It’s back!! Pesky upper trough will bring cool temperatures and rain this weekend
Some things in life are unfair. We experienced a cool/wet spring due to a persistent low pressure area just offshore.
Yes, it has its good points: eliminating drought, providing an abundant snow cover and preventing wildfires. But Northwesterners with mold need a break from the sun and warmth.
And if we’re going to have dry weather it should bebecause the second half of July is climatically the driest period of the year, as shown below.
But this is no ordinary year.
A menacing low pressure area has hovered offshore, and one of its evil descendants will enter our region on Saturday and Sunday.
To see this, here is the upper level map (pressure level 500 hPa, about 18000 ft) for today at 11am. You can think of these lines as pressure, and blue/gray indicates much lower pressure than normal. This is also known as trough.
A high pressure peak lies deep inland, keeping us near-normal temperatures and relatively dry.
But look at the forecast for 8 a.m. Sunday morning (below), the low pressure is headed towards the coast, with an extreme low just off Vancouver Island.
Not good for sun lovers. This will drag clouds into the area, especially on Saturday and Sunday.
But there’s more than that.
Temperatures will be much cooler than usual on Sunday, with the Central European model hitting just 67F that day. You want Sun above Sunday? Head east to WA.
But the good news is… the bottom will pass quickly, with temperatures recovering next week.
Notification
I’ll be doing a special online zoom session for Patreon supporters at 10 a.m. Saturday. Accompany your question….and I will also talk about summer outlook.