textproduct: Columbia

WHAT HAS CHANGED

Daily afternoon storm chances and increasing heat/humidity continue into next week. Aviation discussion updated for 00z TAFs.

KEY MESSAGES

- 1. Diurnal showers and thunderstorms, some strong, each day.

- 2. Increasing heat and humidity is expected next week.

DISCUSSION

- 1. Diurnal showers and thunderstorms, some strong, each day.

Onshore surface flow in conjunction with the strong bermuda high across the western Atlantic is forecast to continue providing significant surface moisture to the region. Dewpoints are forecast to remain in the low to mid 70s over the next several days and into next week, with daily SBCAPE values more than sufficient to yield diurnal chances for showers and thunderstorms. Isolated showers have all but diminished this evening with any additional activity ending shortly after sunset. A similar picture is likely to be painted over the next few days as we continue to reside on the southwestern side of this expansive surface high. Upper level ridging is forecast to build in by next week, likely helping to keep showers/storms more isolated to scattered in nature, but the daily chances will remain. There is a signal, albeit inconsistent, that a deeper trough will push into the eastern CONUS by the end of next week, helping to possibly increase storm coverage again. Strong storms will be a possibility each day as CAPE will be sufficient for wet microbursts in the strongest convection.

- 2. Increasing heat and humidity is expected next week.

A low amplitude upper level ridge is forecast to begin developing over the next several days, with 90th percentile 500 hPa heights overspreading the area by Sunday. With southwesterly flow common and afternoon storm coverage expected to lower a bit by early next week, afternoon highs are forecast to bump up into the mid 90s. With persistently high dewpoints in the low to mid 70s, LREF guidance continues to indicate a high likelihood of daily, peak heat index value exceeding 100F. While this isn't at heat advisory criteria, it isn't crazy to think we may have a day or two next week where we approach 105F-108F for afternoon heat index values. Be sure to practice good habits when dealing with the heat next week!

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

IFR restrictions possible early Saturday morning.

Light winds tonight and dry air aloft should yield another night of restrictions through early Saturday morning. HREF guidance shows stratus pushing in from the coast overnight with SE flow in place. We would expect this to lead to MVFR/IFR ceilings at all terminals with highest confidence at OGB. Reduced visibilities will also be possible, although with no TAF sites receiving heavy rain today any fog may not be as dense as the previous night. Restrictions should lift by 13Z or 14Z again with light SE winds from 5 to 10 kts through Saturday afternoon. CAMs, which handled today's convection well, show little coverage for Saturday so we have kept any mention of TS out of the TAFs at this point.

EXTENDED AVIATION OUTLOOK...A seasonal pattern of early morning restrictions and diurnal thunderstorms is likely through much of the extended.

CAE WATCHES/WARNINGS/ADVISORIES

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