textproduct: Wilmington

WHAT HAS CHANGED

Upgraded to a Winter Storm Warning for the entire area.

Issued a Cold Weather Advisory for tonight into Saturday.

Introduced some mixed precipitation across our southern counties late Saturday night into Sunday morning.

KEY MESSAGES

1) Cold Weather Advisory in effect into Saturday morning.

2) A significant winter storm this weekend will bring heavy accumulations of snowfall, with impacts to travel expected to continue through Monday.

3) Cold temperatures into next week.

DISCUSSION

KEY MESSAGE 1) Cold Weather Advisory in effect into Saturday morning.

A cold front will move southeast across the area through daybreak, allowing for an arctic airmass to settle into the region through Saturday. Lows tonight will be in the single digits with highs on Saturday only in the teens. Northwest winds of 10 to 15 mph will produce sub zero wind chills at times. Have extended the Cold Weather Advisory across our northern areas through Saturday morning and issued a Cold Weather Advisory for the rest of our area for tonight through Saturday morning.

KEY MESSAGE 2) A significant winter storm this weekend will bring heavy accumulations of snowfall, with impacts to travel expected to continue through Monday.

A major winter storm will develop across the region this weekend. The first wave of precipitation will develop into our southwest late Saturday morning and overspread the rest of our area through the afternoon as an inverted trough begins to nose up into the mid Ohio Valley. With an arctic airmass in place, highs on Saturday will only be in the teens. This will allow for the precipitation to be all snow. The forcing will be somewhat weaker with this initial wave, but while initial QPF amounts will not be as high, SLRs should be on the higher side.

After the first round of snowfall Saturday night, a second more robust and impactful round of wintery precipitation moves in on Sunday morning. This round of winter weather is expected to cause significant travel impacts across the area that last at least into Monday given the cold temperatures during and after the precipitation.

Precipitation likely starts off as snow Sunday morning across the entire area when low level frontogenesis (~850 hPa) ramps up as the Ohio Valley enters a region of strong ascent in the duel jet structure aloft (poleward exit region of a jet streak to the south and equatorward entrance region of a jet streak to the north). This robust forcing driven by the frontogenetic circulation overlaps anomalously high PWATs supporting liquid equivalent QPF approaching an inch or greater along and southeast of I-71.

There is a growing question surrounding the QPF and which precipitation type will occur. Locations further northwest of I-71 are more likely to have thermal profiles that support snow for a longer period of time. Locations south and east of I-71 have higher likelihoods of experiencing a mix of some sleet and perhaps a period freezing rain near the Ohio River due to warm air around 850 hPa. This warm nose aloft has the potential to significantly reduce snow totals due to poor SLRs and QPF falling as sleet and freezing rain. A much better idea of the binning of the QPF into various precipitation types (snow, sleet, and freezing rain) should be gained over the next 24 hour with mesoscale guidance coming in. Thus, storm total snowfall and ice forecasts remain highly uncertain and subject to significant adjustments.

Again, regardless of the exact precipitation type, significant winter storm impacts are expected on Sunday. Lasting impacts could persist into early next week given the difficulty in removing snow and ice with bitterly cold temperatures in place.

KEY MESSAGE 3) Cold Temperatures into next week.

Well below normal temperatures build into the Ohio Valley through into next week. Multiple periods of temperatures near zero along with wind chills below zero are expected. Wind chills Tuesday morning may be as low as -10F to -20F.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

A cold front will move through the region this morning with a dry, arctic airmass settling into the region. VFR conditions will prevail through the TAF period.

OUTLOOK...Snow with IFR or lower visibility likely Saturday afternoon through Sunday.

ILN WATCHES/WARNINGS/ADVISORIES

OH...Cold Weather Advisory until noon EST Saturday for OHZ026-034-035- 042>044. Winter Storm Warning from 10 AM Saturday to noon EST Monday for OHZ026-034-035-042>046-051>056-060>065-070>074-077>082-088. Cold Weather Advisory from 6 PM this evening to noon EST Saturday for OHZ045-046-051>056-060>065-070>074-077>082-088. KY...Winter Storm Warning from 10 AM Saturday to noon EST Monday for KYZ089>100. Cold Weather Advisory from 6 PM this evening to noon EST Saturday for KYZ089>100. IN...Cold Weather Advisory until noon EST Saturday for INZ050. Winter Storm Warning from 10 AM Saturday to noon EST Monday for INZ050-058-059-066-073>075-080. Cold Weather Advisory from 6 PM this evening to noon EST Saturday for INZ058-059-066-073>075-080.