textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 12Z 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 /12Z SUNDAY THROUGH THURSDAY/

Low Ceilings at the Terminals this Morning.....

Ceilings have fallen to at least IFR restrictions this morning and are currently LIFR at CAE/AIK/AGS/DNL/OGB. In addition to the low clouds, there are areas of patchy fog across portions of the forecast area though there is minimal impacts at any of the terminals at the moment. There may also be brief periods of drizzle or a passing shower this morning, especially at CAE/CUB but any precipitation should not result in further reductions. Ceilings are expected to rise later this morning, returning to VFR by 17-19Z. Attention will then return to restrictions associated with scattered showers and thunderstorms, which are possible from 18Z through at least this evening. It is possible that showers and thunderstorms persist into the overnight period, as suggested by some of the model guidance, so opted for VCSH for the moment to allow new guidance to come in. Ceilings are also expected to fall again towards daybreak Monday.

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

CAE WATCHES/WARNINGS/ADVISORIES

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