Marine Weather and Tide Forecast for Carolina Beach, NC

UPDATE
The forecast is on track. No changes planned at this time.

NEAR TERM /THROUGH TONIGHT/
A 500 mb ridge extending north from a high centered over the west central Gulf will reach the Carolinas later tonight into tonight.
The surface high already has drifted off the NC/VA coast and our winds should generally be southeasterly today, transporting in enough low level moisture to feed scattered cumulus clouds mainly across South Carolina. A strong subsidence inversion between 5000- 7500 feet AGL will cap off these clouds, preventing any significant vertical development and keeping forecast PoPs near zero percent today and tonight.

The overall airmass has warmed by a couple degrees since yesterday and forecast highs range from the mid 80s across the Pee Dee region to the mid 70s on the beaches. Winds should diminish tonight with enough radiational cooling expected to dip lows into the upper 50s with lower 60s at the coast with mainly clear skies continuing.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
Mid-level ridging and associated subsidence/dry air will remain in place through this period while surface high pressure offshore keeps a warm, moist southerly low-level flow going.
Fair weather cumulus and passing high clouds can be expected under this regime, with a pop-up shower not entirely out of the question along the sea breeze. Very dry mid-level air and capping should prevent anything beyond an isolated pop-up shower.

High temps will remain about 5-10F above normal for this time of year, with mid-upper 80s inland and low-mid 80s nearer to the coast. Morning lows on Thursday and Friday in the low-mid 60s in tandem with dew points in the low 60s will make for a somewhat muggy feeling early.

LONG TERM /FRIDAY THROUGH MONDAY/
Summary: Recent guidance trends support a slower arrival to the cold front over the weekend, with it potentially not pushing through until Saturday night instead of the previous expectation for it to push through early on Saturday. This will need to be monitored closely as the slower scenario would support another abnormally warm day on Saturday followed by scattered to numerous showers and storms during the afternoon into the overnight along and ahead of the front. The main changes to the forecast reflecting this potential include higher rain chances (up to 50%) on Saturday and dew points lingering in the mid 60s, but high temps and PoPs may need to raised further in future updates. Behind this delayed cold front, cooler and drier air than originally anticipated would filter in, knocking high temps down into the 70s for Sunday and Monday.

Detailed discussion: Some notable trends in both the operational guidance and ensembles over the last several runs have made for some notable changes to the forecast with this update. The trends point toward the arrival of mid-level troughing becoming increasingly delayed as a potent shortwave dives southeastward from the Northern Plains, causing a sharper trough to take shape further west on Friday and Friday night while more amplified ridging builds over the central US. This delays the arrival of the surface cold front until late Saturday or Saturday night and subsequently raises the chances for showers and thunderstorms considerably on Saturday while somewhat lowering chances on Friday. In addition, the sharper trough would lead to a stronger push of cool, dry air in the wake of the front for Sunday and Monday. With this all in mind, the GFS and its ensembles are on the more progressive side (which is typical), so this will need to be monitored in future runs to see if it continues to trend slower and more amplified with the troughing and later with the cold front's arrival.

While weak to moderate instability and less capping should support pop-up showers and storms on Friday, nebulous forcing and weak shear should keep these isolated and disorganized at the worst. Otherwise, mixed clouds and sun with continued above- normal highs in the mid-upper 80s away from the coast are expected. On Saturday, a delayed cold front and sharper trough would present more of an opportunity for instability to develop and wind shear to increase, leading to the potential for scattered to numerous showers and thunderstorms, some of which could be strong. At this point, PoPs are held at high chance to begin the trend upward. In addition, while high temps are presently forecast to reach the low 80s, a delayed front would allow for temps to reach the mid-upper 80s inland for one more day. Thus, notable changes to the temp forecast are possible in future updates.

Behind the cold front, winds veer to northerly as high pressure over the Midwest builds in, bringing considerably cooler temperatures and much lower dew points for Sunday and Monday, with high temps and dew points showing downward adjustments of several degrees in this update.

AVIATION /18Z TUESDAY THROUGH SATURDAY/
There is high confidence in VFR conditions persisting over the next 24 hours. Only FM groups will be to address minor changes in wind direction.

Extended Outlook...Generally VFR. MVFR/IFR is possible Thursday morning in ground fog.

MARINE
Through Tonight...
1028 mb high pressure centered off the Outer Banks will drift slowly eastward over the next 24 hours, maintaining a slowly veering onshore wind across the coastal Carolinas. Synoptic wind speeds around 10 knots will be supplemented by this afternoon's seabreeze and should increase to near 15 knots nearshore. Seas of 2- 3 feet this morning should build mainly due to an increasing S/SE chop to a solid 3 feet this afternoon into tonight.

Wednesday through Saturday...
Offshore high pressure will dominate the entire period with south-southwesterly winds expected. The pressure gradient tightens late in the week as a cold front draws closer, but gusts are still expected stay just below SCA criteria. These gusts could change depending on the timing and strength of the weekend cold front. Nearshore pop-up showers and thunderstorms will be possible on Friday while scattered to numerous showers and thunderstorms are possible on Saturday, especially if current trends towards a later and stronger cold front continue.

Seas around 2-3 ft through Friday morning due to a combination of ESErly 8 sec swells and southerly wind waves rise to 3-4 ft for Friday through Saturday as wind waves come to dominate the wave spectrum ahead of a cold front.

TIDES/COASTAL FLOODING
This month's New Moon was two days ago but tidal ranges remain large. Latest projection of observed anomalies onto the astronomical tide implies we'll again exceed minor coastal flood thresholds at Myrtle Beach and at downtown Wilmington during tonight's high tide by about 0.2 feet at both locations.
Wrightsville Beach may fall show of criteria there by about 0.2 to 0.3 feet. Given the limited impacts I'll hold off issuing an advisory on this shift and let the day crew look over anomalies again.

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