Last month was the coolest May in the West Kootenay in 26 years, but it was drier than normal.
Forecaster Jesse Ellis of the Southeast Fire Centre in Castlegar says that at 11.1 degrees, the mean monthly temperature was more than two degrees below normal which was “quite a departure” from the average and the lowest since 1996, but “not quite record breaking.”
The highest temperature of the month was 22.5 on the 3rd. Not since 1977 did temperatures fail to reach 25 degrees at some point during the month. The all-time record local high for the month of 34.5 degrees was set on May 18, 2006.
The lowest temperature was 0.9 degrees on the 12th, well above the record low of minus-4.7 set on May 1, 2013.
Ellis says total rainfall was 18 per cent below average. We received 57.6 millimeters of rain, whereas normal is 70.1 mm. The record high for May of 157.4 mm was set in 1996 and the record low of 17 mm was established in 1970.
However, 20 out of 31 days last month had measurable precipitation compared to the normal 16, which may have left the misimpression that it was a wetter month.
“We saw more days with rain than average, but if you take all that rain and add it up, it was lower than average,” Ellis says. “We had a more active storm pattern but they weren’t packing as much moisture as on average.”
Ellis says cooler temperatures and precipitation don’t necessarily go hand in hand.
He explains the unseasonably cool temperatures were the result of a large upper trough that dominated for most of the month. Such troughs are associated with cool air, often with a northwesterly flow, he said. It remained stalled over the area for a good portion of the month.
Ellis adds the longer range forecast calls for precipitation at least every few days through to mid-month. From the middle to the end of June, things become harder to predict, but he says the best guess is that we will see average or slightly below average temperatures, along with average or slightly above average precipitation.