CZU Lightning Complex, West Central California

The Warrenella Fire and the Waddell Creek Fire as well as additions smaller fires would combine together to become what is known as the CZU Lightning Complex. While this fire burned for 37 days, the destruction it left in its path was extensive. But how well was this event messaged by NWS San Francisco/Monterey (NWS Bay Area) ahead of the event?

Central California west from no drought concerns at the beginning of January to a moderate drought by the middle of August. Let's look a little closer at the months before the Big Event with data collected at the Bend Lomond RAWS station in the Santa Cruz Mountains, which happened to be in the center of the area that burned. The time frame looked at was January 1st through August 15th.

The average high temperature was 78.3° (4.8° above normal).

The average low temperature was 44.7° (0.9° above normal).

The total precipitation that fell for 2020 was 11.21 inches, which is 20.44 inches below normal.

The lack of precipitation in the Santa Cruz Mountains was apparent as trees and underbrush continued to dry out. With records dating back to 1937, this was the 18th driest record with dates ranging from January 1st through August 15th.

• August 16: Fire Reported
• August 17: 1,000 acres (Evening Estimate)
• August 18: 7,500 acres (Evening Estimate)
• August 19: 10,000 acres (Evening Estimate)
• August 20: 40,000 acres (Morning Estimate)
• ....
• August 23: 78,000 acres (Morning Estimate)
• ...
• September 22: 86,509 acres (100% Contained)

The NWS Bay Area office issued a Red Flag Warning for much of the area starting during the night on August 16th. While the fires started during this Red Flag Day, windy conditions on August 19th along with another Red Flag day on August 23 would be the allow for the main spread of the fires.

As August 16th approached, the NWS Bay Area office began to ramp up messaging 24 hours in advance due to increasing chance of dry lightning and erratic winds and low humidity levels. This included the following.

• August 15th at 2:19 AM PDT: Fire Weather Watch issued for Fire Weather Zone 512. Light winds except for breezy onshore winds with humidity as low as 10% with poor overnight recoveries. High based, fast moving storms will lead to a risk of isolated dry lightning strikes through the period.
• August 15th at 10:27 AM PDT: Red Flag Warning issued for Fire Weather Zone 512. Light winds except for breezy onshore winds with humidity as low as 10% with poor overnight recoveries. Thunderstorms are forecast to develop over the South Bay and Santa Cruz region before midnight and then spread northward overnight. Not all locations will see thunderstorms but any lightning strikes will likely lead to new fire starts given the current heat wave. Increase in wildfire starts in proximity to thunderstorms due to lightning. Fires may spread rapidly due to dry fuels and, if nearshore, breezy onshore winds.

NWS Bay Area did a great job making sure that the public was aware that conditions were about to change as thunderstorms over the ocean moved onto land. With how dry and exceptionally warm the area had been, there was concern over dry lightning.

Fires don't have to start during the day. In the case of the CZU Lightning Complex, lightning strikes started 7 new fires in San Mateo and Santa Cruz Counties overnight. This was the beginning of what would be the CZU Lightning Complex.

As day broke, smoke was visible on the cameras south of San Francisco. They were small for the time being but that was about to change.

NWS Bay Area made a post about where lightning strikes occurred from 5 AM on August 16 to 2 PM. The purple on the map below is the negative strikes while the red is positive. Studies have shown that fires are more likely to start from positive strikes than negative.

The fire grew to 1,000 acres on the morning of August 18th with 0% containment.

The first evacuations were issued on August 18th as the fire grows to 1,000 acres.

This wasn't the only fire complex that started from lightning on August 15th and 16th. Also burning in the region was the LNU Complex, the SCU Complex, Carmel and River Fires. This was stretching resources thin across central California.

It took a few extra days to get posted but a firefighter on the CZU Complex filmed a video while on Highway 236 in the Big Basin Redwoods State Park on August 18th.

Explosive growth of the fire was observed as firefighters continued to battle the blaze due to gusty winds along the coast.

Winds were forecasted to increase throughout the day on August 19th, which would help spread the fire quicker than firefighters were able to battle it.

The first fatality was reported on August 19 as 73-year-old Tad Jones of Last Chance. He was found a distance from his home and is believed to have been unable to escape. Learn more in the article below.

As the fire continued to rapidly spread, highways were jammed as people scrambled to evacuate the Santa Cruz Mountains. Overnight, the fire would grow 30,000 acres.

GOES17 is a newer satellite used to enhance forecasters abilities to monitor ongoing situation. Satellite is not only used for severe weather but can be used to track fire hot spots. You can also see NWS Bay Area talking about a mesosector. There are currently 4 mesosectors that NWS can move that allow specified areas to view one minute data rather than 5 minutes. That can make a world of difference when changes are occurring quickly.

Jeff Northam evacuated his home on August 18ths and when he returned to his house the next morning, he found that everything had been destroyed.

Updated information was provided on the morning of August 20th after the winds caused the fire to increase to 40,000 acres, up 30,000 from the report the morning before.

NWS Bay Area provided information that another round of dry thunderstorms was possible from August 23 to the 25th. This could bring erratic winds that could help fuel the fires.

77,000 people were evacuated after the first wind event that caused the fire to rapidly grow.

NWS Bay Area put together an informative video for the public about what would occur on August 23rd and 24th.

The windy conditions along with thunderstorms caused the fire to grow from 40,000 acres to 71,000 acres by the afternoon of the 23rd.

Damage was extensive for many communities in the Santa Cruz mountains including the communities of Boulder Creek, Bonny Doon, Swanton, and Last Chance. Many historic buildings were destroyed within the State Parks. View the application below from Cal Fire on more specific damage information.

Struggles continue for those whose homes were destroyed from the CZU Complex. As of the end of February, many were still not able to begin rebuilding due to a lack of water and power resources.

This fire was relentless, moving through HEAVY fuels of a Coastal Redwood Forest in the Santa Cruz Mountains, California. The weather was extremely hot and dry for the coast, with temperatures into the 90s and 100s. The tempo was incredible, combined with the covid regulations and learning curve. It was a very stressful situation. over 1400 homes were lost on this fire.