Global warming does not cause more tornadoes

I certainly agree with Dr. Roy W. Spencer, Ph.D, and Head Climatologist and Principal Research Scientist at the University of Alabama at Huntsville, that "we can't blame global warming for all weather disasters."

If there is one weather phenomenon that the global warming theory does NOT predict more of, it's TORNADOES, those deadly 'twisters.'

In fact, tornadoes are almost unheard of in the tropics despite frequent violent thunderstorm activity producing torrential downpours.

Instead, tornadoes require strong WIND SHEAR weather patterns, the kind which develop when widely-opposing cold and warm air masses 'collide,' fighting furiously for the same air space. Heat and cold must both be present for tornadoes to occur, not just unusually warm air supposedly linked to global warming, manmade or otherwise.

Of course, other various meteorological elements must be present in order to produce tornadoes. A particular air mass must be 'unstable' and contain sufficient amounts of both lower and mid level moisture.

But, powerful wind shear is the 'key' that unlocks the 'tornado door.' It is caused by warm air advection that occurs when much hotter air is suddenly lifted 'up and over' a dense mass of colder air trying to reach the surface of the ground. Cold air is much heavier than warm air. I should likewise mention that tornadoes often occur when wind speeds and directions change rapidly along the boundary line between the widely-opposing air masses.

Active tornado seasons in the U.S. are almost always due to the presence of unusually COOL air persisting over the nation's heartland. For example, the super outbreaks of tornadoes in 1974 and 2011 occurred during extremely chilly 'La Nina' sea-surface temperature events in the waters of the eastern Pacific Ocean. La Nina years, rather than warm 'El Nino' seasons, seem to favor increased tornadic activity. Arctic cold fronts push much farther to the south during the spring months during a La Nina which, of course, leads to many more violent collisions of air masses, hence more tornadoes.

Due to the fact that we are currently in an 'in-between' sea-surface cycle called 'La Nada,' I'm expecting a near-normal amount of tornadoes this spring east of the Rockies, especially in "Tornado Alley" from Kansas southward into Texas.

However, if our current La Nada develops into a frigid La Nina sometime soon, as many climate scientists predict, we could see a 'rash of twisters' later in May or June. Only time will tell.

NORTH IDAHO WEATHER REVIEW AND LONG-RANGE OUTLOOKS

As of this Friday, March 15 writing, only an inch of snow had been gauged this entire month on Player Drive in Coeur d'Alene. Last March, in 2012, my station measured 13.5 inches of snow, more than double the normal March snowfall since 1895 of 6.3 inches.

Our seasonal snowfall since last July 1, as of March 15, stood at 71.4 inches, a bit above our normal for an entire winter season since 1895 of 69.8 inches and last winter's 83.4 inches.

I'm still expecting some late winter/early spring snow showers both this week and again in early April, even at the lower elevations. I haven't taken my snow tires off just yet, but I will before the end of March. I'm in no hurry.

As far as total precipitation is concerned, we've only gauged 0.75 inches since March 1, far less than normal, as of March 15. Our annual rainfall total on Friday was just 5.89 inches. What a huge difference a year makes. Last March was the wettest on record since 1895 with a whopping 7.51 inches. We went on to establish our all-time record annual rainfall since 1895 in 2012 of 43.27 inches.

The first half of March was also much milder than normal thanks to a high pressure area over the region that gave us warm, southwesterly winds aloft, this despite cooler than normal sea-surface temperatures in the eastern Pacific waters. Thursday's high of 63 degrees was our warmest reading since we observed 65 degrees on Oct. 15, 2012. Post Falls also had 63 degrees.

This chilly 'La Nada' event may persist through much of this spring season. That's why I'm looking for a 'sun and shower' type weather pattern between now and at least mid June, maybe later.

But, as I said last week, the outlook for this upcoming summer of 2013 weatherwise, and perhaps otherwise, still looks GREAT!

SPECIAL NOTE

Wednesday, March 20, is the first day of spring. Happy Birthday to my friend, Dennis Williams, who is 10 in 'DOG YEARS.'

Cliff Harris is a climatologist who writes a weekly column for The Press. His opinions are his own. Email sfharris@roadrunner.com