Area Forecast Discussion
Issued by NWS Wilmington, NC

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734 FXUS62 KILM 161507 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1107 AM EDT Fri Mar 16 2018 .SYNOPSIS... A weak cold front will push into the area from the north late today and tonight and should tend to lift north of the area during Saturday before getting shoved to our south in the wake of a weak wave of low pressure early Sunday. This will bring a period of unsettled weather. A storm system approaching from the west should bring a much better chance for showers late Sunday night and through Tuesday. Dry and colder weather will follow during the middle of next week. && .NEAR TERM /THROUGH TONIGHT/... As of 1000 AM Friday...Beautiful day shaping up across the Southeast as high pressure centered across FL extends into the Carolinas, south of a slow moving cold front draped west to east along the VA/NC border. This front will continue to sag southward through tonight, but before that a warm and sunny day is on tap for the local area. 850mb temps on 12Z U/A soundings were above any available forecast guidance, and this supports the latest trend in the LAV numbers which show temps rising well into the 70s this afternoon. This is in part due to the warmer column, but also deep W/NW downslope flow and a dry column/mid-March insolation will all help to warm the region today. 850mb winds of around 40 kts will persist through early aftn before waning during the latter half of the day, so wind gusts of up to 25 mph are possible. The only caveat to the afternoon forecast will be slowly increasing cirrus as moisture within the subtropical jet shifting across the southern tier of the CONUS impinges upon the Carolinas beginning this aftn. Any sea breeze due to the warm temperatures will be pinned near the coast. Previous discussion from 500 AM below: As of 500 AM Friday...There is a backdoor front as seen on satellite imagery this morning just south of the NC/VA line. Its progress will slow with daytime heating, but it should push southward later this afternoon with little fanfare before stalling tonight. Tonight`s lows should be a tad cooler than this morning with overall readings dipping into the middle 40s. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 300 AM Friday...The short term forecast is a little more uncertain than we would like. Mid-level shortwave energy traversing well to our N will help to knock down the remaining upper level ridging across the eastern CONUS Sat. Low pressure at the surface will be moving through the Tennessee Valley Sat before crossing the southern Appalachians Sat eve and should be moving across the Carolinas Sat night, exiting the coast early Sun morning. This weak area of low pressure will be moving along a frontal boundary. Out best effort at timing brings a stalled front across northeast South Carolina early Sat back to our N by/during Sat afternoon. This will return SW winds to the area. Moisture profiles show considerable moisture above about 3 kft. Given precipitable water values do spike just above an inch, will include a small risk for showers Sat and Sat night. The risk should be ending by/during Sun morning, lastly across the Cape Fear area as the weak wave exits and the front gets shoved back to our S. Drying is modest in the wake of this system and the NAM is depicting an elevated warm layer which helps to lock in the lower cloud cover for most of the day. The GFS is showing the low level moisture Sun morning eroding through the day. However, both models are showing higher level moisture increasing ahead of next system out in the Plains with isentropic upglide just beginning to increase ahead of a warm front late in the period. Thus, we are going to be a little pessimistic in regards to cloud cover. Will bring at least a good chance of showers back into the forecast Sun night and Mon, first across the southern zones. Temps will hinge on cloud cover and relative location and timing of aforementioned fronts. At this time, we are forecasting highs around 70 or lower 70s Sat. However, the beaches will be cooler, mainly mid 60s. Sun should be slightly cooler throughout, but no cooler than seasonable. Lows will be above normal Sat night. The coolest weekend readings are forecast for Sun night, but no cooler than the 40s. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 300 PM Thursday...Moisture comes flooding back Monday according to model soundings (GFS has entire column saturating). This is in response to warm advection developing aloft yet some surface ridging holding and serving as a surface to be overrun. Rain should break out area-wide on Monday. Initially QPF should be fairly light due to the surface wedge and zonal mid level flow. Rain prospects look better and heavier Monday night and early Tuesday as the warm front lifts through accompanied by a developing surface low. Drying trend begins later Tuesday though it may be gradual at first. The late period will trend towards cooler weather as a deep trough returns in the east. Shortwave energy rotating through this trough could bring clouds and even light showers on Thursday. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... As of 12Z...Weak high pressure will keep VFR conditions through the forecast period. Moderate west winds are expected at the surface, with some speed shear climbing to 2k feet. Winds diminish tonight with no weather expected. A chance of precip is expected by Saturday afternoon. Extended outlook...VFR. Slight chance MVFR Sat night/Sun. MVFR/SHRA likely Mon/Tue. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 1000 AM Friday...SCA conditions continue this morning thanks to persistent gusty west winds driving seas to 3-6 ft, but slow improvement is expected. This reduction in winds and seas is due to the eastward progression of the low level jet, and after morning winds of 15-25 kts, expect only around 10 kts before a shift in direction to the NE occurs tonight. This will allow the SCA to expire, likely on time. Previous discussion from 500 AM below: As of 500 AM Friday...Later today the westerly flow will diminish from the current 20-25 kt to 10-15 kt and seas will subside from 4 to 7 ft to mainly 2 to 4 ft. Later tonight, a brief wind shift to the northeast will occur as a backdoor front slips south with speeds 10 kt or less. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 300 AM Friday...A front will be stalled across the area Sat morning and is expected to move back to the north as a warm front during Sat before returning south across the area as a cold front in the wake of a weak wave of low pressure Sun morning. A storm system will approach from the west Sun night. Its associated warm front will approach form the south very late in the period. This will create multiple wind direction changes this weekend. SW winds will develop Sat and increase. A period of Small Craft Advisory conditions may briefly redevelop Sat afternoon and eve with wind speeds of 20 to 25 kt and seas of 5 to 6 ft. SW and WSW will decrease during Sat night with the wind direction shifting to NW and N Sun morning. NE winds Sun afternoon and eve will veer to easterly by Mon morning. LONG TERM /MONDAY THROUGH TUESDAY/... As of 300 PM Thursday...Flow will be turning onshore early in the period as a wedge of high pressure weakens to our north. A southerly component will become established on Tuesday as a warm front lifts through the area. Winds and seas in the warm sector could increase as surface low pressure approaches to the point where an advisory is needed. && .FIRE WEATHER... As of 1000 AM Friday...Slightly warmer temperatures and lower dewpoints are forecast for this aftn. After coordination with forestry official, an SPS for Increased Fire Danger has been issued for the entire area through 6pm. Although the overlap of strongest winds and low RH will be short as the winds ease later today, very dry fuels could lead to fires getting out of control and behaving erratically. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory until 2 PM EDT this afternoon for AMZ250- 252. && $$ SYNOPSIS... NEAR TERM...JDW/SHK SHORT TERM...RJD LONG TERM...MBB AVIATION...SHK MARINE... 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