textproduct: NWS Wilmington

WHAT HAS CHANGED

As of 700am... Aviation discussion updated for 12Z TAFs.

As of 244am...Shower chances this morning have been mainly limited to coastal South Carolina and should largely end by 8 AM. Forecast thunderstorm chances have been increased slightly along the cold front this evening. And forecast low temperatures have been adjusted down by 1-2 degrees for Tuesday night/Wednesday morning in the Canadian airmass.

KEY MESSAGES

1) Rain will fall early this morning mainly across South Carolina, then a wave of gusty thunderstorms is possible late this afternoon into this evening.

2) Canadian air spreading southward should bring temperatures 10 to 15 degrees below normal Tuesday and Wednesday.

DISCUSSION

KEY MESSAGE 1: Rain will fall early this morning mainly across South Carolina, then a wave of gusty thunderstorms is possible late this afternoon into this evening.

The wave of rain produced via isentropic lift in eastern South Carolina covers a much more limited geographic area than models 24 hours ago were suggesting. In terms of depicting the current precipitation observed on radar, the best models currently appear to be the 00z NAM and 00z HREF. The 03z RRFS and 05z HRRR are both too dry in the Myrtle Beach/Georgetown area.

Tracking isentropic ascent on the 305-310K surfaces, substantial precipitation may wrap up along the South Carolina coast before 8 AM with only a few lingering showers continuing through the morning. Once low clouds break and sun heats inland areas into the 80s, a seabreeze will develop which could bring a few more isolated showers or t-storms near the coast.

Of greater concern will be the arrival of a cold front late this afternoon into this evening. Most models show this front will be accompanied by a line of showers and thunderstorms with surface CAPE in the 1000-1500 J/kg range. Bulk shear across the 0-6 km layer should be around 30 knots which could allow multicell organization. Assuming a line of storms can develop, there should be enough dry air in the mid levels to produce some gusty winds as the convective mass sweeps southward during the evening hours. Forecast PoPs are in the 60-70 percent range.

KEY MESSAGE 2: Canadian air spreading southward should bring temperatures 10 to 15 degrees below normal Tuesday and Wednesday.

Deep northerly flow out of Canada on the back side of the vertically stacked cyclone east of the Outer Banks Tuesday should drag unseasonably chilly air southward. Model mean 850 mb temp forecasts reach a minimum of +7C to +9C Tuesday night. Compared to 24 hours ago, models have gotten a bit chillier and MOS guidance for Wilmington Wednesday morning now includes 52 on the GFS and 51 on the ECMWF.

The all-time record low for the month of June in Wilmington is 48 set back on 6/2/1983. If we end up dipping to 52 Wednesday morning (the current forecast) it will be the coolest June temperature since 6/5/2023 and only the second time this century the temperature has dipped so low in June.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Primarily MVFR cigs at the SC terminals are expected to persist through most or all of this morning before mixing/scattering out in the afternoon. Scattered light shower activity over northeast SC should come to an end within the next few hours, although any shower which directly hits a terminal could bring brief MVFR restrictions. North of the cloud cover and light showers, daytime heating will help develop sea breeze cloudiness and showers as soon as 15-16Z with potential to impact the KILM airport vicinity. A southward-moving cold front appears likely to bring a more concentrated line of showers and thunderstorms late this afternoon into this evening. MVFR to brief IFR conditions and locally gusty winds are possible at this feature sweeps across the area.

Extended Forecast...There is moderate to high potential for MVFR ceilings into Tuesday morning behind the cold front. VFR conditions should develop during the day Tuesday and persist through Friday under high pressure.

MARINE

An area of low pressure is developing along a stalled front off the Georgia coast early this morning. This feature should slowly deepen as it moves eastward, crossing the Gulf Stream this afternoon and continuing eastward tonight. After morning showers and a few thunderstorms bring wet weather south of Cape Fear this morning, generally light southeasterly winds are expected for the remainder of the day.

A cold front dipping toward the area late this afternoon should be accompanied by a line of showers and thunderstorms. This activity could become rather strong with gusty winds possible. Storms should pass through Cape Fear between 6-8 pm, and should be south of Georgetown by midnight. In its wake, increasing northeasterly winds are expected overnight into Tuesday as 1030 mb high pressure over the Great Lakes builds southeastward toward the Carolinas. Small Craft Advisory conditions are likely Tuesday into Wednesday, and it's possible there will be a short period of gale force gusts east of Cape Fear within the 20-60 mile offshore forecast zone. Seas should build to 5-6 feet inside 20 miles of shore, and to 7-9 feet for the 20-60 mile offshore zones.

Lighter winds are expected for the latter half of the week.

ILM WATCHES/WARNINGS/ADVISORIES

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