Tornado Prediction From The Experts

Like a hot air balloon as long as the parcels remain warmer than their surroundings they’ll continue to rise. As described by SPC the Midwest has an added feature this weekend–the jet!

There’s a big severe weather outbreak still underway this weekend. At least one Iowa town was flattened yesterday with 31 tornadoes reported overall. Today it’s ‘only’ six. The evening is young. Three Four tornado watches and one severe thunderstorm watch are up as I type.

The prevailing wisdom is tornadoes form during a clash between warm moist and cool dry air. That’s a situation likely to exist in the Midwest every spring.

However, if you listen to the experts from the Storm Prediction Center you’ll see there’s more. Tech stuff first. I’ll translate after you read it.

SCATTERED VIGOROUS STORMS ARE ONGOING…FROM NEAR THE DEEP SURFACE CYCLONE CENTER MIGRATING ACROSS NORTHWEST WISCONSIN…SOUTHWARD TO THE VICINITY OF A 90 KT SOUTHWESTERLY 500 MB JET AXIS ACROSS SOUTHWEST WISCONSIN. AN EMBEDDED SPEED MAXIMUM IS IN THE PROCESS OF NOSING ACROSS THE UPPER MISSISSIPPI VALLEY TOWARD THE UPPER GREAT LAKES REGION…WITH A REGION OF ENHANCED UPPER DIVERGENCE CONTRIBUTING TO CONVECTIVE DEVELOPMENT.

  • Deep surface cyclone is a low pressure system at ground level.
  • 90 kt southwesterly 500mb jet axis means there’s a wind blowing between 110-115 mph at approximately 18,000 feet. The exact height isn’t important.
  • Enhanced upper divergence means as the wind is moving by it’s spreading out.
  • Convective development means thunderstorms born of air moving upward in the atmosphere

These conditions paint a serious situation because of how thunderstorms form and what make them strong (sometimes strong enough to spawn tornadoes).

In a thunderstorm parcels of relatively warm air rise into a colder atmosphere. Like a hot air balloon as long as the parcels remain warmer than their surroundings they’ll continue to rise. As described by SPC the Midwest has an added feature this weekend–the jet!

A strong jet streak will help rising air ascend even faster and make the situation much more volatile. Divergence means additional air will need to be sucked up from below to fill an increasingly large atmospheric void. It’s a scary and vicious cycle.

The good news is this severe weather is exceptionally well forecast. It’s tough to believe anyone in the bullseye doesn’t know what’s going on.

The bad news is sometimes there’s just nowhere to hide.

13 thoughts on “Tornado Prediction From The Experts”

  1. I’d rather see a snow storm coming across the country than a path of bad weather like that. Scary stuff Geoff.. very scary. I would never be able to live in that part of the country. I would die from fear. No doubt in my mind. Hate that T word!!!

    1. Tornados happen everywhere. I live in Bridgeport CT. We had two the year before last. One was within a mile of me. My sister’s apartment was blown away in a tornado in Virginia (the April 1 tornado that was reported in US News & world report about 40 years ago, with a picture of her building!)

      I’m glad to live in New England. Would never want to live in California….

  2. I just marvel at the videos of tornado’s It is just amazing how these storms develop, and that it can flatten one house but another house mere feet away is virtually untouched! just awesome and amazing.

  3. So scary…my sister has lived in the Memphis area for 20 years..don’t know how she can stand it. Is the weather generally becoming more volatile, or are we more informed?

  4. I’m astounded at how well you can break down information and give it to us in layman’s terms so it’s understandable. That being said, why don’t you look into teaching atmospheric science or something along those lines? Although I’m sure you’ve looked into all the possibilities. It just seems such a waste of such a good brain that you’re not doing more. However, the up-side is that you’re giving us this valuable information in your blog.

    I have never witnessed a tornado close and in person. Seeing them on television is close enough for me. I really have sympathy for those folks who have to live with them and all the damage they cause. Snow and hurricanes is plenty enough for me.

    1. TV’s close enough for me too.

      I have mentioned before I don’t think I have the kind of credentials academia desires. There’s an overabundance of qualified teachers at the college level.

      1. But you have a recognition factory that could attract students to a program.

        You never really know till you try, and the worst that can happen is they turn you down.

  5. Geoff thanks for breaking that all down. I read the NWS discussion often and sometimes I can figure out what they’re saying but a lot of times I can’t follow it. You shed some light on what I’ve been reading.

  6. For only the 9th time since 2000, the SPC issued a moderate risk for today three days in advance. They had the location of strongest possibility of tornadoes pinpointed (within a 50 mile radius) more than 48 hours in advance. Pretty impressive stuff!

    Unfortunately, even with the sun going down, there is still enough energy to spawn some tornadoes, which is always a very scary situation at night.

  7. My aunt in Memphis should move to Connecticut! Someone did a study a year ago or so and determined that the safest place to live in the US in terms of atmospheric and geological events was in the northern part of the town of Mansfield, not all that far from UConn. Of course you’ve got to be careful choosing your neighborhood, because there is UConn’s notorious Spring Weekend!

  8. This blog is what I miss in the news. That is an ‘explanation’! It doesn’t have to be academia, but I do like to have a layman’s description of why something is happening.

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