Area Forecast Discussion
Issued by NWS Wilmington, NC

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581 FXUS62 KILM 170134 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 934 PM EDT Mon Oct 16 2017 .SYNOPSIS... Strong Canadian high pressure will advect a much drier and cooler airmass across the forecast area tonight thru Wednesday. Some modifications to this airmass will occur during the mid to late week period as the high re-situates itself across the NE states but continues to ridge southwest across the Carolinas. Dry weather and seasonable conditions will prevail through the mid-week period, followed by a warming trend Fri thru the upcoming weekend. && .NEAR TERM /THROUGH TUESDAY/... As of 900 PM Monday...POPs have been removed from the forecast. Via latest Sat imagery trends, the back edge of the cloud shield has now made some progress thru portions of the ILM CWA...and at the moment extends from Jerome across Lumberton and Florence to Sardis. The progressive mid- level trof will continue to push the cloud shield eastward to finally off the Carolina Coasts during the pre-dawn Tue hours, and likely before sunrise Tuesday. Excellent CAA under gusty NNE to NE winds thru the atm column from the sfc to 8H. 8H temps have already dropped from around 14 degrees C this afternoon to around 9 degrees C at the moment. Could see 8H temps further drop another 1 to 2 degrees C overnight to a low and steady of 7 to 8 degrees C thruout the day on Tuesday. The gustiness to the sfc wind field is coincidental to the stratocu/altocu cloud deck. As the cloud shield pushes east of the FA, the gustiness in the sfc wind field will temporarily drop. The exception is for the immediate coast where gustiness will continue all night. Once the days insolation commences Tue daytime morning, mixing in the boundary layer will likely bring down those hier winds aloft to the sfc as wind gusts. No major changes to temps other than a tweak of a degree or 2. Previous................................................... As of 300 PM Monday...Downslope wind-flow in the warm sector earlier, ahead of a cold front allowed temperatures to spike across the eastern zones of NE SC and SE NC, with 86 degrees reached at ILM, just one degree shy of tying a 42 year old record of 87. The strongest convergence and robust convection will move off the NE SC coast through afternoon. Aside from embedded weak showers, we may see a brief period of patchy and light, wind-blown, stratiform rain or drizzle, as pronounced over-running interacts with residual H9-H7 moisture in wake of the front, mostly from the late afternoon through mid evening, before low-level drying gains an overwhelming foothold. Gusty north winds are now buffeting our western zones as the leading edge of cold air advection begins to fan SE. This will be trending throughout the area, along with sharply falling temperatures overnight. Lows daybreak Tuesday almost 20 degrees F cooler in spots than this morning`s minimum temperatures. North wind gusts up to 25 mph should be common this evening as the Canadian High sets in. Mixing and turbulence should bring dry air all the way to the surface Tuesday resulting in plenty sunshine, albeit breezy to windy with highs not cracking 70 inland away from the milder ocean air influence. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 300 PM Monday...Cool and dry advection bringing a cool and cloudless Tuesday night. The cool advection relaxes Wednesday and some dewpoint recovery is forecast despite surface flow remaining NE (some Atlantic moisture moves onshore above the surface layer in easterly flow). Afternoon highs will be quite seasonable, generally in the low 70s. Wednesday night will show some moderation from the two previous ones along the coast whereas a few upper 40s still possible well inland. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 300 PM Monday...It will remain high and dry through much of the period as one area of high pressure slips off the northeast coast and another one takes hold over the Southeast. An h5 shortwave will ride through Thurs night, but with such a dry column in place do not expect anything except a few clouds possible. Will maintain a northerly flow throughout much of the period. The pcp water values remain down near a half inch Thurs and Fri with a slight rise as winds come around to a more easterly direction Sat aftn. Any clouds or pcp over the waters should remain off shore as winds stay parallel to the coast through Saturday, but as coastal trough develops Sat night into Sunday may see greater potential for clouds along the coast and some pcp, mainly over coastal SC. At this time the pcp water begins to increase as moisture profiles show an increase in shallow moisture below 4k ft Sat night into Sun and increase in potential for higher clouds through Sunday. The moisture returns just beyond the long term period when a deep southerly return flow develops heading into Monday as coastal trough/warm front pushes on shore and north. The temps will warm through the period as air mass modifies and winds come around to a more easterly direction allowing for some moisture return off at the low levels. Min temps within a few degrees of 50 Thurs night and Fri night will end up around 60 by early next week. Max temps will make a return to 80 or above over the weekend. Overall temps will be running above normal once again. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... As of 00Z...High pressure will build into the TAF sites for the next 24 hours. VFR cigs 3-5k this evening will sct tonight and remain sct for the remainder of the period. LLWS is possible overnight but ATTM will monitor. Winds generally from 10-40 degrees 10-15 kt with gusts 20-25 kt, decreasing by late afternoon. Extended Outlook...VFR. && .MARINE... NEAR TERM /THROUGH TUESDAY/... As of 915 PM Monday...SCA continues across all ILM waters. CAA and a tightened sfc pg after the CFP will combine to produce SCA conditions initially from wind thresholds followed by significant seas thresholds. With widespread mid to upper 70 degree SSTS, air-sea interaction will be in full gear. Looking at NNE 20 to 30 kt winds...along with few gusts up to Gale force across the outer waters. Significant seas will climb to 4 to 7 ft, locally higher off Cape Fear in the vicinity of Frying Pan shoals. Wind driven waves at 3 to 6 second periods will dominate the significant seas. Previous..................................................... As of 300 PM Monday...A difficult marine period as strong N-NE winds prevail in wake of a cold front, as the leading edge of strong Canadian High pressure barges in. Gusts to at least 30 KT can be expected this evening through all of Tuesday, well offshore Gale gusts may be approached. Seas of 5-7 ft expected late tonight and Tuesday, 7-9 feet around Frying Pan Shoals and the outer marine waters. Showers and few TSTMS will impact the waters tonight, and the west wall of the Gulf Stream will light up late tonight with strong storms. The `Small Craft Advisory` flags will be flapping tonight through all of day Tuesday. SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 300 PM Monday...A moderately strong NE surge will be underway early in the period and Small Craft Advisory to be in effect. The exception will be Horry County waters where adequate wave shadowing off of Cape Fear should preclude the need for the headline. Though the cool air push will be ending on Wednesday the gradient does not relax much and the Advisory will continue. LONG TERM /THURSDAY THROUGH SATURDAY/... As of 300 PM Monday...Northerly winds up to 10 to 15 kts initially will shift around to the NE by Fri and become more easterly over the weekend. The northerly surge will abate as winds diminish as well, allowing for seas to subside from 4 to 5 ft Thurs morning down to 2 to 4 ft Fri and Sat. && .TIDES/COASTAL FLOODING... As of 300 PM Monday...Astronomical tides are increasing as we approach a new moon. This coupled with strong NE winds, may breach minor coastal flooding thresholds at Wrightsville Beach beginning tomorrow, and advisories may be needed along portions of the coast the next several days. The same will be true of the lower Cape Fear including the downtown Wilmington area.* Add discussion here. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Beach Hazards Statement from 6 AM EDT Tuesday through Tuesday evening for SCZ054-056. NC...Beach Hazards Statement from 6 AM EDT Tuesday through Tuesday evening for NCZ106-108. MARINE...Small Craft Advisory until 6 PM EDT Wednesday for AMZ250-252- 256. Small Craft Advisory until 9 PM EDT Tuesday for AMZ254. && $$ SYNOPSIS...RGZ NEAR TERM...DCH/MJC SHORT TERM...MBB LONG TERM...RGZ AVIATION...MRR MARINE... TIDES/COASTAL FLOODING...

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