For a while, it was looking like July would feature no rainfall for the second straight year. Sure, there a few days, most notably on the 4th, in which Seatac only recorded a trace while others nearby got wet. But our summer really seemed to come to a screeching halt on the 23rd, when a low pressure system partially cut-off from the jet stream meandered ashore. Seatac recorded a daily record 0.76 inches, 0.06 inches more than what is normal for the entire month. July became the fifth wetter-than-average month in an already much wetter-than-average year.

The map above reveals a curious precipitation pattern. Most of Western Washington was drier than normal, except for a few stripes aligned southwest-northeast. If every month featured only one storm, we’d probably see similar striated patterns. Interestingly for Seattle’s water resources, the most significant wet anomaly occurred more or less directly atop SPU’s Cedar River Watershed.

As mentioned, the greatest 24-hour rainfall total of the month occurred on the 23rd. (It was Seattle’s 7th 24-hour daily record of the year, by the way). That, of course, was the only day in which 0.50″ and 0.10″ were recorded. “Heavy rain” was reported once, “rain” was once, and “light rain” 3 times.

References:
Image Source: NWS Advanced Hydrological Prediction Service
SPU Climate Change program