textproduct: Columbia

WHAT HAS CHANGED

Slight tweaks to today's forecast along with 18z aviation update.

KEY MESSAGES

- 1. Another round of showers and thunderstorms expected later this afternoon.

- 2. Above normal temperatures last into next week with drier conditions returning.

DISCUSSION

KEY MESSAGE 1: Another round of showers and thunderstorms expected later this afternoon.

Clearly seen in the water vapor, upper troughing continues to move across the southern tier over the next 24-36 hours, with rich moisture continuing to advect into central GA this afternoon. PW will continue to increase above 1.8" and eventually surpass 2" in the next few hours. Convective temps are forecast in the upper 80s and lower 90s again this afternoon, and combined with a weak shortwave passing through the region, there should be enough instability for showers and thunderstorms to go another round but not until later this afternoon thanks to lingering morning stratus; likely best timing for any stronger convection will hold off until 4pm or later. That said, compared to Friday, DCAPE values are largely unimpressive and any downbursts will likely be forced mainly by precip loading. Associated with the shortwave and convection still in western GA, CAMs depict more of a linear segment moving through the FA this afternoon and evening, but shear appears to be minimal. Given the high moisture in place, expect fairly decent coverage of precip across the region with the potential for some heavier rainfall totals.

KEY MESSAGE 2: Above normal temperatures last into next week with drier conditions returning.

Sunday into early next week, the trough moves offshore and strong ridging builds over the eastern CONUS. Precip chances are expected to diminish as a result, and PW values fall below 1.6". The ridge is then forecast to remain in control much of next week, and temperatures should remain above normal with decent confidence and small IQR's. Monday should be the warmest day with a notable drop several degrees by Tuesday due to a generally dry backdoor front crossing the region. Surface dewpoints also look to drop further, helping make the airmass more fall-like. Still, highs remain above typical mid-September values. We'll continue to watch for some weakness on the eastern side of the ridge. Models are depicting an interesting feature mid to late next week regarding an upper low rotating around the high from New England south along the Atlantic Coast and eventually retrograding into the Gulf. There is still plenty of uncertainty regarding this low's evolution in the extended, including if or when it may influence our sensible weather.

AVIATION /18Z SATURDAY THROUGH WEDNESDAY/

Scattered to numerous storms expected later this afternoon into the early evening. Another round of morning fog/stratus will be possible Sunday.

Restrictions are gradually lifting, giving way to SCT to BKN cumulus with light winds out of the south to southwest. Stratus lingered a bit longer than forecast this morning, limiting destabilization, but with better heating starting, still expect scattered to numerous thunderstorms this afternoon into the evening. The bulk of this activity has trended a bit later, thus the PROB30 group for each site has been pushed back a few hours. This activity could bring brief vsby restrictions and erratic/gusty winds. Any convection should clear through the evening hours, giving way to light and variable winds with some lingering debris clouds. Tonight, another round of at least patchy stratus/fog is expected, especially for any locations that receive heavy rainfall. These restrictions could continue through 14-16z Sunday before VFR conditions return with 4-6 kt winds out of the west.

EXTENDED AVIATION OUTLOOK...Lower rain chances Sunday but the potential for early morning fog/stratus persists into early next week.

CAE WATCHES/WARNINGS/ADVISORIES

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