Area Forecast Discussion
Issued by NWS Wilmington, NC

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709 FXUS62 KILM 230609 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1041 PM EDT FRI JUL 22 2016 .SYNOPSIS...
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Increasingly warm temperatures and high humidity will produce dangerous heat in places across the area over the weekend. This heat wave will last into the early or middle part of next week all while rain chances remain minimal.
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&& .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... As of 1030 PM Friday...500 mb high pressure centered over the Texas Panhandle will build eastward across West Virginia over the next 12-18 hours. The rising heights to our north will turn our upper level steering flow from northerly to northeasterly. This readjustment due to rising heights is already apparent in the gradual curving motion of the persistent cluster of thunderstorms currently moving south through the Lumberton area. Despite what should be a fairly capped surface layer by this point, wind gusts in these storms were still able to exceed 25 mph about an hour ago. The 00z/01z HRRR runs were much better initialized than the earlier 21z run and are most likely correct in their idea of the storms weakening due to stabilizing low-level parcels. Debris cloudiness and some lighter showers will veer more southwesterly and move across Florence for the next several hours, otherwise mainly clear skies are anticipated overnight. Bermuda High pressure dominates the surface weather map. A modest low level jet is already in place over the Coastal Plain but will only be able to keep light southwesterly winds in place at the surface. Given the airmass, this should yield lows in the lower to middle 70s for most locations. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... As of 330 PM Friday...Hot with increasing humidity forecast for the weekend as this hot July continues. Massive ridge across the central part of the country will expand to become a broad feature across nearly the entire southern tier of the CONUS. As this occurs, a weak closed mid-level low off the SC coast will be suppressed to the SW, driven by increasing heights to its north. This keeps this feature weak and away from the Carolinas, moving across Florida Sunday night. No surface reflection is progged with this impulse, but as it moves overhead Florida late, it will cause a better SE moisture tap and increasing clouds are forecast Sunday night. The big story this wknd is a return to uncomfortable and dangerous heat as the mid-level dome of high pressure expands overhead. This occurs in conjunction with persistent Bermuda ridging, and 1000- 500mb thicknesses approach 580dm by Sunday. Developing SW flow this wknd will pump in additional moisture, and this means humidity will be on the rise at the same time temperatures climb back well into the 90s. While isolated convection is possible each aftn during peak heating, widespread tstms are not forecast thanks to warm and relative dry air aloft, and will carry only SCHC along the sea breeze and piedmont troughs, highest Sunday. Very little airmass change is forecast Sat to Sun, so highs both days will be in the mid 90s, slightly warmer Sunday, and a bit cooler at the coast each day, with lows in the mid to upr 70s. The combination of these hot temps and high dew points will create heat index values just below 105 (heat advisory criteria) on Saturday, but a heat advisory will likely be needed on Sunday and will mention in the HWO. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 330 PM Friday...The extended period as would be expected, offers little change in the summertime pattern. The eastern Carolinas will be in between a subtle northwest flow aloft and at times ridging building in from the central Atlantic. Any synoptic forcing mechanisms are relegated to the Piedmont trough with the more local feature being the seabreeze. Precipitable water values remain somewhat unimpressive with perhaps an increase later next week. This warrants no more than either slight or low chance pops for any period. 850mb temperatures remain pegged right around 20 degrees C so surface readings should be a few degrees above normals for both daytime highs and overnight lows. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
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As of 06Z...VFR at TAF issuance time at all terminals. Lingering high clouds streaming in from the north across mainly inland areas. Confidence is high for VFR through sunrise, although where rainfall occurred last evening at KLBT there is a chance of MVFR vsbys despite 20kt boundary layer winds. Models continue to show another impulse moving down in the deep northerly flow aloft tomorrow. Timing should be aftn into eve with Shwrs/Tstsms possible at terminals. Confidence is low when it comes to timing and strength of this disturbance and therefore potential for convection. Winds will be WSW, but will back to the SSW-SW by mid-late morning. EXTENDED OUTLOOK...Brief periods of MVFR/IFR from isolated afternoon convection Sunday through Wednesday. Otherwise expect VFR.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 1030 PM Friday...Bermuda High pressure offshore is in control of our weather, and that means a completely normal pattern for mid-summer. Southwest winds 10-15 kt and seas 2-3 feet in an east-southeast swell will continue overnight. Radar shows shower activity well inland with only a small potential that showers could develop later tonight. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 330 PM Friday...Bermuda high pressure will be the dominant feature this weekend as it expands again into the Carolinas. This produces SW winds around 10 kts Saturday, increasing to up to 15 kts Sunday thanks to a sharper piedmont trough. Seas will be formed through an amplifying SW wind wave and a persistent SE swell, producing wave heights of of 2-3 ft Saturday, and more widespread 3 ft on Sunday. LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 330 PM Friday...South to southwest winds of 10-15 knots will continue across all waters through the period. There is a little hint of higher winds overnight Tuesday into Wednesday morning with the low level jet and this is reflected in the forecast. Significant seas will be mostly in a range of 2-3 feet. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...RGZ NEAR TERM...TRA SHORT TERM...JDW LONG TERM...SHK AVIATION...RGZ is the U.S. government's official web portal to all federal, state and local government web resources and services.