Good afternoon,

It’s been fairly quiet in the realm of severe weather (at least in the plains) since my last blog post back on May 27 with localized pockets of severe weather, which is to be expected in the summer. For the past two years, I’ve filmed tornadoes on June 12. In 2009, I filmed a tornado just west of the D/FW metroplex with a high precipitation supercell, and last year I filmed one up in the Texas Panhandle. The June 11-13 timeframe has always been good luck to me, and its beginning to look like that luck my continue on this year with another possible series of chases should everything pan out. Lets dive in and take a look.

 

 

This graphic depicts heights and wind direction/speed at 500 MB, which is about 18,000 feet ASL (above sea level). We’re in a typical summer pattern with a 5880 meter ridge over the southern/southeastern sections of the United States. This pushes the jet stream up into the northern plains and into Canada, and promotes a stagnant pattern over the southern US. We need winds in the mid and upper levels of the atmosphere in order for organized convection.  You need at least 30 knots of wind at 500 MB, but preferably 35-40 in order to support organized convection, such as supercells. As the graphic above shows, most of the southern plains is currently experiencing ten knots or less of wind at 500 MB, thus the only convection occurring in these areas is your typical pulse-type thunderstorms that occur in the summer time (AKA popcorn storms).

As we enter the weekend, a piece of energy will move down across Oklahoma/Kansas as the ridge weakens a bit. As the graphic above shows mid-level winds will increase to at least 40 knots, allowing for enough wind shear to promote organized convection, including the possibility of supercells. We’re still a few days out and because of how small this piece of energy appears to be, it will be imperative to watch how this progresses over the next few days to determine if it is traveling slower or faster then what the models are currently showing, it will greatly affect the setup.

As we look at the projected surface chart, the first thing that sticks out at me is the impact of the drought over Texas. Notice how the dewpoints mix out into the 40′s over the hardest hit areas. In a severe drought, it’s hard to sustain decent dewpoints because the ground is so dry, it helps mix out the atmosphere in the hottest parts of the day. A boundary is evident over Kansas, where the winds turn easterly and moisture pools up. This boundary will act as a focus for possible convection, and perhaps enhance the potential for significant severe weather (destructive hail and possible tornadoes). This setup continues into Sunday. We’ll see how this ends up playing out, but if it continues to appear like it is right now, I plan on chasing this weekend in S. KS and N. OK, for what will likely be my last chase of the spring severe season before we transition into the hurricane season, which I might add is already ramping up in the Pacific (refer to our facebook/twitter pages for more updates on that).

- David