Frost/Freeze in Lower Columbia Basin, Washington

The ASOS KPSC recorded temperatures at or below 32 degrees for approximately 11 hours ending at 0935 PDT. The Mesonet station KF7FMI-13 Prosser recorded temperatures at or below 32 degrees for approximately 12 hours ending at 0840 PDT. The AWOS KRLD recorded temperatures at or below 32 degrees for approximately 12 hours ending at 0915 PDT. The Hanford meteorological station HHMS recorded temperatures at or below 32 degrees for approximately 9 hours ending at 0900 PDT.

Increasing northerly flow reinforced by a cold arctic airmass behind a shortwave trough passage starting October 26th lead to temperatures region-wide dropping well below normal. Overnight temperatures across the lower elevations in the intermountain Pacific Northwest were able to cool well below freezing across the region for much of the overnight period. This lead to all lower elevation zones experiencing their end of season freeze by the morning of October 28th.