textproduct: Wilmington

WHAT HAS CHANGED

Minor adjustments to temperatures. Resultant lower apparent temperature led to an upgrade to extreme cold warning for part of the area.

KEY MESSAGES

1) A significant/prolonged arctic outbreak will continue through this weekend, with periods of dangerous extreme cold. Outdoor exposure should be limited.

2) A few chances for snow.

DISCUSSION

KEY MESSAGE 1) A significant/prolonged arctic outbreak will continue through this weekend, with periods of dangerous extreme cold. Outdoor exposure should be limited.

Tricky temperature/apparent temperature forecast for tonight. Clouds sinking south into the northwest part of the forecast have been eroding, although expect additional clouds to move into that region from time to time until late tonight when a more solid deck of clouds will move in from the north. Temperatures will likely plummet during clear periods, but periods of clouds will act as something of a limit. In addition, a weakness in the pressure gradient will allow for winds to become quite light in west central Ohio. Meanwhile, high clouds streaming across the far southeast counties will also have some limiting effect on temperature drop.

While it is threading the needle a bit, it does appear that a northeast-southwest axis across the heart of the forecast area will have limited clouds as well as keeping some wind. This brought apparent temperatures down into extreme cold warning range. HREF probabilities are greater than 60% of reaching that threshold. Thus have upgraded part of the area. There is certainly some potential for wind chill to not be quite this cold if the cloud forecast is off. Greatest confidence, where apparent temperatures is furthest below warning threshold, is in central Ohio.

Temperatures will not be quite as cold on Saturday night, although there may be a little more wind. Do not expect to flirt with warning threshold that night, but HREF probability of reaching advisory levels are 60 to 90 percent. So there is a very good chance of another cold headline for Saturday night.

Warm air advection spreading into the region on Monday will bring much warmer temperatures, relatively speaking since readings will still be a good deal below normal. But this will bring to an end the week of extreme cold.

KEY MESSAGE 2) A few chances for snow.

Disjointed short wave moving southeast on Monday in addition to the warm air advection will bring some weak lift across the region. Still cannot rule out a bit of light snow across northern counties, although probabilities of measurable (liquid) precipitation remain quite low. That does not mean that less than 1/4 inch of snow accumulation could occur if any snow does occur.

Short wave dropping southeast out of the Plains will amplify as it passes across the mid Mississippi Valley into the Tennessee Valley Monday into Tuesday. Spread in solutions has been narrowing, leading to somewhat more confidence. The main surface low will pass well south of the area, but the northern edge of the snow shield is forecast to move into the area Tuesday afternoon. Greatest potential for snow will be Tuesday night with highest (conditional) accumulations in southern counties. This does *not* look like a repeat of last weekend's storm in terms of snowfall.

Reasonably good agreement, for that far out in time, that a clipper will push across the region on Friday which would bring some light accumulations.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

A FEW/SCT VFR stratocu near nrn terminals will slowly dissipate within the first few hours of the TAF period as some cirrus streams across SE parts of the local area. Aside from some cirrus, mostly clear skies are expected area-wide from about 02z-10z before some MVFR clouds overspread again from the N toward daybreak and beyond. This will lead to MVFR CIGs increasing in coverage between 12z-15z and persisting for the remainder of the TAF period. Some brief MVFR VSBYs cannot be ruled out at KDAY during the morning.

Light N/NE winds will subside to less than 5kts early in the period before increasing past 15z to around 10kts for the afternoon. Winds will go more out of the NW at around 5kts past 00z Sunday.

OUTLOOK...MVFR CIGs and VSBYs are possible on Monday and then again Tuesday during the daytime with some light snow.

ILN WATCHES/WARNINGS/ADVISORIES

OH...Cold Weather Advisory until noon EST Saturday for OHZ034-035-074- 081-082-088. Extreme Cold Warning until noon EST Saturday for OHZ026-042>046- 051>056-060>065-070>073-077>080. KY...Cold Weather Advisory until noon EST Saturday for KYZ089>100. IN...Cold Weather Advisory until noon EST Saturday for INZ050-058-059- 066-073>075-080.