textproduct: NWS Wilmington

WHAT HAS CHANGED

Discussions updated.

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

KEY MESSAGES

1) Beneficial rain expected from late Friday through Saturday.

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

DISCUSSION

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

A frontal zone is in place 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 today and tonight while lifting the front 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 frontal zone, 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.

Although the highest amounts are generally expected across southern and eastern areas, NBM-based precip probabilities indicate a high chance of 80% or greater for event totals (Friday through Saturday night) to reach at least 0.75" across the forecast area, with a 60- 80% chance for at least 1", and a 40-65% chance for at least 1.5". QPF clustering tools indicate event totals could reach as high as 2- 3" in a narrow stripe somewhere across the southern and eastern areas which see rain the longest.

Confidence in an extended period of steady rain between Friday night through much of Saturday is high. Confidence in the amounts is moderate to high as guidance tools remain generally steady in their estimates, although some variations north or south in the axis of heaviest rain continues to be observed. The lowest relative confidence exists across northern and western areas, which may end up on a rather tight gradient in precip amounts depending on how close to the coast the front ends up being.

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 this evenings, and again Saturday's, high tide cycles. 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 evening's high tide. High tide this evening is at 1032pm and for Sat evening, 1111pm.

AVIATION /10Z FRIDAY THROUGH TUESDAY/

VFR to dominate across the area thru midday. Otherwise, looking at mid and high level clouds thickening and lowering later this morning thru the afternoon. Some weak VFR overrunning light rain to occur later this afternoon thru this evening with patchy light rain reducing vsby to 5sm at times and ceilings dropping into the 2500-4000 ft range, ie. with periodic MVFR ceilings. Winds NE around 10 kt thru midday as a mini surge occurs with high pressure ridging southward across the area. The high slides offshore from the DELMARVA coast, with winds becoming variable in direction this evening. The front will return north later tonight but remain off the coast. Low pressure to develop along it. Looking at overrunning stratiform rains to become more continuous as opposed to intermittent. Will likely observe widespread MVFR with occasionally IFR restrictions.

Extended Forecast...Expect flight restrictions thru Sat evening as low pressure intensifies off the Carolina Coasts while tracking NE, away from the area. VFR returns late Sat night thru Tue except fog/low clouds possible Mon night as low- level moisture returns.

MARINE

Through Tonight...Cold front stalls in the vicinity of Jacksonville FL this morning then begins to lift northward later today into tonight. Sfc low expected to develop along it off the SC Coast tonight while the frontal system itself lifts further north to just offshore from the local coastal waters Sat morning. This will be its closest approach to land given the approaching positively tilted mid-level s/w trof not conducive to pull the front onshore and inland. As a result, winds may actually go variable in direction late this afternoon into this evening. However, thereafter may see wind directions differ quite a bit if the frontal boundary pushes far enough north to bisect our offshore waters. Will evidently observe slight increasing NE to E winds on the north side of the frontal boundary and slightly increasing SE winds on the south side of the front. Coastal waters will observe a slow building trend to the seas, ending at 2 to 4 ft by Sat daybreak. Same for the offshore waters, building to 3 to 5 ft by Sat daybreak. Easterly swell at 10+ second periods will remain present thruout this period with short period wind waves possibly dominating by the end of this period.

Saturday through Tuesday Night... A frontal zone is expected to be near or over the waters on Saturday as multiple low pressure areas track along the boundary, bringing rain and isolated thunderstorms through the day. A tightening gradient between high pressure over the Midwest and these surface lows will result in breezy north winds on Saturday, with speeds of 20-25 kts expected at the highest, mainly during the afternoon into the evening before slackening some overnight. Steady offshore flow will continue through Saturday night before weakening on Sunday. High pressure will maintain control between Sunday and Tuesday, although its rapid trek eastward will result in offshore flow on Sunday turning southerly on Monday.

Seas will rise as winds increase early Saturday, peaking in the 2-5 ft range late on Saturday within 20nmi of shore before gradually subsiding through Sunday night into the 1-2 ft range. Waters from 20- 60nm look to have seas peak in the 4-7 ft range before subsiding to 2-3 ft by the end of Sunday night. Seas will remain benign through Tuesday owing to light winds as high pressure passes over. A combination of northerly wind waves and ENErly swells with a period around 10 sec will be the primary wave groups through Sunday before winds weaken. The ENErly swell will gradually decay through the end of the period with southerly wind waves and southeasterly swells with a period around 7-8 sec expected to arrive on Tuesday.

ILM WATCHES/WARNINGS/ADVISORIES

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