Frost/Freeze in Foothills of the Northern Blue Mountains of Oregon, Oregon

The mesonet station DW9612 Umapine reported at or below freezing temperatures between 0145 to 0645. The Oregon DOT station OD191 reported at or below freezing temperatures between 0251 to 0731. Several other stations across the area reported temperatures at or below freezing for several hours the morning of the 18th.

Clear skies in combination with dry flow regimes aloft resulted in good radiative cooling taking place at the surface. Temperatures in the morning had dropped to or below freezing for several hours in lower elevation locations between April 18th to the 20th.