textproduct: Columbia

WHAT HAS CHANGED

Winds have diminished over the past hour, so the Lake Wind Advisory has been cancelled as of 6 pm. Aviation discussion updated for 00z TAF.

KEY MESSAGES

- 1) Breezy and very warm conditions continue through Friday.

- 2) Chance of rain on Friday with higher chances on Saturday.

- 3) Cold and dry conditions develop early next week.

DISCUSSION

KEY MESSAGE #1: Breezy and very warm conditions continue through Friday.

Breezy and anomalously warm conditions are expected to continue through the remainder of the work week with today expected to have the strongest winds. Winds appear to be lower on Thursday but the pressure gradient is expected to increase once again on Friday as the next storm system moves into the region. The warming trend peaks on Friday, despite partly to mostly cloudy skies and a chance for rain, with highs in the upper 70s to lower 80s.

KEY MESSAGE #2: Chance of rain on Friday with higher chances on Saturday.

Latest guidance continues to support several periods of rain moving through the region Friday and Saturday, with improving conditions on Sunday. The first chance for rain comes on Friday as a cold front moves in from the north and west but should stall near/over the FA. The NBM continues to be aggressive with precipitation chances, so opted to cap PoPs in the Chance category since the best dynamic support passes to the north. The upper pattern diverges significantly this weekend but it appears that Saturday will be the best day for significant rainfall as an area of low pressure develops along the stalled frontal boundary. The deterministic guidance differs on the timing of the heaviest rainfall with the Euro favoring late Saturday into Saturday evening and the GFS suggesting Saturday night into Sunday morning. A few thunderstorms cannot be ruled out this weekend, but the chance for severe weather is low at this time. The rain should end from west to east on Sunday with improving conditions possible Sunday afternoon and evening.

KEY MESSAGE #3: Cold and dry conditions develop early next week.

A potent upper trough is expected to dominate the weather across the Eastern CONUS early next week. At the surface, a cold and dry air mass will move in behind the departing weekend system with below normal temperatures favored. Monday looks to be the coldest day of the next seven follow by a gradual warm up towards the middle of next week. Monday may also be breezy due to a tight pressure gradient but winds should be lighter Tuesday and Wednesday as surface high pressure moves in from the west.

AVIATION /00Z THURSDAY THROUGH MONDAY/

Generally VFR conditions expected through forecast period but intermittent MVFR cigs possible around sunrise Thursday.

Winds have begun to decouple with sunset, and thus wind gusts have diminished. Winds should continue to drop to around 5 knots by 03z, remaining there overnight and into mid-morning Thursday. Winds will once again pick back up after the inversion breaks, and additional wind gusts back up to around 20 knots expected through Thursday afternoon at all sites.

As for clouds, broken stratus around 6kft will continue for the next few hours, with some scattering expected later tonight. Guidance then continues to show redevelopment of those broken vfr ceilings prior to sunrise. In addition, mvfr stratus being indicated just west of ags/dnl, and even cae/cub around the same time, with potential to move into those taf sites through 15z. Have included a tempo group for now at cae/cub due to slightly lower confidence. However at ags/dnl, have gone with a predominant group starting at 12z through 16z. Mixing by 16z should scourer out the mvfr clouds, with the vfr stratus remaining through the day everywhere.

EXTENDED AVIATION OUTLOOK...High low level moisture will bring chances for morning fog/stratus through the remainder of the week and into the weekend. While a couple stray showers cannot be ruled out Thursday, the main rain chance continues to trend toward Friday and Saturday.

CAE WATCHES/WARNINGS/ADVISORIES

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