Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 111331 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 931 AM EDT Fri Aug 11 2017 .SYNOPSIS... An offshore front will meander landward today into the weekend, while a cold front approaches early next week and stalls. These features will maintain rain chances through much of the period. && .NEAR TERM /THROUGH TONIGHT/...
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As of 930 AM Friday...Analysis of morning sounding data shows a very juicy and moderately unstable atmosphere although with a lack of any significant triggers other than the sea breeze front. High-Res guidance concentrates convection today along this boundry and then moves it inland into the afternoon. Have tweaked pop grids to reflect this evolution. Main threat today appears to be from possible localized flooding from slow- moving and training storms. Previous discussion follows: Remains of the frontal boundary moving inland, traced out by some isolated showers now roughly bisecting the area west to east. As this boundary becomes more and more diffuse to our west today there may be little organized forcing for showers and thunderstorms, though smaller scale boundaries may be aplenty. One thing that illustrates this is the precipitation distribution between the GFS and WRF. The former shifts the main precip axis inland while the latter favors the coastal areas for most of the day. More factors seem to favor the WRF solution than the GFS including forecast continuity. Despite fairly widespread cloud cover afternoon temperatures should warm up to near seasonable norms. Some overnight convergence tonight will maintain rain chances mainly along the coast ahead of a very weak low developing over Savannah. In fact, those rain chances may end up being higher than those seen all day.
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&& .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... As of 333 AM Friday...The damp regime continues this period. This is supported by precipitable water values in excess of 2 inches, August heating, and an ample dose of low level convergence over the weekend. While it seems true rain-free stretches will also prevail, the opportunity exists for areas to capture several inches of rainfall this period. The coast and coastal interior may be subject to oceanic convective downpours in the morning hours, while the synoptic flow favors boundary spawned showers and storms well inland in the afternoon to early evening. As has been the case for August so far, this drenched pattern has kept daytime and even average temperatures well below normal for August and this looks to continue. The slightly above normal minimums are being over-shadowed by the larger departures in cooler maximums and across the forecast area, we are nearly 3 degrees below normal for typical August warmth overall so far. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 3 PM Thursday...An abundance of moisture will prevail across a swath over the Carolinas with very high precipitable water values expected by Tuesday. The Carolinas will be between a subtropical ridge far off the mid-Atlantic coast and a developing trough through the Upper Midwest and Midwest through Monday and into the Ohio Valley during Tuesday. The trough will further amplify across the Eastern United States during Wednesday enabling a cold front to push south across the area with drying and cooler temperatures around the middle and latter portions of the upcoming week. In the meantime expect good chance to likely POPs Sun-Tue time frame. MEX highs may be a category on the high side depending on the amount of cloud cover that occurs. MEX lows appear reasonable with lows in the mid- upper 70s at the coast and mid 70s inland, then possibly upper 60s toward the latter half of the week. && .AVIATION /13Z FRIDAY THROUGH TUESDAY/... As of 12Z...Showers will gradually overspread coastal areas today as front moves inland and a coastal trough develops. Inland terminals will deal with some IFR or even brief LIFR cigs and vsbys. Most areas til 15z will be IFR/MVFR while early fog and stratus continue to affect terminals on and off through the afternoon, possibly tapering some this evening. Extended Outlook...Periods of MVFR/IFR ceilings and visibility are possible each day due to scattered showers and thunderstorms. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of 930 AM Friday...Latest guidance shows light southerly winds with 2 to 3 ft seas over the waters this morning. Forecast good to go with no changes need to the near term. Previous discussion follows: Wind has turned back to southerly now that the front has moved inland. As today wears on and the boundary dissipates so to will the pressure trough associated with it. This should add a few knots of wind to the forecast opening up the range to a fairly seasonable 10-15. Seas will run 2 to 3 ft in the very near term but then graduate to 3 ft across most of the area. Not much change during the overnight save for possibly a few gusts to 20 knots due to a small uptick in the winds just off the surface. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 333 AM Friday...Bermuda high pressure building landward Saturday will boost SW winds into a 15-20 KT range as the high interacts with lower pressure inland. As low pressure weakens Sunday, winds should fall about 5 KT compared to Saturday. Scattered to numerous showers and storms will prevail this period as weak boundaries waffle across the waters. Some storms may be strong and a radar update is encouraged over the weekend as winds and seas will be higher in and near TSTMS. Seas of 3-4 feet will be a mix of SSW waves around 2 feet every 5-6 seconds and SE waves around 2 feet every 7-9 seconds. Moderate SW chop can be expected Saturday as well. Any showers or storms this weekend will move mainly toward the N and NE. LONG TERM /MONDAY THROUGH TUESDAY/... As of 3 PM Thursday...Weak troughing inland with high pressure off the coast will support a south to southwest fetch Monday through Tuesday. A front will drop south toward the waters, possibly by late Tuesday night or Wednesday morning. The aforementioned fetch will likely lead to dominant S-SW waves along with weak ground swell from the E-SE.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...99 NEAR TERM...MBB SHORT TERM...MJC LONG TERM...SRP AVIATION...MBB MARINE...MJC/REK/MBB/SRP

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