A large upper ridge built into the Pacific Northwest on December 4 behind a trough which pushed through California the previous day. This resulted in a strong gradient over the southern Sierra Nevada producing Mono type winds over the Southern Sierra Nevada on the evening of December 4 through the late morning of December 5.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS HNX wrote it up.
A large upper ridge built into the Pacific Northwest on December 4 behind a trough which pushed through California the previous day. This resulted in a strong gradient over the southern Sierra Nevada producing Mono type winds over the Southern Sierra Nevada on the evening of December 4 through the late morning of December 5.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Hanford, CA wrote its last area forecast discussion before the first event at Dec 4, 12:09 PM PST, 9 hours 51 minutes earlier.
Area Forecast Discussion National Weather Service San Joaquin Valley - Hanford CA 1209 PM PST Mon Dec 4 2017 .SYNOPSIS...Cool mornings over the next several days, with freezing temperatures likely across the San Joaquin Valley and Kern County Desert. Things will warm up by weeks end, though only marginally. This will lessen the freeze potential and bring a return to the fog. && .DISCUSSION...Big picture over the next week or so will be an amplifying ridge of high pressure across the region. This will keep things quite quiet over that period, other than cool overnight temps and a return to fog late week. Currently, a trough is moving through the region, ushering in cold air and clearing out what little cloud cover there was. The cold air will be the focus of the short term since the area could see temps several degrees cooler than last night. A Hard Freeze Warning is in effect for both the San Joaquin Valley and Kern County Desert overnight. Northerly flow aloft should persist tomorrow re-enforcing the cold, though not expecting as widespread Hard Freeze conditions Tuesday night. Nevertheless, the above areas will likely see sub- freezing temps over the next several mornings, even though there will be a slight warming trend. && .AVIATION...Areas of MVFR in haze will occur in the San Joaquin Valley. Otherwise, VFR conditions will prevail over the central CA interior during the next 24 hours. && .AIR QUALITY ISSUES... None. && .CERTAINTY... The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.php for additional information an/or to provide feedback. && .HNX Watches/Warnings/Advisories... Hard Freeze Warning from 1 AM to 8 AM PST Tuesday CAZ089>092. Hard Freeze Warning from 1 AM to 8 AM PST Tuesday CAZ098-099. && Meadows
1 strong wind. Local standard time, as filed.
California Highway patrol and media reports of several dead trees and power lines downed due to strong wind gusts.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2017Every state in 2017This day in weather historyWarnings in California, December 2017
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 723893.