textproduct: NWS Wilmington

WHAT HAS CHANGED

Aviation section updated for the 12Z TAF issuance.

KEY MESSAGES

1) Deep tropical in place through the weekend will keep rain chances high and increase the potential for isolated flooding.

2) High rip current risk currently in effect for New Hanover and Pender county beaches.

DISCUSSION

KEY MESSAGE 1...Deep tropical in place through the weekend will keep rain chances high and increase the potential for isolated flooding.

Onshore flow near the coast and elevated instability inland will continue to produce isolated showers early this morning. Coastal areas may see a brief shower after sunrise as onshore flow intensifies and surface heating provides a little extra lift. By afternoon, much of the activity will have shifted inland.

Ongoing showers this morning will gradually spread in coverage during the late morning or early afternoon. Air mass thunderstorms will develop along outflows this afternoon due to some help from weak upper level divergence and differential surface heating. Outflows should sustain inland convection.

Deep tropical moisture will linger over the Southeast for much of the upcoming week with a pattern aloft that will promote upward motion. The key to when and where showers and thunderstorms develop will be surface based forcing. Be it from lingering convective boundaries, differential heating, low level speed convergence or a weak sea breeze. With the setup being typical of a summertime pattern expect to see more storms inland during the day with a little more action along the coast overnight.

The first half of the week looks more conducive to widespread showers and thunderstorms compared to the later half of the week. Precipitable water exceeds 2" for a bulk of the Mon-Wed time period and at times is among the highest values recorded at CHS/MHX. The combination of extreme pwat, deep warm cloud layer (13k ft+) and slow storm motions creates a setup perfect for significant rainfall and minor flooding. Multiday rainfall totals well in excess of 5" will be possible in any locations that experience multiple rounds of storm or training storms.

Slightly drier mid-level air works its way north around the middle of the week,bringing about a slight decrease in coverage. Guidance has been showing a front moving in from the north then stalling in the region, but not sold on this yet. Guidance was showing something similar happening with the last front, which ended up stalled to the north. Seems more likely the front stalls before reaching the forecast area, keeping a more convective environment in place.

KEY MESSAGE 2...High rip current risk currently in effect for New Hanover and Pender county beaches.

A high risk of rip currents is in effect for today for New Hanover and Pender county beaches due to 3-4 ft SSE swell leading to strong rip currents, with holiday weekend crowds contributing to increased rescues by lifeguards. Moderate rip risk in effect for beaches south of Cape Fear. The high rip current risk may linger through Monday for beaches north of Cape Fear, and this will be evaluated further later today.

AVIATION /11Z MONDAY THROUGH FRIDAY/

Spotty showers will mix the surface layer and briefly reduce the coverage of low clouds impacting our inland terminals just after sunrise. Beyond showers, gradual improvement is expected due to low level mixing. With these contributing factors, inland terminals should become MVFR rather quickly. Confidence in the exact development of showers and storms is low this morning, but expect coverage to gradually increase through the late morning with widespread showers and storms likely this afternoon. Low clouds are expected to return overnight.

A few isolated showers remain possible this morning at coastal locations. Showers will be shallow and are unlikely to impact terminals beyond their MVFR CIGs. MVFR CIGs will gradually improve through the late morning and early afternoon. Not much activity near the coast this afternoon with a weaker sea breeze than previous days. Marine stratus returns this evening, possibly lowering overnight.

Extended Forecast... Low stratus or fog will continue through much of this week with better chances at our inland terminals. Afternoon showers and storms will impact the terminals through much of this week. A sea breeze near the coast will keep most of this activity inland through Wednesday. Convective activity may reduce in coverage somewhat Wednesday and Thursday and shift preferentially toward the coastal airports KILM, KCRE, and KMYR.

MARINE

Through Monday... Southerly winds continue today. A few gusts to 25 knots are possible in the offshore waters. Seas 3-4 feet in the nearshore waters, and 4-6 feet in the offshore waters. Primary swell out of the SSE at 7 seconds in addition to a 1-3 feet ENE swell mixed in. With the Gulf Stream well into the marine zones, scattered showers and thunderstorms will impact portions of the waters early this morning and tonight.

Tuesday through Friday... Bermuda High will maintain southerly flow through at least Thu. Some indications of a backdoor cold front Thu night into Fri, but the last backdoor cold front failed to reach the area and it seems plausible this one will too. A northeast to east wind is shown developing Thu night and continuing Fri, but confidence in this is low and seems more likely ridging and southerly flow will prevail. Winds will generally be 10-15 kt with afternoon enhancement while the Bermuda High is in place. Exception will be out near 60 nm where winds on the high end of the 15-20 kt range will be possible Thu if the front is able to push into the region. Seas 3-5 ft with occasional 6 ft out near 60 nm.

ILM WATCHES/WARNINGS/ADVISORIES

NC...High Risk for Rip Currents through this evening for NCZ106-108. SC...None. MARINE...None.