textproduct: NWS Wilmington

WHAT HAS CHANGED

The dense fog advisory has been cancelled for most of the area, with lingering patches of dense fog along and west of I-95. The Dense Fog Advisory continues for coastal Horry and coastal Brunswick areas as sea fog continues to impact the coastline. A Marine Dense Fog Advisory continues through 10 AM EST Thursday.

KEY MESSAGES

1) Unseasonable warmth, marine fog, and nighttime fog over land will define the next several days.

DISCUSSION

KEY MESSAGE 1...Unseasonable warmth, marine fog, and nighttime fog over land will define the next several days.

KEY MESSAGE 1 DESCRIPTION... As has long been discussed by now we are locked into a pattern much more characteristic of summertime. High pressure over Bermuda at the surface and a mid level high displaced slightly to its west the theme through most of the forecast period. The former will bring unseasonable warmth and humidity, the latter acting as a convective lid to keep the area rain-free through at least Saturday. Thereafter the mid level ridging moves a bit offshore, weakening our convective lid and also allowing for some mid level moistening. QPF/convective signals in guidance hint that rain chances will be along mesoscale processes especially the seabreeze though with temperatures so warm perhaps inland locales can also reach convective temperatures and warrant rain chances even in the absence of the seabreeze- induced lift.

With the Bermuda High extending an axis into the SE US winds will be very light and each night will reach 90-100 percent RH values and be susceptible to fairly widespread fog. Most of the upcoming nights will be candidates for DFAs.

Unlike the aforementioned radiative fog, marine fog will be present for much of the forecast in an advective manner as high dewpoint air is cooled to saturation by traversing the chilly nearshore waters. This will largely be confined to the marine environment and represent a visibility-related hazard to boaters but it will also lead to forecast headaches in two ways. The first will be the onshore flow along the Brunswick County coast where fog and stratus could severely temper afternoon highs. The second will be a narrow strip along the immediate coast just about anywhere else where the uninhibited seabreeze draws this cool and saturated marine layer inland each afternoon.

AVIATION /13Z THURSDAY THROUGH MONDAY/

Patchy dense fog continues to impact most terminals. A mix of sea and radiation fog is also impacting the coastal terminals. Restrictions will continue for the next couple of hours, but conditions should gradually improve through the morning with VFR expected by mid or late morning as fog lifts to broken stratus. Mostly clear skies expected today outside of afternoon cumulus.

Fog is likely again tonight. The air mass will be similar, so TAFs reflect a generalized forecast which tries to capture the development of fog last night.

Extended Forecast... VFR conditions are expected for much of the extended period, but periods of fog could bring late night/early morning restrictions and sea fog could advect into the Grand Strand terminals through the weekend.

MARINE

Through Tonight... Satellite shows widespread sea fog across our nearshore waters as of midnight Thursday. A Marine Dense Fog Advisory has been issued through 13Z to cover this threat. The environment does not change significantly after 13Z, but mixing may thin the fog sufficiently to amend the existing advisory. Confidence is low. Conditions remain favorable for intermittent sea fog through late tonight into Friday morning. Otherwise, high pressure offshore will bring south and southwest winds around 10 knots through early Friday. Some enhancement is possible near the immediate coast during the afternoon due to the sea breeze.

Friday through Monday...Though it's quite early, the summer doldrums are here for now. Bermuda high pressure will be locked in for the entire period. There are two big differences though when comparing this pattern vs were in in place in July. First, the high will be elongated west-east rather than being more circular. This is because the northern branch of the jetstream will still be dragging lows and fronts off the New England coast leading to the high's latitudinal deformation. The end result locally will be much lighter but still southwesterly winds than normally experienced in the summer. And while this will be good news for mariners the second difference, not so much. Very high dewpoints in the 60s flowing over our nearshore waters that are still in the low 50s will lead to a fairly persistent, long fuse sea fog event. Resolving the times and locations of when/where the fog will be thickest and in need of a marine DFA is difficult but we do expect that many headlines/statements will be needed to address it for much of the forecast period as it falls under the purview of shorter term guidance with each passing day. As far as seas, the east- west elongation of the Bermuda High will channel most wave and swell energy towards FL/Bahamas with just enough of both rounding it's western periphery for a general static 3-4 ft forecast.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Dense Fog Advisory until 10 AM EST this morning for NCZ110. SC...Dense Fog Advisory until 10 AM EST this morning for SCZ054. MARINE...Dense Fog Advisory until 10 AM EST this morning for AMZ250-252- 254-256.