The UW Dawgcast

May 20, 2020

Forecast: May 20th, 2020

By Calen Randall

Hey Huskies,

After the “atmospheric river” on Saturday night, the weather has been pleasantly dry. You can see on the schematic below, the precipitation totals leapt about a half inch over a few hours that night, but have since flatlined with no observed precipitation since Sunday morning.

While today’s weather features no impressive thunderstorms or record-breaking heat waves like previous weeks in May, it has painted a fascinating picture of transition over the state. Earlier this morning, the NWS Seattle tweeted out a very interesting visible satellite image which could be captioned as “A Tale of Two Weather Systems”.

To our east, a strong weather system leaving the state will send 45 mph wind gusts to the Columbia Plateau and a potential inch of rain to the Palouse. Note the clouds following the downsloping topography on the lee side of the Cascades. Offshore to our west sits a shortwave trough, expected to deliver some rainfall to Seattle by this afternoon and evening. Stuck between the outbound and inbound weather systems is western Washington. A strong deck of marine layer clouds blankets our skies. Check out the satellite image from the UW Atmos page below!

Expect the precipitation time series from above to change today as the shortwave trough enters western Washington. While precipitation totals today are not expected to jump half an inch in mere hours like on Saturday night, some areas of Seattle could see around a tenth of an inch. Scattered showers will persist into Thursday, with potential convergence-zone activity likely in the usual Snohomish/North King County area. Most models are forecasting between 0.1”-0.3” inches of rain on Thursday.

Expect highs in the low 60s or high 50s over the next couple of days with cooler lows in the high 40s. High pressure returns to the area on Friday so dryer weather is likely to start off Memorial Day Weekend. This ridge will be no Mother’s Day heat wave, but pleasant weather in the mid 60s is expected.

Reach forecaster Calen Randall at theuwdawgcast@uw.edu. Twitter: @Wx19Calen.

TODAY’S FORECAST SATELLITE