Frost/Freeze — W Central S.j. Valley, California

2017-12-21 · W Central S.j. Valley, California

Event narrative

Several locations reported minimum temperatures below 28 degrees.

Wider weather episode

A strong cold front pushed through Central California on December 20. While rainfall amounts in the San Joaquin Valley were generally light (a tenth of an inch or less), a cooler airmass settled into the valley behind this system. Clearing skies and light winds allowed for strong radiational cooling to take place overnight and temperatures fell into the 20's for several hours overnight. In addition, an area of dense fog formed along the center of the San Joaquin Valley impacting travel on State Route 99 in the Fresno area. On the following morning, less fog was present although some freezing fog was reported as the airmass dried and temperatures dropped even lower than on the previous morning.

Source: NOAA Storm Events Database, event_id 726434. Narrative written by the NWS forecast office that issued the report.