Area Forecast Discussion
Issued by NWS Wilmington, NC

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773 FXUS62 KILM 212343 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 643 PM EST Sat Jan 21 2017 .SYNOPSIS... A warm front over the NC/SC border will lift north through tonight as low pressure moves up into the Carolinas. A more complex and potent storm system will affect the Carolinas Sunday into Monday with potential for severe weather during Sunday afternoon and evening. Total rainfall amounts today 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. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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As of 630 PM Saturday...Convection formerly approaching the forecast area has mostly stratified out as it encountered a much more stable column. So although precip is still quite likely this evening, the severe threat has diminished. 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.
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&& .SHORT TERM /6 AM SUNDAY MORNING 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/... As of 300 PM Saturday...A regime change signaled by a strong cold front Thursday will separate the extended into two distinct seasons. Ahead of this front, Tue-Thu, continued above to well above normal temperatures are forecast. Tuesday is likely the coolest day of this stretch behind Monday`s cold front, but temps will still reach into the 60s, above normal for late-January. Thereafter, 500mb ridging blossoms up the Southeast coast while high pressure moves into the western Atlantic. This will create dry weather and lots of sunshine Wednesday with temps soaring towards 70 once again. Another warm day is forecast Thursday, but a cold front along the leading edge of a deepening mid-level trough will bring a chance for showers, followed by much colder air for Friday. Temps crash quickly behind this front as a significant trough sets up across the eastern CONUS. While the latter half of the period will be dry, this trough will be periodically reinforced so temps will get cooler each day into the wknd, and by Saturday could be several degrees below climo. This cold air looks to remain locked in for quite a while, persisting even beyond this extended. && .AVIATION /23Z SATURDAY THROUGH THURSDAY/... As of 18Z...Difficult flight conditions as periods of IFR and MVFR prevail this TAF cycle. The onshore flow will also plague coastal terminals at times with VSBYS < 1/2 NM. -RA/SHRA also in the mix 22Z-02Z, then again Sunday AFT 14Z. Winds mainly SSE-SSW this period at speeds of 11KT or less. Extended outlook...Thunderstorms are expected on Sunday with IFR conditions possible. There is potential for strong to severe thunderstorms Sunday afternoon into the evening. Monday thru Wednesday, MVFR to mainly VFR conditions expected. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of 630 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 /TUESDAY THROUGH THURSDAY/... As of 300 PM Saturday...Cold fronts moving across the water bookend the period. The first will be offshore Tuesday morning, leaving gusty W/NW winds of 20-25 kts, easing slowly to 10-15 kts while backing to the W/SW by Wednesday morning. An SCA from Monday may linger into Tuesday morning for these winds and 4-6 ft seas, before falling to 2-4 ft by Wednesday morning. Brief ridging creates SW winds increasing to 15-20 kts during Wed and into Thu, before another cold front crosses with a wind shift to the W/NW at the end of the period. Wave heights will build again to 3-5 ft late Wednesday into Thursday before falling behind Thursday`s cold front, but no further statements or headlines are anticipated.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Dense Fog Advisory until 6 AM EST Sunday for AMZ250-252-254- 256. Small Craft Advisory from 6 AM Sunday to 6 PM EST Tuesday for AMZ250-252-254-256. && $$ SYNOPSIS...MJC NEAR TERM...REK/RGZ SHORT TERM...RGZ LONG TERM...JDW AVIATION...MJC/DRH MARINE...MJC/REK/JDW/RGZ is the U.S. government's official web portal to all federal, state and local government web resources and services.