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Georgia Storms on 17 February

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Dave Marshall

Mon Feb 18 2008, 04:23PM

Registered Member #16 Joined: Thu Feb 02 2006, 02:22PM
Location: New Wilmington, PA
Posts: 554

One of my little side hobbies is storm chasing. I've been chasing since I was 10, when my dad and I started what is now the StormNet chase team (one of the largest in the US).

Central Georgia was hit hard yesterday, as was Alabama. A long lived supercell thunderstorm started in the Florida Panhandle, and over the next 7 hours spawned more than a dozen tornadoes as it crossed AL and GA. I intercepted the storm about 75 miles west of my home and followed it for the last third of its journey.

Photos and video can be found at

Here's a quick rundown of the files in there. The red line visible across Georgia in today.png is the supercell mentioned above. I caught up with it about 20 minutes after it crossed the state line.

Photo 1 and Hail.wmv shows the approaching hail shaft. At this point we had gotten a little too far to the west, and were directly in the path of the storm (with supercells like this, you want to be behind the SW corner for the best view and smallest chance of death. We were in the NE corner, the worst possible place). If you watch carefully, you can see the entire storm is rotating very rapidly in a counterclockwise direction.

We were hearing reports of golfball to baseball sized hail in the hail shaft, so we opted to move back to the east to get out of the way. As we exited the area with a police escort (we stopped to tell him it was time to get out of there) a large funnel cloud popped up behind us, just to the east of the hail. In retreat.wmv you can hear me in contact with the NWS office in Atlanta via ham radio to report it, and you can also hear that little 4 cylinder hitting the wall at about 95mph as we ran back to the east.

We hunkered down at a gas station, and Photo 2 shows the hail shaft skirting to our west. Just after it passed, a poorly organized funnel cloud passed almost right over head.

Shortly after, a large wall cloud came into view. Photo 3 and wallstart.wmv shows the wall cloud in its initial stage. At this point there *may* be a tornado on the ground behind those trees visible in the video. I'm still waiting on NWS confirmation. This is why you want to be to the SW of the storm. This ensures your view isn't impeded by rain or hail, and it ensures the most violent sector of the storm moves past you.

Photo 4 shows the wall cloud after the "notch" has appeared to the left, indicating increasingly rapid rotation, and the second funnel appears. In Photo 5 the wall cloud has spun itself into a tight cylinder, and the beginning of a very well organized funnel cloud on the lower left of the wall cloud can be seen.

The video wall2x.wmv picks up right after the end of the wallstart video and gives you a compressed timeline of the entire lifespan of the wall cloud.

Skywarnnet1.wmv is a compilation of some of the conversations I had with the meteorologist. I was in constant contact with the NWS office in Atlanta the entire day.

About 7 minutes after Photo 5 and the end of the wallgensis.wmv video, the wall cloud wrapped itself in rain and dropped an F2-F3 tornado that destroyed at least 15 structures and injured 8 people. By that time it was dark, so I was hanging well back from the storm and was out of view of the tornado.

All in all a good chase, and one hell of a storm. I've been chasing a long time, and I don't think I've ever encountered quite such a classically structured, long lived, and violent supercell, even in the Great Plains where they're famous for this sort of storm.

Dave

HV Enthusiast

Mon Feb 18 2008, 05:39PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

have you actually seen a full-fledged tornado yet, or are they very difficult to capture?

Dave Marshall

Mon Feb 18 2008, 07:12PM

Registered Member #16 Joined: Thu Feb 02 2006, 02:22PM
Location: New Wilmington, PA
Posts: 554

Over the last 10 years I've seen 7 or 8 tornadoes actually on the ground. A vast majority were what chasers call 'gustnadoes'. Small, low level shear driven tornadoes that pop up on the leading edge (gust front) of thunderstorms. They're typically weak, short lived, and extremely tough to predict.

I did witness the Van Wert, Ohio F4 in 2002, and the Americus, Georgia F3 last year in person. Both were somewhere around 1/4 mile wide at their widest, though the Americus tornado struck after dark, making it tough to see except for transformer flashes and lightning.

This particular storm is one of the rarest sorts, but one of the easiest to chase. Long track, discrete, high precip supercells only occur a few times a year in the US (and almost never anywhere else).

With a little bit of experience, once they form, they're easy to predict. They almost exclusively form their most damaging tornadoes on their right rear quadrant (SW corner in the most common, NE moving storm systems), and because of the structure of the storm, they afford a very good view from the SW corner. If you can get just to the south of the storm, the tornado will most likely form directly in front of you, moving away, and with the rain and hail behind it. If you're on the northern edge, the rain and hail block your view. If you're on the NE corner, you're likely to do what chasers call a 'core punch'. Moving directly through the core of the storm is *extremely* dangerous because you may either have a rain wrapped tornado that isn't visible (been there, done that, it sucks), or you may pop out of the back side of the rain, be face to face with it, and have no escape route.

About anyone can find a tornado if a good storm happens to get close to them with today's availability of radial velocity and reflectivity radar online. The real trick is being able to get into position for storms that haven't fired yet, which dramatically increases your chances. A good understanding of the dynamics involved, and lots of experience are about the only way to develop a sense for that. I did about 150 hours of instruction with a severe weather specialist for the NWS, and 6 years of chasing in the field with experienced chasers before I felt really capable and comfortable on my own.

Dave

HV Enthusiast

Mon Feb 18 2008, 09:20PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Cool. Thanks for the info!

I love chasing storms, although my speciality is lightning. Got tons of photos when i lived in Florida (Tampa area), but that was over 10 years ago and everything is on slide film.

Of course, living in NJ, we don't get much as far as storms go . . . maybe one good lightning storm per year thats worthwhile to shoot photos of.

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