textproduct: Charleston

WHAT HAS CHANGED

The Aviation section was updated for the 12z TAFs.

KEY MESSAGES

- 1) Below normal temperatures and gusty winds will continue as a powerful nor'easter meanders offshore of the North Carolina Outer Banks and Mid-Atlantic States. - 2) The risk for high surf and dangerous rip currents will persist into early this week.

DISCUSSION

KEY MESSAGE 1: Below normal temperatures and gusty winds will continue as a powerful nor'easter meanders offshore of the North Carolina Outer Banks and Mid-Atlantic States.

This Morning: Early morning surface analysis and satellite data show broad high pressure centered over the Central Appalachians extending south into the Southeast U.S. with cyclogenesis ongoing about 250 miles southeast of Cape Hatteras. The pressure gradient between these two features is keeping breezy conditions in place with gusts 30-35 mph common at the beaches. Lows this morning are on track to bottom out in the mid-upper 40s inland with lower 50s at the beaches. With breezy conditions holding, downright chilly conditions will occur with wind chills expected to drop into the upper 30s to mid 40s away from the immediate coast as daybreak approaches.

Today and Tonight: The synoptic reasoning has not changed. A nor'easter off the Outer Banks will steadily deepen through tonight as it becomes more vertically aligned with an upper low that is forecast to develop near the North Carolina coast. The system will move little for the next 24-hours or so as it becomes detached from the main belt of the westerlies while broad high pressure builds deeper into the Southeast States. This will keep breezy conditions in place for one more day with clear skies prevailing. Despite full insolation, temperatures will remain well below normal for mid-October with afternoon highs only expected to reach the mid-upper 60s. Clear skies and rain- free conditions will persist into tonight with lows dropping into the mid-upper 40s inland with mid-upper 50s at the beaches, warmest along the Georgia coast where the low- level flow relative to the of the coastline advect a slightly more modified airmass from off the warmer Atlantic.

Lake Winds: Elevated north/northeast winds will persist across Lake Moultrie through early Monday morning. Winds of 20-25 kt with gusts to 30 kt this morning are expected to drop to 15-20 kt with gusts to 25 kt later this afternoon and finally below Lake Wind Advisory criteria during the early morning hours Monday. Waves 2-3 ft will subside to 1-2 ft this afternoon and evening. The risk for some minor lakeshore erosion and overwash remains, mainly along the south side of the lake including Pinopolis, Lions Beach and Short Stay.

Monday through Saturday: A nor'easter will be located off well off the coast of NC Monday morning. Meanwhile, strong High pressure will be located over the Northeast, with it's periphery stretching down into the Southeast U.S. The nor'easter will very slowly shift away from our region through mid and late this week. Though, the periphery of High pressure will persist across the Southeast U.S. possibly weakening its grip. As it does this, dry conditions will prevail and high temperatures will increase. Based on MOS, 850 mb temperatures, and low-level thickness values, high temperatures should be in the upper 60s to lower 70s on Monday under sunny skies. They're expected to rise into the mid to maybe upper 70s Tuesday, again with sunny skies. The 70s will generally persist Wednesday through the end of the week, which is within a few degrees of normal. However, the dry conditions will cause low temperatures to remain several degrees below normal this week.

KEY MESSAGE 2: The risk for high surf and dangerous rip currents will persist into early this week.

High Surf: Today: Breaking wave heights will be highest along the middle/upper Georgia coast through tonight where breakers as high as 4-6 ft can be expected. Breakers of 3-4 ft will be common for the lower South Carolina beaches. A High Surf Advisory is in place through Monday afternoon from Tybee Island south to Sapelo Island. There will also be a risk for beach erosion, especially around the times of high tide.

Monday: Strong and gusty NNE winds at daybreak will ease during the morning and into the afternoon. They'll also shift to the N in the afternoon. This will cause breaking waves to decrease, especially along our GA coast. The High Surf Advisory for our GA coast is in effect until noon, but it's possible this may be dropped sooner if winds and breaking waves are lower than expected.

Rip Currents: Today: The rip current risk is high for all beaches due to elevated winds and seas.

Monday: The combination of strong and gusty NNE winds early in the morning, decent sized breaking waves, and a longshore current that could be moderate to strong in strength will bring a High Risk of rip currents to all of our beaches.

Tuesday and Wednesday: The High risk could continue for portions of our coast on Tuesday, especially during the morning hours. This should be followed by an enhanced risk for our GA beaches on Wednesday.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

18/12z TAFs: KCHS/KJZI/KSAV: Gusty winds will persist at all terminals through this afternoon under VFR conditions.

Extended Aviation Outlook: Breezy conditions on Monday should ease into Tuesday.

MARINE

Through Tonight: An earlier ASCAT pass showed solid northerly gales of 30-35 kt with buoys showing gusts 38-42 kt common across the marine area. Dangerous marine conditions will persist across the waters through tonight as the pressure gradient between strengthening nor'easter off the North Carolina Outer Banks and high pressure building into the region from the north remains enhanced. The risk for gales will linger over the nearshore waters through late afternoon and into the overnight hours for the offshore waters. Gale Warnings remain in force as a result. For the Charleston Harbor, winds of 20-25 kt with gusts to 30 kt with waves 2-3 ft will continue, but begin to diminish this afternoon into the overnight hours with gusts finally dropping below 25 kt early Monday morning. A Small Craft Advisory is in effect until 5 AM Monday. Seas will range from 6-9 ft nearshore and 9-13 ft offshore through tonight.

Monday through Thursday: A nor'easter will be located off well off the coast of NC Monday morning. Meanwhile, strong High pressure will be located over the Northeast, with it's periphery stretching down into the Southeast U.S. The nor'easter will very slowly shift away from our region through mid and late this week. Though, the periphery of High pressure will persist across the Southeast U.S. The interaction between these two synoptic features will be generating strong and gusty NNE winds Monday morning. Winds are expected to ease into Monday afternoon, followed by a brief surge Monday evening, then remaining elevated the rest of Monday night into Tuesday morning. There could be another surge Tuesday evening through Wednesday morning, before winds become noticeably lower on Thursday. Seas will be their highest Monday morning, then gradually subsiding through midweek. Though, the highest waves will remain in the waters beyond 20 nm. We'll likely have Small Craft Advisories in effect on Monday. Though, which marine zones and for how long will need to be determined with future forecasts.

CHS WATCHES/WARNINGS/ADVISORIES

GA...High Surf Advisory until noon EDT Monday for GAZ217-219-239- 241. High Risk for Rip Currents through this evening for GAZ217-219-239- 241. SC...High Risk for Rip Currents through this evening for SCZ148>151. Lake Wind Advisory until 2 AM EDT Monday for SCZ045. MARINE...Small Craft Advisory until 5 AM EDT Monday for AMZ340. Gale Warning until 5 PM EDT this afternoon for AMZ360-362-364. Gale Warning until 5 AM EDT Monday for AMZ380-382-384.