4 June 2014

A Busy Tuesday at the Hazardous Weather Test Bed in Norman,OK

Posted by Dan Satterfield

Overshooting top detection algorithm overlaid  on 1km resolution GOES Visible satellite imagery.

Overshooting top detection algorithm overlaid on 1km resolution GOES Visible satellite imagery.

If a thunderstorm has an extremely strong updraft it will push all the way into the stratosphere before weakening. The air actually starts to get warmer in the stratosphere, and a warm bubble of rising air suddenly finds itself colder than the air around it, and will eventually sink back down. So, the higher the updraft penetrates, the stronger it must be. This is why meteorologists are keen to know which storms have these overshooting tops, because they are highly correlated with severe weather of all types.

We started teh day woth a broefng from the Storm Predicviton Center. On a day with a rare HIGH risk of severe storms and tornadoes in Nebraska and Iowa.

We started the experiment today with a briefing from the Storm Prediction Center (On a day with a rare HIGH risk of severe storms and tornadoes in Nebraska and Iowa). For weather nerds the SPC is through those windows at the back.

We can see them in the daytime on high res. visible images, but infrared images at night have less resolution and make it difficult. One of the products we are evaluating at the Hazardous Weather Test Bed this week is an algorithm that detects these tops. When the new GOES R weather satellite launches in two years, it will have a much more advanced instrument (with much higher resolution) and it should be able to detect them much better.

For now we are using the present 4km IR resolution to evaluate the usefulness of this product to forecasters. The image above is what I was looking at today, and the red dots are overshooting tops. As you can see, there were a lot of them, and large hail and wind gusts over 70 mph were reported across Nebraska. Late this evening a tornado was also reported near Grand Isle.

One of my AWIPS screens from Tuesday afternoon.

One of my AWIPS screens from Tuesday afternoon.

We are also evaluating a product called the Probability of Severe which uses high-resolution numerical weather models, along with radar,satellite data to predict how likely a storm is to produce severe weather. I have found this product very useful and another algorithm uses satellite data to point out rising cumulus towers that are about to become thunderstorms.

A summary of what goes into the probability of Severe estimates we are evaluating this week. This image was part of a training module. It's where science meets operational weather forecasting and hopefully will lead to improved warning lead times.

A summary of what goes into the probability of Severe estimates we are evaluating this week. This image was part of a training module. It’s where science meets operational weather forecasting and hopefully will lead to improved warning lead times. RAP is the name of the model used.

You can look at the current runs of the RAP model used in the algorithm here: http://rapidrefresh.noaa.gov/RAP/

If you’re a student who is interested in studying atmospheric science, I hope this gives you a bit of an introduction to what is happening in the field. If you look at the model data you will understand why my advice to you is to take all the math and physics you can in high school, but don’t let it scare you!  It will open up a whole magical world for you!

If you’re just a taxpayer like me, you should know that very smart researchers and forecasters are working really hard to give you advanced warning of dangerous weather, and to improve short-term forecasts that might some day mean the difference between life and death.