Area Forecast Discussion

WHAT HAS CHANGED

All Key Messages and sections were updated.

KEY MESSAGES

- 1) Minor coastal flooding is possible with the midday high tide along Charleston and coastal Colleton Counties.

- 2) There is a High risk of rip currents for the GA beaches through Wednesday.

- 3) Not as hot today through Thursday, followed above normal temperatures Friday into the weekend. Increasing rain chances this weekend.

DISCUSSION

KEY MESSAGE 1: Minor coastal flooding is possible with the midday high tide along Charleston and coastal Colleton Counties.

Northeast winds will strengthen this morning, becoming strong and gusty. These winds will cause tidal departures to increase. The Charleston Harbor astronomical tide will be 5.98 ft MLLW at 11:46 AM. The tidal departure would need to be just over 1 ft for the minor coastal flooding threshold of 7 ft MLLW to be reached. Guidance indicates this could briefly be achieved, so a Coastal Flood Advisory may be needed. No coastal flooding is expected further south along the far southern South Carolina and Georgia coasts.

KEY MESSAGE 2: There is a High risk of rip currents for the GA beaches through Wednesday.

Northeast winds will strengthen this morning, becoming strong and gusty this afternoon, and persisting through Wednesday. This will lead to an elevated east northeast swell along our coast this afternoon through Wednesday. The strongest winds and highest seas should be along our GA coast. This is where there is a High risk of rip currents through Wednesday. Along our SC coast, there is a Moderate risk of rip currents through Wednesday. Winds and seas should trend lower on Thursday, reducing the risk of rip currents along our coast.

KEY MESSAGE 3: Not as hot today through Thursday, followed above normal temperatures Friday into the weekend. Increasing rain chances this weekend.

Satellite and KCLX shows the backdoor or wedge front pushing south across the forecast area this morning. In the wake of the front, northeast winds will increase to 10 to 15 mph with gusts into the 20s. Northeast winds should bring cooler llvl thicknesses across the forecast area, building a late-summer CAD. Temperatures will peak several degrees lower than yesterday, ranging from the mid to upper 80s along the coast to the low 90s inland. During the afternoon, scattered showers and thunderstorms are forecast to develop along the front, generally tracking across SE GA and adjacent waters.

Wednesday and Thursday, wedged high pressure will remain across the region, maintaining a nose of drier air with cooler llvl thicknesses. High temperatures are forecast to range around normal, generally in the mid to upper 80s. Stable conditions across the CWA should yield dry conditions both days.

Nearly a 600dm ridge will remain centered around southern Appalachians today through Wed, then sliding west on Thursday. Other than scattered showers and thunderstorms this afternoon, dry weather is expected through the rest of work week. On Friday, GFS and ECMWF indicate a closed H5 low tracking west across FL over the Gulf. The closed low will pass over the Mississippi Delta by Sunday afternoon. Circulation around the low will increase moisture across the Southeast U.S. this weekend. Warm and moist conditions should favor scattered to numerous thunderstorms, especially along the sea breeze, this weekend.

AVIATION /06Z TUESDAY THROUGH SATURDAY/

Prior to the 6Z TAFs, IR satellite and KCLX indicated that the backdoor or wedge front was advancing south across the Santee River. The front should push across KCHS and KJZI by 9Z, turning winds from the NE. Once mixing begins this morning, east-northeast winds should develop gusts between 20-25 kts. Gusty east-northest winds will likely continue through the rest of the daylight hours. Gusts should end this evening.

At KSAV, the backdoor front should reach the terminal around daybreak, turning winds from the northeast. By 14Z, gusts between 20- 25 kts should develop across the terminal and will remain until this weekend. Latest HREF indicates scattered showers and thunderstorms may track across KSAV between 16-20Z, highlighted with a PROB30.

Extended Aviation Outlook: Prevailing VFR conditions with the chance of breezy northeasterly winds (gusts up to 20 kts possible) on Wednesday and Thursday afternoons. Otherwise, it will be fairly dry until Friday when rain chances increase again.

MARINE

Today through Thursday evening: A backdoor cold front will push across the marine zones this morning. In the wake of the front, winds across the nearshore and outer waters will turn from the east- northeast and strengthen into the 20s, with gusts in the upper 20s to near 30 kts. Small Craft Advisories have been issued for the nearshore SC/GA waters along with the outer GA waters. Across the Charleston Harbor, gusts should settle into the low 20 kts, remaining just below Small Craft Advisory criteria. Cold air damming pattern should linger through Thursday, supporting gusty winds. Waves heights will build through today, peaking tonight between 5 to 7 ft. Six foot seas may linger over portions of the waters through Thursday. Small Craft Conditions should end Thursday evening.

More favorable marine conditions are expected on Friday into Saturday as winds settle to around 10 kt and seas lower to 2 to 3 ft on Saturday. Mariners should continue to monitor the latest forecast before heading offshore.

CHS WATCHES / WARNINGS / ADVISORIES

GA...High Risk for Rip Currents from 6 AM EDT this morning through this evening for GAZ217-219-239-241. SC...None. MARINE...Small Craft Advisory from 6 AM this morning to 8 PM EDT Thursday for AMZ360. Small Craft Advisory from 8 AM this morning to 10 PM EDT Thursday for AMZ362. Small Craft Advisory from 11 AM this morning to 1 AM EDT Friday for AMZ364-384.