textproduct: Columbia

WHAT HAS CHANGED

Updated current conditions as storms continue across the forecast area. Aviation discussion updated for 18Z 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.

Today/Tonight: Scattered showers and storms will continue through this afternoon and is generally beginning to build northwestward. The main hazard with these storms is potential flash flooding with rates between 1-2 inches per hour over areas that have already received significant rainfall over the past several days.

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. A front will approach the area next weekend with EC EFI signaling below average temperatures for the weekend with precipitation chances increasing.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Scattered afternoon showers and storms impacting terminals with restrictions developing tonight.

Thunderstorms producing heavy rain will continue to impact the terminals through the afternoon hours. Already have observed rapid lowering visibilities to IFR at times within storms. While storm coverage will diminish tonight, lingering showers are possible around the terminals. Low level moisture will support lowering ceilings tonight with highest confidence in MVFR but possible IFR conditions tonight as well. Scattered showers and storms likely once again tomorrow, although the most likely timing will be after 18z.

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.