Western Washington and Vancouver Island Face “Pineapple Express” Atmospheric River With Heavy Rain, Rising Snow Levels, and Flood Risk

WASHINGTON — A powerful atmospheric river commonly referred to as a “Pineapple Express” is expected to impact western Washington and Vancouver Island from late this weekend into early next week, bringing a surge of warm, moisture-laden air from the subtropical Pacific near Hawaii. Forecast guidance shows a prolonged period of moderate to heavy rainfall, rapidly rising snow levels, and an increased risk of river flooding in vulnerable regions.

Meteorologists describe this system as a deep feed of subtropical moisture, a classic Pineapple Express setup that often delivers high rainfall totals over a short period of time across the Pacific Northwest.

What the Pineapple Express Means for the Pacific Northwest

The Pineapple Express is not a single storm but a long, narrow corridor of intense atmospheric moisture stretching thousands of miles across the Pacific Ocean. In this case, the moisture plume originates near Hawaii and is directed northeast into western Washington and southern British Columbia, including Vancouver Island.

Because the air mass is unusually warm for January, it carries significant moisture while also raising temperatures aloft — a key factor in increasing runoff and flood potential.

Heavy Rainfall Expected in Western Washington and Vancouver Island

Forecast data indicates a moderate to high-end rainfall event, especially along coastal areas, the Olympic Peninsula, and northwestern Washington. The most persistent rain is expected as the atmospheric river stalls over the region before gradually weakening early next week.

Rainfall rates may become intense at times, particularly in orographically favored locations where moist air is forced upward by terrain. These areas typically experience the highest totals during Pineapple Express events.

Snow Levels Rising to Around 8,000 Feet

One of the more concerning aspects of this system is the rapid rise in snow levels, forecast to climb to around 8,000 feet. This means that precipitation falling as snow at higher elevations earlier in the season will transition to rain.

As rain falls onto existing snowpack, snowmelt accelerates, increasing the amount of water entering rivers and streams. This process significantly raises the risk of flooding, especially during prolonged rainfall events.

River Flooding Risk Focused on Olympics and North Cascades

The greatest flooding concern is for rivers draining the Olympic Mountains and the north Washington Cascades. These river systems are particularly sensitive to warm atmospheric rivers due to steep terrain, saturated soils, and rapid runoff.

While widespread major flooding is not guaranteed, localized river flooding is possible, especially in areas that have already received recent precipitation.

Improvement Expected After the Atmospheric River Exits

The good news is that forecast models suggest conditions improve once the atmospheric river moves out. A drier stretch of weather is expected to follow, allowing rivers to recede and soils to gradually dry. This transition will be important in preventing prolonged flooding impacts across western Washington and Vancouver Island.

What Residents Should Watch Closely

Residents in affected areas should monitor:

• River and stream levels
• Local flood advisories or warnings
• Mountain pass conditions due to changing snow levels
• Travel impacts from heavy rain and reduced visibility

Preparedness is especially important in flood-prone valleys and near fast-responding rivers.

Stay with NapervilleLocal.com for continued national and regional weather coverage, including major systems impacting the Pacific Northwest and beyond. Share this update with friends or family in western Washington or Vancouver Island, and check back for follow-up developments as the system evolves.