textproduct: Wilmington

WHAT HAS CHANGED

Cold weather advisory issued for portions of eastern Indiana, western and central Ohio.

KEY MESSAGES

1) Bitterly cold temperatures are forecast through Wednesday morning with the coldest temperatures occurring Monday through Tuesday morning.

2) Light accumulating snow is expected this evening through Monday morning. Additional chances for wintry precipitation remain in the forecast Wednesday through the weekend, however, confidence in the exact details are low at this time.

DISCUSSION

KEY MESSAGE 1... The cold front approaching the region late tonight will move through the area Monday morning behind the initial round of snowfall. The cold front will usher in a very cold air mass, with temperatures in the teens and 20s falling into the lower teens and single digits. Temperatures are likely to remain the same throughout the day, but they may even drop a few degrees across a large portion of the area. Winds are strongest behind the frontal passage, generally from 6am to 3pm before gradually relaxing some into the evening hours. Winds are forecast to be in the 15 to 25 mph range with frequent gusts between 25 and 35 mph. A few gusts between 35 and 40 mph are possible.

Confidence was high enough that cold weather advisory thresholds (-10 degree wind chill) will be met that an advisory was issued starting Monday morning through Tuesday morning. This advisory is for portions of eastern Indiana through the I-70 corridor, including Dayton and Columbus metro areas. The rest of the CWA outside of the initial advisory will still see considerable cold too, but after collaboration with surrounding NWS offices, it was decided to wait until confidence increases on the colder values. An expansion of the advisory southward is possible, primarily for the period of Monday evening through Tuesday morning. However, with winds decreasing into Monday evening, wind chill specific values may not be low enough.

To learn about the warning signs of hypothermia and frostbite as well as how to protect your livestock and pets, visit www.weather.gov/safety/cold.

Temperatures moderate late Tuesday morning, likely ending the period of dangerously cold temperatures.

KEY MESSAGE 2...

This evening/tonight: The well advertised reinforcing surge of cold air is arriving behind a cold front moving through the region Monday morning. Ahead of the cold front, the trough driving the air mass change will provide a few hours of light accumulating snow late this evening and into Monday morning, becoming more scattered after daybreak. Given the cold temperatures aloft, snow ratios are very high (18-20:1) so even light QPF will produce snowfall amounts up to and potentially over an inch. Temperatures in the lower 20s, and lack of solar insolation, support accumulation on area roadways so an SPS will cover this potential for the Monday morning commute.

Additional snow, although more scattered in nature, is expected through the remainder of the morning as the cold front moves through. The more concerning thing, especially across northern areas will be the surge of colder air and stronger winds. Much of the area does not have much snow on the ground, but across portions of west- central Ohio there is at least an inch or so. With the snow during the early morning and any additional snow throughout the rest of the morning, blowing snow should be expected in the more rural, wind exposed areas. Given the very cold temperatures, this would likely last the entire day or until winds relax later in the evening. The good news is that overall snow amounts will be light.

Later in the week: On Thursday a cold front and upper level trough move through the region increasing precipitation chances. The highest probabilities for light snow accumulations are along and southeast of I-71. A limiting factor for impacts and precipitation type could be temperatures. There is a moderate amount of uncertainty regarding thermal profiles this far out as the amplitude of the system does not have a good model consensus. A more amplified system would allow more warm air into the region and less snow while a less amplified shortwave would likely lead to snow being favored.

Another round of winter weather is possible this weekend. Details regarding this system are even more uncertain as some models depict widespread snow in the left exit region of a strong jet streak while other models indicate WAA on the western side of an arctic high. The colder, snow scenario appears more likely given strong ensemble support for cold anomalies being centered over the region into the start of next week.

AVIATION /00Z MONDAY THROUGH FRIDAY/

Areas of snow will overspread the area tonight as an upper level disturbance moves through the Great Lakes and Ohio Valley region. The best chance for snow will be at the northern TAF sites where MVFR to locally IFR vsbys will be possible through the early morning hours. At the southern TAF sites, snow should be somewhat more limited so will keep vsbys to occasional MVFR. Meanwhile, VFR cigs this evening will trend into MVFR overnight.

A cold front will move through the region later tonight and into Monday morning with some additional scattered snow showers possible. Winds will also increase with the front with westerly wind gusts to around 30 knots possible into the day on Monday. MVFR cigs will persist into Monday afternoon before beginning to scatter out late in the TAF period.

OUTLOOK...MVFR conditions possible Wednesday and Wednesday night.

ILN WATCHES/WARNINGS/ADVISORIES

OH...Cold Weather Advisory from 7 AM Monday to 9 AM EST Tuesday for OHZ026-034-035-042>046-051>056-060>062. KY...None. IN...Cold Weather Advisory from 7 AM Monday to 9 AM EST Tuesday for INZ050-058-059.