Thunderstorm, tornado season on the way
The thunderstorm season in the Inland Empire is right around the corner. Although we do get our share of thunder, lightning, hail and even a rare tornado, the severity of these storms does not compare to the ones seen east of the Rockies, especially in the Great Plains’ “Tornado Alley.”
The Cascade Mountains to the west and the Rockies to the east often protect our region from the elements needed to produce the extreme weather conditions of thunderstorm and tornado activity.
The warmer and more humid air from the Gulf of Mexico is a necessary ingredient to help produce severe weather conditions across much of the central U.S., the Southeast, the mid-Atlantic states and occasionally the Northeast. Thanks to the Rocky Mountains, the Gulf of Mexico’s influence is very limited across the Northwest.
However, there have been numerous occasions of damaging winds and hail. Last year, there were 48 warnings issued for thunderstorm activity between July 1 and July 15.
The number of warnings during that period was more than the totals of 2005, 2004 and 2003. Mother Nature did put on a fireworks show of her own on July 4 and 5 last year as hail of more than 1 inch in diameter caused millions of dollars of agricultural damage.
In parts of Eastern Washington and North Idaho, radar estimated rainfall totals of 2 to 3 inches in approximately two hours.
One of the worst severe weather and tornado outbreaks ever seen in our region occurred on May 31, 1997. A record six tornadoes touched down in Washington on that day.
The previous mark for an entire year for tornadoes was four in 1989. Before 1997 was over, a record 14 twisters were reported in Washington alone.
The intensity of a tornado is measured by the Fujita Scale. It examines the damage caused by the twister.
An F0 or F1 tornado inflicts generally minor damage, but an F5, the most severe, causes widespread destruction.
On May 31, 1997, four F1 twisters hit Stevens and Spokane counties, with one F1 tornado striking Athol in North Idaho and an F0 spotted near Lewiston.
Severe thunderstorms also produced hail up to three inches in diameters, heavy rainfall and wind gusts of more than 80 miles per hour. Fortunately there were no deaths or injuries.
The deadliest tornado outbreak in Washington’s history happened on April 5, 1972. An F3 twister struck Vancouver and swept through a grocery store, bowling alley and a grade school. Another F3 tornado touched down west of Spokane, with an F2 twister seen in rural Stevens County.
There were a total of six deaths, 300 injuries and $50 million in damage.
The average number of days with thunderstorms in the Inland Empire is 11 (one in April, two in May, three in June, two in July, two in August and one in September). Last year, nine days were reported with thunder and lightning.
The normal number of extreme severe weather days for an entire year is slightly less than one.
If one owns expensive electronic equipment, such as a plasma television or a computer, it’s a good idea to get a good power surge protector. I have learned the hard way to protect valuable equipment, because thunderstorms have ruined my weather station, VCR and other electronic devices.
My father’s computer monitor actually exploded during a thunderstorm.
Get a good surge protector, one the company guarantees if your equipment is damaged or destroyed.
Speaking of thunderstorms, the last week of March may produce our first one of the season. We should also see frequent light rain showers occasionally mixed with snow in the overnight hours above 2,500 feet.
The first part of April will have cooler temperatures, but much warmer weather is expected toward the end of the month. Overall, April should be drier than normal despite some increased precipitation during the first part of the month.
May and June look cooler and wetter, but not nearly as damp as last year. In next week’s column I’ll have more details on the spring and summer outlook, which will feature at least double the number of thunderstorms than the heat and drought summer of 2006 produced.