textproduct: Columbia

WHAT HAS CHANGED

Increasing confidence in hot, humid, and dry conditions this week. Aviation discussion updated for 06z TAF issuance.

KEY MESSAGES

- 1. Generally dry weather and well above normal temperatures expected with dangerous heat index values possible next week.

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

DISCUSSION

KEY MESSAGE 1. Generally dry weather and well above normal temperatures expected with dangerous heat index values possible next week.

Ensemble guidance remains consistent in depicting a strong upper- level ridge building eastward across the region through the week, supporting a period of intense late-summer heat. This pattern will promote strong subsidence, with ensemble mean 700mb temperatures forecast near the 99th percentiles at around +10C. The anomalously warm temperatures, combined with a pronounced inversion will increase the overall lack of convection through the period. This combination will support highs climbing into the mid to upper 90s (or around 10 degrees higher than normal). Overnight temperatures will also remain anomalously warm, with EC EFI values around 0.7-0.8 and a nonzero shift of tails (similar to the max temperatures) with values about 5 to 10 degrees above normal. Persistent southeast to southwest flow will maintain ample low-level moisture across the region resulting in heat indices to exceed 100F throughout the week. Some values have the potential to approach heat advisory criteria by the mid to latter part of the week.

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

Global models remain in good agreement depicting the strong ridge to retrograde westward across the Plains by next weekend. This evolution will favor the development of upper troughing along the East Coast and support a gradual cooling trend across the region. Shortwave energy is expected to drive southeastward along its backside, bringing increasing chances for rainfall back to the FA. This pattern should provide some relief from the heat starting next week.

AVIATION /06Z MONDAY THROUGH FRIDAY/

Restrictions possible again towards the morning hours.

Skies have been clearing out on satellite. Winds generally light to calm. Still a good amount of low-level moisture in place. This setup has the potential to produce some morning fog or low stratus across the area. Guidance leaning more towards patchy to areas of fog towards sunrise. Went with more scattered clouds overnight and towards morning, with mvfr visibilities possible after 08z. Continued with tempo from 09z-13z for some ifr/lifr fog development at all locations for now. Moderate confidence in some fog formation, but how widespread it may become and how low remains the question for now. Conditions should improve after 14z at all sites, with vfr expected through the late morning and the afternoon. Winds will be light, around 5 kts, through the day Monday and out of the east, but could also be variable for large portions of the day. Showers and thunderstorms should be limited in coverage once again so we have left out mention of afternoon convection for the time being.

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

CAE WATCHES/WARNINGS/ADVISORIES

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