textproduct: Columbia

WHAT HAS CHANGED

Minimal changes to the Key Messages. Aviation discussion updated for 12z TAF issuance.

KEY MESSAGES

- 1. Generally dry weather and well above normal temperatures expected with heat index values over 100F this week.

- 2. Active weather and decreasing temperatures possible this weekend.

DISCUSSION

KEY MESSAGE 1. Generally dry weather and well above normal temperatures expected with heat index values over 100F this week.

A mid- to upper-level ridge will continue to build eastward through the week becoming centered over the southeast by Thursday. Both deterministic and ensemble guidance remain in good agreement on this evolution. NAEFS guidance indicates 500-mb heights will approach the climatological max Tuesday into Wednesday before decreasing slightly toward the end of the week. With the ridge overhead, generally dry conditions are expected to persist all week. The main concern will be the heat, with temperatures gradually increasing each day and reaching the upper 90s. Increasing humidity will result in heat index values exceeding 100F during the afternoon, potentially beginning today and through the remainder of the week. There is potential for conditions to approach Heat Advisory criteria late in the week, though this will depend largely on how well the atmosphere mixes each day. Regardless, heat-realted illnesses will remain possible.

KEY MESSAGE 2. Active weather and decreasing temperatures possible this weekend.

Global ensemble guidance still suggests the ridge will retrograde westward, allowing a trough to dig southward along the East Coast. As this occurs, shower and thunderstorm chances are expected to increase from late this week into the weekend ahead of a cold front. Cooler afternoon temperatures are also anticipated behind the front as well as drier air.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

VFR conditions generally expected except possible early morning fog/stratus.

Calm conditions expected Tuesday morning before some sunrise stratus-fog is possible. Primary confidence is AGS and OGB as typical, but AIK and CAE could possibly see brief restrictions as well between 10-13z; as of 1030z, some MVFR fog is developing at AGS and OGB but is overall very shallow. Some brief drops to IFR- LIFR conditions possible mainly at OGB and AGS through 13z, but confidence is low. Any residual fog- stratus will clear out after 14z for all sites. Into the afternoon, typical summer cu field once again tomorrow with little chance for storms and generally light winds.

EXTENDED AVIATION OUTLOOK...Early morning restrictions still possible despite a drier outlook for the week.

CAE WATCHES/WARNINGS/ADVISORIES

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