Area Forecast Discussion
Issued by NWS Wilmington, NC

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097 FXUS62 KILM 180142 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 842 PM EST Tue Jan 17 2017 .SYNOPSIS... A warming trend will continue Wednesday ahead of a cold front which will drop south through the Carolinas from late Wed morning thru late Wed afternoon. Weak but cooler and drier high pressure will follow on Thursday. Low pressure moving up from the Gulf Coast will drag a cold front across the area on Friday. High pressure will build in on Saturday before another system brings unsettled weather for late Sunday into Monday. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... As of 800 PM Tuesday...Latest sat imagery trends and various model rh time height displays across the ILM CWA, both indicate mainly opaque Ci/Cs to affect the FA tonight. Some low and mid level clouds may become present during the pre-dawn Wed hours ahead of the approaching cold front. Have kept POPs Nil across the FA with the pcpn staying north of the FA closer to the oriented west to east frontal system. Very mild night in store for the ILM CWA with a 20 to 30 kt low level jet developing overhead later tonight. This will keep the sfc and low levels well mixed, negating any fog issues unlike what occurred last night. Widespread 50s will be tonights lows, which climatologically are actually the normal highs across the ILM CWA for this time of the year. Again, no fog issues, however, with a SW to WSW flow across the adjacent Atl Waters and 50s to near 60 sfc dewpoints moving across low to mid 50s SSTS. Sea fog may develop and clip the Cape Fear Region or eastward portions of Brunswick County Beaches. ATTM, will mention the sea fog in the marine forecast and refrain from the Zone Fcst but continue to monitor its possible formation. Previous..................................................... As of 3 PM Tuesday...Though it took most of the day the fog and stratus has finally mixed out over inland zones. The resulting insolation has made the front jump inland in a weakening state. The remainder of the period will feature a gradually increasing southwesterly flow keeping temperatures very mild and also importing plenty of clouds into the area. The deepest moisture and mid level ascent both remain to our north and so will rain chances in all likelihood. Some marine fog/stratus may develop and if so could affect mainly just eastern Brunswick and southern New Hanover counties if the persistent SREF is to be believed. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... As of 3 PM Tuesday...Another fairly cloudy and unseasonably mild day on Wednesday as a backdoor cold front sinking through is hard pressed to generate meaningful rain chances as the dynamics for lift slide off the coast to our north. High temps will fairly quickly rise into the low 70s and may tumble just a few degrees later in the day as the cold air advection gets underway. The cold advection will only be in the relative sense as Wednesday night`s lows in the mid 40s is still a solid 10 degrees above climo. Thursday will continue the trend of mild weather as high pressure slides by just to our north. Later in the day and moreso Thursday night as the pattern progresses there should be marked increase in moisture return && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 3 PM Tuesday...Amplified mid level pattern during the period will result in an extended bout of active weather. Period begins with occluded front moving into the region, spreading showers over the forecast area. The 5h low associated with the surface system lifts north from the midwest into central Canada over the weekend as weak 5h ridge briefly builds north from the eastern Gulf of Mexico into Sat. Ridge axis quickly slides east and by Sun morning deep southwest flow is spreading abundant moisture over the region. Showers and thunderstorms develop Sun and continue into Mon as highly amplified 5h low moves across the southern CONUS, ejecting shortwaves over the southeast ahead of it. Associated 5h trough begins to acquire negative tile as it pushes a cold front into the region Mon, setting what could be the stage for some stronger storms early next week. Still too early to say when or how strong but pattern certainly appears favorable. Period ends dry with mid level ridge building back from the north. Temperatures will be above to well above normal through the period. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... As of 23Z...Surface warm front has moved north of the terminals and lifting low clouds north of the area as well. Satellite imagery shows some partial clearing across the southwest and southeast. Main issue for this forecast period will be a southwesterly low level jet increasing to 25-35 knots at about 1500 feet AGL this evening, have kept the mention of low level wind shear to the forecasts for Florence, Wilmington, and Lumberton. Another concern is Sea fog potentially developing off the coast but as of now it is expected to remain just offshore of the two Myrtle Beach airports, however a slight shift in the wind direction could bring this fog onshore. Not much change from previous discussion regarding stronger westerly winds in advance of a cold front mixing down to the surface during the morning on Wednesday with wind gusts in the 18-25 knot range possible. Some light showers from a mid-cloud deck could also sweep across the area near the front, best potential in the Wilmington area. Will keep mention of prob in the tafs for the other terminals with a tempo for KILM and MVFR conditions in ceilings, VFR throughout across all other terminals. Extended Outlook...IFR ceilings are possible in low stratus Friday and Friday night as the next warm front and rainfall event develops. IFR ceilings could continue into Saturday morning as models indicate a cool air wedge possible. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 800 PM Tuesday...Finally the ILM Waters are now in the warm sector with the frontal system now having lifted north of the FA late this aftn. A cold front will approach from the north and likely at the Surf City doorsteps around daybreak Wed. Ahead of it, look for the sfc pg to quickly tighten with wind speeds around 10 kt increasing to 10 to 20 kt by daybreak with some gusts up to 25 kt outer waters off Cape Fear where SSTS are higher than closer to the immediate coast. The sfc pressure pattern will yield SSW wind directions becoming SW except WSW north of Cape Fear. Will continue with patchy sea fog with wind directions mainly keeping the fog away from the immediate coast except it could possibly clip the Cape Fear Region prior to the winds becoming more westerly late. Significant seas will build to 2 to 4 ft...with the 4 footers primarily affecting the waters off Cape Fear to east of Little River Inlet. Wind waves at 3 to 5 second periods will dominate the significant seas, with an underlying but degrading 9 second period 1 to 2 foot Easterly ground swell remaining present. Previous................................................... As of 3 PM Tuesday...Light southwesterly flow and manageable seas expected through the period implying fairly ideal boating conditions. However a less certain factor will be the possibility of sea fog. Earlier guidance displayed rather harmonious agreement in its development which given the very high dewpoints encroaching upon the environment looked pretty plausible. Now there is some discord however regarding the timing and areal coverage with the latest RUC surprising abandoning its formation altogether. Have scaled back slightly in deference to these optimistic suggestions and have for now dropped the `dense` wording but still show sea fog developing this evening and overnight especially SC waters (the latter point being an SREF idea whereas the WRF was more widespread). SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 3 PM Tuesday... Prefrontal flow regime will see a tightening gradient Wednesday as front approaches from the northwest. Low level jetting could lead to some gustiness but the stabilizing effects of the cooler SSTs will act to inhibit vertical mixing and for now no advisory or even headlines are anticipated. FROPA will bring a sharp veer and may represent a more likely time for some wind gusts though this window appears narrow as the gradient really collapses. A fairly weak high builds overhead on Thursday keeping wind and seas quite minimal though the former will veer most of the day as the high moves east. LONG TERM /FRIDAY THROUGH SUNDAY/... As of 3 PM Tuesday...Occluded front will move across the waters during Fri with southerly flow increasing to 10 to 15 kt in the afternoon. Weak gradient persists into Fri night and Sat with winds veering from offshore Fri night to northerly Sat. Speeds drop under 10 kt by Sat morning and remain under 10 kt into Sun. Front stalled south of the area into Sun lifts back north during the day with southerly flow developing and increasing to near 20 kt by the end of the period. Seas 2 to 3 ft for much of the period will start to build late Sun in response to increasing southerly flow. Seas could exceed 6 ft after midnight and headlines may be required early next week. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...III NEAR TERM...DCH/MBB SHORT TERM...MBB LONG TERM...III AVIATION...MAC

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