textproduct: Charleston

WHAT HAS CHANGED

Updated key message 1.

KEY MESSAGES

- 1) Unseasonably hot weather with strong to severe thunderstorms today.

- 2) Showers and thunderstorms expected to continue into early next week with a persistent summertime pattern.

- 3) Minor coastal flooding possible along Charleston and Colleton County coasts during evening high tides tonight and Monday evening.

DISCUSSION

KEY MESSAGE 1: Unseasonably hot weather with strong to severe thunderstorms today.

Showers and thunderstorms have quickly developed across SE GA as temperatures crossed the convective temperature. These storms over inland GA were developing within a broad sfc trough. KCLX showed that the sea breeze was still near the coast early this afternoon. As the inland convection continues to develop, the associated outflow boundaries may intersect with the sea breeze. This process should yield a large cluster of thunderstorms, generally along the I- 95 corridor from Savannah to Berkeley County. SPC mesoanalysis indicates that SBCAPE may exceed 4000 J/kg with DCAPE values between 600-800 J/kg. In addition, PW values across most of the area is expected to remain around 2 inches. Storms within this very hot and humid should develop very strong and tall updrafts, with core heights reaching around 40 kft. Machine learning guidance indicates the potential for damaging wind gusts may peak around 30% within 25 nm of any given point this afternoon. A few Severe Thunderstorm Warnings could be need later this afternoon into early this evening, highlighting any expected damaging wind gusts. The primary time window for severe thunderstorms is expected between 4 to 7 PM from the I-95 corridor to the coast.

KEY MESSAGE 2: Showers and thunderstorms expected to continue into early next week with a persistent summertime pattern. Isolated strong-severe thunderstorm possible today.

A classic early-summer pattern will remain established across southeast South Carolina and southeast Georgia through early next week. Atlantic high pressure will remain anchored offshore while mid- lvl ridging across the western Atlantic periodically interacts with embedded shortwave perturbations rotating around the ridge periphery. Low-lvl flow remains generally south to southwest, maintaining a rich maritime tropical airmass through next week. This pattern will yield afternoon showers and thunderstorms each afternoon and evening.

Similar to last couple of days, forecast soundings indicate PWAT values ranging from 1.9 to 2.3 inches through the period (near the 90th percentile for mid-June). This combined with surface dewpoints in the low to mid 70s should yield SBCAPE values between 2500-3000 J/kg amid peak heating. Mid-lvl lapse rates remain relatively modest with values ranging from 5.5-6.0 C/km, suggesting pulse-type convection will dominate through the period. Expect the afternoon seabreeze to push inland each day and collide with other outflow boundaries, yielding the primary focus for convection initiation.

As we head into early to mid-week, broad mid-lvl troughing will likely encompass the eastern half of the CONUS. At the surface, a weak cold front will approach the region on Monday, and then push offshore by Tuesday evening. Convection coverage will likely increase from late morning near the coastline before expanding more inland in the afternoons. Highest PoPs will likely occur along and west of I-95 corridor where seabreeze interactions maximize.

This pattern should remain active into the end of the week as this broad mid-lvl troughing continues aloft, with another cold front moving towards the area by late week/early weekend.

KEY MESSAGE 3: Minor coastal flooding possible along Charleston and Colleton County coasts during evening high tides tonight and Monday evening.

Based off of the latest tidal departures and local climo tool, we will issue a Coastal Flood Advisory for Charleston and coastal Colleton Counties from 7 PM to 10 PM this evening.

Breezy south-southwesterly winds each day along with today's lunar Perigee (June 14th) and New Moon (June 15th) should result in elevated tidal departures above 1/2 ft today into early next week, setting the stage for minor coastal flooding along the Charleston and Colleton County coasts during evening high tide cycles. The latest TWL forecast calls for 7.0 - 7.2 ft MLLW in the Charleston Harbor this evening, and 7.0 - 7.2 ft MLLW are possible during evening high tides Monday night as astronomical influences peak and breezy onshore winds persist. Coastal Flood Advisories may again be needed for the Charleston and Colleton county coastlines.

AVIATION /19Z SUNDAY THROUGH FRIDAY/

Prior to the 18Z TAFs, KCLX and visible satellite detected a sea near KSAV, with some developing Cu near KCHS and KJZI. The TAFs will feature a TEMPO during the heat of the day to indicate the potential of moderate thunderstorms. Overnight, conditions should remain VFR with light SW winds.

Extended Aviation Outlook: VFR conditions expected to prevail at CHS/JZI/SAV terminals. However, brief flight restrictions are possible with afternoon showers and/or thunderstorms through the middle of this week.

MARINE

Tonight through Monday, the pressure pattern will support southwest winds between 10 to 15 kts with gusts in the lower 20s. Wave heights are forecast to remain between 2 to 4 ft. Winds should generally continue tonight into Monday. Some thunderstorms could push off the SC coast this evening, possibly requiring Special Marine Warnings.

Tuesday through Friday: Expect generally south-southwesterly winds with speeds ranging from 15 to 20 kts with gusts up to 22-24 kts as Atlantic high pressure persists across the local waters. There could be the need for Small Craft Advisories for Thursday evening into Friday ahead of an approaching cold front. Seas should remain below 6 feet throughout the period.

Rip Currents: A Moderate Risk of rip currents is forecast through this afternoon and Monday along the southeast South Carolina and southeast Georgia beaches given the combination of elevated winds and a lingering south-southwesterly swell.

CLIMATE

Record High Temperatures:

June 14 KCHS: 99/2010 KCXM: 97/1981

June 15 KCHS: 98/2015

Record High Minimum Temperatures:

June 14 KCHS: 79/2010 KCXM: 81/2010

June 15 KCHS: 80/2010

June 18 KCHS: 78/2015

June 19 KCHS: 79/2025 KCXM: 81/2025 KSAV: 79/1881

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...Coastal Flood Advisory from 7 PM to 10 PM EDT this evening for SCZ149-150. MARINE...None.