continue wedging into the area. These features lead to surface convergence, mainly over the western portions of the forecast area. The convergence along with multiple shortwaves moving overhead are expected to lead to daily chances of showers and storms. The southwest flow aloft and southerly surface winds continue to keep moisture levels high, PWATs ranging from 1.7-2" across the forecast area, which is about 150-175% of normal for this time of year. The high moisture levels will likely lead to very efficient rain makers like we have seen the past couple of days. Due to this and the recent heavy rainfall, localized flash flooding instances are possible each day through Tuesday before the pattern begins to shift somewhat. The areas with the highest chances to see localized flash flooding are generally north and west of I-20, where the heaviest rains have occurred the past couple of days. Daily chances for showers and storms continue through the rest of the week ahead, but the chances for localized flash flooding decrease as the upper low over the lower Mississippi Valley begins to shift northeastward, bringing in some drier air to the area and flattening out the offshore ridge.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

Ceiling Restrictions Expected at the Terminals Tonight.....

Radar tonight is much quieter with only a few lingering showers. The area of rain moving through the CSRA continues to dissipate and is unlikely to have significant impacts at AGS/DNL. The main issue tonight will be a reduction in ceilings. All terminals except OGB are currently reporting IFR to LIFR ceilings and all terminals are expected to see at least brief LIFR restrictions by daybreak. Some model guidance suggests that showers will redevelop towards daybreak but confidence is not high enough to include in the TAFs at this time. Ceilings are expected to rise after daybreak, returning to VFR by 18Z. Attention will then return to restrictions associated with scattered showers and thunderstorms which are possible from 18Z through the remainder of the TAF period.

EXTENDED AVIATION OUTLOOK...Abundant low level moisture will bring more rounds of morning restrictions from fog/stratus to finish the holiday weekend and to start the next work week. Scattered afternoon showers and storms are possible each day into the middle of the week.

CAE WATCHES/WARNINGS/ADVISORIES

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