News DetailTornado Watch in South Texas!
Posted At: May 9, 2007 @ 6:55 PM
Posted By: Reed Timmer
Related Categories: Tornadoes
As of 6:45 pm, CDT, a line of thunderstorms was moving east across South Texas just north of Del Rio to around Abilene, TX. The Del Rio radar image at that time is shown below:
Three tornadoes have been reported in Texas, including one near Throckmorton, TX that was produced by a very small supercell. However, it appears the risk for significant tornadoes is VERY low across the watch region above, because of the very weak (<20 kts) flow in low-mid levels. Here is the VAD from Del Rio at 6:45 pm CDT, showing the vertical wind profile with time.
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Click my name above to get to an overlay showing before and after destruction in Greensburg, Kansas in Google Earth. Amazing...
I've never understood the upside down flag thingy graph.
I'll try to explain it.
Every vertical line is a snapshot of the wind profile in time. Each line is labeled at the bottom for the time it was taken (ie. the furthest right shows 0058 which is 7:58 pm central). The numbers on the left show the height in thousands of feet (ei 2 is 2000 feet above the surface, 5 is five thousand feet above the surface).
Normally you want winds of at least 30 knots at all levels to have good tornado potential. This VAD shows most of the winds below 15000 feet to be ten to fifteen knots, meaning the tornado potential is very low. For a higher tornado threat, you would want the lowest barb to be close to or greater than 30 knots with winds veering and increasing as you go up.
I hope that helps...
Oops!!!
Thats thousand of feet above sea level, not the surface.
OK that helps me understand it, but I still need to know about what the direction of the flag thingys mean! and how many bars they have attatched.
Chris: the direction the flag lies in represents the direction the wind is coming from at that location. Each long bar represents 10Knots and each half bar represents 5 knots. So a long bar and a short bar together means there is 15 knots winds. The other option which is shown here in the very top left hand corner of the figure is a triangle which represents 50 knots winds.
I hope that is clear and Joel doesn't mind me answering it.
Yes that helps. Perhaps I would need to see a strong flow graph to notice the difference!