It won’t be Snowmageddon, but we will have snow

Thursday afternoon, the National Weather Service in Pendleton posted Winter Storm Watches for their entire warning area. For the Tri-Cities and Hermiston, the statement calls for 3-6 inches of snow falling Friday Night through Saturday Night. Right now, they’re expecting 3-5 inches in Walla Walla and Pendleton for Friday Night through Sunday Morning.

This is on top of the snow we have left over from the beginning of the week. As an added bonus, it looks like Benton, Franklin, and the western third of Walla Walla County could see winds gusting to 35 mph on Saturday.

HRRR modeled precipitation from 5pm Thursday to 9am Friday. (Source: Tropical Tidbits)

This isn’t even the first in an incoming train of storms slated to impact the area. During the day Friday, some snow showers are possible in the area thanks to a low-pressure system headed for northern California. The weather model above, the 23z HRRR, shows a decent band of snow even developing and progressing southeastward after sunrise.

It’s important to note here, though, that the 18z GFS (another model) is not showing this band developing. Many of us in the Columbia Basin will probably see small snowfall amounts during the day Friday, but these are anticipated to remain fairly light compared to what is expected Saturday.

Strong Winds and Snow

While we’re having intermittent snowfall from the low headed to California, another low will be developing on the coast of Vancouver Island. This low, which is what we call a BC Slider (Charlie explains the meteorology behind BC Sliders in his latest post). In December 2008, we saw several BC Sliders impact the area, resulting in over two feet of snow for parts of the Puget Sound Region. I don’t recall specific numbers, but moving here from Texas that month I distinctly remember arriving in a very snow covered Tri-Cities.

WRF-GFS modeled wind gusts for 10pm Saturday. (Source: University of Washington)

Along with the snow mentioned in the first paragraph, these systems can bring quite windy conditions. Gusty winds will develop in Benton and Franklin Counties Saturday morning and are currently expected to peak after nightfall. The WRF-GFS model image I included shows wind gusts for 10pm Saturday. The yellow, red, and green around the Tri-Cities indicate gusts to around 40 mph in exposed places, with higher gusts possibly to 50 mph around Benton City.

This model has sustained winds in the Tri-Cities to around 25 mph in parts of town, with higher values toward Benton City. If this model verifies, some areas could see blizzard conditions, which the National Weather Service defines as three or more consecutive hours of snow with sustained winds or frequent gusts above 35 mph.

Whether the National Weather Service decides to call this a blizzard or not, it will still make for extremely unsafe travel conditions, particularly on I-82 from Prosser to Plymouth and US 395 from Plymouth to Connell. Even in winds below blizzard criteria, whiteout conditions can reduce visibility to near zero. If you have plans to travel through Benton or Franklin Counties on Saturday, now is the time to consider whether you should change them or not.

Interestingly, outside of Benton and Franklin Counties, winds look like they will be rather calm. This was the case earlier this week, too. I had to drive to Kennewick on Monday to get my car worked on and immediately once I crossed the Umatilla Bridge into Washington I was met by a wall of strong winds. When I went to Hermiston for work later, I found the same thing – very windy in the Horse Heaven Hills, but almost calm at work. Still consider changing any travel plans outside of Benton and Franklin Counties, but it looks like the situation won’t be quite as severe.

Beyond Saturday

There are several more storm systems aiming for the Pacific Northwest after Saturday’s BC Slider, but confidence remains fairly low on their impacts for the Columbia Basin. In their latest Area Forecast Discussion, the NWS in Pendleton had this to say:

Model timing and placement differences begin past Monday but the general trend is for a combo of upper-level lows to drop south out of the Gulf of Alaska along the BC coast and towards the PacNW, but these look like they may remain far enough offshore that the best potential for significant snow will likely be the Cascades and points west with less potential east of the Cascades.

Essentially, as it stands right now the weather systems for the beginning of next week will be too far away to give us any significant impacts. Updated model runs with new information could indicate an increased chance of snow, but as I said in my Facebook Live earlier this week – don’t get too excited.

This article is accurate as of 6:15pm Thursday.

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