textproduct: NWS Wilmington

WHAT HAS CHANGED

Coastal Flood Advisory was issued for the Lower Cape Fear River for high tide this evening.

A Small Craft Advisory was issued for Saturday afternoon into Saturday evening.

Confidence in beneficial rain tonight into Saturday remains high, with the primary uncertainty being how much rain falls, especially across northwestern portions of the forecast area, or generally west of I-95.

KEY MESSAGES

1) Beneficial rain expected from late today through Saturday.

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

3) Another round of much needed rain possible Thursday.

DISCUSSION

KEY MESSAGE 1: Beneficial rain expected from later today through Saturday.

A stalled front remains well south of the area, draped across the northern Gulf Coast and extending off the east coast of Florida. A weak low pressure area is expected to track along this front through tonight while the front lifts closer to the forecast area, bringing an initial batch of mainly light rain to southern and eastern areas this afternoon into tonight. As a notable shortwave trough pivots southeastward towards the Deep South and sharpens, increasing upper-level divergence will result in the development of multiple surface lows along the front, bringing an extended period of rain from the latter half of tonight into Saturday, with rain tapering off from west to east during the afternoon and evening. A consolidated and deepening surface low will emerge and accelerate away from the northeastern NC coast on Saturday night, bringing an end to the precip as cooler and drier air filters in behind it.

The greatest chc of rain will exist between daybreak Saturday and early Saturday aftn. A rather tight gradient in precip amounts should exist as the axis of greatest pcp should be aligned near or just off the coast depending on how close to the coast the wave of low pressure tracks. Looks like most of the area should receive between .75 and 1 inch with greater amounts possible closer to the coast, especially across Georgetown coast and lesser amounts possible west of I-95. Overall, expect a cloudy, cool and rainy day on Saturday.

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 Wednesday or Thursday.

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

As a result of the full moon and relatively high astronomical tides, the latest tidal gage forecasts for the Lower Cape Fear River has it eclipsing minor coastal flood thresholds (5.5 ft mllw) during high tide this evening, and again Saturday. This will effect low-lying locations in the vicinity of the river from downtown Wilmington and southward. The minor coastal flooding will occur generally within a 3 hour window centered around the high tide this evening. High tide this evening is at 1032 pm and for Sat evening, 1111 pm.

KEY MESSAGE 3...Another round of much needed rain possible Thursday.

Going from the mid to late week period the mid level flow will transitions from zonal/weak ridging to a deep trough that gets carved out from the NW. This drives a cold front through the area on Thursday. There are some conflicting indicators as to how much rain this setup may be capable of generating. Arguing for rain is both the strength of the surface front as well as the mid level support in the form of height falls. Arguing against meaningful rainfall/drought releif is the fact that there is no big high downstream of the front offshore. This limits prefrontal moisture flux into the Southeastern U.S. There is also a good signal of convection in the Gulf States that always famously robs the Carolinas of rainfall. In the end what seems likely is that high POPs will in fact be warranted but lower QPF model solutions will verify best.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

Mid to high level clouds will continue to thicken and lower through this afternoon. Expect some sub-VFR patchy light rain reducing vsby to 5sm at times and ceilings dropping into the 2500-4000 ft range. High pressure shifting off the coast will cause a veering of winds to the E through this afternoon remaining around 10 kt with some higher gusts. As the high slides farther offshore from the DELMARVA coast and a weak cold front reaches into the Carolinas from the NW, winds become variable in direction this evening.

Waves of low pressure will develop along a cold front draped across the Gulf coast as it shifts back north later tonight remaining off the coast. Looking at overrunning stratiform rains to become more continuous as opposed to intermittent. Will likely observe widespread MVFR lowering to IFR after 07z and remaining through the end of this TAF period with steady rain across most of the terminals.

Extended Forecast...As low tracks from off the Coastal Carolinas to the NE, away from the area Sat aftn into Sat eve, expect a return to mainly VFR through Tue. Fog/low clouds could reduce visibilities Mon night as low-level moisture returns.

MARINE

Through Saturday...Cold front stalled across the Gulf Coast to the coast of Fl will lift northward into tonight. Low pressure will develop along the front off the SC Coast tonight while the front lifts farther north to just offshore from the local coastal waters Sat morning.

Winds this afternoon will veer a bit more easterly around 10 kts with higher gusts as high pressure shifts off the Delmarva coast to the north. Winds will lighten and become more variable later today before they shift back to the N as the front and low lift northward into Saturday. Depending on the track of the low and frontal boundary, you should see increasing NE to E winds on the north and west side of the low and slightly increasing SE winds on the east and south side, but most of the local waters should be in an increasing northerly flow as the low lifts northward. Coastal waters will observe a slow building through early Sat with 2 to 4 ft seas near shore. Same for the offshore waters, building to 3 to 5 ft by Sat daybreak. A tightening gradient between high pressure over the Midwest and surface low off the NC coast will result in increasing N winds on Saturday, up to 20 to 25 kts in higher gusts through Sat aftn. Easterly swell around 10 seconds will mix in.

Saturday night through Wednesday...Advisory-worthy winds will be tapering at the start of the period as low pressure exits to the NE along frontal boundary. High pressure quickly builds behind the front/low Sunday and transitions offshore for winds that veer while growing considerably weaker late in the day. In fact by Sunday night speeds could drop as low at 5-10kt. Light southerly winds and the absence of appreciable swell energy on Tuesday will allow seas to fall to 2 ft. Winds and seas will both be on the rise Wednesday as a cold front approaches but no headlines are anticipated at this time.

ILM WATCHES/WARNINGS/ADVISORIES

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