Tis the season for ... thunderstorms

Last Monday, April 10, was another example of our extreme weather pattern across the Inland Empire. During the early morning hours, Cliff measured 3.3 inches of snow in northwest Coeur d’Alene, taking our seasonal snowfall total to 115.4 inches. That’s the sixth-highest total since records began in 1895. It’s also the fourth time we’ve gone over 100 inches of snow for a season in less than 10 years. I thought there would be some snowflakes into the middle of April, but not 3.3 inches worth.

The 3.3 inches of snow broke the record for the date of 1 inch set back in 1933. Our normal April snowfall is only 0.7 inches. Since the snow starting last December, every month from that point has reported above normal amounts of the white stuff. By the way, Cliff tells me that on April 10, he received a half-inch of snow in 7 minutes, which was the most seen for any 7 minutes period of the season. Very unusual for this to occur in April.

In addition to the morning snow, there were scattered thunderstorms across the regions that April 10 afternoon. Our moisture total for this month is only just .04 inches below the April normal of 1.77 inches.

As I mentioned last week, weather patterns are starting to show a few signs of change. Cliff and I think that we’ll see more storms through the end of the month. However, there should be some breaks that will give us some days with some sun and temperatures warming into the 60s with some areas coming close to 70 degrees during the “last quarter” lunar phase of April 19-25. Then, we see more showers, thunderstorms and cooler temperatures arriving late in the month.

Speaking of thunderstorms, during the spring and summer season, our region sees approximately 14 days with thunderstorms. 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 and Midwest’s “Tornado Alley.”

According to the National Weather Service, there are approximately 100,000 thunderstorms in the U.S. each year. About 10 percent of these storms are considered to be “severe” with very heavy rainfall, large hail and occasional tornadoes. The state that receives the most days with thunderstorms is Florida with as many as 100 to 120 per year. Lakeland, Fla., averages about 100 thunderstorms per year, the highest for any city in the U.S.

During the summer monsoon season in the southwestern portion of the country, thunderstorm activity becomes more widespread. In extreme southeastern Arizona in the Huachuca Mountains, there are an average of 32 thunderstorms in July, which is slightly more than one per day during that month. For an entire year, this region normally reports over 80 thunderstorms.

In the Midwest and central and parts of the southern Great Plains, there are about 50-60 thunderstorms each year. The Gulf Coast has 70-80 storms with 30-40 thunderstorms across the northern Great Plains and southern Texas. The Far West and Northeast average from as few as 5 thunderstorms along the coastal areas of the West Coast to 20-30 thunderstorms in the interior locations and Northeast.

Across the globe, there are over 40,000 thunderstorms forming every day. That’s nearly 1,700 per hour. For an entire year, our planet receives approximately 14.6 million thunderstorms. The stormiest place in the world is Lake Victoria located in Uganda, Africa. Lightning and thunder are reported an average of 242 days per year. The Amazon Basin in South America has just over 200 thunderstorms per year.

Here in North Idaho, the average number of days with thunderstorms, which include thunder, lightning and rain, across the lower elevations is 14 (1 in April, 2 in May, 5 in June, 2 in July, 2 in August, 1 in September and October). When you include days with thunder with little or no rain, the average number of days is 25. The normal number of extreme severe weather days in the Inland Northwest for an entire year is slightly less than one.

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 and the cooler air from Canada 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.

In 2015, thunderstorm activity was less than normal with 9 days. In 2016, there were only 6 days with thunderstorms, including Oct. 1, the start of our record-breaking precipitation pattern. Cliff and I believe that the total number of days with thunderstorm activity for 2017 is expected to be around 15 days.

Contact Randy Mann at randy@longrangeweather.com