Wednesday 21 May 2014

2014 Chase Day 9 - Denver (CO) supercell

Today was forecast to exhibit the best potential for a tornado of the Chase thus far, primarily in northeast Colorado where moist upslope flow over the Rockies, coupled with the Denver Convergence Vorticity Zone (DCVZ) significantly increases the risk of tornadoes being spawned near and to the east/northeast of Denver (CO) from any well-organised supercells that happen to drift across the particular terrain in this part of Colorado.

Beginning in Cheyenne (WY) we drove for an hour or so southwards, stopping for some time in Greeley (CO) for lunch in a well-known fast food establishment. A cell had already formed to the southwest of Denver (CO), and was also severe-warned, but was not chaseable in it's current location since it's progged trajectory would take it through the Denver metroplex - not ideal chase territory.

We waited a while, but it became clear that if any storm was going to produce a tornado today it would be this one - the only problem being we were to the north of the cell, which was moving northeastwards, and the only way to get to the tornadic part of the storm (the southeast quadrant) involved a rather long-winded journey east and then south around the periphery of the storm - going down the western side would see us get slammed by large hail in the Rear Flank Downdraft (RFD). So we had a painfully slow journey east to Brush (CO) and then south to, ironically named, Last Chance (CO). During this journey we heard that 3 brief, rain-wrapped tornadoes had touched down in Denver (CO) from this supercell, along with copious amounts of hail at the airport, causing flight delays.
About as good as the supercell got - rotating wall cloud visible
We arrived at the storm as it was passing just north of Byers (CO), and within 20 minutes a well-defined, rotating wall cloud had developed in front of us. The inflow winds were insanely strong, never felt anything like it before. Unfortunately it failed to produce a tornado, and although we sat very close to the mesocyclone for another 2 hours, very slowly moving eastwards along the road (since the storm was moving at just 10-15mph), it failed to produce a tornado - it did, however, have several attempts at reforming the wall cloud. There were multiple chasers all along Highway 36, just a continuous stream of headlights visible parked on the side of the road, all watching the storm. Even Doppler on Wheels (DoW) turned up and decided to park in front of our vehicle.
Doppler on Wheels (DoW) parked in front of us
Gradually with time multiple new cells began to form to the south and southeast of our main supercell, all eventually merging into one long line of thunderstorms, which effectively killed our supercell's inflow as they moved at a faster pace to the northeast and into northwest Kansas. An early finish to the day, we decided to turn around and head for a hotel in Aurora (CO) ready to drop Kerry off at Denver International Airport tomorrow morning.

STORM CHASE 2014 STATS thus far
McDonald's tally: 12
States visited: 8
Distance driven: 3,248 miles

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