Area Forecast Discussion
Issued by NWS Wilmington, NC

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331 FXUS62 KILM 131758 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 158 PM EDT Sun Aug 13 2017 .SYNOPSIS... A cold front will approach the area from the northwest today then stall and meander across the forecast region thru midweek. This will continue the daily threat for showers and thunderstorms across the area for much of the upcoming week. && .NEAR TERM /THROUGH TONIGHT/... As of 910 AM Sunday...The radar scope is clear of precip for the moment but expect that will be changing before too long. Analysis of morning data and guidance shows a very juicy atmosphere primed for whatever triggers may happen by, in this case the sea breeze boundry near the coast and a cold front dropping in from the NW. Present forecast remains on track with no changes needed. Previous discussion follows: A cold front was easing into the Central Carolinas analyzed just east of Charlotte in the overnight hours. Shwrs continued to develop ahead of this front, mainly near and west of the I-95 corridor and farther south into SC. Models show shortwave digging down through today pushing this cold front south and east but low pressure developing over SC and then push of aftn sea breeze will hold boundary closer to west and northern reaches of CWA later today. The deep SW flow ahead of this front will keep deep level moisture through the column with pcp water values remaining up near or above 2.25 inches. The focus of convective development will be the front and the sea breeze boundary as it pushes inland this aftn into early eve with PoPs trending downward along the coast and upwards inland through later today. Also should be in a more favorable region of upper jet as it rides by around upper trough just north. With these forcing mechanisms along with abundant moisture expect shwrs/tstms to produce very heavy rain with potential for localized ponding and flooding. The steering flow will only be about 10 to 15 kts out of the SW pushing the storms off to the NE. Guidance shows temps running in the mid 80s most of the day with intervals of sunshine pushing temps closer to 90 most places. This will push heat index values close to 100 in spots. Convection should diminish into tonight as heating of the day cuts off but still expect a warm and humid air mass to keep overnight lows well into the 70s most places. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 300 AM Sunday...Little change in the atmosphere during this period as the surface front remains stalled over the eastern half of the Carolinas and the forecast area continues to be engulfed with copious amounts of deep moisture, that is 2+ inches of precipitable water values. Synoptic scale forcing shows weak disturbances in the southwest flow which will help with the development of convection through out the period. Best chances for convection will be with daytime heating and focus of convection on the west side of the sea breeze. High temperatures are expected to be in the upper 80s with a few mid 80s at the beaches. Lows each night are expected to be in the mid 70s. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 300 PM Saturday...A stalled cold front just to the northwest will gradually move into the forecast area early Wednesday morning as an upper level trough pushes eastward across the Great Lakes and off the eastern US coast. Showers and thunderstorms will be more numerous ahead of the front with periods of heavy rainfall and minor flooding possible, especially in poor drainage areas, as southwest flow and ample available moisture remain in place. PW values will decrease from over 2 inches on Tuesday to around 1.8 inches Wednesday into the latter part of the week as the front settles just south of the area. Somewhat zonal flow aloft and high pressure gradually pushes into the Carolinas on Thursday, and though drier air attempts to push into the area, will carry the potential for typical summertime diurnal convection the remainder of the forecast period. This comes from the uncertainty of the placement of the front as it becomes stalled just south of the area, along with the afternoon sea breeze and any lingering boundaries. With increased cloud cover and a possible cold front, high temperatures should remain slightly below average Wednesday, in the low to mid 80`s, with overnight lows in the lower 70`s. Thereafter, anticipate a gradual warming trend through the end of the week into the weekend, with high`s in the upper 80`s and overnight low`s in the low to mid 70`s. Heat indices could reach near 100 degrees on Friday. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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As of 18Z...Tropical moisture will continue to stream over all the TAF terminals through the valid period. Scattered showers and thunderstorms this afternoon will be the primary concern for aviators in the near term. For the overnight hours good confidence that IFR cigs will develop over our inland terminals of FLO and LBT, with lesser confidence that these cigs will develop at ILM. Also moderate confidence that IFR vsbys will develop at FLO/LBT overnight. Extended Outlook...There is a greater chance of MVFR/IFR ceilings and visibility in showers and thunderstorms Mon through Wed as a stalled cold front meanders in area and another one moves in.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 910 AM Sunday...Latest obs show SW winds of around 10 kts with seas of 2 to 4 ft. No changes expected to the forecast with in the near term. Previous discussion follows: Southwest flow 10 to 15 kts will continue ahead of an approaching cold front through today. The front will push south and east from Central Carolinas but should remain inland and north of the local waters as low pressure develops over SC and aftn sea breeze pushes inland. The seas will continue to subside as gradient weakens with approach of cold front. Overall expect seas between 2 and 4 ft. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 300 AM Sunday...Mainly southwest winds over the waters this forecast period as a stationary front remains inland. Wind speeds are expected to be in the 8 to 13 knots range and seas will be between 2 and 3 feet. The 00 UTC run of the WNAWave model shows the significant waves from tropical depression 8 to remain to the east of the center. The model indicates there will be little impact to the nearshore waves as the depression passes well to the east of the area. LONG TERM /WEDNESDAY THROUGH THURSDAY/... As of 300 PM Saturday...Southwest flow will persist across the waters ahead of an approaching cold front, which is expected to reach the local waters Wednesday, but may stall or push back north through Thursday. This may cause a temporary disruption to the SW winds, becoming more variable or northerly for a brief period before returning back to the SW. Seas should remain between 2 and 4 ft through mid week. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...99 NEAR TERM...REK/RGZ SHORT TERM...DRH LONG TERM...SGL AVIATION...REK MARINE...REK/RGZ/SGL/DRH

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