Area Forecast Discussion
Issued by NWS Wilmington, NC

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278 FXUS62 KILM 211001 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 601 AM EDT Fri Jul 21 2017 .SYNOPSIS... Hot and humid conditions will prevail today through the weekend with only isolated rain chances. Storms will increase next week as a series of weak fronts approach the coast, with near normal temperatures for late July. && .NEAR TERM /THROUGH TONIGHT/... As of 324 AM Friday...Hot and dry day on tap for the region as mid- level ridge expands atop filling low dropping to the south. Upper low spinning near N FL will drift SW today as high pressure expands both from the west and east across the Carolinas. As this occurs the Bermuda type ridge will expand at the surface back into the Southeast, producing increasing warmth along with continued high RH. 850mb temps are forecast to climb towards 20C today, as a finger of the strong thermal ridge across the Great Plains advects eastward around the periphery of the mid-level ridge. GOES-16 low-level WV imagery shows exceedingly dry air locally, and forecast profiles suggest very little in the way of column saturation through the near term. This suggests that despite heat and humidity driving MLCape over 2000 J/kg, tstms are unlikely today as the dry air and warm 500mb temps of -3 to -4C provide the convective lid. The big story today is then heat index values approaching advisory criteria across most of the area. Expect at least some dry air entrainment and mixing during peak heating, so dewpoints in the 70-73 range this aftn will combine with highs rising well into the 90s away from the beaches, to produce heat index values of 101-104 degrees. A few locations may touch 105, but these are not expected to meet the spatial or temporal extent needed for a heat advisory. Increasing SW flow tonight as the Bermuda Ridge continues to back to the west will create a very warm night as well, with mins struggling to drop below 75, and may remain near 80 at the immediate coast. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 324 AM Friday...Maximum temperatures will run 3-6 degrees above normal over the weekend making for hot conditions. The apparent temperatures during the afternoon hours will generally range from 98 near the coast to 104 well inland. It is not out of the question that a Heat Advisory may be needed for portions of the area with only a slight increase in air temperature or dewpoint. The heat will drive a vigorous afternoon sea breeze, prompting gusts of 20-25 mph along the coast and the coastal interior over the weekend. Frisky nocturnal SW boundary layer winds will keep minimum temps elevated and above normal, with a range from the upper 70s to near 80 at the coast to 75-78 over the interior of NE SC and SE NC. A little bit of mid-level moisture increase on Sunday brings mentionable POP values into the isolated range Sunday afternoon. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 3 PM Thursday...Long term will be marked by gradually decreasing temperatures and increasing chances for precipitation as ridging at the surface and aloft breaks down and a cold front approaches and then moves across the eastern Carolinas. A consensus of guidance has the front stalling in our vicinity by late Tuesday or Wednesday, where it will linger into Thursday. Above normal temperatures Sunday and Monday will drop back down to or below climo for the remainder of the long term. Tuesday looks to be the best day for convection, with deep moisture in place in advance of the impending front. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/...
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As of 10Z...High confidence in VFR through the valid period as stacked ridge of high pressure dominates the synoptic regime. A weak piedmont trough and 20 kts of wind at 2kft on VWP early this morning is preventing winds from going calm in many places close to the coast. This combined with very warm mins will prevent any fog this morning. A dry day is expected Friday as very dry air aloft precludes convection. SCT to at times BKN VFR CU is likely, but will not create any restrictions. The biggest impact may be slightly higher winds within the sea breeze at CRE/MYR this aftn, increasing from the S/SW at 10-15 kts, while remaining 10 kts or less at the other terminals. Most CU will erode after dark leaving clear sky conditions and lighter winds, still from the SW. A nocturnal increase in wind overnight will likely prevent fog overnight. Extended Outlook...VFR through Sunday. Brief MVFR/IFR possible in scattered showers and tstorms Mon and Tue due to a slowly approaching cold front from the NW.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 324 AM Friday...Bermuda high pressure slowly expanding from the west will persist SW winds across the waters this period. The gradient will be slightly pinched compared to the past few days, so widespread 10-15 kt SW winds are forecast, especially this evening and tonight. Very hot temperatures inland will produce a strong sea breeze, so wind gusts up to 20 kts are likely near-shore as well. A 2ft/10sec SE swell will develop this aftn but will become increasingly masked by an amplifying 4 sec wind wave, and seas will grow from around 2 ft this morning, to 2-4 ft late. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 324 AM Friday...Conditions will approach `Exercise Caution` due to 15-20 KT winds and seas around 4 feet offshore. The afternoon sea breeze circulation will keep winds gusty and seas choppy near shore each afternoon to early evening. The good news is that very little TSTM activity is expected over the weekend although early and late Sunday may see a few showers offshore. Seas of 3-4 feet will be dominated by S-SW wind-seas running in 3-4 second intervals mixed with a weakening SE swell every 9 seconds. LONG TERM /MONDAY THROUGH TUESDAY/... As of 3 PM Thursday...Circulation around high pressure over the western Atlantic will keep winds from the SW through the period. An approaching cold front may briefly tighten the gradient enough to warrant Exercise Caution headlines or a Small Craft Advisory late on Monday, but confidence on this is low at this time. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...MJC NEAR TERM...JDW SHORT TERM...MJC LONG TERM...REK AVIATION...JDW

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