Area NWS Forecast Discussion
445 FXUS62 KILM 180101 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 801 PM EST Fri Jan 17 2020 .SYNOPSIS... High pressure will slip offshore late tonight, allowing for a brief weekend warmup prior to the next cold frontal passage Sun morning. Scattered showers will occur ahead of the front from late Sat afternoon up until it`s passage Sunday morning. Much colder temperatures will follow during the upcoming work-week as air, of Arctic origin, dips into the Carolinas. && .UPDATE... Public: Latest fcst looking aok. No major changes needed or expected. Will however tweak a few elements based on latest observations and resulting trends, but again no categorical changes needed. Marine: Latest winds and seas across the ILM NC Waters have dropped below SCA thresholds and as a result the SCA has been allowed to expire at 6 pm. This overall diminishing and subsiding trend will continue, with the ILM SC Waters still progged to fall below SCA thresholds by Midnight tonight. The elongated center of sfc high pressure will drop into the Carolinas tonight, resulting in the sfc pg relaxing-some. Significant seas will peak early this evening followed by a subsiding trend due to the reduction and size of the short period wind-driven waves. An underlying 2 to 3 foot Easterly swell at 9 to 11 second periods will persist overnight into Sat. && .NEAR TERM /THROUGH SATURDAY NIGHT/... Dry wx continues through tonight with strong sfc high pressure centered just NE of the local area. With diminishing winds, temps will bottom out in the low/mid 30s most areas, except upr 20s in the normally coldest spots. As the high slides eastwards, the NE flow tonight will transition to SE on Sat allowing for warmers temps and dewpoints than today...highs in the 50s to near 60. After a dry morning, rain chances will increase a bit through the day as moisture increases ahead of an approaching cold front. Not much in the way of forcing during the daytime period, so PoPs are capped in the 20-40% range, highest near the coast where low-level convergence will be greatest. Better chance for rain arrives after midnight Sat night (50-60% PoPs everywhere) with the fropa, but not expecting heavy pcpn. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... Majority of the rain will be offshore by Sunday morning, with a few lingering light showers possible. Cold front moves through Sunday morning with winds shifting to the NW and dewpoints dropping fast throughout the day. Cold advection, however, lags behind and doesn`t really set in until Sunday night, allowing temps Sunday to rise to low 60s under clearing skies. Temps drop fast to around 30 degrees Sunday night as surface high pressure builds in over Central US. Temps around 10 degrees below normal Monday and Monday night due to strong cold advection of arctic air, with highs in the mid 40s and lows in the mid 20s. && .LONG TERM /TUESDAY THROUGH FRIDAY/... Tuesday and Tuesday night is setting up to be one of the coldest days so far this season, with highs in the low 40s and lows around 25 degrees. A strong upper level trough digs down across the SE US Tuesday into Tuesday night, that may lead to some clouds and a possible flurry or two. Will be pretty tough though given very dry air in place at the time. The European model has a low pressure system develop off the east coast Wednesday through Thursday keeping precip close to our coast, but favoring a more dry forecast for now. Air mass will begin to modify Wed night into Thurs as ridge builds over the Southeast and surface high shifts slowly eastward. Overall, will see a rebound toward normal or above normal temps Thurs into Fri, with any rain holding off until possibly this weekend. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... VFR conditions expected thruout the 24 hr TAF Issuance period. Thin to occasionally opaque cirrus expected thru the night, with some increase in a mid-level cloud deck during Sat afternoon. Expect some onshore movement of stratocu across the SC portions of the ILM CWA, affecting MYR and CRE terminals with 3k-4k foot ceilings. The threat for steady and measurable pcpn will hold off for the most part until after 05z Sun. Winds generally NE-ENE around 5 kt tonight, veering slowly to E-SE early Sat aftn and S to SW immediately ahead of the approaching cold front. Extended Outlook...Mainly VFR thru the period except for possible showers ahead of a CFP . Showers possible Saturday night into early Sunday, could briefly lower ceilings and vsby to MVFR early Sunday. && .MARINE... A Small Craft Advisory continues through this evening, with gusts to 25 kt and 6 ft seas continuing out 10-20 nm. Improving marine conditions then for late tonight and Sat as sfc high pres retreats to the E and CAA ends. Winds and seas then ramp up again Sat night ahead of the next cold front, with another round of Small Craft Advisory conditions expected by the evening hours, with SW winds gusting to 25 kt and seas again up to ~6 ft. Dominant periods in the 5-6 second range. Small Craft conditions likely continue through at least Sunday afternoon. SW winds early Sunday around 20 kts become NW by the evening around 15 kts, with seas 5-7 ft slowly decreasing to 3-5 ft by Sunday night, a 7 sec SW swell. High pressure builds over central US Sunday night, setting up northerly winds across our area Mon- Thurs. Some guidance hinting at a development of an offshore low late Tues into Wed that would lead to winds increasing to possible SCA criteria, but confidence low. Winds veer to northeasterly Thursday and then easterly on Friday as the aforementioned surface high shifts north of our area and then further offshore to the northeast allowing return flow to develop. Seas 2-4 ft Monday through Friday, with occasional 5 footers late Tuesday and again on Thursday, predominantly 5-6 sec NE wind wave. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory until midnight EST tonight for AMZ254-256. && $$ SYNOPSIS...DCH UPDATE...DCH NEAR TERM...MAS SHORT TERM...VAO LONG TERM...VAO AVIATION...DCH MARINE...DCH/MAS/VAO