textproduct: Columbia

WHAT HAS CHANGED

Little change to the overall forecast. Aviation discussion updated for 18z.

KEY MESSAGES

- 1. Above average temperatures continue through the end of the week.

- 2. Storm coverage will be limited again today, with increasing potential late week into the weekend.

DISCUSSION

KEY MESSAGE 1: Above average temperatures continue through the end of the week.

A Heat Advisory continues through until 8pm today along and south of I-20 with heat indices expected to rise to around 108F. Temperatures will likely be similar each day through the end of the week with the interquartile range of blended guidance showing limited spread leading to relatively high confidence in highs in the mid to upper 90s each day through Friday. A weak front moving through the area today will do little to affect temperatures but will push in some slightly drier air, allowing for increased drier air mixing to the surface. Dew points as a result will likely dip to or below 70F during the afternoon today, tomorrow and Thursday. This will likely still lead to heat indices between 100F to 105F, although keep us below Heat Advisory criteria. Moisture increases Friday as the ridge begins to break down. A decrease in temperatures would be offset by the moisture increase, although higher chances for showers and storms will also limit temperatures. More seasonable conditions expected for the weekend, finally providing us a break from the oppressive heat.

KEY MESSAGE 2: Storm coverage will be limited again today, with increasing potential late week into the weekend.

A capping inversion similar to yesterday is expected again today across the area, which should limit convection despite weak convergence along a surface front. However, given the heat and humidity in place a stray shower or thunderstorm cannot be completely ruled out, especially closer to the Coastal Plain. Scattered afternoon thunderstorms will be possible each afternoon Wednesday and Thursday, favoring the eastern portion of the forecast area where moisture will be highest and the sea breeze and stalled weak surface boundary will provide some forcing. As the upper ridge breaks down Friday and Saturday, more widespread showers and storms expected.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

VFR conditions are expected through the TAF period with a very low chance for spotty shower or storm this afternoon.

FEW to SCT cumulus are developing this afternoon as light winds out of the northwest to north-northwest develop. These conditions likely continue the remainder of the day with a stray shower/storm possible, but this is looking rather unlikely. Tonight, passing cirrus will be possible again with light and variable winds as a 20-25 kt LLJ develops. Winds likely become a bit more northerly to northeasterly after 14-16z Wednesday, but remain light. VFR conditions likely persist to the end of the TAF period with SCT cumulus slowly developing again Wednesday afternoon.

EXTENDED AVIATION OUTLOOK...Diurnal chances for thunderstorms increase through the week, peaking this weekend.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Heat Advisory until 8 PM EDT this evening for SCZ016-022- 027>031-035-037-038-041-135>137. GA...Heat Advisory until 8 PM EDT this evening for GAZ064-065-077.