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April 2014
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March 2014 Precipitation Summary

Posted: April 1st, 2014

ahps_mar_2014

 

9.44 inches. Never before has that much rainfall been recorded at either Seatac or anywhere in Seattle during the month of March. If it had been November, our wettest month, it still would have been in the top ten. It was our wettest month since November 2006—Seattle’s wettest month ever. It was wet.

 

The 30-year average for March is 5.72 inches. The AHPS image above shows that most of Western Washington received 150- to 300% of normal precipitation. Parts of the North Cascades and north slope of the Olympics had the largest anomalies. And you can actually count the below normal pixels, there are so few (32).

 

The greatest 24-hour rainfall total of the month occurred on the 5th when 1.84 inches fell. There were 3 days with total rainfall greater than an inch. The daily average was 0.30 inches. There were 8 days with with greater than 0.50″, 15 days above 0.10″, and 20 above 0.01″. “Heavy rain” was reported twice, “rain” 10 times, “light rain” 21 times and “snow” once.

 

Despite the fact that up to four atmospheric rivers hit the region, the only statistically significant rainfall event occurred during the March 5th storm. City neighborhoods closest to Puget Sound generally got the most during the quasi-extreme event, with Admiral leading the way at 0.42 inches over a 1-hour period, and 1.14 inches in a 6-hour period. That said, ground and drainage system saturation was very high the entire month; any rain had the potential to cause problems.

 

References:
AHPS montly precipitation image
SPU Climate Change program
Email SPU’s Climate Change team