While a low cloud deck inhibited fog formation across much of the San Joaquin Valley during the evening of December 4 and the morning of December 5, some dense fog formed in the south end of the valley. The fog lifted into a low cloud deck by late morning.
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The episode as NWS HNX wrote it up.
While a low cloud deck inhibited fog formation across much of the San Joaquin Valley during the evening of December 4 and the morning of December 5, some dense fog formed in the south end of the valley. The fog lifted into a low cloud deck by late morning.
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, 3:55 PM PST, 2 hours 55 minutes earlier.
Area Forecast Discussion...UPDATED National Weather Service Hanford CA 355 PM PST Sat Dec 4 2021 .UPDATE... Updated AIR QUALITY ISSUES section. && .SYNOPSIS...Dry conditions will prevail across the area through the weekend, although a cooling trend will take place. A storm moving north of our area will bring a slight chance of precipitation on Monday night. Seasonably cool and dry conditions will prevail on Tuesday and Wednesday. A low pressure system will impact the area late next week bringing precipitation chances and much cooler temperatures. && .DISCUSSION... The area remains under a very stable blocking Rex pattern with plenty of dry air aloft as noted on water vapor imagery. In the San Joaquin Valley, trapped surface moisture continues to form dense fog in the overnight hours and a very slow burn off is occurring this afternoon. It will be interesting to see of the ever shortening daylight period and sun angle will allow off the fog and stratus to dissipate or not. For tonight a return to fog in the San Joaquin Valley seems likelyh and another Dense Fog Advisory may be needed. For the remainder of the area under the blocking ridge pattern, mainly clear skies and above normal temperatures will continue through Sunday. There is a change in the weather pattern beginning Monday as forecast models bring a weakening frontal system into Northern California. Deterministic models continue to show this front weakening as it drops into the region and any precipitation will be light and spotty in nature. It will bring cooler temperatures to Central California with highs retreating to near normal for early December. In the wake of the trough passage ridging again flexes its muscle on Tuesday and Wednesday. Expect dry weather for these two days however by Thursday deterministic and ensemble models bring a more significant weather disturbance into the forecast area in northwest flow as the blocking ridge pattern breaks down. This should be the first rain and snow event in quite some time for the area and although welcome, it will not likely bring a huge amount of rain or snow as it will move through the area quickly. National Blend of Models ensemble probability gives Fresno a 44% chance of 0.50" of rain on Thursday and Bakersfield a 37% chance of the same 0.50" Definitely something to look forward too. Dry weather returns for Friday through next weekend as a short wave ridge moves into the West Coast. && .AVIATION... Areas of MVFR visibilities will prevail over the San Joaquin Valley through 05z in haze. LIFR conditions are possible in the San Joaquin Valley once again tonight due to dense fog. && .AIR QUALITY ISSUES... On Sunday December 5 2021...Unhealthy for sensitive groups in Fresno... Kern...Kings and Tulare Counties. Fireplace/Wood Stove Burning Status is: No Burning Unless Registered in Kern (Greater Frazier Park Area)... Kings...Madera...Merced and Tulare Counties. No Burning For All in Fresno and Kern Counties. Further information is available at Valleyair.org && .CERTAINTY... The level of certainty for days 1 and 2 is medium. 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.html for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... None. && public...Dudley aviation....Dudley weather.gov/hanford
The national radar mosaic for the moment the first event began.
2 dense fog. Local standard time, as filed.
Visibility below a quarter mile was reported in Porterville.
Visibility below a quarter mile was reported in Bakersfield.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2021Every state in 2021This day in weather historyWarnings in California, December 2021
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: 988112, 988113.