textproduct: NWS Wilmington

WHAT HAS CHANGED

Updated aviation discussion for 00Z TAFs.

KEY MESSAGES

1) While some mixing of snow with rain is possible before precip ends this afternoon, mainly across western and northern portions of the forecast area, snow accumulation is highly unlikely.

2) Black ice remains a significant concern across most of the forecast area away from the immediate coast tonight into Monday morning.

3) Wind chills could require a Cold Weather Advisory Monday and Tuesday nights.

DISCUSSION

KEY MESSAGE 1: While some mixing of snow with rain is possible before precip ends this afternoon, mainly across western and northern portions of the forecast area, snow accumulation is highly unlikely.

Temperatures are presently in the middle 40s across the region with 4-inch soil temperatures in the upper 40s. Steady light to moderate rain will continue through about 3pm before tapering off from west to east through about 6-7pm. The end to the precip will be associated with a mid-upper trough axis swinging through, which will quickly cut off lift. Meanwhile, colder and drier air will eventually arrive on westerly winds, but with the high pressure system responsible for this airmass all the way down in Texas and its surface ridge axis placed along the spine of the Appalachians, the colder near-surface air has been dammed up against the mountains and is in no rush to get here (not to mention the descent of this air as it travels from the mountains down to the coast results in warming as well). The latest hi-res guidance suite is picking up on this and has backed off of even having a brief mixing of snow before precip ends. Nevertheless, some flakes may be able to reach the surface as colder air arrives aloft first, and have opted to maintain at most a chance of snow in northern and western areas during the last few hours of precip. Due to the warm ground temps and anticipated brief period of snow (if any even occurs), no accumulation and subsequently no impacts are expected due to snow.

KEY MESSAGE 2: Black ice remains a significant concern across most of the forecast area away from the immediate coast tonight into Monday morning.

This concern is driven by skies clearing out and winds becoming light or calm early tonight, allowing for lows to dip into the mid- upper 20s while roads remain wet from today's soaking rain. Although warm ground temps will help to delay or even prevent the freezing of water on some roadways, bridges and overpasses will be most susceptible to seeing slick spots. The one caveat to this threat is the potential for a lingering band of low clouds to slow down cooling, mainly across the Cape Fear area. Some hi-res guidance tools indicate a pesky area of low clouds which could stick around through about 1-2am before gradually shifting offshore or dissipating, and this would reduce how much time these areas see below-freezing temps, and reduce (not eliminate) the risk for black ice. Regardless of this caveat, anyone traveling early tomorrow morning should be wary of road and sidewalk surfaces that appear wet but are actually frozen. Patchy freezing fog may also develop where skies are clear, but this carries low confidence as lower dew points advect in.

KEY MESSAGE 3: Wind chills could require a Cold Weather Advisory Monday and Tuesday nights.

The combination of well below normal temperatures (in the 20s Monday night and mid teens to mid 20s Tuesday night) and light wind will lead to wind chill values around 15 to 20 degrees. Thus, Cold Weather Advisories are possible especially Tuesday night.

AVIATION /00Z MONDAY THROUGH FRIDAY/

IFR cigs have just transitioned to MVFR and will become VFR by 02-04z at LBT and FLO followed by coastal terminals by 06z. Low confidence of visibility restrictions with a chance of patchy freezing fog inland terminals with mainly MVFR to VFR vsbys. Clear skies and light westerly winds will be the rule after 13Z.

Extended Forecast...VFR likely through Wednesday, then restrictions possible Wednesday night into Thursday as a cold front pushes through.

MARINE

Through Monday...Northwest winds will temporarily increase this evening after the rain ends as a surge of cold advection arrives with speeds around 15-20 kts. Winds will decrease after midnight, back to westerly, and settle to around 10 kts through sunrise Monday. West winds will continue through Monday with speeds around 10-15 kts as high pressure shifts across the Gulf. Seas will hold around 2-4 ft through midnight before subsiding to around 1-3 ft by sunrise. The slight increase in winds on Monday will bring wave heights into the 2-3 ft range during the daytime. Wind waves will be the primary contributor to the wave spectrum through midnight before a southeasterly swell with a period around 8 sec takes over as the dominant wave group on Monday.

Monday Night through Friday...Sub-SCA conditions expected to continue for the duration of the week, as the CAA following two cold fropas (Monday night and late Thursday) will not be particularly strong.

ILM WATCHES/WARNINGS/ADVISORIES

NC...None. SC...None. MARINE...None.