textproduct: Columbia

WHAT HAS CHANGED

Shower activity continues to wind down tonight. The threat for flash flooding on Tuesday is decreasing somewhat. Aviation discussion updated for 06Z TAF issuance.

KEY MESSAGES

- 1. Daily shower and thunderstorm chances continue into the upcoming week, with localized flash flooding possible through Tuesday.

DISCUSSION

Key Message 1: Daily shower and thunderstorm chances continue into the upcoming week, with localized flash flooding possible through Tuesday.

Shower activity continues to dissipate tonight, but some light showers are moving through the CSRA and far eastern Midlands as the latest shortwave passes over the area. After tonight, the overall forecast hasn't changed too much. Southwest flow is expected to persist at least through the first half of the week with the synoptic pattern favoring ridging offshore and an upper low over the lower Mississippi Valley. NAEFS mean indicates PWATs remain around or above the 99th percentile through Tuesday, generally around 2". Heavy rain and isolated flash flooding will be possible with afternoon convection today and Tuesday. However, a strong trough digging south from the Pacific Northwest strengthens the ridging over our area which would limit forcing, particularly on Tuesday, limiting the flash flood threat for that day compared to previous forecasts. With moisture so high and moderate destabilization each afternoon, scattered storms are anticipated to develop. Storm coverage Wednesday through the end of the week may be a bit more limited as southwest flow weakens but isolated diurnal showers and storms remain possible.

AVIATION /06Z MONDAY THROUGH FRIDAY/

Restrictions from Low Clouds Likely to Develop By Daybreak....

Radar tonight shows a few showers moving through the forecast area, not impacting the terminals at this time. A mostly dry overnight period is expected with a return to the low ceilings during the next few hours ranging from IFR to MVFR levels. In addition, there may be patchy fog at AGS and it cannot be ruled out at the other terminals. Ceilings rise after daybreak with another round of showers and thunderstorms expected. Confidence in timing is not as high as previous days so for now the TAFs feature VCSH at 18Z, though convective development may begin sooner than that. Winds continue to be mostly light and variable, favoring a southerly direction.

EXTENDED AVIATION OUTLOOK...Abundant low level moisture will bring more rounds of morning restrictions from fog and/or low clouds. Scattered afternoon showers and thunderstorms are possible each day.

CAE WATCHES/WARNINGS/ADVISORIES

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