Imagine the arrival of a squall line; the darkening skies, sudden blast of wind, and deluge of rain.
This is how the onset of the pre-Christmas winter storm will be experienced. But instead, it will be a sudden drop in temperature and bursts of heavy snow accompanying the sudden blast of wind.
This is a dangerous winter storm. And here's why.
Commodity weather apps and traditional snowfall maps won't do it justice. Roads will go from dry and mild to snow-covered and treacherous in a matter of just a few miles or minutes. All while millions of Americans are trying to reach their holiday destination before the weekend. This is especially true for motorists heading west or north into the storm.
I will summarize the most dangerous routes to avoid, followed by a "deadline to arrival" day and time for your destination.
There won't be a lot of rain or a big warm-up ahead of this storm in most areas. Snow events in the Ozarks and lower Ohio Valley are usually a changeover event, with a gradual drop in temperature as the precipitation winds down. Instead, temperatures with this front will drop more than 20 degrees in an hour, and winds will gust over 40 mph as snow picks up rapidly. Visibilities could be less than 1/8th of a mile for several hours after the passage of the front.
Here is an example of what this will look like on a graph for Cape Girardeau, Missouri on Thursday.
The following interstate routes will most likely experience something similar when the front arrives. Suggested time of arrivals for select cities are available in the following section.
Motorists who are traveling west, northwest, or southwest along the interstates mentioned above are at much greater risk of getting stranded. That is, if you don't leave in time to BEAT the Siberia-like onslaught.
That's why I've created a map with deadlines to your destination.
Please note: If you are traveling east, which is the same motion as the storm, you will likely need to plan on arriving 4 to 6 hours sooner than displayed on the map above.
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.
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.