Area NWS Forecast Discussion
000 FXUS62 KILM 180126 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 826 PM EST Mon Feb 17 2020 .SYNOPSIS... A frontal system will bring a good chance of rain to the area Tuesday into Wednesday. Cold high pressure will follow late Wednesday, but a coastal low offshore, should bring rain into Thursday and possibly some light snow across the area later on Thursday. Unseasonably cold but dry conditions will arrive for the weekend, with freezing temperatures likely both Friday and Saturday morning. && .UPDATE... Adjusted temps a bit to account for a slight drop before clouds increase and help to flatten the curve out. Overall forecast on track with mainly altocu around 8k this evening, but lowering and thickening overnight with fog and stratus developing. Winds remain near calm backing slightly to the NE before coming back around to the SE and S on Tues. && .NEAR TERM /THROUGH TUESDAY NIGHT/... Most of the low-level stratus has cleared out of our area, with mid-level clouds beginning to move in from the south. Cloud cover will increase through tonight, with low stratus again possible in the early hours. This will help to limit how low temps get tonight, with current forecast lows in the mid-50s. Weak surface ridging from the north currently across the eastern Carolinas will break down early tomorrow, allowing weak southerly flow to develop and temps rising to the upper 60s. Rain chances will be on the rise tomorrow, with the best chances starting tomorrow afternoon into overnight hours, as moisture will be on the rise throughout the day and a few upper- level impulses will traverse the area. Bulk of precip will arrive Tuesday night into Wednesday morning with the passage of a cold front. Cold front moves through overnight Tuesday, with CAA lagging into Wednesday, allowing temps to remain steady through the night around 60 degrees before falling early Wed morning. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... Rain ongoing at start of period, possibly stratiform as leading high pressure undercuts moist SW flow aloft, with precipitation slipping just S and E of land zones 12z Thursday, associated with cold frontal passage. Concurrently, cyclogenesis off the Georgia coast may aid in spreading rain northward on Thursday as cold air advection strengthens, leading to a chance frozen precipitation just beyond this period into Thursday night. The advent of cold air flux, and evaporative cooling on Thursday with little sun, likely keeps max-Ts stuck in the 40s, yielding a cold wet day. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Falling temperatures Thursday night, combined with a good deal of moisture off shore, north of a developing surface low, and amplifying coastal trough in vicinity of the coastal waters, should spread light rain over the forecast area, which would transition to a period of sleet, then snow, as temperatures continue dropping late Thursday. Drying will win the battle with precipitation ending by 12z/7am Friday. With comparatively mild road/ground temperatures, QPF, and likely upcoming model changes, cannot commit to accumulations if any, as yet, but certainly bridges and overpasses, as always, could become hazardous if precipitation and falling temperatures prevail through the night, The situation clearly bears watching, and please stay tuned to future forecasts regarding frozen precipitation late on Thursday and into early Friday. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... VFR conditions to start with mainly mid cloud deck around 8k ft into tonight, but near calm conditions will allow IFR stratus/fog to return after midnight. Tuesday, return flow will begin, with winds veering to the southwest by late morning, allowing cloud bases to lift temporarily mainly to MVFR before clouds will thicken and lower with -RA returning from the S-SW between 19-22z. IFR will return to the TAF sites into Tues night as rain spreads across the area. Extended Outlook...MVFR/IFR conditions expected thru Thu Night. This a result of weak waves of low pressure moving ENE along a stalled front across the Carolinas. Improving to dominate VFR late Thu night thru Fri as the stalled front finally pushes south of the Carolinas followed by strong cold and dry Canadian high pressure. && .MARINE... Quiet marine weather period through Tuesday night, with exception being chance for sea fog Tuesday afternoon into overnight hours as southerly flow develops across the cool waters. Veering winds between now and Wednesday morning, with NE winds around 10 kts tonight, easterly winds tomorrow morning, southerly tomorrow afternoon, and westerly by Wednesday morning behind cold front. Winds and gusts expected to remain below 15 kts throughout period. Current 3-4 ft seas will decrease to 2-3 ft by tomorrow morning and remain steady through Tuesday night, combination of a 2 ft 8 sec E swell and a 2-3 ft 5 sec wind wave. Chance of rain over coastal waters tomorrow afternoon into Wednesday morning. Batten down the hatches, this to be a difficult and hazardous marine period, beginning Wednesday, and ending late Friday, as a cold frontal passage and an Arctic High impact the waters. Gale force winds gusts are beginning to look likely, late Thu to early Fri, so a Gale Warning is possible during this time. Rain will reduce marine visibility Wednesday and again Thursday and Thursday night. Bitterly cold air late Thursday, may result in periods of sleet and eventually a chance of snow near the coast Thursday night and very early Friday. Gale force gusts and a potential for low visibility makes this possibly a dangerous marine period. Latest wave height forecast bulletins, show buoy 41013, Frying Pan Shoals, shows 10-11 foot NE waves every 9 seconds Thursday night and early Friday. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...ILM UPDATE...RGZ NEAR TERM...VAO SHORT TERM...MJC LONG TERM...08 AVIATION...RGZ MARINE...MJC/VAO