From the Other Side of the Planet

Severe Thunderstorm Warning in Lashkar Gah, Afghanistan.  Tomorrow?  Maybe some local pictures.

Not sure what this is.  But if it was a funnel, I doubt the group of four would be gazing at it like it was in Kansas.

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KC skywurm

Special thanks to Ruminator Brenton Fatherree who captured this in Olathe yesterday.

The skywurm commeth.

Cold Air Funnels

From Ruminater David Darrow

Sedgwick Co. Kansas recently had a couple cold air funnel events happen near the city of Wichita.  Both events, this last Wednesday and the previous Thursday, were created by cold air masses over the city.  The air mass tends to cause a little spin in the atmosphere and cold air brings it down.  Sometimes rain can help form them as well.  They are usually high based, weak, and rarely touch down.  If they do, they may cause weak EF0 damage (65-85 mph winds).  For a little longer discussion on cold air funnels, look below. 

From Ruminater David Darrow

Looking to the SW from Kechi, Kansas.  Funnel is very faint in the middle of the photo.

I took this from the Sioux Falls, SD National Weather Service.

What is a cold air funnel?

There is much debate about what causes a "cold air funnel" and scientists are still researching this phenomenon, however, the term "cold air funnel" is one of the terms used by meteorologists to identify funnel clouds that are not produced by a mesocyclone and/or are not in an environment typically associated with severe thunderstorms. Basically all funnel clouds are the same. The over-all weather pattern in which they form may be different but the mechanism for producing the funnel, namely, increasing cyclonic (or counter-clockwise) rotation, is the same and involves the vertical stretching of vorticity.

Vorticity can basically be thought of as the amount of "spin" inherent in the atmosphere produced by wind shear. As cyclonic vorticity (or rotation) is stretched vertically the area of rotation decreases so the speed of rotation must increase to compensate. This is analogous to an ice skater pulling in their arms and legs and increasing their rotation.

Based upon observations of cold air funnel events during the past few years we have noticed that they seem to generally prefer an environment when there is large scale cyclonic (counter-clockwise) rotation associated with a large, slow moving, closed low in the upper atmosphere. Since these lows have been circulating in the atmosphere for a long time (compared to the time scale of severe thunderstorms) they stir the air and generate smaller scale rotation providing a "vorticity-rich" environment. These lows also have a cold pool of air associated with them resulting in unstable conditions for weak thunderstorms to form. This is why the term cold air funnel got its origin.

However the fact that there is cold air aloft does not govern how these funnels form, it only provides the instability for thunderstorms (convection) to form. Based on our observations one explanation of how cold air funnels form may be that in the growth stage of these weak thunderstorms the updraft stretches pre-existing smaller scale vortices within the vorticity-rich airmass causing an increase in rotation and the formation of a funnel. This process is similar to that shown by research meteorologists in the formation of landspouts which typically form on the High Plains. Cold air funnels generally are weak, short lived, and usually do not touch down. One of the reasons that they do not touch down and, by definition become a tornado, may be that there is little rainfall associated with these storms to produce a downdraft in order to generate a low level circulation. Recent research suggests that the interaction of descending rainfall near the surface and the thunderstorm updraft may be very important in generating a low level circulation which links with the upper level mesocyclone circulation to form the tornado in typical severe thunderstorms. These processes are not present with "cold air funnels".

Chase Log 4/25/09

Started seeing Storms initiate about 4:30. Decided to run like hell to Wellington. If we were lucky, we'd make it on the back side of the storm.

It was very overcast and there was a lot of precipitation falling around so once we were under the storm, we had some difficulty deciding where to go.

We hit Wellington and then decided to head East into Winfield. We waiting a while in Winfield hoping the storm would figure out what it wanted to do.

Off to the west I could see a "beaver tail" (an area where warm moist air feeds into a storm and gives it a lot of intensity) build. Another thing that caught my attention was the nice clear slot that had developed next to it.

We had our wall cloud.

Couldn't tell what the cloud in the center was trying to do, I don't believe it was a funnel.
The wall clouds of this storm didn't survive. The storm seemed like it was attempting to organize but fell short. The wall cloud above did cause the warning for Sumner Co.

We kept chasing and I had the driver (Nichole Conard) back up for this:

The wall clouds continued to generate and created a few odd clouds like the "O" cloud.

We followed up to Oxford, where the radio was claiming the wall cloud was overhead.

It didn't last too long either. We watched as the cloud tried to rebuild and hopscotched to the East.

With the sun going down, we decided to call it off. We found Udall road and headed back. This storm went on to cause a brief tornado in or near the town of Douglass. At this time no one was reported hurt and it was limited damage.

Keep your eyes to the sky tomorrow. Round two is less than 16 hours away. They are predicting a major outbreak tomorrow. Be prepared.

More pics of this storm, forthcoming.