The Storm Prediction Center (SPC) has issued an Enhanced Risk and several 5% Tornado Threat Rings for today. However, the risk is for Mesoscale Convective Systems (MCS), and bowing segments versus discrete supercells, so I will not run a full prediction today.
Instead, I will post an analysis of the 6/5/15 Storm Chase Day.
On 6/5/15, the SPC had issued a Slight Risk for much of the Northern High Plains.
Associated with the Slight Risk was a 5% Tornado Threat Ring over eastern Colorado.
As we departed Colby, KS, the visible satellite imagery was not promising along the I-70 corridor. Cloud cover and fog dominated much of the area, as shown on this image.
Even though it was clearer over Kansas, most of the other parameters were better farther west. We took a gamble that the cloud cover would mix out and headed west towards the better dynamics.
Just a few miles out of Limon, CO, we stopped at a rest area to reevaluate. The conditions had only become more foggy and the skies had become clearer over Kansas. We didn’t want to leave behind the dynamics, but if the sky didn’t clear, there would be limited diurnal heating, and storms would not fire. We trekked east again, stopping in Burlington, CO, for lunch. This was near the edge of the cloud cover, though the clouds were thinning everywhere.
After lunch, we headed north towards Wray, CO. In Wray, we were almost in two separate car accidents due to people not watching where they were driving. In both cases, we were doing the speed limit and had someone cut out in front of us without looking. Thankfully, we never made contact.
We waited at a 7-11 in Wray, CO, to watch some cumulus clouds build. After a little while, we could see that a storm had formed southwest of us- near Limon! We headed south to get in a position to see into it.
This storm quickly developed into a supercell, and produced a very obvious hook echo. Then another storm along its flanking line produced an obvious hook echo. Here is the base reflectivity image at 5:20 pm local time of this storm.
The 5:24 pm storm relative velocity image shows a tight couplet on the northeasternmost tornado-warned cell.
We traveled slightly west to Idalia, CO, and watched a lowering turn into a wedge tornado. It was a long ways away, but it was confirmed by several of our storm chaser friends who were south and southwest of this storm. The radar imagery at 5:32 pm local time shows our location (the blue crosshairs) relative to the leading hook echo.
This radar image also shows that there are storm approaching Burlington, CO, from the southwest. This cuts off our escape route to the south. With the hook echo approaching from the southwest, we could not go west. With the storms approaching Burlington, if we went south, we could only retreat north, as Burlington had the eastern escape route. With the line of storms south, we could not count on being safe by dropping south and then turning north again. The precipitation core for the supercells was going to cut off our northern route from our current location, leaving us with only an eastern option. We punched east into Kansas.
The 5:40 pm storm relative velocity imagery shows our position (blue crosshairs) relative to the center of circulation (red very close to green signatures).
As we move east, this system becomes much more linear. Here is the 5:59 pm base reflectivity imagery. Some of the features (hook echoes) are not as visible, and the entire system looks more linear than as discrete supercells. Also notice the outflow boundary passing through Goodland, KS, hanging out from yesterday’s storms.
By switching to a linear mode, these storms weakened slightly. However, I thought the system may get one last chance as it approached the outflow boundary. Often, an outflow boundary can produce rotation in otherwise non-rotating storms.
Sure enough, by the 7:33 pm base reflectivity scan, we see another hook echo out in front of the line of storms near where that outflow boundary had stalled. There was a tornado near Colby, KS, though I do not have any radar imagery from it, as I was driving at the time, and did not capture any images. Our location on this image is noted by the blue crosshairs again.
The tiny cell south of Bird City, KS, would persist for many hours. We passed through the southern edge of it, then turned north and passed through the western edge of it. We continued our drive towards Kearney, NE, for the night, only to pass through it again along I-80 in Nebraska. I don’t think it was ever severe warned for very long, but it did produce some heavy rain. We sprinted back and forth between the cars and vans and our hotel in the heavy rains produced by this cell.
Thank you for reading my post.
The Severe Weather Outlook is from the Storm Prediction Center website.
The satellite imagery is from the NOAA Satellite and Information Service.
The surface observation and upper level charts are from Unisys Weather.