textproduct: Charleston

WHAT HAS CHANGED

All sections have been updated.

KEY MESSAGES

- 1) Increasing chances for showers and thunderstorms this weekend, though no hazardous weather is anticipated at this time.

DISCUSSION

KEY MESSAGE 1: Increasing chances for showers and thunderstorms this weekend, though no hazardous weather is anticipated at this time.

A weak stationary front remains draped across the region, with a surface high pressure centered over Bermuda. Despite precipitable water values near 1.75" and dew points in the upper 60s to lower 70s, dry air in the lower levels will keep conditions on the drier side during daylight hours with temperatures in the upper 80s to lower 90s away from the immediate coast. Light onshore/southerly flow and broken sunshine today should provide the moisture and instability necessary for isolated summer-like convection across the Southeast, though given the lack of deep-layered shear rainfall is expected to remain fairly unorganized. Chances for rain will first take place this morning for areas east of the I-95 corridor, but as the moisture is depleted chances for rain shift towards areas west of the I-95 late this morning into the afternoon hours. A weak shortwave looks to move out of the Gulf Friday evening into early Saturday morning, bringing additional chances for light scattered showers and thunderstorms primarily for areas west of I-95.

The upcoming holiday weekend looks to be somewhat unsettled (especially inland) as the sprawling upper-level anticyclone centered off the Southeast U.S. coast slowly meanders east and an approaching cold front stalls over east-central Georgia, the South Carolina Midlands and into the Piedmont/Coastal Plain of North Carolina. Warm and moist conditions will remain in place with the region holding south of the front. PWATs are forecast to average between 1.5-2.0" through the period with surface dewpoints in the upper 60s/lower 70s and highs into the upper 80s/near 90 yielding modest levels of surface based instability each afternoon. With the center of the subtropical anticyclone centered offshore, ribbons of mostly channeled mid/upper-level vorticity will pass through aloft with the front stalled to the west and northwest. This should result in a modest coverage of showers/tstms each day with the greatest coverage occurring across the far interior closer to where the front stalls. Coastal areas may very well see a limited amount of showers/tstms both days with a fairly progressive sea breeze circulation expected to occur each afternoon. Of course, mesoscale interactions may eventually augment the convective pattern at times with the sea breeze potentially sparking off convection itself and possibly intersecting with outflow boundaries generated by convection farther inland. No significant hazards are expected although gusty winds, cloud-to-ground lightning and locally heavy rainfall could occur, mainly during the afternoon and evenings.

The front will retreat north by early next week as the upper high offshore retrogrades back to the west. This will bring a more summer- time diurnal convective pattern.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

KCHS/KJZI/KSAV: Generally VFR conditions expected, though isolated areas may see brief periods of flight restrictions from rain showers/storms, which should remain limited to the MVFR category. Chances for rain will first take place this morning for areas east of the I-95 corridor, but as the moisture is depleted chances for rain shift towards areas west of the I-95 late this morning into the afternoon hours. Did remove the PROB30 at the KSAV terminal as the latest trends would suggest any such shower/storm would occur well west of the KSAV terminal.

Extended Aviation Outlook: There are no high confidence concerns with the bulk of showers/tstms expected to remain west of the terminals this weekend into early next week.

MARINE

Today and Tonight: The region will remain between a surface high pressure to our east and a stalled front across the area, keeping conditions well below critical thresholds. Southeasterly winds will continue today, becoming marginally breezy this afternoon. After the morning round of showers and isolated thunderstorms, expect mostly quiet conditions the rest of the day with some additional scattered chances for rain returning overnight into Saturday morning.

Saturday through Tuesday: The coastal waters will remain along the western periphery of Atlantic high pressure into early next week. This will keep a southerly flow regime in place with classic summer- time surges occurring along the land/sea interface and Charleston Harbor each afternoon into the early evening hours. Speeds will generally remain below 15 kt, although gusts could approach 20 kt at times within the sea breeze itself. Seas will average 2-4 ft.

Rip Currents: A modest easterly swell around 3ft/9s and sea breeze influences each afternoon will keep the rip current risk in the moderate category through Saturday.

CHS WATCHES/WARNINGS/ADVISORIES

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