Storm Chasing For Newbs (or Noobs)

DON'T PANIC!!!!! You don't have to understand the following charts. I will explain them to you.

Call me Bill Nye the Weather Guy, because I'm about to take you on a crash course in basic storm prediction. Feel free to take notes :-)

One of the first things meteorologists or "junior meteorologists" such as ourselves look for when determining the potential for severe weather is the upper level wind patterns. To put it simply, the best conditions for severe storms occur in the presence of an upper level trough, and this trough has nothing to do with horses [/dry science joke]. A trough is a kind of upper level flow that moves from the southwest to the northeast...or sometimes, even south to north. You can tell which way the wind is going by the wind barbs on the weather map, which consist of a line with diagonal extensions on the end. The wind direction is always FROM the small extensions at the end TO the center. For instance, the following barb...


...represents wind FROM the northeast TO the southwest. The speed of the wind is represented by the number and size of the little barb extensions at the end (but don't worry about that). So when meteorologists plot this information on an upper level map using colors to represent wind speed, the result looks like this...








Ooooo...pretty...







By the way, The lines on the map represent areas of constant barometric pressure, which almost always line up parallel to the wind direction. And which way is the wind going over the plains, class? GOOD! Southwest to Northeast! Cookies for everyone!

So now you know what you're looking at. A large trough/jetstream across the Rockies with some high speed wind making it's way as far as Texas, Kansas, and Nebraska. This is one forecast model's output for 00Z Monday (Z stands for Zulu Time. I heart the word "Zulu") This isn't the most impressive setup I've ever seen, but there should be enough difference between the upper level wind and the lower level wind to cause some rotation in certain storms that develop. Oh, and this change in wind speed or direction with height is called wind shear, and it is one of our main ingredients for extreme severe weather. So based on this map, I would want to chase somewhere in the TX panhandle to Kansas to Nebraska to the Dakotas region.

But wait!!! Wind shear isn't the only ingredient for severe weather. We also need strong updrafts. To get strong updrafts, we need colder air aloft. We call this instability. In the following picture, you can see where the coldest air aloft is...over SW Kansas to SW Iowa.



But remember, we won't get anything tornadic without both windshear AND instability. So, the best location where these two ingredients overlap is going to be the TX Panhandle, western KS, and Southern Nebraska areas.






There are only two ingredients left to discuss for severe weather...The first is moisture. Since thunderstorms are basically gargantuan water factories, they need lots and lots and lots and lots and lots and lots and lots and lots and lots of moisture to thrive. Basically, we're glad that clouds don't spontaneously condense all in one place, because they would crush us with the weight of all their water. Owie. But back to my point.. The moisture in the air comes from the Gulf of Mexico, and we can see the forecast for this moisture right here...


50's are okay, 60's are pretty good, and 70's are excellent. And as you can see, in those areas I mentioned, we'll probably be in the lower 60's. So that checks out muy bueno.













Lastly, we need a triggering mechanism-something to kick off the show and get our pot a bubblin'. This can be many different things: A front, a jetstream max, elevated land, daytime heating, a dryline, etc. For our sunday chase, I'm guessing that we'll be relying on a combination of the dryling in western Kansas/Texas and daytime heating to get explosive development. Btw, a dryline is a line between moist and dry air. It forces moist air up, since dry air is actually more dense than moist air (just trust me...I know it doesn't make any sense. But a lot of things in life don't make any sense...like why Paris Hilton is a celebrity) So the dryline will be right in our target area, which is nice.


Well, look at that...after 5 minutes, you're 5 times smarter about weather!


To review:

4 ingredients for tornadic storms~

Wind Shear: Change in wind speed or direction with height.
Instability: A parcel of air being warmer than it's surroundings. (aka cold air aloft)
Moisture: Derrrrr
Triggering Mechanism: Like fronts, topography, drylines, or yo' momma. ...MacroMomma. Oh yeeeah.



Oh, and I might as well note that this forecast model I've shown will probably change with time... Models are never a definitive prediction, since the weather still outwits computers on a daily basis. So the aformentioned target area may very well change between now and Sunday.

My point is that models are inconsistent...try dating one.



Ciao,
~Jared O'~