Dense Fog, Foggy Bottom
- When
- February 5, 2:05 AM PST to 9:15 AM PST
- Where
- Foggy Bottom forecast zone
- Reported by
- ASOS
Hanford reported visibility below a quarter mile. Webcams along SR 198 in Hanford showed very low visibility in fog.
Dense Fog in California, February 5, 2021
Offshore high pressure built inland and strengthened over central California during the morning of February 5. With clear skies and light winds previaling over the area combining with residual low level moisture in the San Joaquin Valley, an area of dense fog formed near the center of the valley during the early morning hours.
The toll
- Deaths
- 0
- Injuries
- 0
- Property damage
- None recorded
- Crop damage
- None recorded
- Events
- 1
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.
What happened
The episode as NWS HNX wrote it up.
Offshore high pressure built inland and strengthened over central California during the morning of February 5. With clear skies and light winds previaling over the area combining with residual low level moisture in the San Joaquin Valley, an area of dense fog formed near the center of the valley during the early morning hours. The fog mainly imapcted the Hanford area and reduced visibility to below an eighth of a mile along State Route 198 through Hanford. The fog burned off by late morning and visibility rapidly improved by midday.
What forecasters said that day
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 Feb 4, 5:45 PM PST, 8 hours 20 minutes earlier.
Area forecast discussion, Feb 4, 5:45 PM PST, 8 hours 20 minutes before
Area Forecast Discussion...UPDATED National Weather Service Hanford CA 545 PM PST Thu Feb 4 2021 .UPDATE... Updated AIR QUALITY ISSUES section. && .SYNOPSIS...A warming trend will commence on Friday, and will continue through the end of the weekend. Temperatures will remain at to slightly above average through the middle of next week. No precipitation is expected through at least the next 7 days. && .DISCUSSION...A cool northwesterly flow, along with persistent low stratus along the east side of valley has kept our afternoon high temperatures slightly below average across the district. As of this writing, we're still keeping some low level clouds along the valley facing side in Kern County, but overall we have mostly sunny skies this afternoon. With clear skies and light winds, tonight's low temperatures will fall to near the freezing mark for portions of the valley, especially into rural areas. Patchy dense fog is also a possibility on Friday morning, but at this time I am not expecting anything widespread nor very dense. A ridge of high pressure will begin to strengthen in the east Pacific on Friday. The ridge will continue to strengthen and slowly shift eastward closer to the west coast on Saturday. The ridge will then slightly flatten out and move inland into central California by Sunday. Strong synoptic scale warming will start on Friday, and will continue through the weekend. Afternoon high temperatures will be between 4 to 8 degrees above average for most of the district by Saturday and Sunday. For Monday into the end of the 7-day period, the NAEFS keeps the region under a weak ridge. This will allow for temperatures to remain at to slightly above average. No precipitation is expected through at least the middle of next week as the main storm track stays to our north. && .AVIATION... Areas of IFR/LIFR in fog and low ceilings for portions of the Southern San Joaquin Valley from 10Z to 18Z Friday. Also, areas of IFR/mountain obscurations along the valley facing side of the southern Sierra foothills and Kern County mountains from 10Z through at least 20Z Friday. Otherwise,VFR conditions will prevail across the central CA interior for the next 24 hours. && .AIR QUALITY ISSUES... On Friday February 5 2021...Fireplace/Wood Stove Burning Status is: No Burning Unless Registered in Fresno and Kern Counties. Further information is available at Valleyair.org && .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.html for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... None. && public...CMC aviation....MV weather.gov/hanford
Event by event
1 dense fog. Local standard time, as filed.
What these are
- Dense Fog
- Fog reducing visibility to a quarter mile or less, filed where it caused accidents or disruption.
After NWS Directive 10-1605, the rules offices file Storm Data by.
The same day elsewhere
- Winter Storm in Montana, February 5 to 7, 2021
- Extreme Cold in North Dakota, February 5 to 15, 2021
- Winter Storm and Winter Weather in Nebraska, February 5 to 7, 2021
- Heavy Snow and Winter Weather in Montana, February 5 to 8, 2021
- Cold in Montana, February 5 to 15, 2021
- Winter Storm in Nebraska, February 5 to 6, 2021
- Winter Weather in Michigan, February 5 to 8, 2021
- Heavy Snow and High Wind in Colorado, February 5 to 7, 2021
- High Wind in Nevada, February 5, 2021
- Winter Weather in Maryland, February 5, 2021
- High Wind in Texas, February 5, 2021
- Marine High Wind in Lake Erie, February 5, 2021
More
Every storm in California in 2021Every state in 2021This day in weather historyWarnings in California, February 2021
Sources
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: 931903.