textproduct: Wilmington

WHAT HAS CHANGED

Increased wind gusts late tonight into early Thursday morning.

Winter Storm Watch for heavy snow issued for a portion of the area for the weekend.

KEY MESSAGES

1) Gusty winds tonight.

2) Accumulating snow expected this weekend, along with very cold conditions from Friday through Tuesday.

DISCUSSION

KEY MESSAGE 1) Gusty winds tonight.

Have seen some 25-35 MPH wind gusts this afternoon, though winds should gradually diminish over the next few hours. One item to watch will be the potential for another period of gusty winds early Thursday morning. A cold front is expected to move through the area during the 04Z-10Z time frame, shifting winds from SW to W, with some steep boundary layer lapse rates developing as winds aloft also increase. There may be a pocket of 30-35 knot winds immediately behind the front, focused on the northern third of the ILN CWA. Have increased gusts in the forecast. Not out of the question that some 40-45 MPH gusts could occur in the northern one or two tiers of ILN counties early Thursday morning.

KEY MESSAGE 2) Accumulating snow expected this weekend, along with very cold conditions from Friday through Tuesday.

An axis of sfc high pressure settled in nrn OH will break down on Saturday. East winds will inhibit deep saturation of the column through early Saturday afternoon as viewed from a Cincy-Portsmouth line. Some light snow will precede the accumulating snow that should begin over a narrow period of time late Sat afternoon/early Sat evening. A steady snowfall will occur as upper heights fall ahead of an inverted trough oriented from central TN through the OH/WV border.

ATTM it appears that the main driver of heavy snow in this system is found at h850 where a cutoff low near MO/AR at 06Z Sun reaches OH/IN by 18Z Sun. This approach brings considerable moisture ahead of it on ssw winds, then wrings it out in rapid fashion Sat-Sun. Snowfall rates of over 1"/hr are going to be likely late Sat, favored in srn/se 1/3 of CWA.

Winter system south of the region that's prompting the watch issuance will bring a winter storm for southern CWA and at least some accumulating snow for the remainder. Per collaboration with WPC and neighboring WFOs, have issued a watch from Sat through Sun night for srn 1/3 of CWA, where 4" is noted along the I-71 corridor, ramping up as you move southeast to 6"+.

Timing shows a rapid precip cutoff between midnight and daybreak Mon. There is a very high potential for changes in track/strength of this system. Given the arctic nature of the air snow will be generated in, SWE will be very high which could lead to a more fluffy and subsequently deeper snowpack. Highs on Sat are only expected to reach into the teens.

For Friday AM, an arctic front will bring in the start of the very cold air mass that will be in place for the next several days. Wind chills will drop below zero for part of the area Friday during the daytime hours, and will get colder from there. For Saturday AM, with a generally sustained 8-12 mph wind, apparent temps will drop below zero area-wide, below -10 from Columbus to Cincy and then nwd through eastern IN. This is just warmer by about 5-10 deg than our guidance for issuing an extreme cold warning, so headlines may also be necessary to heap onto Saturday's forecast. Very cold conditions will continue through Tuesday.

AVIATION /00Z THURSDAY THROUGH MONDAY/

MVFR ceilings across the region will move east of the terminals by 06Z. VFR will prevail through the rest of the period. Gusty southwest winds will be diminishing. But a dry cold front will cross the region between 07Z and 10Z. In addition to winds veering to the west, speeds and gusts will increase as well. It appears that there will be a 2 to 3 hour period with some stronger gusts. Winds will then settle down, although some gusts around 20 kt will remain possible. OUTLOOK...Snow and IFR to LIFR conditions are likely Saturday afternoon through Sunday.

ILN WATCHES/WARNINGS/ADVISORIES

OH...Winter Storm Watch from Saturday morning through late Sunday night for OHZ073-078>082-088. KY...Winter Storm Watch from Saturday morning through late Sunday night for KYZ089>100. IN...Winter Storm Watch from Saturday morning through late Sunday night for INZ075-080.