Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 171100 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 700 AM EDT Tue Oct 17 2017 .SYNOPSIS... Canadian high pressure building into the Mid-Atlantic states today will bring several days of cool, dry weather to the Carolinas. Temperatures should begin to warm up this weekend as the high moves off the coast. && .NEAR TERM /THROUGH TONIGHT/... As of 300 AM Tuesday...A somewhat potent mid level trough continues to move eastward this morning as high pressure, centered across the Tennessee Valley continues to build in. Some high level moisture will continue to stream across the area for the next few hours, but that should be about it. Soundings are very dry and do not support any kind of thin convective clouds later today. So its high and dry through the period. Highs today, with guidance tightly clustered should be in the upper 60s. Wednesday`s lows with still some boundary level wind to contend with especially eastern areas should be in the middle to lower 40s slightly higher southernmost areas. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 300 AM Tuesday...Classic fall weather will remain in place Wednesday and Thursday across the Carolinas. The mid and upper level flow should be northwesterly as a 700-500 mb ridge develops across the lower Mississippi Valley. Subsidence downstream of this ridge should support a surface high across the Mid-Atlantic states and a well-defined subsidence inversion across the Carolinas. The only potential for cloud cover through the period appears to be Wednesday night or early Thursday as some thin maritime stratocumulus developing just beneath that subsidence inversion could approach the coast. As the surface high sinks southward later Thursday and Thursday night any clouds should get squashed back offshore. Models are in good agreement with highs (71-73 Wednesday and 75-77 Thursday) but only in fair agreement with lows given differences in low-level winds and their impact on the strength of the nighttime radiational inversion near the coast. My forecast is on the low end of MOS guidance, especially near the coast Wednesday night. && .LONG TERM /FRIDAY 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. Will maintain a northerly flow throughout much of the period. The pcp water values remain down near a half inch 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 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 /12Z TUESDAY THROUGH SATURDAY/... As of 12Z...High pressure will persist across the TAF sites for the next 24 hours with VFR/no cigs. Winds generally from 10-40 degrees 10-15 kt with gusts 20-25 kt, decreasing by afternoon. The only potential...albeit low...for low clouds would be at KILM after 09Z where thin maritime stratocumulus could develop as moisture gets trapped just beneath a subsidence inversion. Extended Outlook...Possible MVFR cigs Thurs AM. Otherwise VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 300 AM Tuesday...Strong small craft conditions still reside across the waters as expected. 41013 is reporting sustained winds near 30 knots and seas are between 6-9 feet at the buoys. Winds should decrease gradually through the period ending up at 15-20 knots from the northeast by Wednesday morning. Seas will follow suite but still remain elevated by the end of the period with small craft conditions continuing. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 300 AM Tuesday...High pressure will remain situated across the Mid- Atlantic states through the period. This should maintain a 15-20 kt northeasterly wind across our coastal waters Wednesday and Wednesday night. By Thursday night the center of the high will begin to sag into North Carolina, reducing the pressure gradient across the area and allowing wind speeds to fall to only 10 knots or so. Winds and seas will probably remain high enough for the Small Craft Advisory to remain posted through the day Wednesday. LONG TERM /FRIDAY THROUGH SATURDAY/... As of 300 PM Monday...Winds will become more easterly over the weekend. The northerly surge will abate as winds diminish as well, allowing for seas to subside 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 today, 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. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Beach Hazards Statement through this evening for SCZ054-056. NC...Beach Hazards Statement through this evening for NCZ106-108. MARINE...Small Craft Advisory until 6 PM EDT Wednesday for AMZ250-252- 256. Small Craft Advisory until 9 PM EDT this evening for AMZ254. && $$ SYNOPSIS...TRA NEAR TERM...SHK SHORT TERM...TRA LONG TERM...RGZ AVIATION...MRR

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