Pueblo, CO
Weather Forecast Office
The unusual cloud formation that occurred Friday, December 10th, 2010, stirred quite a bit of discussion nationwide on social and broadcast media.
The basic formation was a rotor cloud in the lee (downwind) side of the Wet Mountains, caused by air flow over the mountains. The amazing corkscrew appearance was a manifestation of Kelvin-Helmholtz waves named after Lord Kelvin (1824-1907) and Hermann von Helmholtz (1821-1894).
The rolling eddies seen at the top of the rotor cloud were evenly spaced, which is typical of KH billows. This cloud formation is an indicator of atmospheric instability and the presence of turbulence. When two different layers of air are moving at different speeds in the atmosphere, a wave structure can form. The upper layer of air is moving at higher speeds and can form the top of the cloud layer into these wave-like, rolling structures. They can be seen if other conditions are just right. If there is a marked difference in densities of the air, such as with a temperature inversion, the mild, strong winds aloft blowing over cold air can develop the wave pattern at the top of the cold, relatively still air.
looking southwest - courtesy K. Torgerson
As the rotor cloud and KH waves continued to evolve, the waves in the cloud broke, similar to waves on an ocean beach or lakeshore.
looking southwest - courtesy K. Torgerson
Other images submitted to WFO Pueblo were from Canon City looking southeast...
courtesy Judith Sanchez
Shortly after the rotor cloud dissipated, strong westerly winds came to the ground in Pueblo County with winds gusting around 40 mph at WFO Pueblo.
---------------------------------------------------------------------------------------------------------
In June of 2007, the author took a photo of a wave cloud feature in the lee of Cheyenne Mountain over southwest Colorado Springs. It was around sunrise, with a cool, still air mass at and near ground level, and mild air aloft with strong westerly winds. This feature, shown below, is more subtle than the images above, but still very interesting to see.
Tom Magnuson, WCM, WFO Pueblo (updated 12/15/2010 at 2:40 p.m.)
ACTIVE ALERTS
Warnings by State - click ATOM button
Excessive Rainfall Forecasts
River Flooding
Convective Outlooks
Hurricanes
Fire Weather Outlooks
UV Alerts
Space Weather
Winter Winter Forecasts
Enhanced Data Display(EDD)
PAST WEATHER
Climate Monitoring
Astronomical Data
Certified Weather Data
CURRENT CONDITIONS
Radar
River Levels
Observed Precipitation
Surface Weather
Upper Air
Marine and Buoy Reports
Climate Monitoring
Snow Cover
Satellite
Space Weather
Enhanced Data Display(EDD)
FORECAST
Severe Weather
Drought
Fire Weather
Front/Precipitation Maps
Graphical Foreast Maps
Rivers
Marine
Offshore and High Seas
Hurricanes
Aviation Weather
Climate Outlook
Enhanced Data Display(EDD)
WEATHER SAFETY
Owlie Skywarn - for kids
NOAA Weather Radio
StormReady
Natural Weather Hazard Statistics
Red Cross
Federal Emergency Management Agency(FEMA)
National Weather Service SafetyBrochures
US Dept of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
Pueblo, CO
3 Eaton Way
Pueblo, CO 81001-4856
(719) 948-9429
Comments? Questions? Please Contact Us.