textproduct: Columbia

WHAT HAS CHANGED

Lowered dewpoints for the afternoon and evening as observations are consistently below model guidance. Otherwise, forecast is on track. Updated aviation for 18z TAF issuance.

KEY MESSAGES

- 1. Seasonal temperatures with increasing thunderstorm chances as the week goes on.

DISCUSSION

KEY MESSAGE 1: Seasonal temperatures with increasing thunderstorm chances as the week goes on.

Skies are partly to mostly sunny at midday with passing mid to high level clouds and a few fair weather cumulus. The latest surface analysis shows the front has cleared the forecast area as dry air continues to filter in with dewpoints in the mid-50s to mid-60s. As expected with such dry air in place, the chance of rain is very low and should be limited to our southernmost counties which are closest to the boundary. Highs today are on track to reach the upper 80s to lower 90s.

By Wednesday, moisture will begin to increase as the stalled boundary to our south moves back overhead. LREF probabilities indicate a 50-70 percent chance of PWAT values exceeding 1.75 inches. Low-level winds will veer to the south/southwest, allowing dewpoints and afternoon humidity to (unfortunately) return to more typical summertime levels. Combined with increasing upper-level troughing and moistening profiles, this should support increasing chances for scattered showers and thunderstorms beginning Wednesday afternoon and through the remainder of the week.

Models remain in good agreement regarding the overall increase in convective coverage, though uncertainty remains in terms of the timing and location of more robust convection. A widespread organized severe threat appears low; however, stronger to marginally severe thunderstorms cannot be ruled out each day. Damaging winds and heavy rainfall producing localized flash flooding will be the primary concerns. Overall, daily rain chances will remain in the high chance to likely range through the remainder of the work week, with some decrease possible this weekend. Temperatures should remain near normal, while increasing dewpoints will bring a return to more muggy conditions.

AVIATION /16Z TUESDAY THROUGH SATURDAY/

VFR conditions continue through this evening with dry air in place. Potential for brief restrictions Wednesday morning.

The frontal boundary has largely shifted south of the CWA with much drier air in place, seen by surface dewpoints in the upper 50s to lower 60s. Mostly dry conditions and VFR conditions likely continue the remainder of the day with light winds out of the northeast. Tonight, low level moisture begins to increase where forecast soundings depict light and variable winds with the lowest 1000 ft nearly saturated. Due to this, the 12z HREF, recent HRRR runs, and LAMP guidance are beginning to hint at patches of stratus mainly after 08-10z tonight. Due to the patchy nature, confidence in impacts at any one terminal is a bit lower, but OGB seems to have the highest chances at this time. Trends will continue to be assessed through the remainder of the day. Any restrictions should clear by 14-16z Wednesday with light easterly to southeasterly winds developing along with a SCT cumulus deck. Chances for showers/storms increase after this TAF period.

EXTENDED AVIATION OUTLOOK...Isolated to scattered storms each afternoon through this weekend.

CAE WATCHES/WARNINGS/ADVISORIES

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