Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 160526 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 126 AM EDT Mon Oct 16 2017 .SYNOPSIS... High pressure will migrate well offshore overnight. A strong cold front will cross the coast Monday, accompanied by a few showers. Drier and much cooler air will build into the area behind the front Monday night and Tuesday, as Canadian high pressure drops in. Dry weather and seasonable conditions will prevail through the upcoming week, with a warming trend into next weekend. && .NEAR TERM /THROUGH TODAY/... As of 930 PM Sunday...Clear skies across the ILM CWA at the moment. The furthest east of the main cloud shield and pcpn associated with the strong cold front lie along the spine of the Appalachians across the far western Carolinas. The mid-level ridging responsible for an outstanding weekend will get replaced by a mid-level s/w trof beginning late in the overnight thru Mon. Clouds and pcpn associated with a cold front is progged to reach the western portions of the ILM CWA, ie. along the I-95 corridor, after daybreak Mon. With the sfc pg remaining somewhat relaxed ahead of this cold front, winds will likely decouple across much of the ILM CWA especially with skies remaining mostly clear thru the night. With this said, have hit the fog potential a little harder and wouldn`t be surprised to see some locations report dense fog. The low stratus deck does not look as prominent tonight like the previous nights when examining model sounding data for specific points across the FA. Widespread mid to upper 60s for lows still aok. Previous................................................... As of 244 PM Sunday...High pressure will give way to a fast moving cold front and the 12 utc models are indicating it moving off the coast around 8 PM Monday. In the mean time, winds will remain weak overnight and with the low-level moisture expect to see stratus and fog develop again overnight. The tricky part is how long will it stay around. The models are indicating it will make it to sunrise as the models are slower with the fronts progression. The models are depicting an anafront structure thus will slow the onset of precipiation a few hours than previous forecast. Also, the nam precipiation structure is broken in a south and north coverage to our west, but with the influx of moisture the models increase the rain coverage as it makes it to the coast. Mainly showers expected with an isolated possible in the late afternoon. Lows over night will once again be in the mid 60s temperature overnight with highs on Monday ranging from around 70 in Marlboro County to the upper 70s along the Georgetown coast. && .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... As of 244 PM Sunday...Forecast soundings show precipitable water values plummeting to 0.25" Monday night in a strong cold air advection regime following the daytime FROPA. It`ll be a breezy night with lows in the mid to upper 40s and a bit of a wind chill. The wind and cold advection both ease during the day Tuesday and mixing to about 3000ft should allow for highs close to 70. Thermal advection shuts off Wednesday night and there appears to be just enough wind to prevent radiational cooling. This should yield lows very close to those of Monday night...perhaps a few degrees cooler inland where lightest wind expected. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 244 PM Sunday...A broad upper trough of moderate amplitude at the beginning of the forecast period just upstream, will translate eastward through the period. This feature will exit the coast late in the week, while a short-wave upper ridge of high amplitude edges in from the west. This pattern in terms of sensible weather should bring a mainly pleasant Fall-like mid week period, transitioning to a warming trend late week and next weekend. The expansive surface high itself will budge only a bit east into next weekend, and should still have a pronounced foothold on the region. As a result, the radiational cooling potential could still allow seasonable, to slightly above normal minimums into late week. Tropospheric cross-sections through time, show arid air remains in place above 8000 feet, and thus a dry week upcoming. Return flow should re-introduce moisture into the area during next weekend, in the mild/warm sector, as long range models appear to be resolving a cold frontal passage next Monday day 8. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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As of 06Z...VFR conditions currently across the area. There is some light fog formation as seen in regional observations, but little in our area. Guidance has backed off significant fog formation probably due to the affects of slightly stronger winds advecting in from a cold front to the west. Most of the aviation impacts will occur with this front in the form of MVFR ceilings later today. Showers probably won`t be heavy enough for visibility restrictions. I did put a tempo group in for Lumberton and Florence for MVFR fog for the early morning hours in case a lower observation or two sneaks in. Extended Outlook...MVFR stratus possible near the coast TUE morning in blustery post-frontal NE wind. Otherwise VFR in the extended.
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&& .MARINE... NEAR TERM /THROUGH MONDAY/... As of 945 PM Sunday...Center of high pressure and associated ridging across the local waters this evening will pull out toward the east and further offshore late tonight. Current winds are basically variable in direction at 5 kt or less will become SW at 5 to 10 kt toward daybreak Mon. The sfc pg ahead of the cold front does not tighten very much however after the CFP the sfc pg dramatically tightens with speeds reaching SCA threshold Mon afternoon. Significant seas will run a solid 3 ft except 2 to 3 ft south of Cape Fear to South Santee River. An E-ESE ground swell at 9 to 10 second periods will dominate the significant seas with very little if any input from wind driven waves. Previous.................................................... As of 244 PM Sunday...Currently over the waters, light winds at less than 5 to 10 knots are being observed. The winds are expected to shift to the southwest tonight ahead of a cold front. The 12 UTC models are showing the frontal boundaries wind shifting by late afternoon Monday and are expected to increase to 20 to 25 knots late in the day. Significant wave height are 2 to 3 feet with a 9 sec, 2.5 to 3 ft swell from the east south-east this afternoon. Seas will increase in height as wind increase in response the approaching frontal boundary. Seas will increase to 3 to 5 feet by the end of the afternoon. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 244 PM Sunday...Rather unfriendly marine conditions in store for the period. Near term FROPA to be followed by cold surge/tight gradient that will keep wind and seas both solidly in Advisory criteria. Low level jetting present Monday night into early Tuesday at which time a few gale force gusts possible but these winds should taper by midday Tuesday even as the surface winds remain fairly unchanged. Wind and/or seas may start to drop below Advisory thresholds towards the very end of the period. LONG TERM /WEDNESDAY THROUGH FRIDAY/... As of 244 PM Sunday...This appears to be a period of improvement across all marine locations, as gusty NE winds begin to abate, allowing wave-heights to also drop. This should allow for what could be a `Small Craft Advisory` still effective early on Wednesday, to be dropped as the day progresses. The sea recovery period will be a gradual one, as the high builds very slowly to the SE. Seas of 4-7 feet early Wednesday, will subside to 3-4 feet by early Friday, with a light to moderate NE-E chop in the mix then. The period is dry and no TSTMS are expected at this time over the 0-20 NM waters. && .ILM WATCHES/WARNINGS/ADVISORIES...
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SC...None. NC...None. MARINE...Small Craft Advisory from 5 PM this afternoon to 6 PM EDT Tuesday for AMZ250-252-254-256.
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&& $$ SYNOPSIS...MJC NEAR TERM...DCH/DRH SHORT TERM...MBB LONG TERM...MJC AVIATION...SHK MARINE...

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