Latest SPC Outlook Still Shows Some Potential for Strong Storms

Posted on: 2:58 pm, October 30, 2013, by , updated on: 05:46pm, October 30, 2013

First of all, this is not a classic set-up for a major severe weather outbreak; however, some of the pieces are there for scattered strong to severe storms over the Midsouth, Middle Tennessee and the Tennessee Valley region on Thursday. What does that mean? It means that this is not an April 27, 2011 or even March 2, 2012 kind of weather event where widespread damaging thunderstorms will occur.

The Storm Prediction Center’s Day Two Outlook came out earlier this afternoon, and you can see how your county stacks up in their boundaries (outlook & probabilities):

Photo Gallery Expand 1 of 2
  • SPC Day Two Outlook

  • Day Two Severe Weather Probabilities

Those probabilities above are defined this way by SPC: The probabilities that you see on the graphics represent the probability of one or more events occurring within 25 miles of any point during the outlook period.

In other words, the 5%, 15%, and 30% probabilities are the chance of a severe weather event occurring within 25 miles of a single point. For Huntsville, Florence, Muscle Shoals, Russellville, Moulton, Haleyville, Decatur, Athens and Fayetteville, the chance is about 15% that the wind could get strong enough to be considered severe within 25 miles of you. This is what a 25-mile radius of Huntsville looks like:

Screen Shot 2013-10-30 at 2.41.25 PM

The chance is even lower, only 5 percent, within 25 miles of a point in Guntersville, Cullman, Arab, Albertville, Boaz, Fort Payne, Scottsboro, Gadsden, Oneonta and Centre.

Why is this probability scheme important? It tells us one big thing about the SPC forecaster’s expectations of the storms as they move east: they will be weakening.

“Weakening” does not mean “weak;” it is a term to describe how the storms should be most intense in West and Middle Tennessee as well as Mississippi and slowly weaken as they move east across the Tennessee Valley on Thursday evening and Thursday night.

Here’s how the morning run of the NAM looks for Southern Tennessee along with North and Central Alabama:

18Z (1 PM) NAM forecast radar from 1 PM Thursday to 1 AM Friday.  Model data for example; not an exact time of arrival for a specific place.

18Z (1 PM) NAM forecast radar from 1 PM Thursday to 1 AM Friday. Model data for example; not an exact time of arrival for a specific place.

The timing works out like this for the heaviest rain & storms:

The Bottom Line:

What you need to do is have a way to get a warning if one is issued for your area. Expect that a Severe Thunderstorm or Tornado Watch will be issued at some point Thursday. A WATCH means it’s time to listen up for WARNINGS; WARNINGS are when you need to take immediate action.

Odds are, most of us will get through Thursday and Thursday night with nothing more than just a windy, rainy day. There is a chance that a few spots could have some trouble; that’s why we’ll be here watching things closely the whole day and night until the threat is gone.

We offer several mobile and web applications to help you stay ahead of weather like this:

WHNT.com’s Maps & Radar Page
Mobile Applications (including Baron-Saf-T-Net App)
Baron Saf-T-Net (text messaging alerts)

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