A landspout tornado that touched ground three miles northeast of Firestone and caused havoc for about 30 minutes has been classified as an EF1.
Although a landspout tornado is much weaker than a traditional tornado, it produced wind gusts of up to 99 mph on Monday. Landspouts also form in a single cell storm cell compared to a multiple cells inside a supercell, which can produce multiple tornadoes.
But these types of tornadoes are fairly common in Colorado as most of the supercell tornados only form in the Eastern Plains as there is traditionally a higher dew point, said Robert Koopmeiners, a meteorologist for the National Weather Service office in Boulder.
“Out here we get a lot of them. I’d say the lion’s share are weak landspout tornadoes,” said Koopmeiners.
Due to the lack of the supercell, tracking these types of tornadoes can be difficult and on Monday, weather service officials got reports of a tornado on the ground before it appeared on radar.
“It didn’t even show up on radar for at least the first 10 minutes,” said Treste Huse, a hydrologist with the NWS Boulder.
Initially the tornado was designated as an EF0, which means speeds did not exceed 85 mph, NWS officials have classified it as an EF1 as it reached over 85 mph, but did not exceed 99 mph, said Huse.
Monday’s tornado traveled northeast of Firestone to southwest of Platteville. It caused more than $500,000 in damage at the seven properties it hit, Weld County officials said.
Weld County officials said the tornado destroyed two homes — meaning more than 50% of the home sustained damage — for an estimated cost of more than $400,000. Damage to three other home was estimated at more than $100,000 .
The storm damaged two businesses, including a feedlot where two buildings were damaged — one from a fire caused by a downed power line and the other from the tornado's winds. A dairy dairy had damage to its buildings. Cost estimates to repair the businesses were not released.
Weather Service officials inspected the six-mile path of the tornado. Huse said the agency will continue to investigate by using the data collected and produce a report.