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12:05 pm LE CLAIRE, IOWA

It's Tuesday April 12th, and for the first time in more than two years I'm doing something special just for me. I'm departing to chase tornadoes with a couple of my buddies who are into that sort of thing. This post is starting at noon Tuesday as I head out the door and will stand as a diary of the days events. This is the point in time when optimism runs high. After watching the charts for days and studying the latest data, my team and I have selected a general target area for potential tornadoes around Ft. Dodge, Iowa. This specific region will most likely be revised as we get closer to reaching the target and initiation time which we think will be in the 4-5 PM window. Our focus in on a triple point and strong warm front where winds are backed. Tornado breeding ground.

At this time, SPC has a moderate risk in effect for all modes of severe weather including strong long tracked tornadoes. This is not common verbiage and if parameters are reached it could be a volatile day where we are headed. We'll need to be on our toes if things trend in this direction. Below are some of the early day assessments of where concerns are expected to be the greatest.


By now we've been pounding down the interstate for 90 miles. We just made a pit stop at the McDonalds near the Tanger outlet mall on I-80. It's windy as heck and still on the cool side. We remain north of the warm front that should kick up severe weather later in the day. In SW Iowa temperatures are near 81 while just over the Iowa border it's 46 in Austin, Minnesota. That's driving plenty of instability to the southwest of us. By evening CAPE should be near 3200 j/kg close to our target area. That's what's known as a "juicy air mass" for early April in the state of Iowa. We want to be right on the northern edge of the CAPE gradient by 5:00 pm.

The HRRR ( a short term convective allowing model) is showing a significant tornado parameter of 17 in NC Iowa early in the evening. That's maxed out. The question for us is can we get a storm to fire near that warm front/triple point where we expect it? If so, things could get wild in a hurry. Any storm that fires here is going to rotate at its inception. We are looking at exceptional least on paper.


We have exited I-80 and are now headed north on I-35 towards Ames. One hour and 34 minutes before we reach our target of Ft. Dodge. The sun has popped out and the temperature has soared to 73. We are right on the warm front and will head back into cooler air where eventually we will pause and let the warm front intercept us in a couple hours. It's our hope that storms initiate near us by 6:00 pm. If so, we expect they will rapidly intensify and then the game begins as the chase commences. If storms have not come to fruition by then we wait or move to a better location. No matter what, we will have a bit of time to regroup and go over the latest data which will include models, radar, and satellite imagery.

The latest satellite imagery available now indicates the clearing over the SW half of Iowa which identifies the warm sector with temps 70-80 degrees and dew points in the range of 60-65. Its the edge of that instability that we want to play because that's where the shear for tornado development will be maximized.

My phone just dings, the first tornado watch of the day has been issued. It's to the west of us. We expect another to be issued for our target play in an hour or so. If not, that's a bad sign for our plans and it could be a long ride home.

4:52 PM Webster City

On radar we have just witnessed the cell we hoped would develop spring to life near Wall Lake, 67 miles to our southwest. It's already displaying mid level rotation and rapidly intensifying. So far it's discrete (all by itself) and that's the type of supercell we are looking for. We are optimistic about its potential forming in such an optimal environment. If it continues to morph into a strong mesocyclone we will stick with it. Time to fill the gas tank. Nothing worse than being on a hot chase and then running out of fuel. Topping of is a top five chase rule, Relieving the bladder is another. We can now see the anvil poking more than 40,000 feet in the western sky. It's really magnificent if you take the time to appreciate its structure and bruising colors.

Ding, there it is on my phone, a thunderstorm warning has just been issued for our storm until 5:45. It's not a tornado warning but it's the next closest thing. Game on!

5:07 West of Webster City

Things are evolving fast as the cap that's held storm development back all day has broken. A tornado watch is now in effect for our target area. Forecasters at the Storm Prediction Center agree with our thinking, tornado potential is high. Our storm continues to grow and out the car window I can see the updrafts building to our southwest. Billowing marshmallow clouds with an anvil shaped top where the upper level winds have sheared it off. So far everything is going like clockwork.


Skies are now filled with ominous clouds as our supercell has matured into a beast. Cloud to ground lightning is becoming a regular feature. Significant rotation is evident on radar and we pause to commend each other with the fact that the chase is going exactly as we planned. That never happens! We also note that SPC has issued a mesoscale discussion for strong supercells capable of producing tornadoes from Storm Lake to Ft. Dodge, Iowa, exactly where we visualized them developing. We know things are going well but it's nice to have the confirmation just the same. We are excited and anxious, you can witness with your eyes the angry atmosphere of the sky. Stiff southeast winds are cranking at 40 mph feeding moisture into the storm. It's now or never as far as this chase is concerned.


Our radar is now depicting a tight couplet. We can clearly see a wall cloud vigorously rotating 5 miles to our southwest. Just looking at the magnitude of the wall cloud and the radar signature, we can't believe a tornado warning has not yet been issued. Finally, a few minutes later everybody's phone goes off with the warning tone. The NWS has issued the tornado warning designed to save lives and property.


By now we are enthralled watching the wall cloud approaching, it's spinning like a saucer with fingers of clouds going up and down in a circular fashion at the base of the mesocyclone. The sequence below.

Finally, after several minutes, the tornado begins its slow motion descent until there was a swirl of dirt. The twister has reached the ground. In a matter of minutes we had watched the genesis of a tornado and it was a monumental experience. In seconds it had swollen in size and was already producing a trail of destruction south of Gilmore City. At one point a tree floated above us like a down feather. We watched as long as we could before bailing into the truck effectively removing ourselves from harms way. Below are several images.

After a 15 minute chase, the storm cycled and the tornado lifted. However, the mesocyclone remained intact and 15 minutes later a second "stove pipe" tornado formed out of the rain curtains directly in front of us. This was not far from Humboldt, Iowa. Again we watched the funnel descend and then it appeared to occlude and took a turn to the northwest directly towards us. We were within 1/8 of a mile and received an unwanted up close and personal view of its power when it blew the roof off a house directly ahead of us. It went straight up in one piece and then was obliterated in the blink of an eye. We scrambled to turn around and managed to outrace the funnel which was approximately 1/5 of a mile wide (several hundred yards). We could hear its roar and feel its power. We had a very intimate encounter, one that I would prefer not to experience again. Here's the twister before it veered towards us.

Below is the house whose roof exploded before our eyes. An unbelievable site. Something out of a scene from Twister.


Our day ended with golf ball size hail and winds of 80 near Britt, Iowa. Then we called it a chase outside of Belmond. It was the day I had envisioned but in all honesty did not expect to see, especially coming face to face with two tornadoes. Even more remarkable, we hit our target with nearly perfect precision and timing. It was one of the most amazing experiences of my life but it's not for the faint of heart. I came eye to eye with the serpent and what an experience it was for myself, Pravin Gupta, and Kholby Martin, the man who navigated our converted snow plow truck into a chase vehicle. For the record, we were plowing tornadoes, not snow. The sign says it all as I stand witness to an approaching tornado.

Tomorrow, it's back to the real world of forecasting. Thanks for letting me indulge myself! Roll weather...TS

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