Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 220830 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 330 AM EST Sun Jan 22 2017 .SYNOPSIS...
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A complex and potent storm system will affect the Carolinas today through Monday with potential for severe weather during this afternoon and evening. Total rainfall amounts through Monday should amount to one to three inches. This storm system will slowly depart through Monday leaving high pressure for Tuesday and Wednesday. The next cold front will move across the area on Thursday. Much colder weather will follow Friday and into next weekend.
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&& .NEAR TERM /THROUGH TONIGHT/... As of 1030 PM Saturday...This evening`s round of rain has ended, other than some lingering sprinkles over the Cape Fear region. Guidance brings our next round in from the SW by around daybreak. Previous discussion from earlier this afternoon follows: Sfc winds coming around to the SE to S most places and will see a deep warm and moist S-SW flow across the area by tonight as warm front lifts north. Models continue to show a sfc low moving along this boundary as a shortwave tracks up from the SW. As the low exits off to the north a line of convection will move E-NE through SC. The warm front boundary will get a slight push south again as low pulls off to the NE but it looks like it should be aligned closer to the VA/NC border by Sun morning leaving our forecast area well entrenched in a warm and moist air mass overnight. The best shortwave energy will move across the area this afternoon through this evening with better chc of thunderstorms and showers with heavier rain. Strongest convection to the southeast will weaken as it moves toward the area but could see some stronger storms reach the area into this evening. Best chc of convection with heavy rain and gusty winds will be between 4 and 8pm over northeast SC, but overall expect weakening with time. Expect a break in pcp overnight with another period of low stratus and fog with temps and dewpoints remaining near 60. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... As of 300 PM Saturday...SPC latest forecast continues to keep slight risk over northern fringe of forecast area and enhanced risk elsewhere for Sunday. Therefore we are still looking at an active late day on Sunday with potential for damaging winds and potential for tornadoes. Similar to Sat morning, areas of fog will start out the morning and low pressure will be lifting off to the N-NE off the VA coast. This will swing boundary back around but should be just north of local forecast area Sun morning as potent storm system tracks up from the southwest. The parent low will be stacked over the lower Mississippi Valley Sun morning and will track slowly east to northeast through Sun into Monday. Strong upper level energy will rotate around this system into the southeast through late Sunday. Although some pcp will brush over the area through Sun morning, the main threat of stronger convection and heavier rain will come later in the day on Sunday as the upper low shifts east over the Carolinas. It looks like the brunt of the convection will reach the eastern Carolinas between 6p and midnight. The models differ in terms of exact location of low and timing and therefore will keep a wider window for now. The position of the low will be key in terms of potential for tornadoes, but either way, the enhanced upper level support will produce potential for strong to severe storms storms with damaging winds. Gearing up for a high shear, low cape event with main threat Sun evening. LLJ cranks up to 50 to 60 kts running right up through the tip of Cape Fear around 7 to 10 pm. Pcp water reaches up close to 1.7 inches at this time with CAPE values up 500 to 800 j/kg through late Sun evening. This potent low will move slowly off to the E-NE reaching the VA coast Mon evening. The cold front extending south will push well east of the FA late Sunday night into early Monday. Some dry air will wrap around the back end into the Carolinas through Mon morning but stacked low will drift across VA and off the VA Cape by Tuesday daybreak. Enough moisture will continue to wrap around maintaining a good deal of clouds along with a low end pcp chances. The 850 temps will drop from 13c Sun aftn down to 5 to 6 c by Mon aftn as cooler air makes its way in on the back end. This will bring temps down a good 5 to 10 degrees on Monday but still keeping well above normal temps for this time of year. && .LONG TERM /TUESDAY THROUGH SATURDAY/...
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As of 3 AM Sunday...Period begins warm and dry with surface high off the east coast and mid level ridge axis overhead. Ridging aloft shifts off the coast during Wed but subsidence will continue suppressing upward motion while pushing highs close to 70 degrees. Cold front moves across the area Thu morning possibly accompanied by isolated showers, however low level convergence is weak and the front lacks strong dynamical support. Inherited low chc pop may be a little generous but will not make any changes at this time. Regardless of shower coverage any rainfall would be meager if forecast soundings are correct in showing a brief 6 hour period of precipitable water values over 1 inch. By Thu afternoon PWATs are around 0.30 inch. Following the cold front cooler air will start building into the region, but its arrival is likely to be later Thu which will result in one last day with temperatures above climo. 850 temps drop 5-10 degrees C between Thu morning and Fri morning and highs on Fri may struggle to reach climo (mid 50s). Temperatures will trend even cooler for the weekend with a reinforcing shot of cold air Sat keeping highs around 50 with lows hover around freezing. Deep westerly flow will keep skies mostly clear and prevent any rainfall.
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&& .AVIATION /09Z SUNDAY THROUGH THURSDAY/... As of 06Z...With the exit of the 1st round of pcpn, the FA has become more stable due to the subsidence in the wake of the pcpn now exiting off the Outer Banks. Sfc SSW-SW winds will remain active across the FA keeping dense fog development to a minimum early this morning. As winds back to the SSW and S later this morning, will have to keep an eye on any sea fog development and any inland push to it. The next round of pcpn is already making headway from the Gulf Coast states as a warm front lifts northward early this morning. This pcpn should be pushing across the FA from SW to NE, roughly between 08Z thru 15z. The pcpn will be moving over an airmass that has been stabilized and thus the thunderstorm activity, if any, will be held to a minimum. And finally, the final round of pcpn, with an increased potential for severe Thunderstorms, will occur between 1/22 at 21Z thru 1/23 at 05Z. This will be associated with the intensifying upper closed low and its accompanying sfc low, both finally lifting NE from the Gulf Coast States to the western Carolinas by 1/23 06Z. The dry punch in the mid-levels will push across the area during the mid to late evening hours, ending the pcpn after pushing across. Plenty of atmospheric dynamics associated with this final round of pcpn along with a meandering sfc boundary. Enough to warrant placing Gusts up to 45 kt during the convection this evening. Extended outlook...Expect mainly VFR, except for possible MVFR/IFR during Mon from clouds and reduced vsby from pcpn. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of 100 AM Sunday...Cancelled dense fog advisory over the waters. As of 1030 PM Saturday...Dense Fog Advisory remains in effect for all waters for areas of fog with vsbys less than a mile. SCA for all coastal waters beginning at 6 am Sunday and persisting thru 6 pm Tuesday. A sfc frontal boundary will move back north as a warm front as low pressure tracks up into the Carolinas through this evening. Winds to the north of this boundary will shift from E-SE to S-SW and south of the boundary the winds will be S to SW. Winds 10 kts or so will pick up to 10 to 20 kt overnight into Sunday morning as southerly winds increase ahead of next system. This southerly push will drive seas from 2 to 3 ft this afternoon up tp 3 to 5 ft by Sun morning. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 300 PM Saturday...Strong SCA conditions through the period as a potent low pressure system moves across the Carolinas and up to the VA coast by Mon night. Increasing SW winds ahead of this system on Sunday will reach up to 20 to 30 kts. This strong southerly push will drive seas rapidly up to SCA thresholds through the morning and possibly as high as 7 to 9 ft by Sun night. Winds will begin to veer to the W-SW through the day on Monday which will help to lower the heights near shore but still expect seas up to 6 to 8 ft through much of the day on Monday in SW winds up to 20 to 30 kts. Winds will continue to veer with strong off shore westerly winds by Tues morning keeping the highest seas in the outer waters but strong winds will persist through the period with SCA conditions throughout. LONG TERM /WEDNESDAY THROUGH THURSDAY/... As of 3 AM Sunday...Southwest flow around western side of high pressure will gradually increase Wed and Wed night as gradient increases ahead of a cold front. Front moves across the waters late Thu morning with offshore flow developing in the afternoon. Ahead of the front southwest winds will peak around 20 kt Wed night and Thu morning. Winds veer to west-northwest Thu afternoon with speeds remaining 15 to 20 kt into Fri morning. Seas 2 to 3 ft at the start of the period will build to 3 to 5 ft later Wed and could exceed 6 ft in some areas late Wed night. Cannot rule out short duration SCA just prior to the front passing. Post front offshore flow will knock seas down, from 3 to 5 ft Thu afternoon to 1 to 3 ft Fri morning.
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&& .ILM WATCHES/WARNINGS/ADVISORIES...
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SC...None. NC...None. MARINE...Small Craft Advisory until 6 PM EST Tuesday for AMZ250-252-254- 256.
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&& $$ NEAR TERM...REK/RGZ SHORT TERM...RGZ LONG TERM...III AVIATION...DCH

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