textproduct: Columbia

WHAT HAS CHANGED

Lowered dewpoints north and west of I-20 as a weak front moves into the region. Updated 18z Aviation.

KEY MESSAGES

- 1. Seasonal temperatures with afternoon thunderstorm chances each day this week.

DISCUSSION

KEY MESSAGE 1: Seasonal temperatures with afternoon thunderstorm chances each day into next week.

Afternoon satellite imagery shows scattered cumulus starting to develop, mainly along and southeast of the I-20 corridor. A weak frontal bounday is ushering in drier air into the FA. As a result, opted to lower both dewpoints and PoPs for much of the region. Modeled soundings and mesoanalysis data show ample CAPE and DCAPE along and south of this boundary but any thunderstorm will have to overcome the mid-level dry air moving in order to develop. Expecting isolated convective activity to develop during the next few hours, with the greatest probability along and southeast of I-95. Any robust thunderstorm that forms has the potential to approach severe limits and produce small hail and strong downbursts winds, so trends will be monitored as the day goes on. With decreasing PWATs, the flash flood risk is low.

Generally quiet conditions are expected through the first half of the week as a relatively dry air mass remains in place. Rain chances should stay low through tomorrow, with only isolated diurnally driven thunderstorms possible during the early part of the week. Moisture will gradually increase from mid to late week, resulting in a trend toward higher afternoon storm coverage. LREF probabilities indicate a 50-70 percent chance of PWAT values exceeding 1.75 inches from Wednesday onward. Upper- level troughing will also begin to shift into the region, supporting increasing moisture and greater chances for afternoon thunderstorms. Weak shortwaves embedded within the flow should also provide additional forcing for convection. Temperatures are expected to gradually warm as this overall pattern persists into next weekend.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Mainly vfr expected, with brief mvfr visibilities in patch br/fg towards sunrise.

Drier air is filtering into the area through this afternoon. Highest dewpoints and moisture seemingly confined to the eastern Midlands, southern CSRA, and the coastal plains of SC/GA. This should limit any shower formation for the majority of the taf locations this afternoon and evening. Highest probability would be at kogb, with an isolated showers not completely out of the question. Elsewhere coverage generally less than a 10 percent if anything could develop. Probabilities not high enough to warrant even placing in the tafs at this time. Winds will be mainly light and variable this afternoon and tonight, then becoming more westerly around 5 knots towards 15z Monday. With limited moisture overnight, do not expect any widespread fog, even with light to calm winds. Best areas for any brief visibility restrictions around sunrise will be near bodies of water, with any formation being shallow, brief, and remain patchy at best.

EXTENDED AVIATION OUTLOOK...Isolated storms each afternoon with higher coverage of storms expected by midweek.

CAE WATCHES/WARNINGS/ADVISORIES

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