RAIN! First fall storm brings much needed moisture to Tri-Cities, Northwest

A powerful Atmospheric River is bringing heavy rain & mountain snow to Washington and Oregon.

KENNEWICK, WA-  Autumn officially begins Wednesday, but fall couldn’t wait! The last official weekend of summer 2021 brings cooler temperatures, wind and significant rainfall to the Northwest.

Right now, it looks like the Cascades will get the bulk of the rain and snow in the higher elevations. During the exceptionally dry conditions, heavy rain is much needed for regional wildfire fighting efforts.

Here’s a look at the Interactive Radar from early Saturday morning:

09.18.21 Radar Image at 7:24am

There is for the potential of burn scar flooding on high elevation slopes. Recently burned areas, coupled with the extreme drought, will make water absorption of water by the moisture-starved ground very tough. Watch for minor to moderate flash flooding in burn scar areas. Otherwise, the cooler and wet conditions should significantly help fight fires.

The soggy weather should improve drought conditions, with the highest amount of precipitation expected since winter. Rainfall amounts this weekend will range from a couple of tenths of an inch in the valleys and plains to an inch or more up in the mountains.

EXPECTED RAIN TOTALS SATURDAY-SUNDAY:

Tri-Cities: 0.10″-0.40″

Yakima: 0.10″-0.40″

Pendleton:0.25″-0.50″

Hermiston: 0.25″-0.50″

Walla Walla: 0.50″-0.75″

Estimated rain totals this weekend

WEEKEND TIMELINE OF RAIN/WIND:

SATURDAY AM: Periods of heavy rain, slick pavement, and gusty winds. SW 15-30MPH. Temperatures in the mid 50s to low 60s.

SATURDAY PM: Off and on showers, mostly cloudy. SW 15-30MPH. Temperatures in the low to upper 60s.

SATURDAY OVERNIGHT: Light showers mainly between 11pm and 4am, increasing after 6am Sunday. Winds light SW 10-15MPH. Cool lows in the 40s & 50s.

SUNDAY AM: Off and on showers, mostly cloudy. Winds SW 10-20MPH. Temperatures in the low 50s to low 60s.

SUNDAY PM: Shower chances continue until late Sunday evening. Winds gusts in the afternoon from SW15-30MPH.

MONDAY: Drying out, mostly sunny and mild. Highs in the low to upper 60s.

5-day rain chance forecast

Rain will come to an end by Monday. We will soon settle into a cool fall weather pattern with highs in the 60s and lows in the 40s and a mix of clouds and sunshine to start off next week. The Autumn Equinox is Wednesday September 22nd at 12:20PM PT.

RELATED: Wet and chilly conditions for the weekend