textproduct: NWS Wilmington

WHAT HAS CHANGED

Discussions updated.

Probabilities for rainfall amounts of at least 0.5, 0.75", and 1" have increased.

KEY MESSAGES

1) Beneficial rain expected from late Friday through Saturday

2) The Lower Cape Fear River to experience minor coastal flooding during the next 2 mid to late evening high tide cycles.

DISCUSSION

.KEY MESSAGE 1: Beneficial rain expected from late Friday through Saturday

A frontal zone will be in place south of the area on Friday, draped across the northern Gulf Coast. A southern stream shortwave is expected to deamplify as it ejects out of Baja California and tracks eastward along this boundary while a sharpening northern stream shortwave pivots southeastward through the mid-Mississippi Valley. These are forecast to phase over the Deep South, resulting in multiple surface lows developing and tracking along the front while it lifts back towards the forecast area. A consolidated and deepening surface low should emerge and accelerate away from the NC coast on Saturday night into Sunday, bringing an end to the precip as much cooler and drier air filters in on gusty north winds.

This pattern evolution will result in an extended period of rain with intermittent light rain starting Friday afternoon or evening across far southern areas before gradually lifting northward over Friday night and becoming light to moderate. The steadiest/heaviest rain is anticipated on Saturday morning, with rain coming to an end from west to east during the afternoon Ann evening. Although the highest amounts are generally expected across southern and eastern areas, ensemble probabilities indicate a high chance of 70% or greater for event totals to reach at least 0.5" across the forecast area, with a 45-60% chance for at least 0.75", and a 30-50% chance for at least 1.0". QPF clustering tools indicate event totals could reach as high as 1.5-2.5" in a narrow stripe somewhere across the southern and eastern areas which see rain the longest and where some convective enhancement to the rain may occur.

Confidence in an extended period of steady rain between Friday night through much of Saturday is high. Confidence in the amounts is moderate as the track of low pressure and proximity of the front it tracks along will modulate how much rain falls and where the stripe of highest amounts set up. Although guidance tools have shown a general trend northward with the low's track, which results in greater rainfall totals overall, a nudge north or south could change how much falls, particularly across northwestern portions of the forecast area.

Behind this system, a surge of cool and dry air will make for below- normal temperatures between Saturday night and Sunday night. A gradual warming trend will commence thereafter before another front arrives with the next chance for rain around or on Thursday.

.KEY MESSAGE 2: The Lower Cape Fear River to experience minor coastal flooding during the next 2 mid to late evening high tide cycles.

Latest gage forecasts for the Lower Cape Fear River has it reaching minor coastal flood thresholds (5.5 ft mllw) during this evenings high tide cycle as well as Friday evenings. At this time both evening forecasts reach 5.7 ft mllw. This will effect locations in the vicinity of the river from downtown Wilmington and southward. Look for the potential for minor flooding to occur in generally a 3 hour window centered around high tide. High tide Thu evening is at 952pm and Fri evening at 1032pm

AVIATION /12Z THURSDAY THROUGH MONDAY/

VFR to dominate early this morning. Look for potential MVFR ceilings and/or reduced vsby from scattered showers/isolated tstorm later this morning thru early to mid afternoon as an embedded mid-level s/w trof moves across while a sfc cold front sinks south of the area. There may be a brief period of IFR but confidence too low to include at this time. VFR to dominate later this afternoon thru the end of the 24 hr period. NW-N winds 4 to 8 kt will veer to NE later tonight as the front sinks further south of the area and sfc high pressure ridges south across the region. Winds may go calm this evening before that NE surge occurs around or after 06Z.

Extended Forecast...VFR early Fri will succumb to flight restrictions late Fri into Sat as the frontal boundary lifts northward to or just south of the area and sfc low develops along it and pushes out to sea. Looking at mainly stratiform rains and low ceilings with MVFR/IFR likely Fri night thru Sat evening. VFR returns late Sat night thru Mon

MARINE

Through Tonight...Cold front sinking southward, will push into the coastal waters around daybreak and thru the offshore waters by late this morning or around noon. SW winds 10-15 kt, except 15-20 kt offshore, will become NNW-N 10-15 kt across the coastal waters and around 15 kt offshore. The front will stall south of the area tonight while high pressure from the north ridges across the area, resulting with a NNE-NE surge of 15 to 20 kt winds with periodic 25 kt gusts across the offshore waters. Expect scattered convection ahead and along the cold front as it pushes southward later today. Other activity in the form of scattered convection may broad brush the coastal and offshore waters between Surf City and Masonboro Inlet during these pre- dawn hrs. Seas generally 2 to 3 ft today and 2 to 4 ft tonight except some 5 footers across the offshore waters later tonight.

Friday through Sunday Night... As high pressure shifts offshore north of the waters on Friday, expect northeasterly winds of 15 kts or so to continue veering while weakening through the day. A frontal zone is expected to lift towards the waters from offshore and bring an extended period of rain and occasional thunderstorms from Friday afternoon into Saturday night as multiple low pressure areas track along it. Initially easterly winds on Friday night are expected to back to northeasterly, although depending on the front's position, eastern portions of the 20-60nmi zones may see southeast winds instead. On Saturday, a surface low will lift northeast of the waters and bring increasing northerly flow which may necessitate a Small Craft Advisory for the coastal waters. This offshore flow weakens on Sunday as high pressure builds in and the gradient weakens considerably.

Seas around 2-4 ft on Friday will temporarily subside before rising again as winds increase early Saturday, peaking in the 2-5 ft range late on Saturday before gradually subsiding through Sunday night into the 1-2 ft range. While wind waves will dominate the wave spectrum initially, a NE swell with a period around 9 sec will contribute more substantially from Saturday night into Sunday night.

ILM WATCHES/WARNINGS/ADVISORIES

NC...None. SC...None. MARINE...None.