Friday, April 23, 2010

Anatomy of a thunderstorm

Todd's Conservation Minnesota Outlook for the Twin Cities and all of Minnesota

Today: Showery rains, a few T-storms possible over southern MN. Winds: E 10-20. High: 57

Saturday Night: Scattered showers possible. Low: 46

Sunday: Showers taper, some PM sun possible. Winds: NE 10-15. High: near 60

Monday: Partly sunny, drier statewide. High: 63

Tuesday: Plenty of sun. High: 65

Wednesday: Clouds increase, showers possible late. High: 64

Thursday: Chance of rain. High: 65

Friday: May have to take along your thunderwear: High: Near 70

A bit storm system wrapping up in the Desert Southwest earlier this week has been responsible for quite a few tornado reports over the last few days. In fact, this will likely be the biggest severe weather outbreak of the season so far with more to come. Here is a map of the tornado reports over the last few days:

Interestingly, it has been a fairly quiet severe weather season thus far. According to the Storm Prediction Center, as of Thursday, there was only 97 tornado reports nationally, about 1/3 the normal tornado reports by this time of the year - see below:

Take a look at this storm that was in southwestern Arkansas last night that was tornado warned, this view of course is the traditional radar view that most of us are accustomed to looking at.

The neat thing about technology these days is that we don't have to look at storms on radar in 2D anymore... we can look at them in 3D and dissect them to see inside the storm and diagnose them, to see where the most intense part of the storm is and if it is capable of producing a tornado. Again, the 2D version is above and the 3D version of the same storm is below:

This is what the storm would have looked like 'in some fashion' if you would have seen it in person.

This is what the storm looks like when we begin to peel away the outside layers. The image below shows the most intense part of the storm:

We can actually turn the storm to get a better view and see that there is almost a funnel cloud appearance on the southwest quadrant of the storm, which is normally where you'd find a funnel or tornado.

This particular storm did not, in fact, produce a tornado... but it was close! What we'd look for is the red color in this location extending all the way down to the surface, like this image below:

In fact, this radar image is from the May 3rd, 1999 Moore, Oklahoma tornado. This is the damage path from a NASA satellite:

Severe weather will again be possible today, but the action will be taking place well south of us. Here's the SPC Convective Outlook for Saturday:

The good news for us is that we will likely get some much needed rain from this system. Note the light blue coloring through central and southern Minnesota. This forecast has these locations under 0.50" to 1.00" total accumulation through 6pm Sunday:

Have a good Saturday - Todd Nelson

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