WeatherWhys: Current weather pattern could cause dangerous drought conditions for the west
Last week’s WeatherWhys looked at the high pressure system sitting off the west coast and why that was causing the current prolonged dry spell in the Treasure Valley.
We’re going to stick with that high pressure system this week, but there’s been a slight change in its position. The large area of clockwise moving air has moved inland over the Oregon and California coast, pushing the jet stream north and east of Idaho and allowing warm air from the south to flood into the area.
Temperatures in the Boise area hit as high as 58 degrees on Thursday as a result of system shifting inland.
“(The system) is floating over Western Oregon and just shooting the temperatures up,” Idaho News 6 chief meteorologist Scott Dorval said. “That’s why we’re warming and it’s creating a huge block and pushing the snow into Canada.”
A bull in a china closet
This year’s weather pattern is currently in a La Niña pattern, which is characterized by cooler sea-surface temperatures in the central and eastern tropical Pacific Ocean and often leads to dryer seasons for the United States.
It’s for that reason why the vast amount of snow in the Treasure Valley in December was a pleasant surprise. But a dry January is being followed up by an equally dry February and things don’t look to be changing anytime soon.
Temperatures for the next week in the Treasure Valley will remain above average in the high 40s and even 50s. Dorval expects that to continue through the end of the month when the average temperature in Boise will go from low 40s in early February to about 50 degrees.
“This is a month where the temperature is starting to climb, that the sun is getting higher in the sky,” Dorval said. “And so if you’ve been colder than normal that all of a sudden you switch to warmer than normal, and the normals are going up anyway, you have a dramatic shift of like, ‘wow, it’s totally changed.’”
And it’s all because of the high pressure system.
Dorval likens it to a ‘bull in a china closet,’ because not only is the area of high pressure so large but as it moves it can completely change the temperatures and weathers of huge regions such as the Pacific Northwest. When the system moves offshore cold air filters in from Canada and when it returns back over land all that cold air is blocked off and sent toward the Midwest.
It’s the same high pressure system that caused temperatures in western Canada to soar to 121 degrees last summer and cause a whole town to burn to the ground.
What does it mean moving forward?
In Dorval’s words, “When we needed the precipitation, it wasn’t there.”
Nearly the whole state of Idaho is in some form of drought, with most of the state in a moderate to severe drought. January through April is the prime time for Idaho to pick up moisture, but it’s looking like for at least the next couple of weeks that moisture won’t come to the area.
Boise could see a slight rain shower on Monday while higher areas like Brundage Mountain and Bogus Basin could see a couple of inches of snow but nothing substantial.
Beyond the Treasure Valley, the clockwise rotation is bringing winds down the valleys and mountains along the west coast and already causing wildfires to spread. Orange County in Southern California has already experienced one wildfire this week due to the dry weather and high winds.
“It’s going to be rough,” Dorval said. “Because they’re going to need a wet spring and I don’t know if they’re going to get it. They don’t typically get it in alignment (with La Niña).”
