Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 210536 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1235 AM EST Wed Feb 21 2018 .SYNOPSIS... Unseasonably warm and humid conditions will persist thorugh the weekend across the Carolinas as Bermuda high pressure dominates the weather. Temperatures should run 20 degrees above normal through Sunday. A cold front will bring a chance of showers Sunday night or Monday, with temperatures cooling back toward normal by Tuesday. && .NEAR TERM /THROUGH WEDNESDAY/... As of 300 PM Tuesday...Temperatures reflective of late April and early May across the region this afternoon, and this pattern will not change much into Wednesday. Anomalously strong upper ridge north of the Bahamas, will hold surface high pressure under its thumb near Bermuda, drawing markedly warm air for late February into the Carolinas. The only appreciable moisture resides from the surface to 875 mb. With clearing skies this evening, S winds 20-30 kt in the boundary layer, increasing relative humidity, and ground temperatures near to several degrees below dewpoints, areas of fog and stratus, are expected overnight. This developing perhaps in some areas by midnight. As diurnal cooling affects ocean air-temperatures slightly, sea fog may again make a debut along the coast, and have painted chances for fog throughout, excluding the milder outer marine waters. With the nocturnal buoyancy increasing offshore tonight, and a little bit of low-level convergence, isolated coastal showers may be seen in the predawn and early morning hours, with very little if any, measured rain. Records for Wednesday 2/21 include, ILM 78 in 2014, FLO 81 in 1997, and CRE 76 in 1953. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 300 PM Tuesday...Little change in the synoptic pattern for the short term period. Strong mid level ridging will remain entrenched over the Western Atlantic as will surface high pressure. With good low level moisture fog is a good possibility both Thursday and Friday mornings as well as sea fog. No rainfall is expected. Regarding temperatures the NAM is off to an abysmal start with the airmass and will follow the MAV numbers for the most part. Lows will be in the upper 50s to lower 60s both mornings although guidance is just a tad lower for Friday. Thursday`s highs will be in the middle 70s along the coast to near 80 inland. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 300 PM Tuesday...An exceptional upper level ridge will remain anchored off the East Coast through this weekend. Model consensus 500 mb heights peak on Wednesday at 593 dam along the coast, nearly 3 standard deviations above normal, and among the highest values ever measured this early in the year. By Friday heights should drop by about 40 meters to 589 dam, a typical mid-August value. Nestled beneath this upper ridge will be the Bermuda high at the surface. This summerlike feature will maintain a south-southwesterly wind across the Carolinas and very warm conditions continuing. For the past several days models have been showing a backdoor front dropping into eastern NC Friday morning. The latest model consensus is the front should remain far enough north to have no impact locally. Record high temperatures could occur on Sunday ahead of a cold front, with highs all weekend ranging from the upper 70s to lower 80s away from the cooler beaches. A strong subsidence inversion on Friday and Saturday should keep the area dry despite what should be plenty of cumulus around. By Sunday an upper trough shearing northward as it moves into the ridge may punch a large enough hole in the inversion to allow some deeper convection to develop. As the cold front moves through the area early Monday, the GFS and Canadian models suggest more showers could develop in a brief period of overrunning behind the front, however the ECMWF is dry. All models show the front should be far enough south by Tuesday for drier weather to develop with temperatures falling much closer to normal. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... As of 06Z...Another night of low vsbys in fog across the terminals. Altough the vsbys may fluctuate, expect periods of LIFR vsbys and VV around 200 to 300 ft mainly between 07z and 13z. Shortly after sunrise LIFR fog will lift, and IFR/MVFR vsbys and cigs will improver by 15z across most terminals, leaving some mainly VFR strato cu across the area this afternoon with plenty of dry air and subsidence through the mid levels. Soundings show potential for some broken clouds around 5k this afternoon. Extended Outlook...VFR. Morning IFR/BR possible through Thur am. Sea fog possible through Thu but confidence is low. && .MARINE... NEAR TERM /THROUGH WEDNESDAY/... As of 300 PM Tuesday...A welcoming wind and wave environment through Wednesday, and summer like. Areas of sea fog and mist however may develop and impact parts of the local waters. This mainly due to moist and balmy air interacting with still chilly sea water inshore. A marine dense fog advisory could be needed later tonight, if visibilities over the water fall below 1 NM. With high pressure to hold offshore, a steady 9-12 kt S wind is expected, with gustiness to 16 kt in the afternoon, due to the sea breeze. SE waves around 2 feet every 6 seconds will dominate the wave spectrum, with moderate afternoon chop inshore Wed afternoon. No TSTMS, but isolated showers should be expected early Wednesday morning over the 0-20 NM zones. SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 300 PM Tuesday...Essentially a summer like setup for the coastal waters outside of the sea fog that may develop at any time through the period. With surface high pressure remaining offshore, south winds around ten knots will remain over the waters. Significant seas will remain steady-state as well with 2-3 feet with maybe a few four footers into the mix across the outer waters late. LONG TERM /FRIDAY THROUGH SUNDAY/... As of 300 PM Tuesday...High pressure will remain anchored off the East Coast between Cape Fear and Bermuda through the weekend. This should maintain a south-southwesterly wind direction through the period. Models for the past several days have shown a backdoor cold front making its way down into eastern North Carolina on Friday morning. The latest model consensus is that the boundary could make it Cape Lookout Friday morning, but will almost immediately lift back to the north with no impact this far south. As a cold front crosses the southern Appalachians Sunday our pressure gradient will tighten substantially. Relatively gentle winds Friday and Saturday should increase to around 20 knots on Sunday with seas building to a very choppy 5-6 feet. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...MJC SHORT TERM...SHK LONG TERM...TRA AVIATION...RGZ

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