Skip to main content

The Storm Prediction Center is planning a major redesign of their severe weather outlooks, replacing the current system with a more detailed scale that's aimed at better relaying the threat for severe weather to the public. The agency released some examples of the redesign on their website, and they're asking for public comments through June 17.

As many of you know, the current scale the SPC uses for severe thunderstorm forecasts follows four general categories:

-General Thunderstorms (green shading)
-Slight Risk (yellow shading)
-Moderate Risk (red shading)
-High Risk (purple shading)

Common sense dictates that a high risk for severe weather has a much higher potential to be devastating than a slight risk for severe weather. The SPC is adding two more categories into the mix with "marginal risk" and "enhanced risk," which will respectively fall on either side of the "slight risk" zones. The scale now runs from 1 to 5, with a 5 denoting a high risk.

Here's the new scale:

0: General Thunderstorms (light green shading)
1: Marginal Risk (dark green shading)
2: Slight Risk (yellow shading)
3: Enhanced Risk (orange shading)
4: Moderate Risk (red shading)
5: High Risk (purple shading)

The update is meant to convey more information about the risk for severe weather on any given day, preventing people from being lulled into a false sense of security.

Here's an example from the infamous tornado outbreak of April 27, 2011. This is what the categorical severe weather outlook looked like that afternoon as the massive tornadoes were starting to tear through Mississippi and Alabama:

And here is what the same forecast would have looked like with the new scale:

You can see that Memphis is under an enhanced risk for severe weather, which is a 3 on a scale from 1 to 5. Birmingham has a high risk for severe weather, putting it at a 5 out of 5 on the severe weather scale.

Here's another example from a severe weather outbreak along the I-95 corridor on June 1, 2011. This is how the old outlook appeared:

And this is what the new scale would look like on the same map:

You can see that the new outlooks provide a much more detailed look at the threat for severe weather across the slight risk area, while also showing that there's a marginal risk for severe weather across much of the Midwest and Florida in areas that were previously labeled as "general, non-severe thunderstorms."

The new outlook has the potential to greatly impact how the public receives severe weather forecasts, but it could also confuse people: several people pointed out to me today that the terms "enhanced" and "moderate" are subjective, and that enhanced sounds worse than moderate. That might be an issue that the SPC needs to work out.

What do you think of the update?



I write regularly for The Vane, which is a new weather website I launched with Gawker. I'm also on Facebook and Twitter.

Poll

What do you think of the new severe weather forecasts?

62%93 votes
25%38 votes
3%5 votes
8%13 votes

| 150 votes | Vote | Results

EMAIL TO A FRIEND X
Your Email has been sent.
You must add at least one tag to this diary before publishing it.

Add keywords that describe this diary. Separate multiple keywords with commas.
Tagging tips - Search For Tags - Browse For Tags

?

More Tagging tips:

A tag is a way to search for this diary. If someone is searching for "Barack Obama," is this a diary they'd be trying to find?

Use a person's full name, without any title. Senator Obama may become President Obama, and Michelle Obama might run for office.

If your diary covers an election or elected official, use election tags, which are generally the state abbreviation followed by the office. CA-01 is the first district House seat. CA-Sen covers both senate races. NY-GOV covers the New York governor's race.

Tags do not compound: that is, "education reform" is a completely different tag from "education". A tag like "reform" alone is probably not meaningful.

Consider if one or more of these tags fits your diary: Civil Rights, Community, Congress, Culture, Economy, Education, Elections, Energy, Environment, Health Care, International, Labor, Law, Media, Meta, National Security, Science, Transportation, or White House. If your diary is specific to a state, consider adding the state (California, Texas, etc). Keep in mind, though, that there are many wonderful and important diaries that don't fit in any of these tags. Don't worry if yours doesn't.

You can add a private note to this diary when hotlisting it:
Are you sure you want to remove this diary from your hotlist?
Are you sure you want to remove your recommendation? You can only recommend a diary once, so you will not be able to re-recommend it afterwards.
Rescue this diary, and add a note:
Are you sure you want to remove this diary from Rescue?
Choose where to republish this diary. The diary will be added to the queue for that group. Publish it from the queue to make it appear.

You must be a member of a group to use this feature.

Add a quick update to your diary without changing the diary itself:
Are you sure you want to remove this diary?
(The diary will be removed from the site and returned to your drafts for further editing.)
(The diary will be removed.)
Are you sure you want to save these changes to the published diary?

Comment Preferences

Subscribe or Donate to support Daily Kos.

Click here for the mobile view of the site