Storm Highway by Dan Robinson
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Wednesday, May 9, 2007 - 10:15PM EDT

Back home - Trip #2 stats and looking ahead again

By DAN ROBINSON
Editor/Photographer
25 Years of Storm Observing
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I just arrived back in Charleston this evening, finishing up the 7th day of travel for Trip #2 (the 13th day of travel overall this season). Here are the stats for Trip #2:

States: 7
Chase days: 3
Tornadoes: 8
Miles: 3,800

Season totals as of May 9:
States: 8
Chase days: 7
Tornadoes: 12
Miles: 6,900

12 tornado intercepts (including an F5) and almost 7,000 miles, and we still have yet to start our main planned trip! Now that Trip #2 is over, it's back to model watching for what will be our third and most likely final expedition, the one that all four of us will be embarking on (Bill, Tom, Matt and I).

After this exceptionally active late April and early May, the models indicate the Great Plains will be slipping back into a quiet pattern for quite some time. In fact, the extended GFS suggests that things will be inactive for two weeks or more, with no good western 500mb trough showing up through day 16. During this 'down time' though, good moisture will be present on the Plains, with a periodically decent dryline and surface low pressure systems developing every few days on the Front Range. This could make for some Front Range and high Plains severe weather episodes, but little in the way of tornado potential (aside from the isolated Colorado landspout). Despite the ingredients for storms in the lower levels of the atmosphere being present, without the support of strong mid- and upper-level southwest winds from a nice western trough, classic tornadic supercells will be hard to come by.

So, we'll prepare for an extended downtime for a week or two while we wait for the Plains to wake up again. The wild card in all of this is the long-range models' well-known reputation for flip-flopping. It wouldn't be surprising to me for a western trough to suddenly start showing up for next week in the next few days of model runs. For that reason, we won't completely take our eyes off of the forecast while we wait out the 'downtime'.

You'll notice in our table below that I increased the 'no trip' probability from 2 to 5 percent. This is due to the fact that we've already had nearly two weeks of observing travel days over the course of the two unplanned weather expeditions. While I still have a budget for the main trip, it will definately be a little tighter. Therefore, I've raised the standards even higher for the quality of a severe weather setup that would result in us observing. In other words, the main trip will only be made in the event of a well-above-average strong system that has a high potential for tornadoes. However, we're coming up on the peak of tornado season in the Plains, so I don't expect that to not occur.

Based on the current outlook, this probability table charts the chance of our trip starting on a particular date:

2007 Weather Expedition - Departure Date Probability as of May 9
May 12-1810%
May 19-2521%
May 26-June 232%
June 3-1532%
No trip5%

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