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Washington Voices

Weak La Niña hints at heat, but first, thunder

Thu., April 14, 2011

Many folks continue to ask, “when will we see the warmer and drier weather?” There have been more days with clouds, rain and even a little snow compared to ones with lots of sunshine during the last four weeks.

The overall weather pattern points to above-normal moisture and below-average temperatures through mid-May. But, there will be days with sunshine and mild-to-warm afternoons.

As we get further along into the spring season, we’ll start to see an increasing number of thunderstorms. The number of thunderstorms expected this spring and summer across the Inland Northwest should be slightly above average. This year, I’m predicting approximately 13 to 15 days in Spokane and surrounding areas with thunder, heavy rains, hail and damaging winds.

The average number of days with thunderstorms in the Inland Northwest is 11 (one in April, two in May, three in June, two in July, two in August and one in September). Although it’s possible that one or two of those severe storms may produce a tornado, the chances of that happening are low. But, don’t be surprised to see at least one or two days with severe weather conditions.

The spring and summer period is the peak of the thunderstorm season in the Inland Northwest. 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.” We’ve already seen severe weather with tornadic activity in parts of the central U.S. last weekend.

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 waters from the Gulf of Mexico are necessary ingredients to help produce the 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 limited across the Northwest.

La Niña, the cooler-than-normal sea-surface temperature, is weakening in the waters of the Pacific Ocean. If this trend continues, I still believe that we’ll have a warm and dry summer season as a strong stationary ridge of high pressure could build into the region by late May and last through at least early September.

This should mean many days this summer with afternoon highs near or above 90 degrees. It’s possible we’ll see at least three or four afternoons with readings near or above 100.

Contact meteorologist Randy Mann at

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