3/8/11 storms

[Dan Hildebrand]

Hi everyone, I just downloaded the trial of GR2 A and was following a cluster of thunderstorms moving through Texas. A couple cells had Tornado Warnings on them. I made some observations and would like your guidance, as its likely that im misguided.



Here is the rotation in a cell that had a tornado warning on it.



Here is the same cross section where the rotation was taking place. My first instinct was HOOK ECHO!! But then i quickly realized that this didn't look like a hook echo. I think I thought this because of the way the green seems to wrap around the yellow. But hook echoes are usually at the far end of a storm aren't they? I'm very much a novice, so forgive the simplicity of my statements/questions. The GR3 detected strong meso activity in that same area. I'm assuming that and its associated rotation (which was viewable in analyst) was the reason for the tornado warning.

My question, since it was obviously NOT a hook echo. Just looking at a radar image, is there any evidence of tornado rotation? Sometimes there are those obvious signs like a hook echo, but tornadoes can also be "within" the storm, so what are those indications?

Next, a few hours later i was just observing a line of storms in eastern Texas. In the analyst mode, i noticed how the high clouds extended outwards in front of the storms. At first i figured that was the "shelf cloud" or gust front, until a few minutes later i realized a gust front was actually viewable on radar as a thin strip proceeding the storms.



My question. Since the clouds in first picture are not the shelf cloud, what are they? How are they associated with the storms, if at all?

This whole afternoon made me really excited, especially to see the rotation inside the storm. I'm sorry if my questions seem naive.

Thanks,
Dan

 

[Jeff Duda]

I can't say too much for sure on the tornadic storm of the day, but from the reflectivity images you posted it looks like the tornadic storm is actually being preceded by another less organized storm to its immediate southeast. There does not seem to be any apparent hook echo in the reflectivity signature (hook echoes tend to spiral out the other way - i.e., like a backwards comma - and are usually much smaller).

As far as the line of storms, the higher reflectivity you are seeing at the upper levels is probably the anvil or perhaps some hydrometeors being flung out ahead of the updraft by higher upper level winds. You are right in that it is not a shelf cloud or gust front, as both of those are low-level features and are generally not visible on radar except gust fronts being seen by a fine line of light reflectivity on the lowest few tilts. A gust front will run parallel to the front gradient of high reflectivity with spacing on the order of a few kilometers.