Update Friday morning

The "enhanced risk" of severe storms capable of producing a tornado or wind damage has been expanded north to include the greater St. Louis metro area, according to an update from the Storm Prediction Center Friday morning.

Latest forecast data also suggests the storms may form several hours later than originally posted in Missouri and Arkansas. My latest thinking is listed below.

• St. Louis to Chicago corridor: 8 to 11 pm
• Southeast MO & eastern AR: 10 pm to 2 am
• Western KY/TN & northern MS: 2 am to 6 am
• Southern IL/IN: first round late evening, then again overnight near Ohio River

Original post Thursday morning

A powerful cold front is expected to develop across the Central Plains Friday, igniting strong storms ahead of it as it encounters an increasingly unstable airmass across the Mid-South Friday night.

The strongest storms will be capable of producing a tornado or damaging wind gusts up to 60 mph. The risk is greatest after dark across portions of eastern Arkansas, southeast Missouri, northern Mississippi, and western Kentucky and Tennessee.

Forecast data suggests the first cells might not even develop along the front until after 4 pm CST Friday.

Confidence in this forecast is near average for two days prior to the event. The highest degree of uncertainty exists on the location of storm initiation Friday evening. This will depend on the forward motion of the cold front as it is matures and accelerates over the Ozarks Friday afternoon. Storm coverage may also be a bit disorganized or scattered at times, preventing this from becoming a widespread or larger scale event.