textproduct: Columbia

WHAT HAS CHANGED

Separated key messages to reflect today's convective potential and a pattern shift into early next week.

KEY MESSAGES

1. Another round of showers and thunderstorms expected today.

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

DISCUSSION

KEY MESSAGE 1: Another round of showers and thunderstorms expected today.

Upper troughing continues to move across the southern tier over the next 24-36 hours, with rich moisture continuing to advect into the area. 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. That said, DCAPE values are largely unimpressive and any downbursts will likely be forced mainly by precip loading. 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. Additional uncertainty lies in how long it takes to reach convective temperatures given the remaining debris clouds from Friday's convection, and whether stratus is able to develop in the pre-dawn hours this morning. This could push back timing of convective initiation.

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 /00Z SATURDAY THROUGH WEDNESDAY/

Scattered showers and thunderstorms will diminish overnight. Brief restrictions possible again early Saturday.

Scattered -SHRA and a few -TSRA will continue to diminish over the next few hours this evening. Lingering debris cloudiness is likely through the night as winds become light and variable. There is generous spread across model guidance regarding the development of fog/stratus tonight. Given plentiful low level moisture in place and rainfall from earlier today, at least patchy CIG/VSBY restrictions seem plausible early Saturday morning. As any stratus lifts through the morning, MVFR ceilings could be seen before giving way to VFR cumulus early Saturday afternoon. Winds should pick back up out of the south-southwest at less than 10 kts. Another round of scattered -SHRA/-TSRA will be possible late in the TAF period, with the potential for restrictions at all terminals.

EXTENDED AVIATION OUTLOOK...The highest rain chances will be this afternoon with widespread thunderstorms expected. The potential for early morning fog/stratus persists this weekend and early next week.

CAE WATCHES/WARNINGS/ADVISORIES

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