textproduct: Charleston

WHAT HAS CHANGED

All of the sections have been updated.

KEY MESSAGES

- 1) Less thunderstorm activity this afternoon.

- 2) Minor coastal flooding is possible along the Charleston and Colleton County coastline with the evening high tide.

- 3) Dry conditions Wednesday to persist into the weekend. Fire weather concerns are low at this time.

DISCUSSION

KEY MESSAGE 1: Less thunderstorm activity this afternoon.

A cold front is located south of our area. Behind this front and across our area, PWATs are trending lower as High pressure and drier conditions build in from the north. Instability has also been rather low, with SPC Mesoscale Analysis showing MLCAPEs below 1,000 J/kg, mainly across our GA counties. As a result, radar imagery is indicating limited thunderstorm activity, mainly along the GA sea breeze and a little further inland. CAMS are in good agreement that this activity will dissipate at sunset, followed by dry weather later this evening and overnight.

KEY MESSAGE 2: Minor coastal flooding is possible along the Charleston and Colleton County coastline with the evening high tide.

Gusty northeast winds will produce elevated tide levels, especially around the time of this evening's high tide (occurring around 10:15 PM). The astronomical tide level is 5.5 ft MLLW, so it would require a rather anomalous 1.5 ft departure to reach the minor coastal flood threshold of 7 ft MLLW. For context, historical analysis shows that a departure of 1.5 ft or higher has only occurred with ~7% of all minor coastal flood events on record. Still, minor coastal flooding is possible, and a Coastal Flood Advisory could be needed for the Charleston and Colleton county coasts.

KEY MESSAGE 3: Dry conditions Wednesday to persist into the weekend. Fire weather concerns are low at this time.

Cool, dry Canadian high pressure will expand across the eastern CONUS on Wednesday before settling over the Mid-Atlantic and Southeast later this week. This pattern will bring ample sunshine and rain-free conditions through the remainder of the week and into the upcoming weekend.

The dry airmass will result in notably lower humidity levels, especially on Wednesday, when minimum RH values could drop below 30% away from the immediate coast and below 25% in isolated spots. Despite breezy conditions also expected Wednesday, recent rainfall has wetted fuels sufficiently to limit fire weather concerns at this time.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

18Z TAFs:

KCHS and KJZI: VFR. Gusty ENE winds should ease later this evening, then increase again Wednesday morning.

KSAV: Mainly VFR. The probabilities for impacts from convection will decrease late this afternoon. Gusty ENE winds should ease later this evening, then increase again Wednesday morning.

Extended Aviation Outlook: No high confidence concerns.

MARINE

Tonight: Gusty NE winds will cause Small Craft Advisory conditions to persist for the Atlantic waters.

Marine conditions will gradually improve through the week as high pressure builds in from the north. Ridging moves nearly overhead by the end of the week, with exceptional marine conditions possible Thursday into the weekend.

Rip Currents: Northeast winds will remain strong through Wednesday and swell energy and wave action will be higher than today. This will result in a high risk of rip currents for all area beaches. A moderate risk is in place for all area beaches Thursday.

CHS WATCHES/WARNINGS/ADVISORIES

GA...High Risk for Rip Currents from Wednesday morning through Wednesday evening for GAZ217-219-239-241. SC...High Risk for Rip Currents from Wednesday morning through Wednesday evening for SCZ148>151. MARINE...Small Craft Advisory until midnight EDT Wednesday night for AMZ360-362. Small Craft Advisory until 5 AM EDT Thursday for AMZ364. Small Craft Advisory until 8 PM EDT Thursday for AMZ384.