Marine Weather and Tide Forecast for Florence, SC

NEAR TERM /THROUGH SUNDAY/
Little in the way of convection expected through Sunday under mostly clear/partly cloudy skies and warm temperatures for the season. Lows tonight will fall to the upper 60s to lower 70s with highs Sunday away from the beaches in the upper 80s to near 90.



SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/
Mid-upper ridging builds up west of the area on Sunday night with northwesterly flow aloft becoming well-established while the stationary front remains just south of the forecast area.
Lower dew points behind the front will support a slightly cooler night, with middle 60s expected away from the coast by sunrise Monday morning. On Monday, dry air and subsidence in the middle atmosphere should keep any convection at bay aside from shallow fair-weather cumulus and passing high cirrus. With ridging nudging eastward, the stalled front should begin drifting northeastward with continued above-normal warmth as highs reach into the mid-upper 80s away from the coastline. Late in the day, guidance indicates that a shortwave and potentially an MCS will be sliding southeastward from the mountains parallel to the front, although the time of its arrival well after dark will likely mean it will be weakening as diurnal cooling causes instability to wane. Regardless of whether rain occurs (with PoPs only in the 10-20% range at this point), debris clouds will keep Monday night's lows mild, in the mid-upper 60s.

On Tuesday, the ridge axis is expected to move nearby or overhead, which will keep mid-level dry air and subsidence in place, leading to a low-level cap and meager mid-level lapse rates. However, highs in the upper 80s to around 90F and dew points in the upper 60s to around 70F should be enough to develop weak to perhaps moderate instability in tandem with effective shear of 40-50 kts. Thus, if convection develops, the potential for severe weather is there. However, whether or not convection will manage to develop is still a question given the proximity of the ridge axis and a lack of shortwave impulses to spur convection. Thus, PoPs are held in the 20-30% range at this time.

LONG TERM /WEDNESDAY THROUGH SATURDAY/
Confidence remains on the low side for the extended period as a complex mid-upper pattern evolution takes place during the latter half of the week. In general, guidance indicates that troughing and embedded vort maxes from the western US early in the week will track eastward and interact with a lobe of vorticity extending northwest from a closed low southeast of Nova Scotia around midweek. As these features interact during the latter half of the week, multiple vort maxes are expected to develop and pivot around each other while a broad trough is carved out over the eastern US. Model depictions of this pattern vary considerably and model trends do not show any particular solution becoming more likely, pointing to the known complications with closed lows as they are notoriously difficult to forecast.

Ultimately, one or more surface lows should develop across the eastern Ohio Valley and Mid-Atlantic as a result of this trough and lead to increased shower and thunderstorm chances on Wednesday as a cold front approaches and likely sweeps through the area either late in the day or during the overnight. Model soundings and tools like the ECMWF EFI and CSU Machine-Learning probabilities indicate that a favorable environment for severe weather may be in place, with SBCAPE around 2000 J/kg and effective shear of 40-50 kts supporting a severe wind and hail threat. Nevertheless, finer-scale details related to the timing of the front and any shortwaves rotating around the broader closed low may enhance or hinder severe thunderstorm chances, so this will need to be re-evaluated in future updates.

Otherwise, cooler and drier air will filter in behind the front for late in the week, with guidance honing in on a shortwave and associated northwesterly wind surge arriving on Thursday, which should knock temperatures and dew points below-normal for the first time in a while. Par for the course in these closed low situations, the departure of its associated trough differs considerably across the model output, but when it does leave, temperatures will start to rise again as ridging builds in from the west, setting up yet another northwesterly flow regime.

AVIATION /00Z SUNDAY THROUGH THURSDAY/
VFR with SW winds that will lose their gustiness soon after sundown and regain it late tomorrow morning. The cirrus should also continue to thin.

Extended Outlook...VFR conditions are expected through much of the period but a frontal system could bring scattered showers and storms with restrictions on Wednesday.

MARINE
Through Sunday...
Frisky SW winds of 15 to 20 KT with higher gusts this evening into tonight will become westerly at 10 to 15 KT Sunday. Seas of 3 to 4 FT with a some 5 footers nearer 20 NM northern waters tonight will abate to 2 to 3 FT Sunday. No flags but not pleasant boating conditions either.

Sunday night through Thursday...
A stalled front near or just south of the southern waters will gradually lift back northeastward early in the week, leading to changeable wind directions, although speeds will be generally 10 kts or less through Tuesday. The pattern amplifies during midweek with a rather strong cold front approaching on Wednesday, leading to solid southwesterly winds in the 15-20 kt range which may necessitate a Small Craft Advisory. These winds eventually turn westerly behind the cold front by early Thursday morning before a northwesterly wind surge potentially arrives on Thursday.

Light and variable winds are expected to keep seas in the 1-2 ft range through Tuesday before increasing winds ahead of the next cold front raise seas into the 3-5 ft by Wednesday afternoon.
Seas will gradually subside behind the cold front through Thursday as offshore flow weakens. Wind waves will be a diurnal contributor to the wave spectrum while a 1-2 ft southeasterly swell with a period of 8-9 sec remains in place.

ILM WATCHES/WARNINGS/ADVISORIES
NC...None.
SC...None.
MARINE...None.