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Marching through a record-breaking rainfall in Seattle

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Posted: Apr 1, 2014 5:42 PM by Meteorologist Robert Gauthreaux
Updated: Apr 1, 2014 5:42 PM
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  Rating: 5.0 (2 votes)

Topics: weather, Seattle, rainfall, record, record-breaking, Baton Rouge, Washington, Washington State, Louisiana, Darrington, mudslide

BATON ROUGE - As reported in the media, there's no question that rainfall totals in the month of March for western Washington were high. Many locations throughout the state flirted with record rainfall, if not completely shattering prior records. This is what helped initiate the terrible mudslide in the town of Darrington.

When one thinks of Seattle weather, umbrellas, rain jackets, and gloomy skies come to mind. While it does rain often in Seattle, it's not like the rain we experience here.

The Seattle-Tacoma International Airport (in Seatac, Wa.) has one of the oldest and most complete data records for the area. On average, the airport sees 3.75 inches of rainfall for the month of March. How can a city famous for wet weather see only 3.75 inches in an entire month? It seems that one bad squall line or one intense pop-up thunderstorm in Baton Rouge could give us that much in an hour. In Baton Rouge, our average rainfall for March is 5.07 inches. Annually, Seattle sees about 38.39 inches while we receive 58.05 inches!

While Seattle is known for being wet, the Seattle area typically can't compete with our rainfall totals. However, Seattle handily beats us for number of rainy days. While western Washington may not have the heavy rainfall as often as we do, they do see a constant barrage of drizzle, mist, and light rain that can last for days. Thus, imagining the Emerald City as a wet and cloudy metropolis holds water.

The Olympic Peninsula is home to temperate rainforests along its western edge. As moist air masses from the Pacific Ocean ride up the Olympic Mountains, they squeeze their moisture like a sponge in the form of rain upon the Olympics. Thus, rainfall totals across this region can easily total over 100 inches, crushing little old Red Stick in rainfall totals. It's no wonder why this was the perfect setting for the Twilight movies. The area around the town of Forks, where the movies are based, receives 10.98 inches of rain in March. This March, they received 15.8 inches, about 144% of normal.

Seattle sees its wettest time of year typically in November, December, and January; averaging 5-6 inches per month. However, don't assume it's all gloom. Seattle's climate gives way for absolutely beautiful and comfortable summers. The climate of the Pacific Northwest is classified as a coastal Mediterranean climate which includes cool, wet winters and dry summers. Many summer days in Seattle consist of sunshine, temperatures in the 70s, and comparatively low humidity. In other words, Seattle is a weather paradise during the summer months.

With the recent terrible mudslide in Darrington, Wa., how much rain did the area actually see? As stated earlier, the SeaTac Airport receives 3.75 on average. This March, the airport received a record-breaking 9.44 inches which is 252% of normal! According to the National Weather Service in Seattle, this is the 14th wettest month ever for Seattle. As explained before, the wet season is usually earlier in the winter season.

The same orographic effect along the Olympic Mountains occurs along the Cascades, leading to wet conditions, only not the same magnitude. Darrington is on the western slope of the Cascade Mountains, northeast of Seattle. On average, the town of Darrington receives 7.26 inches of rain. This March, the NWS stated that Darrington received 19.3 inches (266% of normal), just shy of their record of 19.92 set in 1997.

The wettest month for Baton Rouge is typically in July, where we average 6.0 inches, usually a result of summertime thunderstorms and tropical disturbances. The wettest month on record in Baton Rouge is June 1989 when we received 23.19 inches, over half the average annual rainfall of Seattle!

One thing Seattleites can be thankful for is a dry start to April thus far, as well as an 8th straight opening day victory for the Seattle Mariners; Sodo Mojo.

Meteorologist Robert Gauthreaux, a New Orleans native, spent 12 years of his life in the Seattle area. You can get forecasts from Robert on weekend evenings. Additionally, you can get the fastest and latest forecasts and weather news by checking in with wbrz.com/weather, liking Robert on Facebook, and following him on Twitter.

Data compiled from the Southern Regional Climate Center.

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