textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 00Z TAF Update.

KEY MESSAGES

- 1. Rain chances increase as a slow-moving front approaches. Unsettled weather continues for the remainder of the week.

DISCUSSION

Key Message 1: Rain chances increase as a slow-moving front approaches. Unsettled weather continues for the remainder of the week.

The anticipated cold front will continue to slowly sag southward, eventually stalling near or over the FA. A modest moisture fetch from TS Bertha well to our SW will help advect tropical moisture to the region. Overall, this slow-moving pattern will be in place through at least Saturday.

PWATs are currently over 2" amid deep southwest flow, with relatively skinny CAPE profiles, and deep warm cloud depths. Mean flow will remain nearly parallel to the front, favoring training convection and highly efficient rainfall production. Hi-res guidance depicts more organized showers and clusters of thunderstorms developing tonight, primarily across the northern Midlands. Locally heavy rainfall rates within these bands could quickly boost storm-total amounts. Scattered showers are expected to continue through Friday before another more organized round of storms develops during the afternoon and evening, with the greatest coverage shifting south toward the central/eastern Midlands and CSRA.

Given the expected convective evolution and tropical environment, rainfall totals are likely to vary considerably over relatively short distances. The 3 day rainfall forecast focuses the highest amounts in the northern Midlands and Pee Dee region. Further south, the rainfall is expected to be more intermittent with lower amounts. Repeated rounds of heavy rainfall will increase the potential for localized flooding.

Showers and thunderstorms will remain possible into Saturday, although coverage should become more scattered as the front weakens and eventually dissipates. Increased cloud cover and rainfall should provide some relief from the heat, especially across northern areas with afternoon highs generally in the lower 90s and potentially remaining in the upper 80s where rainfall occurs. A more typical late-July pattern is expected to return by next week, bringing back hot and humid conditions with diurnal thunderstorms.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

Increasing chances of restrictions tonight in the central Midlands with MVFR/IFR cigs late tonight and periods of rain moving in. Other locations across the CSRA and southern Midlands may remain mostly vfr.

Surface front/boundary is moving into the central Midlands this evening, with front showing up on radar and the associated wind shift showing up in surface obs. This boundary should be able to push just south of cae/cub towards 01z then slow even more. At this time do not have it making it to ogb/aik and areas further south overnight. Along and north of this front, winds will turn northeasterly, while areas south of it remain southerly. Speeds mainly around 5 knots, with periods of light and variable overnight expected. Areas of showers and even a thunderstorm will be possible along the front, with cae/cub seeing the greatest potential for rainfall this evening and overnight. In addition, guidance continues to show mvfr/ifr ceilings developing north of the front. Southward, more likely that vfr will be seen for much of the period, with brief mvfr ceilings possible at areas closer to the front. All this to say there remains a lot of uncertainty with conditions overnight and into Friday due to the front draped across the region. There will continue to be rain chances along all taf locations on Friday, with highest potential from 18z-00z it appears.

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

CAE WATCHES/WARNINGS/ADVISORIES

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