Pacific Northwest storm still on track, could delay holiday shipments (with forecast video)

Satellite animation over the U.S. Pacific Northwest.

With only a week to go until Christmas, a powerful storm will begin its approach into the Pacific Northwest today, Dec. 18, possibly lasting through Friday, Dec. 20 in some spots. It will gradually develop today before cranking up overnight and tomorrow, producing ice, abundant snowfall and rainfall, and gusty winds. Holiday gifts shipped by ground and air could arrive later than expected.

The forecast hasn’t changed much since FreightWaves first reported on this potential storm yesterday, Dec. 17. Storm totals of one to three feet of snow will be dumped in many high elevations of the Olympics in Washington state (west of Seattle), as well as the Cascades in Washington (east of Seattle) and Oregon. Some lower elevations, including Pendleton, will see freezing rain with up to one quarter of an inch of ice accumulation.

There’s potential for road closures due to hazardous conditions and downed trees/power lines. It’ll be risky for drivers to go over Stevens Pass (US-2), Snoqualmie Pass (I-90), Blewett Pass (US-97), Loup Loup Pass (WA-20) and Santiam Pass (US-20). The storm will also impact the city of Mount St. Helens, Mt. Baker and Crystal Mountain ski areas and Mt. Rainier National Park. Check chain laws here for the latest updates on winter driving.

Jonathan Hunter, Weather Department Manager at Covenant Transport Services Group (NYSE: CVTI), told FreightWaves that this storm couldn’t come at a worse time. He and his team have been forced to re-position drivers.

“Because Christmas falls on a Wednesday this year, most drivers want to be home on Monday [Dec. 23],” said Hunter. ” The timing of this weather means that we had to keep everyone who wanted to be home for Christmas out of the Northwest and put them on different freight.”

While snow and ice cover the mountains, prolonged periods of heavy rainfall could lead to flooding in the valleys and lowest peaks, from the I-5 corridor to the Washington and Oregon coasts. Totals from today through Saturday, Dec. 21 could range from three to six inches for many areas. The heaviest rainfall will likely be Thursday night, Dec. 19 through Friday night, Dec. 20.

At this time, the northern Oregon coast range and the southern Washington Cascades will probably receive the heaviest rain. However, these “atmospheric river” events are notoriously difficult to precisely predict more than 24 hours in advance. Look for updates on the FreightWaves website and social media accounts.

Further complicating the issue, Cascade snow levels will rise from the 2,000- to 3,500-foot range tonight to above 5,000 feet by Friday. There’s a good chance for creeks and rivers rapidly rising. The greatest concern for flooding will be along creeks and rivers that do not have flood control reservoirs.

The final layer of this storm will be the winds. Travel will be difficult on US-101 with gusts possibly reaching 60 mph. The winds may also cause property damage and beach erosion in coastal communities.

Besides hazardous road conditions, short-term disruptions at the ports of Seattle and Portland are possible due to high winds and heavy rainfall. It’s typically a slow time of the year for overall air cargo at Seattle-Tacoma International Airport (ICAO code: SEA), but whatever is out there may be delayed. Shippers, carriers and brokers who subscribe to FreightWaves SONAR can locate these types of assets at potential risk of weather disruptions. They are shown as color coded dots and “doughnuts” inside the Critical Events platform based on the anticipated level of disruption, as shown on the map above, and are updated as conditions and forecasts change.

Other areas of snowfall today, Dec. 18

Lake effect snowfall and gusty winds that started yesterday continue today from Michigan to upstate New York. Look for an additional three to six inches from in Sault Ste. Marie, Traverse City and Cadillac, Michigan; six to 10 inches around Erie, Pennsylvania; and eight to 14 inches in Jamestown, Watertown and Oswego, New York. Gusty winds could produce blowing snow, resulting in occasional white-out conditions.

Periods of heavy snowfall will also hit parts of the Sierra Nevada in eastern California, in addition to the northern Rockies of Montana and Idaho today through Friday.

Other notable weather today, Dec. 18

High winds will come back to southeastern Wyoming late tonight through Friday morning, Dec. 20, with westerly gusts up to 65 mph. There will be an elevated risk of blowovers along I-80 over the summit between Cheyenne and Laramie; I-80 between Arlington and Elk Mountain; and I-25 near Bordeaux between Chugwater and Wheatland. Less-than-truckload (LTL) drivers and drivers deadheading (hauling empty trailers) will need to be especially careful.

Another region of wicked winds will be west of I-15 in northwestern Montana, from Thursday night, Dec. 19 through the following evening. Gusts could reach 70 mph at times over Logan Pass and Marias Pass, as well as in Heart Butte and Cut Bank, affecting drivers on US-2 and US-89.