textproduct: Columbia

WHAT HAS CHANGED

Wednesday trending drier with scattered afternoon storms still expected Thursday through the weekend. Aviation discussion updated for 18z TAF issuance.

KEY MESSAGES

- 1. Above average temperatures with chances for afternoon storms Thursday through the weekend.

DISCUSSION

KEY MESSAGE 1: Above average temperatures with chances for afternoon storms Thursday through the weekend.

Relatively cooler and drier today with PWATs near an inch towards the northern portion of the forecast area to near 1.4 inches in the southern area. High pressure centered to the north of the forecast area will slowly move offshore towards the end of the week which along with gradually strengthening mid level ridging over the central CONUS will lead to a warmer conditions tomorrow through the end of the period. Blended guidance favoring highs in the low to mid 90s and lows generally in the low 70s. Low level moisture increase late week into the weekend may push heat indices to near triple digits but not expecting to near heat advisory criteria.

Moisture also expected to increase towards the end of the week and while ridging expected to remain strong over the forecast area a shortwave moving into the Mississippi Valley will likely pull Gulf moisture inland leading to rising PWATs and chances for afternoon storms. This moisture increase has trended a bit later as ensemble means favor slightly below average PWATs for most of the area along with a strong warm nose aloft Wednesday which will likely keep most of the area dry. Scattered storms will be possible Thursday, although once again forecast soundings indicate a capping inversion may inhibit convection as 700mb temps likely around 10C. Sufficient weakness in the ridge this weekend along with ensemble mean PWATs approaching 150 percent of normal will likely lead to scattered to potentially widespread showers and storms Friday through the weekend, favoring the afternoons. Mid level lapse rates in forecast soundings look generally unimpressive leading to limited concern for severe storms.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

VFR conditions expected to prevail through 18Z Wednesday.

High pressure off the Mid-Atlantic coast and a relatively drier airmass will generally preclude the formation of convection this afternoon, but scattered cumulus clouds are expected during peak heating hours. Winds will be easterly through the day on the southern periphery of the surface ridge axis, with speeds up around 5-10 kt with a few higher gusts possible. Tonight, winds will become light and variable and mainly high level cloudiness is expected. Increasing low and mid level moisture could bring some broken stratus by mid-late Wednesday morning, but ceilings should remain VFR based on the latest guidance. A few showers could develop toward the end of the forecast period across the eastern Midlands, but will leave mention out of the KOGB TAF until confidence in timing/coverage increases.

EXTENDED AVIATION OUTLOOK...Dry through mid-weeek before diurnal storm chances return in the later part of the week.

CAE WATCHES/WARNINGS/ADVISORIES

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