Memorial Day weather? Don’t even try to guess

The Memorial Day weekend is often referred to as the “unofficial” start of the summer season. Climatologically speaking, temperatures toward the end of May are not particularly summerlike, with average highs around 70 degrees and average lows in the mid-40s. Though that might feel toasty on a windless day on land, it could still be perceived as cool over area lakes, if there is a bit of a wind.

Taking a look at the Memorial Day weekends across the Spokane/Coeur d’Alene area over the last five years, temperatures have been anything but consistent. High temperatures have been as cold as the 50s in 2007, and as warm as the upper 70s in 2005, which was also the only completely dry holiday weekend out of the last five years.

As temperatures warm up and we head toward our peak thunderstorm season in June, I wanted to update you on the criteria by which severe thunderstorm warnings are issued by the National Weather Service. In previous years, a storm which produced 3/4-inch diameter hail would be considered severe. According to weather service officials, “In an effort to better represent hail that produces damage and to reduce user complacency to severe thunderstorm warnings based solely on 3/4-inch diameter hail, effective June 1, NWS forecast offices in the NWS Western Region will use a new, experimental hail criterion of one-inch diameter or larger…” Scientific research conducted by Texas Tech University demonstrated that significant property damage did not occur until hailstone size reached 1 inch in diameter. These changes will not likely have a huge impact on the number of warnings issued in our region, as damaging winds occur much more frequently around here than large hail.

For those who would like to delve deeper into the world of weather, an opportunity awaits you. My friend and fellow meteorologist Randy Mann is planning on teaching a Weather and Climate course this fall at North Idaho College. Classes will be held Tuesday and Thursday morning beginning in late August. It’s a freshman-level course which will feature an introduction to local weather and global climate.