After a cold, snowy February with just one tornado (in California), it began to warm up in recent days in March. Today, March had its first tornado -- near Elk City and Hammon in western Oklahoma. Early reports indicated that 5 homes (some or all were mobile homes) and a county barn were destroyed in Hammon.

I've drawn labels on two photos below from twitpic.com -
http://www.twitter.com/kc5fm The first photo shows the broad swirling cloud pattern, with the upper cloud deck moving from left to right across the picture. It's a band of clouds along and above a gust front - the leading edge of rain-cooled and sometimes hail-cooled downdraft and outflow. That downdraft and outflow is in the lower left below that dark cloud and is called the rear-flank downdraft in the case of a rotating, supercell thunderstorm like this one. The tornado is evident, and there is a wider column of cloud above it called a wall cloud -- associated with the storm's rotating updraft.

from twitpic.com - http://www.twitter.com/kc5fm

The next picture zooms in on the tornado and its wall cloud. In this case the funnel doesn't totally reach the ground, but there is a light-gray dust cloud from the bottom of the funnel to the ground that indicates that the tornado winds were present near the surface.

from twitpic.com - http://www.twitter.com/kc5fm

Initial reports are that the tornado lasted more than a half hour, and certainly took on a wide "stove-pipe" or cone shape for part of the time. That's pretty impressive, considering that its parent storm wasn't that big. It's what could be called a low-topped supercell, with top at about 35,000 feet (not the 50,000+ monsters of May). The radar images below are from about the time when the tornado was hitting Hammond. The storm was far from the NWS radars, so the lowest scan through it was at about 8,000 feet, so it doesn't have the type of low-level hook echo often seen when the storm is near the radar. The white line shows the orientation of the slice, shown in the subsequent image. (radar imagery using GrLevelX)

Here's a slice through the storm, showing its top at about 35,000 feet. The violet core indicates hail -- reported up to one-inch diameter.

This was what is also called a "cold-core" tornado situation. It was near the counterclockwise-spinning cold mid-level low, shown below, and centered over the Texas and Oklahoma panhandles.

That cold pocket aloft gave the thunderstorm its instability, as the surface temperature was only 61F and the dewpoint only 50-53F, as shown by the weather map below, much colder than a typical tornado situation. The temperature is to the upper left and the dewpoint to the lower left of each station circle. I've placed a T near the tornado location. The dashed blue line was mainly a dryline -- separating moister air to the east from drier air to the west. With clouds holding down the temperature in the moist air, and sun out in the dry air, it didn't have much of a cold front character, but will probably turn into one overnight when the dry air cools faster than the moister air.

I feel a little like a cousin to Punxsutawney Phil -- yanked suddenly out of my hole near the end of his six more weeks of winter weather -- and into the start of what may be a stormy spring.