Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 090543 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1240 AM EST Sat Dec 9 2017 .SYNOPSIS... Periods of cold rain under blustery conditions will continue tonight through midday Saturday. Conditions will improve late Saturday thru Saturday night as the last of the sfc lows lift northeast of the area. Sunshine will return for Sunday, with temperatures remaining well below normal through Monday. A strong, dry cold front will move across the area late Tuesday, followed by another round of arctic air for the middle of next week. Temperatures will gradually moderate late next week. && .NEAR TERM /THROUGH SATURDAY/... As of 915 PM Friday...Blustery and wet conditions slated for tonight thru daytime Saturday. Cold, dank and dismal are the resulting conditions as weak areas of low pressure move northeast along a stalled frontal boundary oriented offshore and parallel to the coastline of the Carolinas. These sfc lows are associated with potent and embedded mid-level s/w trofs or vorticies. This is the type of path that you want a sfc low to take for snow to occur across the local ILM CWA. Unfortunately, not enough cold air is in place, and, the colder air that does arrive until late Saturday and this will be too late for snow due to the bulk of the moisture having lifted northeast of the FA. At this point, there is a very low possibility that locations well inland and along the northern periphery could see a few snow flakes may occur at the very end of this pcpn event. For temps, the diurnal spread between tonights lows and Saturday`s highs will likely be less than 10 degrees. Previous........................................................ As of 3 PM Friday...Cold and wet conditions will prevail through much of the Near Term. A cold front will remain stalled offshore tonight as an over-running pattern combines with a deeply moist column to produce periods of stratiform rain and drizzle. A series of upper disturbances moving along the leading edge of a deepening H/5 L/W trough will enhance precip at times, with a period of heavier rain moving in from the SW tonight. An additional 1.5 to 2.0 inches of rain is thus possible. However, still do not see flooding as a issue as due to dry antecedent soil conditions and the fact that accumulations will be spread out over the next 24 hours. Temperatures will remain on the cold side, with lows in the mid to upper 30s tonight and highs in the mid to upper 40s on Saturday. The pattern will shift on Saturday, with the upper trough and associated frontal system slowly swinging east and out to sea. Rain chances will linger through the day though while ramping down from roughly west to east. Most of the forecast area should be rain-free by evening, with best chances for lingering drizzle or light rain in the Cape Fear region. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... As of 3 PM Friday...This system that has plagued us with cold rain for the past three days will finally be pulling away from the area. The final digging shortwave will round the base of the mid to upper trough pushing system off to the east and scouring out any clouds and moisture left over the area. Column will be drying out Sat night leaving a dry air mass over the Carolinas on Sunday. Pcp water values up near 1.5 inches early Sat will be down close to .15 inches. CAA through Sat night will allow temps to drop to the mid 20s inland to near 30 along the coast. Deep NW to W flow will back slightly late Sun through early Mon allowing air mass to begin warming. The 850 temps down below -5C will return to 5C by Mon morning. Bright Sunshine will also help to raise Sun temps back into the mid 40s after a very cool start to the day. High pressure will continue to extend across the Southeast through Sun night. Light winds will become near calm under clear skies Sun night. Overall a very dry air mass in place will allow temps to drop out as atmosphere decouples Sun night. This will lead to temps in the mid 20s to near 30 once again Sun night. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 3 PM Friday...Period will be dominated by 5h longwave troughing and temperatures below to well below normal. Precip chances will be limited by a pattern where deep west to northwest flow is dominant. Only chances will be with one of several stronger shortwaves dropping into the trough and helping to reinforce the cold air. Looks like there will be three waves with potential to produce at least limited rainfall. The first arrives late Tue, the second late Thu, and the final one arrives Fri night. Forecast soundings keep precipitable water values below half an inch through the period with numbers dropping as low as a tenth of an inch on Wed. Measurable precip seems highly unlikely given the depth and abundance of dry air but a brief period of increased cloud cover is likely. Temperatures will be below climo to start the period, although only just and will be trending up from Mon into Tue. However, the first shortwave will sweep a strong cold front across the region. The front will be followed by another shot of arctic air and temperatures will tumble. Highs during the middle of the week will be in the 40s with lows in the 20s. Low level return flow is quick to develop on Thu and temperatures will moderate a little for the end of the period. Temperatures will still end up below climo to end the period, but only by a few degrees. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
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As of 06Z...IFR cigs through most of the TAF period as very cold air at the surface is overrun by warmer air aloft. Visibility restrictions in rain will tend to be MVFR but could occasionally dip lower. NE winds will back in direction as the period wears on due to flat low pressure moving up along the offshore frontal boundary. Improving conditions slated to begin right at the end of the TAF forecast, especially at non-coastal terminals. Extended Outlook...VFR developing Sat evening and persisting through Wed.
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&& .MARINE...
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NEAR TERM /TONIGHT THROUGH SATURDAY/... As of 945 PM Friday...Marine conditions will not be very inviting even to the hardiest captain. With the stalled front lying offshore, and even when it`s pulled slightly closer to the local waters, SCA conditions will persist with Gale force gusts possible. If the Gale wind gusts become more frequent, then will need to upgrade from a SCA to a Gale Warning. Looking at NNE wind directions that back to NNW directions in the wake of each sfc low that tracks northeastward along the stalled front. Significant seas will peak in the 4 to 8 foot range late tonight thru Saturday. Fetch constraints due to NNE-NNW wind directions, will limit building significant seas. There is an underlying small E-ESE, 10 to 13 second period, ground swell identified by local and offshore buoys. This combined with 3 to 6 second period wind driven waves will be enough for 6 footers, SCA criteria, to occur. Previous..................................................... As of 3 PM Friday...Small Craft Advisory continues through the period. Expect N to NE winds through as a stalled cold front east of the waters brings periods of cold rain. Winds of 15 to 20 kts with gusts to 25 kts will increase by about 10 kts overnight before relaxing again on Saturday. Seas will range from 4 to 6 ft well offshore, with 2 to 3 ft closer to shore. SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... As of 3 PM Friday...Dry high pressure will finally build in behind exiting storm system through Sat night into Sun. W-NW winds will kick up to 25 kts mainly in gusts through Sat night. The off shore flow will keep highest seas in the outer waters and beyond, but should see some 6 fters overnight Sat into early Sun. Therefore, a Small Craft Advisory will continue through early Sun. By late Sun morning, all seas will be subsiding in continued off shore flow as winds begin to back to the W-SW. Seas mainly 3 to 5 ft will subside to 2 to 4 ft by Sun eve. LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 3 PM Friday...Westerly flow, with a bit of a southerly component at times, on Mon will become southwest and increase Tue as a strong cold front approaches from the west. Wind speeds may require a small craft exercise caution headline by midday Tue but it seems quite likely that seas will reach 6 ft before winds hit 25 kt. Confidence in a small craft advisory headline in on the high side. Strong offshore flow develops in the wake of the front as cold advection kicks in. Offshore flow of 20 to 25 kt is possible while the offshore component works to drop seas. Offshore flow continues through Wednesday with speeds gradually decreasing as strong cold advection shuts off.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory until noon EST Sunday for AMZ254-256. Small Craft Advisory until 6 PM EST Sunday for AMZ250-252. && $$ SYNOPSIS...DCH NEAR TERM...DCH/REK SHORT TERM...RGZ LONG TERM...III AVIATION...MBB is the U.S. government's official web portal to all federal, state and local government web resources and services.