Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 190538 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 135 AM EDT Mon Jun 19 2017 .SYNOPSIS... Isolated to scattered thunderstorms this afternoon and Monday will become more widespread Tuesday as a cold front approaches from the northwest. The cold front is expected to stall and slowly dissipate Wednesday. Bermuda High pressure should reestablish itself late in the week. Tropical moisture will spread northward from the Gulf Coast states, increasing the risk for showers and thunderstorms Friday and Saturday. && .NEAR TERM /THROUGH MONDAY/... As of 8 PM Sunday...Any showers and thunderstorms have pushed inland west of I-95 and were just reaching beyond local forecast area and dissipating. Gusty southerly winds have diminished to 10 mph or less with temps still up around 80 most spots. Convection well south associated with tropical wave/low over Western Carib/Gulf has been expanding deeper layer moisture northward, but showers and thunderstorms associated with plume of deeper moisture should largely stay south and offshore overnight, although prevailing flow is more SSW than SW, so some of the convection may skirt some of the beaches. Continued to include some shwrs possible toward daybreak with increase of clouds and then more convection possible with seabreeze initially along coast and then pushing inland. Previous discussion: On Mon, Forecast Area will be in between Western Atlantic ridge and upstream progressive trough. This trough will help drive a surface cold front as far east as the Appalachians by Mon eve. A mid-level shortwave trough embedded in SW flow is expected to skirt the area to the W as we approach peak heating and then exit during the eve. Precipitable water values do increase to near 2 inches, as the depth of moisture increases through the day. These factors should promote at least scattered afternoon and eve thunderstorms, favoring inland areas, west of the seabreeze as it pushes inland. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... As of 3 PM Sunday...Though it will remain north of our area, an upper longwave trough across much of the eastern US and a slowly approaching/gradually dissipating cool front will bring unsettled weather for the period. Persistent SSW flow will support ample moisture advection into the area as precipitable water values increase to around 2 inches on Tuesday. This along with supportive dynamics aloft and sfc instability will favor the scenario for scattered to widespread showers and thunderstorms Tuesday and Tuesday evening, as is already noted in SPC`s day 3 outlook. While small hail cannot be ruled out, latest soundings would support isolated damaging winds to be the primary threat, along with heavy downpours, given the tropical-like airmass. Temperatures overnight Monday into Tuesday morning will remain in the lower 70s, as temperatures increase into the low to mid 80`s by Tuesday afternoon. A bit of a cool down is on tap for Tuesday night, as temperatures settle into the lower 70`s, and possibly even upper 60`s well inland. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 3 PM Sunday...Stalled front across the southeast Wed, likely just west of the local area, will gradually dissipate as 5h trough starts to de-amplify. Little of the front will remain in the vicinity Thu as Bermuda High and and 5h ridge expand over the region from the east. Despite the expanding/strengthening mid level ridge late in the week diurnal convection will remain a fixture through the period. Best chances on Wed may end up being earlier in the day with the stalled boundary and deeper moisture in place. Moisture shifts east later in the day which may lead to decreasing coverage. It is worth noting the Canadian/ECMWF solutions are being favored midweek with the handling of the low in the Gulf of Mexico. The GFS has been insistent on the low tracking quickly north to the FL panhandle which then leads to an abundance of tropical moisture moving into the region early Wed and lingering well into Thu. The favored solutions eventually spread tropical moisture associated with this system into the region, but not until late in the week. This leads to increased coverage of diurnal convection Fri and Sat despite the aforementioned expansion of the 5h ridge late week. Deeper moisture exits on Sun as the 5h ridge retreats east and 5h trough approaches from the west. Enough moisture lingers Sun afternoon to support convective coverage more typical of summer in the Carolinas. Although a fair amount of cloud cover and convection is expected for much of the period temperatures will run slightly above climo during the day, a combination of starting out warmer due to morning temps well above climo, and warming under the mid level ridge. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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As of 06Z...Rain chances will slowly rise overnight along the coast as plume of deep tropical moisture streams up from the Gulf and Caribbean. Winds will preclude any fog but some low stratus may affect coastal terminals during the predawn hours. Showers and storms will be near the coastal terminals early Monday before being pushed inland by the sea breeze. The remainder of the afternoon will see scattered thunderstorms mainly in the vicinity of of FLO and LBT. Overnight the continued increase in tropical moisture may preclude a rain-free forecast and possibly some lowered ceilings. Extended Outlook...The risk for flight restrictions due to thunderstorms will continue through the period. The probability for reduced ceilings and visibility in thunderstorms with heavy rain should be highest Tue and Wed and possibly again on Fri.
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&& .MARINE... NEAR TERM /THROUGH MONDAY/... As of 3 PM Sunday...The combination of the seabreeze circulation and nocturnal jetting will keep wind speeds near 15 kt through the period. Gusts to around 20 kt will be most common through mid or late eve. The Wind direction will be S, veering to SSW later tonight. Seas will be 3 to 4 ft. On Mon, the seabreeze circulation will again become well established during the afternoon. The pressure gradient will begin to tighten late in the period as a trough approaches from the W. These factors will increase SSW winds to 15 to 20 kt Mon afternoon. These increasing winds will add about a foot to the overall sea heights, up to 5 ft. Weak SE swell on the order of 15 to 17 seconds will persist. SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... As of 3 PM Sunday...Southwest winds will persist through the period ahead of a slowly approaching cool front. Sustained winds Monday night into Tuesday will remain around 15 kts, with gusts around 20 kts on Monday as pressure gradient is temporarily tightened. Into Tuesday night, expect winds to become west- southwest around 10 kts. Up to 4 ft seas will continue Monday night into Tuesday, retreating back to 2 to 3 ft Tuesday afternoon/evening. LONG TERM /WEDNESDAY THROUGH FRIDAY/... As of 3 PM Sunday...Front will remain stalled west of the waters Wed with the boundary expected to dissipate by Thu. Bermuda High will remain the dominate surface feature through the period with southwest winds 10 to 15 kt. Afternoon and evening winds could exceed 15 kt for a few hours, especially later in the period as heating leads to a slight increase in gradient. Seas 2 to 3 ft Wed will build to 2 to 4 ft during Thu, eventually reaching 3 to 4 ft Fri. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...RGZ/RJD SHORT TERM...SGL LONG TERM...III AVIATION...MBB

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