textproduct: Charleston

WHAT HAS CHANGED

All sections have been updated.

KEY MESSAGES

- 1) Scattered to numerous showers and thunderstorms will develop along and ahead of a cold front today. A few thunderstorms could become strong to severe.

- 2) A high risk of rip currents is expected along the Georgia coast on Tuesday.

DISCUSSION

KEY MESSAGE 1: Scattered to numerous showers and thunderstorms will develop along and ahead of a cold front today. A few thunderstorms could become strong to severe.

Recent SPC mesoanalysis indicated SBCAPE around 2000 J/kg with little to no CIN across the the SC Lowcountry and SE GA. In addition, DCAPE is expected to range from 700-900 J/kg through the rest of this afternoon. Visible satellite and sfc observations indicated the backdoor cold front just north of the forecast area. As the front approaches, effective bulk shear across the CWA will increase to around 45 kts. Given the combination of the instability and shear, scattered to numerous showers and thunderstorms should develop along and south of the cold front.

Recent runs of the WoFS, indicates that a cluster of thunderstorms may develop across Dorchester/Berkeley counties by 18z, pushing coastward through 19Z. WoFS indicates strong updrafts with echo heights between 30-35 kft. Convection of this nature would be capable of localized strong to severe wind gusts. To the south of the Charleston Tri-county, coverage of thunderstorms will likely remain a bit less. The potential for deep convection appears greater across the coastal counties.

The cold front should push south of the forecast area by midnight. In the wake of the front, northeast winds, occasionally gusty, will remain across the region through tonight.

KEY MESSAGE 2: A high risk of rip currents is expected along the Georgia coast on Tuesday.

A backdoor cold front will push across the region tonight. Gusty northeast winds will develop behind the front, turning from the east- northeast on Tuesday. The gusty winds should develop a strong longshore current with building breaker heights. Local calculator supports a high risk for the GA beaches with greater onshore flow. The SC coast maintains a moderate risk of rip currents.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Prior to the 18Z TAFs: A cluster of showers and thunderstorms developed near the sea breeze over Mount Pleasant, tracking to the northeast. A sea breeze was located over KJZI, drifting slowly inland. A backdoor cold front will reach KCHS/KJZI between 21-22Z, pushing south to KSAV between 2-3Z. Given weak instability and strong llvl convergence, a few additional showers and thunderstorms may develop along and south of the cold front this afternoon and evening. The greatest potential for TSRA will remain across KCHS and KJZI. In the wake of the front, winds will turn from the northeast and increase to 10-15 kts, with some gusts 2-3 hours following the front. Winds may develop regular gusts to around 20 kts by 15Z Tuesday with the onset of daytime mixing..

Extended Aviation Outlook: A cold front could bring brief flight restrictions due to showers and thunderstorms Wednesday into early Thursday.

MARINE

Today and tonight: A backdoor cold front will push south across the coastal waters. Northeast winds will increase behind the front, with gusts exceeding 25 kts. The cold front is moving slightly quicker the previously forecast, the Small Craft Advisory for the Charleston County nearshore waters will start at 8 PM this evening. Small Craft Conditions will spread across the remaining waters tonight and will continue through Tuesday, with seas peaking Tuesday afternoon between 5 to 8 ft. Seas and winds will improve Tuesday evening as high pressure arrives from the north.

Extended Marine: High pressure will pass well to our north later Tuesday, then shift offshore on Wednesday. Another cold front should quickly move through the waters early Thursday. Though, winds and seas shouldn't be high enough to prompt Small Craft Advisories.

Rip Currents: See Key Message #2 addressing the high risk of rip currents for the GA beaches on Tuesday. The combination of strong northeasterly winds and elevated seas will yield a Moderate Risk of rip currents at all of our SC beaches on Tuesday. Though, internal models are pointing towards a High Risk for our northern SC beaches.

CHS WATCHES/WARNINGS/ADVISORIES

GA...High Risk for Rip Currents from Tuesday morning through Tuesday evening for GAZ217-219-239-241. SC...None. MARINE...Small Craft Advisory from 8 PM this evening to 8 PM EDT Tuesday for AMZ360. Small Craft Advisory from 1 AM to 8 PM EDT Tuesday for AMZ362- 364. Small Craft Advisory from 1 AM Tuesday to 3 AM EDT Wednesday for AMZ384.