November maximum daily temperature records fall below normal. Precipitation prevails over most of the basin.
Pacific northwest mean temperatures departed +5.7 degrees from normal relative to 1961-1990 normals (31 stations). Mean temperature departures ranged from 2.4 to 10.2 degrees.
Early in the month a slow moving flat ridge of high pressure dominated the basin weather picture. Generally dry weather exists during this period, with an exception to northwest basins, where a cold front brought light precipitation. By mid-month this flat ridge moved east of the Rockies and was replaced by a series of storm systems bringing bouts of precipitation mainly west of The Cascades.
During the latter portion of the month, a series of weather disturbances moving along a stalled frontal system tapped a rich supply of moisture originating from the subtropics. This combination of weather features produced moderate to locally heavy precipitation west of The Cascades and locally heavy precipitation across higher elevations east of The Cascades. A mild flow off the Pacific Ocean and lack of Arctic intrusions led to average temperatures ranging from 2 to 10 degrees above normal.
Maximum temperature records were broken at Pocatello (70 deg on the 12th, 67 deg on the 13th, 62 deg on the 30th), Kalispell (69 deg on the 12th, 58 deg on the 13th, 63 deg on the 14th, 55 deg on the 15th), Great Falls (76 deg on the 7th, an all time record high for the month, 69 deg on the 5th, 74 deg on the12th, ), Helena (75 deg on the 12th, 71 deg on the 13th, 63 deg on the 30th), Missoula (73 deg on the 12th, 66 deg on the 13th, 55 deg on the 14th), Astoria ( 66 deg on the 13th,
65 deg on the 15th, 59 deg on the 28th, 62 deg on the 29th),Eugene (71 deg on the 13th, 65 deg on the 15th), Portland (71 deg on the 13th), Salem (70 deg on the 13th).
No daily precipitation or minimum temperature records were broken in the month of November.
For November, precipitation was 148 percent of normal (1961-1990) at Columbia above Coulee; 70 percent of normal at the Snake River above Ice Harbor; and 114 percent at Columbia above The Dalles.
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