Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 200549 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 149 AM EDT Thu Jul 20 2017 .SYNOPSIS... Showers and thunderstorms will be isolated in the days ahead, as an upper ridge builds from the west. The ridge will bring hot and humid conditions through the weekend. Rain chances may increase early next week, as a surface trough deepens inland. && .NEAR TERM /THROUGH TONIGHT/... As of 1000 PM Wednesday...Afternoon thunderstorms dissipated quickly early this eve and the remaining showers have since faded as well. A mid/upper level trough remains across the eastern Carolinas with the low center positioned along the South Carolina coast. In this environment it is always difficult to completely remove POPs, but we feel confident cool and stabilizing outflow has largely worked through the Forecast Area. The high resolution HRRR does not indicate any showers redeveloping across the area overnight. However, given what transpired this morning and with the NAM and GFS showing early morning redevelopment near the Cape Fear area, we do show POPs increasing to slight chance along portions of the coast around and just after sunrise. Fog and stratus should fill in for a time given the wet ground and light flow across the area and have included patchy fog around and shortly after daybreak/sunrise. Lows were notched down as again cool thunderstorm outflow has worked across the area, so mainly lower 70s with mid 70s at the beaches. Guidance brings isolated convection mainly to our coastal counties for Thu. A warming trend commences with highs in the lower to mid 90s and heat index values of around 100F. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... As of 300 PM Wednesday...Two upper ridges, one centered over the western Atlantic and the other over MO "reconnect" Thursday night as upper low retrogrades south and west into JAX. At the surface the gradient will be quite weak as we sit between two areas of high pressure. The area will be rain-free but some fog is tough to rule out. Friday into Friday night the upper low continues to retrograde and weaken allowing the two ridges to further connect to our north while a surface piedmont trough takes shape. Though the latter and the healthy seabreeze will both try to serve as foci for thunderstorm development it looks too dry with midday forecast soundings showing dewpoint depressions of 25C not uncommon at some levels above the boundary layer. Rain-free conditions will persist into Friday night and once again some areas of fog seem possible due to the weakness of the piedmont trough keeping winds light. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 300 PM Wednesday...The first half of the extended period, basically the weekend will feature mostly dry conditions with temperatures somewhat above normal. These conditions will be provided by a weak mid level pattern and Bermuda High Pressure at the surface. The mid level capping is not quite as prominent on soundings as it has been in recent days, but with mid level moisture lacking convection will still drive a hard bargain. The second half of the extended, early next week shows more favorable conditions for convection as cooling aloft and an increase in column moisture to well over two inches warrants. Temperatures fall slightly from the weekend`s warmer readings. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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of 06Z...Diffuse pressure gradient in place across the area has left nearly calm winds at the terminals. The exception to this is near the coast where a land breeze has developed and winds will be from the west at 5 kts or less into Thursday morning. With a very moist ground persisting and these light winds with clear sky conditions, fog is possible tonight. However, local UPS fog procedures are not robust with fog development, and mins remaining above 70 may be too warm for any significant vsby reduction. Have included tempo MVFR at FLO/LBT, but attm do not expect any IFR tonight. Forecast profiles do suggest some IFR stratus inland, but confidence is low in that as well as this setup would seem to favor fog over stratus. At the coast, no restrictions are anticipated. A hot and dry day forecast after sunrise with sct diurnal VFR CU and maybe an isolated tstm. The best chance for this will be near the Myrtles this aftn, but coverage is expected to be too limited for a TAF mention. Winds will remain light, but become S/SW at 5-10 kts all terminals, highest at the coast within the sea breeze. Most CU will erode with loss of heating at the end of the valid period leaving mostly clear sky conditions once again and VFR. Extended Outlook...VFR. Scattered showers and thunderstorms Monday.
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&& .MARINE... NEAR TERM /THROUGH THURSDAY/... As of 1000 PM Wednesday...A weak pressure gradient will prevail through Thu. The waters will continue to be under the influence of a mid and upper level trough. A land breeze will shift light winds to a more W or NW direction overnight. SSW to SW winds will return during Thu and increase to 10 to 15 kt during the afternoon. Seas will be 2 to 3 ft and largely a function of an ESE swell with a period of 7 to 9 seconds. SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 300 PM Wednesday...Conditions generally unchanging through the period and they will be typical of the time of year. Wind will be out of the southwest due to Atlantic high pressure and a piedmont trough will struggle to develop late in the period. Spectral wave bulletins suggest that a 10 second SE swell becomes more pronounced than the 4 second wind chop for a general forecast of 3 ft seas. LONG TERM /SATURDAY THROUGH MONDAY/... As of 300 PM Wednesday...Bermuda High Pressure will maintain a summertime flow across the waters. Mariners can expect a southwest flow of 10- 15 knots with some late morning/afternoon acceleration with the sea breeze near shore. Significant seas, without the assist from any meaningful swell component will fall into a range of 2-4 and mostly 2-3 feet. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...RJD/JDW SHORT TERM...MBB LONG TERM...SHK AVIATION...JDW MARINE...

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