To All You Chasers

This is Leora writing from Fort Morgan, Colorado. I decided, for a change, to inform you of our plans and the reasoning behind them--before we embark. Then we can look back at the end of day and see if they made any sense at all. My source of information in this endeavor is Gabriel Garfield ("like the cat or the 20th president") who kindly stayed up late with me in the hotel lobby to explain exactly how an upslope triggers supercell initiation. He's the navigator of the vehicle named Doghouse, which follows the TIV everywhere. Gabe joined us only recently because he was immersed in finals in the meteorology department at the University of Oklahoma, Norman.

Chasing tornadoes that develop as a result of an upslope is apparently an acquired and localized skill. Gabe, a native of Oklahoma, has never had this experience. Justin, who sat with us briefly, only recalls going on chases of this sort a couple of times. Unlike the supercells of the central plains, which are elements in large systems, the upslope supercells near the mountains (in this case, the Rockies) exhibit what appears to be random behavior. Justin: "Some people refer to it as 'upslop' because it's messy." Gabe: "It's more chaotic and much more limited to what's happening on a local scale...You don't know where the best storms are going to be, it's the proverbial needle in a haystack."

To me this didn't sound encouraging. But apparently Danny, who has a long history of chasing in Colorado, may know where to direct us. Gabe: "It's more difficult but not futile. If you've seen it before, it's much easier to diagnose. If you live in Colorado and these are the types of storms you're used to chasing, you'll recognize patterns."

(The picture to your right was taken a couple of weeks ago. It's the typical on-the-road, impromptu forecasters' consultation. Clockwise: Mark, Josh, Karen and Justin.)

For those of you who don't know what an upslope is, it's a flow of air that rises over mountainous terrain. Under the right conditions, it can act as an alternate catalyst for violent thunderstorm formation. One of the benefits we anticipate tomorrow is early convective initiation because the process isn't dependent on the warming of the earth. If we do intercept a tornado, it could well be in broad daylight, breaking our run of nighttime action. A high cloud base tomorrow reduces the odds of tornado genesis, but, the flip side is that if we cross paths with an isolated funnel, chances are good it will be photogenic because of its great height.

As of tonight, it looks likely that we'll be chasing in northeastern Colorado, but that may yet change. Wyoming and Nebraska have been mentioned too. If we don't cross paths with a tornado, perhaps we'll bump into a few of you dedicated chasers. I can see how the fields here would make a perfect setting for that classic tornado...

Comments

[Verne Carlson]

Hi Leora and DOW/TIV crew - welcome to the High Plains of eastern CO! The thing to look for here is to watch storms that form in two areas of upslope and orographic lifting. First we have the Palmer Divide which gives us the DCVZ (Denver Convergence Vorticity Zone) - storms that fire here take advantage of the wind fields in the 'bowl' of Denver to give them an enhanced spin. Second is the Cheyenne ridge which sounds like your groups target today. Storms here form on the rising terrain coming east from NE into Cheyenne, WY to allow them to fire and drift east into the NE panhandle. These two areas are the areas to watch today. Good hunting out there!
_V

[richard]

Hey I always imagine that tornadic events happened on flat plain areas, well I learnt something new today. Because of this dirty air is there more chance of multiple vortices and does it make it more dangerous to predict than in a normal flat area?

Watch the skies and play safe

Rich

[Stacy]

So I am very curious if you stuck this area of Northeastern Colorado and saw the tornadoes that touched down in Greeley and Windsor, Colorado this morning? Sounds like they were some pretty destructive storms. Good luck in your adventures and thanks for giving us something to talk about in this rural area ;)