Area Forecast Discussion
Issued by NWS Wilmington, NC

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787 FXUS62 KILM 230819 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 419 AM EDT TUE AUG 23 2016 .SYNOPSIS... High pressure will extend along the East Coast through Thursday, maintaining comfortable conditions. Upper ridge will expand overhead late week and into the weekend bringing a return to seasonable heat and humidity. Isolated showers and thunderstorms may return this weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 300 AM Tuesday...500 mb high pressure centered over Florida will retrograde slowly westward today. Massive subsidence in the vicinity of this ridge continues to cover the Carolinas. In fact the scattered clouds we have around the area this morning are mainly due to a thin layer of moisture trapped beneath the subsidence inversion around 7000 feet AGL. Surface high pressure centered over the Mid- Atlantic states is feeding a stream of fairly cool, dry air southward from Southeastern Canada. This airmass has obviously modified a great deal from its passage across the warm western Atlantic waters, but compared to the rest of the summer it`s a refreshing change. Today`s highs should run a degree or two cooler than yesterday, 87- 91, mainly due to the airmass cooling in the continued NE flow. However 850 mb temps of +14C to +15C are only about 1.5 degrees C below normal. The surface high should edge off the Mid-Atlantic coast tonight with NE winds continuing. Lows should range from 65- 70, warmest at the beaches. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 300 AM Tuesday...The 500 mb ridge over the Gulf Coast on Wednesday will move into western NC by late Thursday. Massive subsidence aloft will continue to completely cap the airmass to deep convection. At the surface, high pressure off the Mid-Atlantic coast will move farther out to sea while extending a ridge axis southwestward back into the Carolinas. This should maintain a northeasterly low-level flow with little temperature change expected from today. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 300 AM Tuesday...Broad high pressure centered off the New England coast will remain the dominant feature into next week as it ridges weakly down into the Carolinas. While this occurs, expanding mid-level ridge will amplify and encompass much of the Southeast, leading to a return to above seasonable warmth and humidity while keeping POP very low. 850mb temps climb back towards 20C, which when combined with ample sunshine and easterly flow will bring a return to heat index values a few degrees either side of 100 for the extended. While this heat and humidity would support aftn convection, significant subsidence beneath the ridge will suppress all but the strongest updrafts, which by themselves will be difficult to achieve due to weak lapse rates thanks to the warm mid- level temps. Still, deep E/NE flow this wknd will bring PWATs back to normal values for late August so will continue with very SCHC POP for the latter half of the extended. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/...
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As of 08Z...MVFR cu/stratocu has developed and is beginning to impact the coastal terminals. Recently CRE developed a 2600 ft cig, and 11u-3.9u satellite trends suggest this expanding to MYR and eventually ILM as well. Have added MVFR cigs to these sites through daybreak. It may scatter at times, but is expected to be predominant. Previous discussion below: As of 06Z...High confidence in VFR inland through the valid period, some MVFR level stratocu may advect into the coastal terminals overnight. High pressure will continue to expand down the coast today, with the weak gradient maintaining E/NE winds at 5-10 kts through the period. Strong subsidence aloft and very low moisture will prevent more than sct high level cirrus today. However, at the coast, this E/NE wind may advect some stratocu onshore tonight as moisture gets trapped beneath the subsidence inversion. NAM is very robust in developing a CIG, while the GFS barely shows any low-level moisture. The GFS is matching the current VWP better, but do note some few020 at MYR recently. Do not expect a cig overnight, but have mentioned sct at mvfr levels at ILM/CRE/MYR through daybreak before this will erode by late morning. EXTENDED OUTLOOK...VFR.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 300 AM Tuesday...High pressure centered over the Mid-Atlantic states will move off the New Jersey coast tonight. This should maintain a northeasterly wind through the next several days. While our surface pressures shouldn`t change much through tonight (1022- 1023 millibars), pressures will drop across Florida and the northern Bahamas. This will tighten up the pressure gradient leading to an increase in wind speed. Latest models suggest we`ll see a solid 15 knots developing later today and persisting into tonight. This should build seas to at least 3 feet tonight. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 300 AM Tuesday...High pressure will move farther east off the Mid-Atlantic coast through the period but will extend a ridge axis southwestward across the Delmarva and into western North Carolina. This should maintain a northeasterly wind across the area with speeds 10-15 kt. Seas of 3-4 feet will subside Thursday night as wind speeds diminish. LONG TERM/FRIDAY THROUGH SATURDAY/... As of 300 AM Tuesday...Broad high pressure will move offshore New England but maintain a ridge axis down the coast into the upcoming weekend. This will persist E/NE winds at 5-10 kts both Friday and Saturday, with subtle shifts to SE at times. Seas will feature a low amplitude E wind wave, but will be dominated by an amplifying SE 9 sec swell, creating wave heights of 2-3 ft, with some 4 fters developing late in the period. && .CLIMATE... As of 300 AM Tuesday...Wilmington has broken its record for the most consecutive days with low temperatures of 70 degrees or warmer. It remains to be seen if we make it down below 70 before sunrise, potentially tacking on one more day to this record-breaking string. Wilmington`s temperature records began in 1874. Wilmington`s Consecutive Days with Low Temperatures 70+ degrees #1 57 days 6/27/2016 to 8/22/2016 #2 56 days 6/29/2012 to 8/23/2012 #3 52 days 6/22/1941 to 8/12/1941 #4 48 days 7/ 6/1986 to 8/22/1986 #5 46 days 6/28/1991 to 8/12/1991 In Florence, SC the record for consecutive 70+ degree low temperatures has also been broken. Florence temperature records began in 1948. Florence`s Consecutive Days with Low Temperatures 70+ degrees #1 62 days 6/22/2016 to 8/22/2016 #2 60 days 6/26/2005 to 8/24/2005 #3 55 days 7/ 6/1975 to 8/29/1975 #4 46 days 7/10/2010 to 8/24/2010 #5 45 days 6/11/2015 to 7/25/2015 #5 45 days 6/28/1991 to 8/11/1991 && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...JDW NEAR TERM...TRA SHORT TERM...TRA LONG TERM...JDW AVIATION...JDW MARINE...TRA/JDW CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.