Flight To Oshkosh, Wisconsin, July 2011

Wednesday morning, Aug. 3

Yesterday I wrote: "Bowman, ND is blissfully dry and cool." I should have known better than to wake up the weather gods with such a statement. When we got out of our tents this morning it was sunny and bright, but we could see dark clouds building. We decided to tarp our planes before we left for breakfast. And we're glad we did! We're now sitting in the Airport office watching the thunder and lightning and downpour.

Last night we met a group of "cloud seeders". A fascinating group of people, they are involved with the North Dakota Cloud Modification Project. The objective of the NDCMP is hail damage mitigation and rainfall enhancement. Involved are meteorologists, pilots, and students in the commercial aviation program at the University of North Dakota who vie for pilot internships in this summer program. We've met 5 or 6 of them here. Learning a little about how they seed clouds has been fascinating; it brought to mind Elmer Gantry and a cloud seeding episode of Sky King.

They use a Cessna 340 and a Piper Seneca 2. The Cessna 340 is a hybrid-plane, which can be used to seed at the base of the clouds or at the top of the clouds. The Seneca is strictly a base seeder.

The meterologists monitor radar, satellite and visual sky conditions looking for towering cumulus growth. Once found, a plane is launched to diagnose what is going on within the storm. If all parameters (smooth dark cloud bases, updraft rate, inflow - pulling of bouyant air into the clouds, and size and level of ice pellets) are met, then seeding begins. This is an example of what they're looking at.

They fly out ahead of the clouds, at the base, looking for shelf clouds, (which extend out in front of the main storm clouds,) They use a chemical cocktail mainly composed of silver iodide, in liquid form, which is burned off during flight. The particles are drawn into the inflow of the storm and result in reduction of the size of the hail pieces.

These pilots are looking for conditions that most pilots avoid - high turbulence right below the storm base and flying through the growing cumulus towers. To be PIC , you must 500 hours of multi-engine time; the students don't have to have a certain number of hours; they must have multi-engine time.

I talked with Tony Tollefson, who was an intern and now is one of the PICs. He said that one of the coolest things about this type of flying is the power of the storms, the strength of the growth and development of the storm. You can pull the power to idle and still be climbing even in one of these heavy twin-engine planes. You can put them in 60° banks just to maintain your altitude. We fly really safely - trying to stay in smooth and controlled air where the storm is growing, not into the core of the storm. You always have a "bailout heading" if you get into hail or if you start getting into cloud obscuration. We fly VFR - not going into the clouds at all. The backside of the storm - coming back to the airport - is where the roughest air is.

This is "summer seeding", done from early June until the end of August. "Winter seeding" occurs in areas that are trying to increase the amount of snowfall; in this case, pilots fly into the clouds themselves. Yet these are not thunderstorms - they are mostly high level clouds with only some convective activity.

This has been a major success story - over the course of the past thirty years, they have seen a reduction in crop hail losses of 45%. If you're fascinated by this, you can read more at http://www.swc.nd.gov/arb - and then navigate to Cloud Modification Project.