Some evidence suggests that the combination of a weak El Niño sea-surface temperature event in the Pacific Ocean and relatively high sunspot activity in 2012 – as expected – has led to the all-time record mid-July through early October drought pattern in the Pacific Northwest.
Since July 20, the Spokane International Airport has received only 0.13 inches of moisture, which fell Aug. 21. In September, there were two days with trace amounts of precipitation, the 9th and 23rd. The normal rainfall for September is 0.67 inches.
September was also much warmer than normal. The average temperature was 63.4 degrees, which is 3.2 degrees above normal. The warmest days were Sept. 8 and Sept. 20 with a high of 86 degrees.
Early October did bring light-to-moderate frosts to the Inland Northwest. Many golf courses last week had to delay their openings until the late morning due to frosty conditions.
Also, the first snows of the season fell Oct. 2 and Oct. 3 in Montana in Great Falls, Helena, Butte and Billings. Nearly an inch of rain dampened drought-parched fields along the eastern slopes of the Continental Divide. This was good news for winter wheat farmers needing to plant their crops ahead of even colder, and perhaps snowier, weather conditions expected during the third week of this month during the new moon phase.
Since July 23, a mere 0.03 inches of rain has fallen in Seattle. This is an all-time record for extreme dryness in the region dating back to at least the mid-1880s.
However, this pattern is going to change this weekend. The strong high pressure ridge, which has brought us the very dry, and in some cases, very nice weather, will be breaking down as we approach the new moon weather change of Oct. 15-21. A series of storm systems will move in from the Pacific, bringing our region some much-needed moisture.
Once we get through the end of next week we should have a better idea of the fall and early winter weather pattern. If the high pressure ridge rebuilds into the Northwestern U.S., then we likely will see a drier October and November. By contrast, if the high pressure system holds back, then we should see much wetter than normal weather.