textproduct: Charleston

WHAT HAS CHANGED

All sections have been updated.

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 Afternoon and Tonight: A nor'easter off the Outer Banks will steadily deepen through tonight, helping high pressure to build across the Southeast United States and maintain breezy northerly winds locally through late day into early evening hours. Cold air advection associated with the airmass will help offset a full day of insolation, keeping temps well below normal locally for this time of year. In general, high temps should peak in the mid-upper 60s today. Clear skies and rain-free conditions will also promote stronger cooling overnight, with low temps reaching the mid-upper 40s inland to mid-upper 50s closer to the coast, warmest along the beaches where the airmass is slightly more modified by an onshore flow coming off warmer Atlantic waters.

Lake Winds: Elevated north/northeast winds across Lake Moultrie will persist through the day, but are trending weaker as cold air advection wanes late afternoon. In general, northeast winds between 15-20 with gusts to 25 kt are possible until sunset. Thereafter, guidance supports conditions improving and remain below Lake Wind Advisory thresholds, thus the advisory is now set to expire at 8 PM.

Monday through Saturday: Latest guidance continues to support a nor- easter located well of the NC coast Monday morning while strong high pressure over the Northeast United States stretches south into the Southeast United States. Although uncertainty remains in regards to the nor'easter position and duration at the nearest position off the Mid-Atlantic coast early week, the bulk of guidance indicates it will very slowly shift further offshore and away from the region mid to late week. High pressure looks to prevail across the Southeast as this process unfolds, leading to dry/sunny days through much of the week. The setup supports a modifying airmass early to mid week with afternoon highs in the upper 60s to lower 70s on Monday, returning to the low-mid 70s by mid-week. However, clear skies and weaker winds will still favor cool nights, with low temps generally in the low-mid 40s inland to low-mid 50s near the coast Tuesday morning warming a few degrees for overnight periods mid-late week.

KEY MESSAGE 2: High surf and dangerous rip currents possible into early next week.

High Surf: Gusty north-northeast winds and prolonged fetch will support large breaking waves along SC/GA beaches today, with the largest expected to occur along GA beaches due to a more favorable onshore flow. Breakers as high as 4-6 ft are expected along GA beaches, supporting a High Surf Advisory today into about midday Monday, although it's possible conditions improve sufficiently beforehand as winds weaken late morning Monday and gradually turn more north by afternoon hours. Conditions along the SC coast should support 3-4 ft breakers at times during the same period.

Rip Currents: Strong/gusty winds, building waves, and long period swell associated with a favorable north-northeast fetch along the Southeast Coast supports a High Risk for rip currents today through Monday, although some improvement to marine conditions is expected early week. A Moderate Risk is in place for all beaches Tuesday. An enhanced risk for rip currents could persist into the middle of the week.

AVIATION /19Z SUNDAY THROUGH FRIDAY/

VFR conditions will prevail at CHS/JZI/SAV terminals through 18Z Monday. However, gusty north-northeast winds generally up to 18-22 kt are expected at the terminals during peak heating hours this afternoon before a diminishing trend occurs late day into evening hours.

Extended Aviation Outlook: Breezy northerly winds possible on Monday at CHS/JZI/SAV terminals. Otherwise, VFR conditions are expected through the middle of the week.

MARINE

Through Tonight: Dangerous marine conditions remain across local waters this afternoon and into the night as a tight pressure gradient occurs between a strengthening nor'easter off the NC Outer Banks and high pressure building into the Southeast United States. However, guidance suggests cold air advection is at its peak early this afternoon, with latest obs remaining below gale force/gusts. Given low-lvl wind fields and anticipated cold air advection waning for the rest of the day, Gale Warnings have been replaced with Small Craft Advisories across nearshore waters, but still remain across offshore waters through late night. It's possible the Gale Warnings will be dropped by late evening hours offshore as well. Seas will range from 6-9 ft nearshore and 9-13 ft offshore through tonight.

The Small Craft Advisory across the Charleston Harbor remains during the afternoon, generally for the potential of 25 kt gusts during peak heating hours/low-lvl mixing, but has been shortened to 11 PM this evening, and could be shortened further (dropped prior to sunset) if anticipated trends are not realized during the next few hours.

Monday through Thursday: A nor'easter should be located well off the NC coast Monday morning while strong high pressure over the Northeast United States stretches south into the Southeast United States. The interaction between these synoptic features will continue to generate gusty north/northeast winds Monday morning, but should trend weaker into Monday afternoon. A brief nocturnal surge is possible Monday night, but seas will remain elevated regardless, indicating Small Craft Advisories are likely to persist across nearshore coastal waters through Tuesday. Larger seas hold on across GA waters mid-week (6-7 ft), favoring longer duration Small Craft Advisories across GA waters through much of Wednesday. Winds become noticeably lower on Thursday as the pressure gradient slackens.

CHS WATCHES/WARNINGS/ADVISORIES

GA...High Risk for Rip Currents through Monday evening for GAZ217-219- 239-241. High Surf Advisory until noon EDT Monday for GAZ217-219-239- 241. SC...High Risk for Rip Currents through Monday evening for SCZ148>151. Lake Wind Advisory until 8 PM EDT this evening for SCZ045. MARINE...Small Craft Advisory until 11 PM EDT this evening for AMZ340. Small Craft Advisory until 8 PM EDT Tuesday for AMZ360-362. Small Craft Advisory until 2 PM EDT Wednesday for AMZ364. Gale Warning until 5 AM EDT Monday for AMZ380-382-384.