The next 24 hours will see very active weather across the Pacific Northwest, unusual for what is typically the driest time of the year for our area.
Increasing instability in the atmosphere ahead of an approaching cold front means showers pick up, especially after midnight west of the Cascades. There is even a chance of a thunderstorm or you could wake up to downpours. Our RPM model goes crazy showing a cluster of heavy showers/thunderstorms developing along the east side of the Willamette Valley in the wee hours of the morning.
That may or may not happen, but the point is that we’re in moist southerly flow during the night.
Also, east of the Cascades a strong disturbance moving into northern California rides north this evening, setting off lots of thunderstorms. Some of those could be strong to severe before midnight all the way up through north central Oregon and into southern Washington. The Portland and Boise radars are going to have to work overtime…the Pendleton radar is out of service. It is supposed to be working again tomorrow. Ooops…
Think May…a cold front moves through in the mid morning hours with steady rain, possibly a thunderstorm embedded too. There could be some downpours during the morning commute. Then behind the front, from midday through evening, we’re in the cool and showery part of the system. That means showers, sunbreaks, southwest wind gusts to 30 mph, and a decent chance for hail or thunder with some of those showers. Of course this can also be the type of weather that can give us funnel clouds, so be on the lookout for rotation if you spot one.
Total rainfall the next 36 hours?
Somewhere between a quarter of an inch and one inch in the lowlands depending on where any heavy rain bands set up. Once again note our RPM going crazy with heavy totals on the east side of the valley. Probably misplaced, but the point is that someone is likely going to get a big soaking west of the Cascades.
Chief Meteorologist Mark Nelsen