textproduct: NWS Wilmington

WHAT HAS CHANGED

An Air Quality Alert has been issued for Horry County for fine particulates due to the large wildfire in southern Marion County. The AQA is in effect through tomorrow/Wednesday. 0z aviation discussion below.

KEY MESSAGES

1) Persistent dry weather and near-record warm temperatures may create fire weather hazards this week.

2) A cold front expected to arrive next Sunday will bring a low chance of showers and a cooler airmass early next week.

DISCUSSION

KEY MESSAGE 1: Persistent dry weather and near-record warm temperatures may create fire weather hazards this week.

A 500 mb ridge centered across Florida should expand northward over the next couple of days, leading to continued dry weather and above normal temperatures across the Carolinas. Ridging aloft will support Bermuda high pressure off the East Coast through the period. Dry soils and deep low level mixing will produce afternoon minimum RH in the low 30s or upper 20s.

High temperatures have a reasonably good chance of reaching 90 degrees inland tomorrow, then exceeding 90 degrees on Friday and Saturday. Along the coast, south to southwest synoptic winds plus the afternoon seabreeze should keep high temperatures ~5 degrees cooler in Wilmington and ~10 degrees cooler at the beaches compared to inland areas.

SPC has included a portion of the Carolinas in their Fire Weather Outlook tomorrow citing low humidity, a moderate southwest wind, and a unusually high Energy Release Component (ERC: an index utilizing fuel moisture to indicate how energetically heat will be released by burning woody fuels.) Similar conditions are expected through the weekend.

Record highs coming up later this week: .............Wed Apr 15...Thu Apr 16...Fri Apr 17...Sat Apr 18 Wilmington......92 in 2006...90 in 2006...89 in 2006...93 in 1976 Lumberton.......92 in 2006...93 in 1941...91 in 2006...91 in 1941 Florence........94 in 2006...90 in 2006...93 in 2006...93 in 1981 N Myrtle Beach..90 in 2006...87 in 2006...87 in 1995...89 in 1976

KEY MESSAGE 2: A cold front expected to arrive next Sunday will bring a low chance of showers and a cooler airmass early next week.

An upper trough pushing eastward across the Great Lakes Sunday will push a surface cold front into the Carolinas on Sunday. The latest GFS, Canadian, and ECMWF all show the front moving through during the afternoon hours, but also show only a tenuous and fading connection to any Gulf moisture. Precipitation along the front may be limited to just a smattering of showers or storms with 0-6 km bulk shear possibly too large for the limited moisture and instability present.

Among the dozens of model ensemble members within the NBM, about 30 percent of them show at least .01" of rain across the area associated with Sunday's frontal passage. Increasing the PoP threshold to .10" cuts this to around 20 percent. This system appears unlikely to meaningfully alleviate deteriorating drought conditions across the area.

The biggest impact from this front should be the arrival of a cooler airmass for Sunday night into Monday. Monday's predicted highs are in the low 70s, near to slightly below normal for mid April.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

VFR. Smoke from area wildfires could impact visibility Wednesday morning, prior to late morning mixing deepens enough for any restrictions to become VFR haze. Confidence is low regarding the severity of restrictions. Winds generally out of the SSW through TAF period, with gusts 15-20 kts developing behind the sea breeze at coastal terminals Wednesday afternoon.

Extended Forecast...Predominantly VFR through the week due to high pressure. Only exception could be some MVFR or even IFR fog heading into sunrise each morning.

MARINE

Through Wednesday... Summer-like Bermuda high maintains quiet conditions today and Wednesday. Near the coast, winds will be enhanced by an afternoon sea breeze and gusts up to 20 knots. Inlets could be choppy. Seas 2-3 feet, up to 4 on the 20 nm periphery of the forecast zone due to a lingering 3-foot easterly swell and southerly wind wave.

Wednesday night through Sunday... Not much change in the marine forecast for the rest of the week with dry weather and the S to SW wind direction continuing, with speeds varying from around 10 kt during the mornings to as much as 15-20 kt nearshore during the afternoons and evenings due to daily seabreezes. 2-3 ft seas will consist of an east-southeasterly 8-9 second swell plus local 4-5 second wind waves. Next chance of low rain chances and SCA conditions arrives late Sunday into Sunday night with gusts up to 25-30 kt with a cold fropa.

ILM WATCHES/WARNINGS/ADVISORIES

NC...None. SC...Air Quality Alert until midnight EDT Wednesday night for SCZ054-058-059. MARINE...None.