Frost/Freeze in Blue Mountain Foothills, Washington

The ASOS KALW recorded temperatures at or below 32 degrees for approximately 11 hours ending at 0953 PDT. The mesonet station DW4698 recorded temperatures at or below 32 degrees for approximately 12 hours ending at 0925 PDT. The mesonet station EW4185 recorded temperatures at or below 32 degrees for approximately 12 hours ending at 0957 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.