textproduct: Wilmington

WHAT HAS CHANGED

Expanded Winter Weather Advisory farther north for counties along and north of the I-70 corridor.

KEY MESSAGES

1) Mixed wintry precipitation will occur today, resulting in accumulating snowfall for many, as well as minor ice accumulations near and south of the Ohio River. Impacts to the morning commute are expected.

2) Warmer and wetter conditions expected from Tuesday through the rest of the week, leading to increased potential for areal and river flooding late weekend into the upcoming weekend.

DISCUSSION

KEY MESSAGE 1) Mixed wintry precipitation will occur today, resulting in accumulating snowfall for many, as well as minor ice accumulations near and south of the Ohio River. Impacts to the morning commute are expected.

530AM Update... A narrow east-west band of moderate snowfall has developed and moved through counties just north of the I-70 corridor. OHGO cameras are showing numerous roadways that are snow covered, with conditions expected to worsen over the next couple of hours. Thus, have expanded the Winter Weather Advisory for this subset of counties, along with increasing snow amounts to account for 1-2 inches of potential accumulations.

Previous discussion... Stratiform precip shield will begin to move in from the west around 4-6 AM this morning. Thermal profiles would suggest that precip will mainly begin as snow, but a more rapid changeover to sleet is favored just south of the Ohio River. North of the river, several hours of light to moderate snowfall will occur through the mid to late morning hours. Sleet will be introduced into our far southern Ohio counties and some of the SE Indiana counties around daybreak as the nose of warm air aloft deepens. Thus, snow amounts will be undercut in these locations, with amounts generally less than 1" expected.

There will be a corridor of sustained, moderate snowfall that will result a better potential for 1-2" accumulations, with localized amounts up to 3". This corridor has gradually shifted north with the latest few model iterations, which now places this axis of higher snowfall through portions of the Miami Valley into south-central Ohio.

Localized freezing rain also expected with this system, but thermal profiles don't appear to support a prolonged period of this p-type. Locations near and south of the Ohio River have the best chance for ice accumulations up to 0.1" this morning. Our north-central KY counties, as well as counties near the Tristate likely observe the longest period of freezing rain and thus have a better chance to reach those higher ice amounts near 0.1". While temperatures will be slow to warm, we anticipate that any lingering precip will transition to rain by the early afternoon. As the warmer air pushes in, the axis of freezing rain may shift farther north into southern Ohio during the late morning / early afternoon hours before a transition to all liquid occurs.

KEY MESSAGE 2) Warmer and wetter conditions expected from Tuesday through the rest of the week, leading to increased potential for areal and river flooding late weekend into the upcoming weekend.

The synoptic pattern will favor deep layer southwesterly flow from Tuesday onwards, providing a steady stream of warm, moist air from the Gulf. This will promote a rapid warming trend and result in unseasonably warm and wet air. This unstable air mass will then interact with a stationary front that will stretch from the lower Central Plains up into the northeast CONUS. The stationary front will continue to meander around this region, which will be one forcing mechanism to help with the continuous development of rain showers.

Steady rainfall is expected Tuesday into Tuesday night. By Tuesday, PWAT anomalies will be 2-3x above normal values, highlighting the unseasonably wet air mass in place. Convection appears to be limited during earlier part of the week, which should reduce the threat of any potential flooding early on. However, the prolonged period of rainfall Tuesday may still result in 24hr QPF amounts around 1" or so from Tuesday morning to Wednesday morning, particularly north of the Ohio River. This will serve as a primer for future heavy rainfall.

Models show a robust, shortwave trough ejecting through the Midwest region on Thursday. More instability is expected to be present on Thursday, resulting in better potential for thunderstorms and thus heavier, convective rainfall. Given the wet antecedent soil conditions from the widespread rainfall that occurs on Tuesday and Wednesday, hydro concerns greatly increase at this juncture. Cannot rule out some strong storm potential as well on Thursday, but details are still murky with this particular threat. For now, flooding remains the primary concern.

Won't dive into too many details from Friday onwards, but a continued wet and active pattern persists into the weekend, amplifying the concern for aerial and river flooding.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Band of snow developed out ahead of the main complex, which has impacted KDAY and KCMH/KLCK in particular. Will continue to observe this wintry precip expand southward this morning. Still anticipating that KCVG/KLUK will have a decent amount of IP mixing in, with perhaps a brief period of FZRA. Elsewhere, snow remains the primary pcpn type. Vsbys expected to drop to IFR and perhaps some LIFR with most of the wintry precip.

CIGs remain a bit chaotic. Where the heavier snow is occurring across our northern terminals, a period of IFR/LIFR CIGs is occurring. However, this remains short-lived as VFR CIGs likely return across our north by this afternoon. For some of our southern terminals (KCVG/KLUK in particular), CIGs may only drop to MVFR this morning, but they are expected to drop to IFR by this afternoon and persist through the rest of the taf period. These IFR CIGs will translate northward late today, resulting in widespread IFR (and perhaps some LIFR) CIGs tonight.

Some light rain will develop overnight, so continued to have a -SHRA mention. Additionally, MVFR/IFR vsbys expected overnight with the trapped shallow moisture.

OUTLOOK...MVFR/IFR conditions are possible Tuesday through Friday.

ILN WATCHES/WARNINGS/ADVISORIES

OH...Winter Weather Advisory until 11 AM EST this morning for OHZ042-043- 051>055-060>065-070>074-077>082-088. KY...Winter Weather Advisory until 11 AM EST this morning for KYZ089>100. IN...Winter Weather Advisory until 11 AM EST this morning for INZ050-058- 059-066-073>075-080.