"The atmosphere has been very kind to us," KPLU weather expert Cliff Mass said. "The weekend is going to get progressively sunnier and warmer as we go on."
Friday will be cloudy with some modest rain, but as we get later in the day the front will move out and the rain will come to an end. We'll see 60s and 70s over the weekend for our highs and Mass says by Monday we could see temperatures into the 80s. But it won't be as warm as our record-breaking heat from earlier this month. Mass says it's been a "normal" week.
"That's because the large-scale pattern relaxed back to the normal type of situation where we don't have a big ridge, we have flow coming off the ocean," he said.
Mass says another "normal" for this week has been the increase in cumulus clouds throughout the region.
"We may start off with a little bit of fog and low clouds in the morning, but then when we get into the afternoon, we see these puffy, cumulus clouds start developing. Those cumulus clouds are occurring because the atmosphere is destabilizing," he said.
Mass says what we're experiencing is similar to what happens when you're making your stovetop oatmeal.
"You heat it up and you start seeing the cereal convecting, some going up and some going down. The atmosphere is doing the same thing," he said. "And that kind of convection occurs when there's a big difference in temperature near the ground and higher in the atmosphere."
This time of the year the atmosphere aloft is still cold, but the strong sun has been warming the surface.
"That produces a large difference in temperature in the vertical and that destabilizes the atmosphere," Mass said.
Another component of this "destabilization" means the region has the least chance of fog.
"Fog loves to have stable conditions," he said.
So Mass says that's why fog is seen in the fall when the atmosphere is warm and the surface is cold consistently.
