Today more convective storms moved through areas of eastern Colorado, but at a lower scale of intensity compared with the previous day.
On Friday, the severe storm environment in Colorado was primed for big supercells. The day before, atmospheric models showed tongues of high CAPE, from 4,000 to 4,800 moving in to Colorado, 90/65, and a fairly strong 300mb jet flow of around 56 knots. Even though there was a thermal cap due to high predicted afternoon temperatures, the cap wasn’t strong enough for convective inhibition to stop formation of supercell storms. Coupled with these factors was an increasing a tongue of energy helicity shear of EHI in the 4 to 5 range, and higher than normal dew points in northeastern Colorado. However, just west of these areas, dew points dropped dramatically. This area of low dew points could do two things, either work with high afternoon temperatures and stop storm formation entirely, or mix with cumulus towers (cu) in the higher dew point areas allowing for large thunderstorms with potentially very large hail. On August 7th, 2015, the latter happened and large mesocyclone storms developed with very high tops (in excess of 65,000 feet) and very large hail cores, in some cases in excess of 4 inches, or larger than softballs. Also too, there were a number of highly convective left splitting storms that also exhibited similar severe storm characteristics.
In the afternoon around 2:30pm, storm trackers Colt and Lauren Forney, Forney Communications and Basehunters, encountered an intensifying severe storm that produced a mesocyclone. The storm motion changed directions several times, stalled and then dropped into a east-south-east trajectory, becoming a right moving cell with an exceedingly high top above 65,000 feet. Around the town of Wiggins, Colorado, the storm started producing baseball and even softball sized hail stones. While the storm tracking crew had dropped south to exit the hazardous core of the storm, they still were hit by one more large hail stone that blew clean through their rear vehicle window. They decided to head east ahead of the storm to Brush, Colorado, and get help from family to make temporary window repairs. The Wiggins storm headed towards Ft. Morgan, and now had a strong mesocyclone, and became tornado warned. Colt and Lauren helped their family make it to the basement when tornado warning sirens went off, and they then evacuated the town to get in a better position to view the storm, and into a safer proximity to allow the storm to move to their northeast. In Lauren’s words, “The hail stones were gigantic.”
Later that day, in the early evening hours, a Delta airbus, A320 was making a trip from Boston to Salt Lake City, and was hit by excessively large hail from other storms that formed in the highly convective environment closer to the Colorado and Nebraska border. Passengers from the airbus gave amazing accounts of the large sounds made by grapefruit sized hail stones hitting the wings, and even being ingested into the turbofan jet engines, along with lightning bolts crawling across the wings. Fearing for their lives, they faced little good news from the flight crew, as the pilot informed passengers they would be making an emergency landing instead at Denver International Airport (DIA), as the plane had sustained significant damage to the cockpit windows. The plane went into a reported controlled landing sequence, and touched down safely at the Denver airport.