Green Sky Chaser

8 March 2010 Chase Log

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PHOTOS


Target Area: Lawton/Altus, Oklahoma to Vernon/Wichita Falls, Texas (Click on city names for Yahoo! maps links)

Chase Area: Altus/Carter/Cordell, Oklahoma

Observations: thunderstorms, lightning, and a rainbow

Distance: 340 miles

Time: 8 hours

Chase Team: Jeff Makowski and myself

SPC Convective Outlook: See Text (upgraded to Slight) (Click to see SPC products, data, and storm reports)

Chase Setup: Shortwave trough/upper-level low over eastern Colorado and northwestern Texas with associated surface cyclone over the northern Texas Panhandle, northwestern Oklahoma, and southwestern Kansas. A dryline extended south of the low into the Texas Panhandle. CAPE of about 1000 J kg-1 expected over northwestern Oklahoma, although the greatest CAPE was finally realized in the southeastern Texas Panhandle into southwestern and west central Oklahoma. Dewpoints in the mid- to upper 50s in western Oklahoma. Strongest wind shear mostly in central into eastern Oklahoma and Texas.

Blog Entries:

First Chase of the Year? (before)

Chase #1 (before)

Chase #1 Evaluation (after)


Chase Log: Two squall lines formed early in the day; one was well ahead of the dryline and came through central Oklahoma during the late morning. The second squall line formed just along and ahead of the dryline, and was in western Oklahoma at about the time we left. Based on the marginal outlook for the day, including low instability, low moisture, and a region of instability that was not co-located with the region of best shear, I was expecting to only see a few storms behind the squall line, with perhaps some lightning and hail. As usual, I decided to go after the warm sector of the cyclone, where the best moisture and possibly instability would be. It was a tough choice between the southern target and the northern target, closer to the surface low (where there was less moisture, but possibly greater ambient vorticity near the low). Besides, the clouds looked like they would clear out of southwest Oklahoma before northwest Oklahoma, providing a better chance for more heating and instability in the area.

We left Norman at about 2 pm and drove southwest on I-44. I initially thought I would go west on I-40, to split the difference between the two target areas, but I heard a rumor that there was an accident clogging up traffic on that freeway. By the time we got to Lawton, the clouds were clearing above us and we could see some cumulus clouds forming to our west. We drove west on Highway 62 to Altus. Along the way, we saw a cumulus congestus cloud grow into a low-topped thunderstorm with a nice anvil to our northwest. I told Jeff that that would probably be the storm of the day, but it didn't look terrific, and we were hoping that more storms would form to the south and come up our way.

When we got to Altus, the storm was the strongest on radar, but it was about to cross I-40 and we likely wouldn't have been able to catch up with it unless we made an immediate decision to go north and not waste any time. I have been burned in the past, however, by making a sudden decision to leave the best-looking area to go after a semi-bad-looking storm, only to have my initial target area produce the best storms. So after some deliberation, we decided to meander over to Braum's for some chocolate milk shakes, and then go north on Highway 283.

I heard of some 1-inch hail reports on the large storm, but comforted myself with the fact that we likely would have other storms forming nearby, and we could actually play around with a smaller storm just to the south of the big one. North of the small town of Willow, I stopped for several minutes so that Jeff and I could get some photos. The sun was low in the sky, moving behind a cloud in the middle of the flatlands of western Oklahoma. To our north and east, we saw dark clouds and rain. We even saw an occasional lightning strike! It was quite a peaceful sight.

As we got back in the car, I decided to go due north on Highway 34 instead of continuing northwest on 283. I still hoped to catch some hail and more frequent lightning. However, much to our dismay, I turned on the radio and found out that the initial northern storm had already produced a tornado north of Elk City on I-40, and a second one was on the ground! Gutted, we knew we had missed the surprise show of the day, not 50 miles to our north!

Some chasers, having picked a more northern target, saw a beautiful, multi-vortex, stovepipe tornado that was on the ground for some 40 minutes or more before a second tornado touched down. The tornadoes were rated EF2 and EF0 as they damaged some buildings in Hammon and Butler, Oklahoma, but I didn't hear of any serious injuries.

I am not sure why more storms didn't form to the south; the greater instability was right about where we were, in southwest Oklahoma. Shortly before the tornado was reported, the SPC issued a Mesoscale Discussion and said they expected a tornado might form considering the stronger vorticity in the area associated with the low. By the time the tornadoes formed, the greatest wind shear was well east of us, so I suppose this was the only hope for a tornado to form. Again, we were probably too far away to catch the storm in time from Altus, but I may always wonder if we could have!

It was still a fun, relaxing chase...at least up until the point where we knew there was a tornadic storm and we wouldn't be able to catch up with it...shortly after this, we decided to head home and saw a bit more lightning and a nice rainbow.


PHOTOS