Marine Weather and Tide Forecast for Atlantic Beach, SC

NEAR TERM /THROUGH SATURDAY/
The mid level pattern will continue to deamplify through the period although changes the sensible weather elements are deliberate. Low to middle clouds will stream off to the east later this afternoon and evening leaving behind a weak pressure pattern. Some fog is possible late tonight as well. Saturday promises to be a very nice day ahead of the arctic air mass with highs eclipsing the 60 degree mark most under mostly sunny skies.

SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/
*Arctic air will move into the region Sunday night, producing dangerously cold wind chills near Extreme Cold criteria for Sunday night into Monday morning.*

Saturday night kicks off an atypical diurnal pattern, with temps rising during the night Saturday night and decreasing during the day Sunday. WAA ahead of approaching cold front will increase temps from mid to upper 40s early Saturday night to around 50F by Sunday morning. A strong cold front will push through the area Sunday morning, though with moisture limited to below 700mb, QPF is fairly low with expected scattered showers.
High temps Sunday will depend on the speed of the front, with current forecast highs late Sunday morning in the low 50s near I-95 and upper 50s near the coast before temperatures and dewpoints start to plummet in the afternoon behind the front.
Northerly winds will also be quite gusty Sunday afternoon with the CAA, and gusts of 25-30 mph will be possible. A 500mb trough and associated PVA moves across Sunday evening, but with virtually no moisture to work with there might not even be any clouds with its passage. Strong CAA will bring low temps in the upper teens Sunday night, with low 20s along the immediate coastline.

The primary concern will be the combination of the low temps and the lingering winds, as pressure gradient remains tight between expansive high pressure to the west and front/low well offshore. With wind gusts of 15-20 mph potentially lingering through daybreak Monday, this would produce wind chills in the single digits for most of Sunday night. Due to the timing (heading into the weekend), the significant drop in temperatures, and our forecast only being a couple of degrees above warning criteria, we have issued an Extreme Cold Watch for our CWA for Sunday night. This will either be replaced with an advisory or, if winds look stronger or temps get colder, a warning during a future forecast package. Regardless of whether a Cold Weather Advisory or an Extreme Cold Warning is issued, dangerous cold air is expected Sunday night and precautions should be taken.

LONG TERM /MONDAY THROUGH FRIDAY/
Unusually cold weather lingers into Monday with forecasted high temps barely reaching 40F in the afternoon. With high pressure overhead, Monday night will see good radiational cooling conditions. Though with weaker CAA and no wind, it won't be as cold as Sunday night. Lows Tuesday morning are forecasted around 20F, so still quite cold. High pressure shifts offshore late Tuesday and we'll see a warming trend throughout the week, with seasonable weather expected Wednesday followed by above normal temps Thursday. Another cold front may move across the area Thursday into Friday, though not as strong as this weekend's front.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/
VFR should prevail over the coming 24 hours. At KILM and KFLO there is a low probability that MVFR conditions will develop late tonight as increasing dewpoints may allow patchy fog or even some scattered very low clouds to develop. Timing appears to be after 06z, then dissipating quickly at sunrise.

Extended Outlook...Low level wind shear is possible Saturday night. Surface wind gusts over 30 knots are possible Sunday afternoon and Sunday night behind a strong arctic cold front.
Otherwise VFR conditions should continue through the extended period.

MARINE
Through Saturday...Essentially light and variable winds this afternoon and overnight although the stamped direction will be north then west. Saturday will see a slightly better defined south to southwesterly flow ahead of changeable conditions that will occur later in the weekend. Overall significant seas will be 1-2 feet.

Saturday Night through Wednesday...Southwesterly winds Saturday night will quickly veer to northerlies Sunday afternoon as a strong cold front moves off the coast. Strong CAA behind the front, with an expansive high pressure to our west, will increase winds to 20-25 kts Sunday evening through Monday morning with gale-force gusts possible, along with seas of 4-6 ft. Winds and seas quickly improve during the day Monday as the high pressure moves eastward. Benign marine conditions Tuesday and Wednesday, with WSW winds 5-10 kts and seas around 2 ft.

ILM WATCHES/WARNINGS/ADVISORIES
NC...Extreme Cold Watch from Sunday evening through Monday morning for NCZ087-096-099-105>110.
SC...Extreme Cold Watch from Sunday evening through Monday morning for SCZ017-023-024-032-033-039-054>056-058-059.
MARINE...None.