textproduct: NWS Wilmington

WHAT HAS CHANGED

Based on the 00z HREF, forecast PoPs this afternoon have been increased slightly for locations 5-30 miles inland from the coast where this afternoon's seabreeze front should move inland during peat heating/instability. Minor downward tweaks have been made to forecast temperatures early this week based on latest guidance, but forecasts for more intense heat later in the week remain unchanged.

KEY MESSAGES

1) Scattered showers and thunderstorms are possible this afternoon along the seabreeze front.

2) Well above normal temperatures and humidity will bring heat indices over 100 degrees this week.

DISCUSSION

KEY MESSAGE 1...Scattered showers and thunderstorms are possible this afternoon along the seabreeze front.

Uncapped surface CAPE near 2000 J/kg will develop this afternoon as surface temperatures rise into the lower 90s away from the beaches. The only trigger I can find is the seabreeze front which should push inland beginning around noon. Convergence along the boundary should be sufficient to produce scattered showers and thunderstorms with forecast coverage 20-40 percent, closely following 00z HREF PoPs. There's no shear aloft today so storms should remain unorganized single cells with very little potential for severe weather. Convection should dissipate with the loss of daytime heating early this evening.

KEY MESSAGE 2...Well above normal temperatures and humidity will bring heat indices over 100 degrees this week.

High pressure within the 700-500 mb layer currently centered across Tennessee and Kentucky will migrate slowly eastward across the southern Appalachians and should reach the Carolinas by Thursday. Descending, warming, and drying air in the mid levels should work its way as low as 3000-4000 feet AGL by Thursday, capping surface parcels to moist convection and spiking 850 mb temps possibly up as high as +21C. If the airmass does become this warm, it will be 3 deg C above the climatological 90th percentile at both the KCHS and KMHX upper air sites and very close to record highs, and only 2 deg C away from the highest readings ever observed this late in the season.

Translating this heat aloft down to the surface should yield inland high temperatures around 90 today, lower 90s Tuesday, then mid 90s Wednesday through Friday. Vertical mixing will undoubtedly bring some drier air down into the boundary layer, but heat indices still appear they will exceed 100 degrees for most area each afternoon beginning Tuesday.

A trough zipping southeastward across Quebec and northern New England on Friday may push a cold front southward into the Carolinas on Saturday, tempering the heat and returning temperatures back toward normal by Sunday.

AVIATION /06Z MONDAY THROUGH FRIDAY/

VFR conditions could degrade before sunrise to IFR, especially at KFLO and KLBT where clearing skies, calm winds, and plenty of low level moisture will exist. Model guidance shows a moderate to high potential for visibility restrictions at both airports beginning between 08-10z and lasting as late as 13-14z. Along the coast thicker high level clouds should reduce the potential for fog some, but even here KILM, KMYR, and KCRE have a moderate potential for at least MVFR visibility and some very low clouds through sunrise.

After morning fog dissipates, scattered showers and thunderstorms could develop along the seabreeze front as it pushes inland during the day. There's low potential for direct impacts at KILM, KCRE, KMYR mainly between 17-22z.

Extended Forecast...There is low to moderate potential for MVFR to IFR conditions in low clouds and fog each morning through the middle of this week. As drier air moves in aloft, the coverage of showers and storms is expected to be isolated, if any, Tuesday through Thursday.

MARINE

Through Friday...Bermuda High pressure centered offshore will ridge westward almost directly overhead today and Tuesday. By Wednesday the ridge axis should shift slightly to our south allowing a little stronger south-southwest wind to develop through Thursday and continuing into Friday.

With light winds the first half of the week, seas will consist almost entirely of 8-second 1-2 ft southeasterly swell. As winds increase later in the week, a short period wind chop will develop on top of the swell with combined seas building to around 3 feet.

CLIMATE

As of 300 PM Sunday...Wilmington, NC is currently just below its hottest summer on record. The average temperature (the simple average of each day's high and low temps) is currently 0.1F below 2011 and 2010 as of the official daily climate report from August 29.

#1 2011 81.8 deg F #2 2010 81.8 deg F #3 2026 81.7 deg F (with two days to go) #4 2016 81.4 deg F #5 2022 81.1 deg F

Continuous temperature records began in Wilmington in 1874.

Additionally, August is the second wettest on record for Wilmington. With today's rainfall 15.0 inches was recorded at ILM.

ILM WATCHES/WARNINGS/ADVISORIES

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