Microburst?

[Bill Tabor]

What would you call this storm feature(?):

http://apollo.lsc.vsc.edu/classes/met130/notes/chapter14/graphics/microburst.jpg

It is labeled a microburst, but in my opinion looks closer to a weak multi-vortex tornado. I say that because if you look at it you'll notice multiple individual columns of (likely rotating) and lifting dust. This is similar to what you see on weak or developing tornadoes. This is also similar to what I encountered the other day near Cross Cut (though smaller and weaker), and even southwest of Breckenridge back on whatever day in April that event was.

My idea of a microburst is more of a large combined burst of precip and wind that comes down and hits the ground and goes out like this...
http://skydiary.com/gallery/chase2001/051601burst.jpg
or even better..this:
http://www.cimms.ou.edu/~doswell/microbursts/Figure_20.JPG

 

[Mike Hollingshead]

I don't see anything that suggests tornado. Looks like dust kicking up behind a base. You see dust rising like that all the time around RFD's or gust fronts.

This was an obvious dry micro-burst as the clouds vanished revealing that hole. There was virtually no rising dust, and hardly any clearing before this. Then you see the "cloud hole" start and it's easy to guess what's coming next. Then bam, rapidly rising dust walls, up to cloud base. It all lifts similar to the shot you posted. There was even a run-a-way dust devil churning away like mad with it.


Anyway, I don't even know if I'd label that image you posted a micro burst...and certainly not a tornado(unless there's something unseen there arguing harder for that....which I doubt). Looks like a run of the mill dust plume.

Here's a good chunk of the evolution of this one, not including pre-hole shots though.

Hole/clearing forming fast now....not much of any dust.

Near initial impact.

The upward motion was really incredible on that right side.

 

[Bill Tabor]

I don't see anything that suggests tornado. Looks like dust kicking up behind a base. You see dust rising like that all the time around RFD's or gust fronts.

Yeah I agree...I was kind of thinking RFD also, and I agree you see similar stuff on the RFD. Sometimes it is weak columns of dust...I remember driving through these in the past - other times perhaps more intense. Still, there are often such things as RFD spinups too, and in the pic some of these seem to be weak tubes almost to cloud base - granted likely very weak to be calling a tornado. Actually, now that I bring it up that is key, because with torns we are looking for 'violent' motion. This is probably below the threshold, and we don't have video on this image, but it doesn't look like the individual plumes would be rotating much. I also agree though (I think you said) it doesn't look like a microburst - at least not in the classic sense - appears more lift than downburst.

In my Cross Cut encounter however there was definite rotation. The feature sw of Breckenridge though I don't recall. The dust was blowing like crazy. I was thinking RFD for part of it, not sure the funnel region wasn't active though because it was close to that town to the sw that got hit with weak damage. I saw small broken limbs off trees near there.

Anyway, I was just doing this because I was trying to assemble some pics of the various kinds of weather for my daughter doing a school project on Severe Thunderstorm Forecasting. I was grabbing pics of various kinds of severe weather. I'll post some video or grabs of the aforementioned encounters too. Today I was processing some of my stuff from April 23rd - it takes me forever it seems. I have like 4 chases after that and likely one coming up on Tuesday - so I am behind. I am envious of those that seem to kick it all out so quick and up to date. I have years past with days and lots of torns I never even bothered to post like Calumet Ok, Wayside, Tx, Jayton Tx. Maybe someday.

Seems you have good example pics of a dry microburst.