Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 200539 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1240 AM EST Tue Feb 20 2018 .SYNOPSIS...
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A warm front will move north of the area by mid-morning. Bermuda High pressure will ridge in from the east and bring temperatures well above normal this week with possible record warmth Wednesday and Thursday. A cool front will drop towards the area Friday but likely stalling just to our north. The Bermuda High will again expand over the region for the upcoming weekend. A cold front will approach from the northwest late Sunday night and may stall across the region Monday.
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&& .NEAR TERM /THROUGH TUESDAY/... As of 930 PM Monday...Have raised a Dense Fog Advisory for the entire ILM CWA, in effect now thru 10 am Tuesday. Have not had too many opportunities this winter in forecasting CAD events as well as inland progressions of coastal and warm fronts respectively. A coastal warm front had recently pushed onshore and now extends from Elizabethtown to Florence. With a saturated low level atm, light to calm winds and a semi-stalled boundary in the vicinity, areas of fog quickly developed after sunset over land areas. The fog further dropped to dense criteria especially across locations that show very limited mid and high level clouds present. The dense fog remains quite shallow with the ILM Tower indicating vsby at 6 miles above the sfc based fog layer. Model guidance and latest sfc obs trends indicate the patchy dense fog at the moment should transition to areas of dense fog by midnight and pretty much staying that way possibly up to mid daytime morning Tue. The area from Little River Inlet eastward will see occasional isolated light and brief showers move onshore overnight basically traveling along the periphery of the expanding Bermuda high. Vsbys may briefly improve but will drop back to dense criteria. Some tweaks applied to tonights lows as well as both the hourly temps and dewpoints. Previous...................................................... As of 3 PM Monday...It`s been easy to find the warm front today, outlined by a 20-degree difference in temperature and an almost 180- degree difference in wind direction. The front pushed onshore across SE North Carolina where Wilmington reached 75 degrees before noon, but temperatures have so far stayed in the 50s in Florence, Darlington and Lumberton. A persistent stream of clouds and light showers linked to moisture advecting in from the Gulf Stream off the South Carolina coast has produced waves of light showers across Myrtle Beach and up through Whiteville and Elizabethtown this afternoon. This rain should weaken with time as it slips into the Cape Fear area early this evening. The high-res models have performed quite well with the frontal position today. The NAM, RUC, and HRRR correctly depicted cool inland temperatures and northerly wind directions, while the GFS and ECMWF were rather clueless. All models show shallow low clouds developing across the entire area tonight as tropical moisture continues to advect overhead. Stratus clouds may settle down to the surface becoming fog overnight, perhaps even dense at times. Although no dense fog advisory will be issued yet, we`ll highlight the potential in the Hazardous Weather Outlook. Overall depth of the stratus may be a little too shallow for drizzle. The sun should burn through the clouds and fog by late Tuesday morning, jumping the warm frontal position well inland. As the nearly tropical airmass, now down at the surface, is warmed by the sun look for Tuesday`s highs to approach 80 degrees inland. The beaches may do good to touch 70 degrees for highs with a relatively cool southerly wind across the ocean. Areas of sea fog lingering offshore could reach the beaches at times Tuesday afternoon but should dissipate very quickly after crossing inland. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 3 PM Monday...Short term to be characterized by unseasonable warmth. Temperature deviations from climatology will be about 20 degrees by both day and night making lows warmer than seasonable highs. As for Wednesdays highs in the upper 70s coast low 80s inland could be poised to break some records depending on ocean influence. Record highs for 2/21: ILM: 78 from 2014. FLO: 81 from 1997. CRE: 76 from 1953. The former appear to be in trouble while CRE will be dealing with SSE onshore flow of the marine layer. Speaking of the marine layer, models are still showing areas of sea fog through a good part of the period. SREF VSBY<1nm probs maxing out over SC areas and have for a while now and this seems plausible. This moisture will occasionally affect areas along the Grand Strand and also make for some temperature forecast complications. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 3 PM Monday...Continues to look like a period of extended warmth with potential for record breaking temperatures this week. Bermuda High and 5h western Atlantic ridge team up to bring an extended period of warm southerly flow and mid-level subsidence. GFS continues to slowly back away from bringing a backdoor cold front into the area Thu night and Fri. Meanwhile the Canadian, ECMWF, and WPC all have the front stalling out around the NC/VA border. Given the GFS is trending in this direction and mid- level ridging tends to win out went ahead and removed any hint of a front moving into the area Thu night and Fri. Next shot at rainfall looks to be Sun night as cold front moves in from the northwest. Front lacks a strong cold push and the ECMWF stalls it in the region while the GFS passes it cleanly. Looking at the predicted upper pattern would think the front stalled in the area is probably more likely and for now will carry the Sun night chance pop through Mon. The dynamics associated with the front pass northwest of the area and forcing Sun night would be limited, curtailing rainfall amounts. Might have a better shot on Mon if the front ends up stalled and shortwave activity can get involved, but have low confidence for the start of next week at this point. Partial thickness and 850 temps through the end of the week suggest highs in the upper 70s to low 80s for areas not along the immediate coast. Southeast to south flow will lead to a strong sea breeze that will become a modified resultant as the winds veer to south- southwest late in the period. Onshore flow and water temps in the mid to upper 50s will keep highs at the beaches in the mid to upper 60s at best. Front moving into the area Sun night/Mon will drop temps a little. Even so most areas are likely to end up close to 10 degrees above climo. Lows will be even warmer with potential for lows 25 degrees or more above climo. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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As of 06Z...Low confidence forecast. Combination of low stratus, fog, sea fog, and iso shra will keep IFR/LIFR conditions across the terminals through this morning. These conditions will persist through 14-15Z as fog should lift to MVFR by mid morning with VFR by noon. The exception will be KCRE where sea fog could persist into the afternoon. Winds will be southeast to south 5-10 kt through today. Extended Outlook...VFR. Morning IFR/BR possible Tuesday-Thu. Sea fog possible through Thu but confidence is low.
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&& .MARINE... NEAR TERM /THROUGH MONDAY/... As of 930 PM Monday...Dense sea fog has expanded across the local waters and as a result a dense fog advisory has been issued for all waters til noon Tuesday. Winds and seas will not be the issue for Mariners tonight or the next few days. It will be the dense sea fog. With SSTs in the mid 50s and sfc dewpoints in the mid 60s advecting across theseshelf waters, the outcome is for the development of sea fog. Satellite imagery, specifically GOES East channel difference, ie. the 10.3-3.9 micron, illustrates the sea fog nicely across the local waters as well as the inland fog. And has become a very helpful tool especially across locations that do not have a dense network of observations, like the coastal waters. Winds generally around 10 kt from the SE-S. And seas 2 to 3 ft and mainly comprised of 4 to 6 second wind waves. Previous...................................................... As of 3 PM Monday...A warm front moved across the coastal waters this morning and has pushed inland across the Cape Fear area. Variable winds remain along the Grand Strand coastline with the front still stalled 5-10 miles out, and we don`t really anticipate seeing solid southeasterly winds develop along the Grand Strand beaches until late tonight when the front finally jumps onshore. In terms of model guidance preferences, the NAM model has been far outperforming the GFS with wind directions today. Mainly southeasterly winds should become southerly on Tuesday around 10 knots. Seas 2-3 feet should change little through Tuesday. As tropical moisture continues to move across the cold nearshore waters, the potential for areas of sea fog will remain in the forecast through tonight and Tuesday. The limiting factor with sea fog may turn out to be the overwhelming warmth of the incoming airmass, perhaps not allowing the cold water to successfully cool air down to its dewpoint. No dense fog advisory will be issued at this time, although some potential does remain. SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 3 PM Monday...A quiet and unchanging set of conditions through the period. High pressure off the coast to bring a southerly wind of just 10kt with a few occasional higher gusts. Seas will average right around 3 ft. LONG TERM /THURSDAY THROUGH SATURDAY/... As of 3 PM Monday...Bermuda High will maintain southerly flow through the period. Weak backdoor front will try to drop in from the north Thu night into Fri but appears the boundary will stall out near the NC/VA border. Gradient will be on the weak side with winds 5 to 10 kt Thu and Fri. High strengthens a bit for the weekend with gradient becoming a little more defined as inland areas warm up. Southwest flow on Sat will be closer to 10 to 15 kt. Seas 2 to 3 ft Thu and Fri build to 3 to 4 ft Sat as winds become southwest and increase in speed. && .ILM WATCHES/WARNINGS/ADVISORIES...
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SC...Dense Fog Advisory until 10 AM EST Tuesday for SCZ017-023-024- 032-033-039-054>056-058-059. NC...Dense Fog Advisory until 10 AM EST Tuesday for NCZ087-096-099- 105>110. MARINE...Dense Fog Advisory until noon EST Tuesday for AMZ250-252- 254- 256.
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&& $$ SYNOPSIS...DCH NEAR TERM...DCH/TRA SHORT TERM...MBB LONG TERM...III AVIATION...RGZ

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