Lightning, rain, and Red Flag Warnings in parts of California

lightning California
Lightning during the 24-hour period ending at 7 a.m. PDT August 24, 2020. The yellow strikes are the most recent.

So far the thunderstorms that Californians were worried about that could ignite even more wildfires did not have much effect in the Bay Area overnight. But lightning strikes were detected in the Sierras along with rain — none, or less than 0.05 inch generally, but some locations received more, as is the nature of thunderstorms.

In the Bay Area there is still a chance of thunderstorms Monday morning, with decreasing chances in the afternoon.

Precipitation California
Precipitation during the 24-hour period ending at 7 a.m. PDT August 24, 2020.
Red Flag Warnings for August 24, 2020 fire
Red Flag Warnings for August 24, 2020.

Predicted dry lightning could worsen the fire situation in California and other western states

Red Flag Warning in effect for Northern California Sunday and Monday

August 24, 2020 | 7:45 a.m. PDT

Map fires California Bay Area
Map of fires in the California Bay Area, August 23, 2020.

As if firefighters and residents evacuating or battling lightning-caused wildfires in California didn’t already have enough to worry about, another round of dry lightning is in the forecast for Sunday and Monday.

Thunderstorms with little or no rain is what ignited over 500 fires earlier last week. Now scattered or isolated dry thunderstorms could hit northern California and portions of Nevada, Utah, Wyoming, and Colorado through Monday.

Nick Nauslar, a Fire Meteorologist at the National Interagency Fire Center in Boise, wrote about the forecast in a tweet at 11:30 p.m. Saturday:

Hundreds of new fires are likely if this event pans out. And thunderstorm outflow winds will impact some ongoing fires which would lead to an increase of fire spread/behavior. I hope I'm wrong and this forecast busts. But for now, data points to another big event.

So it’s not just the potential for new fires that that is cause for concern — the strong outflow winds associated with the thunderstorms could greatly increase the rate of spread of the existing fires. It can also put firefighters in even greater danger as the winds can shift 180 degrees very quickly changing the direction a fire is moving, possibly overrunning personnel.

(To see all articles on Wildfire Today about the lightning fires in California, including the most recent, click HERE.)

Check out this video showing the effect the passage of a thunderstorm had on the just-ignited Hennessey Fire August 17 in Napa Valley. That fire has now burned 287,811 acres. The effect of outflow winds is temporary, but a blaze that is suddenly much larger can outstrip the ability of firefighters to quickly suppress it.

Red Flag Warnings are in effect for the northern half of California through Monday evening. The highest threat of dry lightning is Sunday afternoon through Monday morning.

With existing shortages of personnel, equipment, engines, and firefighting aircraft, more fires would put further strain on the systems that are already being managed at the highest planning level nationally, Preparedness Level 5. In PL 5 over 80% of the nation’s incident management teams and wildland firefighting personnel are committed to incidents. Resource orders are being prioritized to fires across California and the west.

Aircraft that can map a fire using infrared imagery have not yet flown all of the large incidents and some maps and acreages are estimates. One of the two mapping aircraft owned by the U.S. Forest Service, N144Z which is the most capable, has not successfully mapped a fire since November 16, 2018 because an avionics issue has not been repaired. The Forest Service has hired privately owned mapping aircraft in an attempt to fill the void.

Below are updates on the largest incidents in California.

LNU Lightning Complex

  • Updated August 24, 2020 at 7:38 p.m. PDT
  • Location: North Bay
  • Counties: Napa, Lake, Yolo, Solano, Sonoma
  • Administrative Unit: CAL FIRE Sonoma-Lake-Napa
  • Acres: 350,030. The largest fire in the complex is the Hennessey Fire, 293,602. The Walbridge Fire west of Healdsburg is 54,068, and the Meyers Fire on the coast north of Jenner is 2,360.
  • Structures destroyed: 871
  • Personnel assigned: 1,857
  • Evacuation information:  CAL FIRE LNU Twitter page
  • Notes: Fires that merged to become the Hennessey Fire include Gamble, Green, Spanish, 5-10, Morgan, and Markley Fires.
LNU Lightning Complex map
Map of the LNU Lightning Complex of fires at 9:21 p.m. PDT August 22, 2020.

SCU Lightning Complex

  • Updated August 24, 2020 at 7:44 a.m. PDT
  • Location: South Bay
  • Counties: Santa Clara, Alameda, Stanislaus, Contra Costa, San Joaquin
  • Administrative Unit: CAL FIRE Santa Clara
  • Acres: 347,196
  • Structures destroyed: 12
  • Personnel assigned: 1,336
  • Evacuation information:  CAL FIRE SCU Twitter page
  • Notes: The complex is comprised of approximately 20 separate fires broken into three zones; the Canyon Zone, the Calaveras Zone, and the Deer Zone.

CZU August Lightning

  • Updated August 24, 2020 at 7:44 a.m. PDT
  • Location: South Bay
  • Counties: San Mateo, Santa Cruz
  • Administrative Unit: CAL FIRE San Mateo-Santa Cruz
  • Acres: 74,000
  • Structures destroyed: 163
  • Personnel assigned: 1,511
  • Evacuation information: CAL FIRE CZU Twitter page
  • Notes: The fires continue to actively burn above the marine layer in the heavy timber and thick undergrowth. Damage Inspection Teams have begun to survey areas where fire activity has diminished and it is safe to do so. The number of destroyed structures reflected may change as teams continue to make progress. Firefighting resources are limited due to the number of fires burning throughout California. Limited visibility due to smoke is hampering aircraft operations. Approximately 77,000 people have been evacuated.
Map SCU Lightning Complex and CZU August Lightning Complex of fires
Map of the SCU Lightning Complex and CZU August Lightning Complex of fires at 7:54 a.m. August 23, 2020.

River and Carmel Fires

  • Updated August 24, 2020 at 7:44 a.m. PDT
  • Location: Five miles south of Salinas, near Pine Canyon Rd. and River Rd.
  • Counties: Monterey
  • Administrative Unit: CAL FIRE San Benito-Monterey
  • Acres: 48,424
  • Structures destroyed: 21
  • Personnel assigned: 1,274
  • Evacuation information: CAL FIRE San Benito-Monterey Twitter page, and see maps produced by Monterey County here.
  • Notes: The Carmel Fire 2 miles southwest of the River Fire has burned 6,695 acres and destroyed 37 structures.

Dolan Fire

  • Updated August 23, 2020 at 9:31 a.m. PDT
  • Location: on the coast 10 miles south of Big Sur
  • Counties: Monterey
  • Administrative Unit: U.S. Forest Service, Los Padres NF
  • Acres: 19,287
  • Structures destroyed: 0
  • Personnel assigned: 488
  • Evacuation information:
  • Notes: On private land and the Los Padres National Forest, threatening the communities of Hermitage, Partington Ridge, and Lucia. Multiple businesses, communications sites, parks and recreational sites are also threatened. On Saturday crews continued to focus on point protection operations around Hermitage and Lucia to the South, and Partington Ridge and Anderson Peak communications infrastructure to the North. As the threat diminishes these priorities will shift. After more resources arrive the plan will expand to include additional perimeter control operations. The fire was mapped for the first time Saturday night with a fixed wing aircraft. This accurate method is the reason for the large increase in the known acreage.
River Carmel Dolan Fires map August 22 California
Map showing the locations of the River, Carmel, and Dolan Fires August 22, 2020.

August Complex

  • Updated August 24, 2020 at 7:44 a.m. PDT
  • Location: 18 miles southwest of Red Bluff
  • Counties: Tehama, Glenn, Lake, Mendocino, Trinity
  • Administrative Unit: Mendocino National Forest and CAL FIRE
  • Acres: 177,750
  • Structures destroyed: 10
  • Personnel assigned: 433
  • Evacuation information:
  • Notes: Of the 20 fires in the Complex the two largest are the Doe (136,430 acres) and Glade (13,088 acres). A Structure Damage Assessment Team has been ordered. Limited information is available about this incident.
August Complex Map
August Complex Map, August 22, 2020. Incident Management Team.

Pine Gulch Fire creates lightning and pyrocumulus cloud

North of Grand Junction, Colorado

Lightning on the Pine Gulch Fire
Lightning on the Pine Gulch Fire at 12:47 a.m. MDT August 19, 2020. Image by Grand Junction NSW. White text and arrows added by Wildfire Today.

The Pine Gulch Fire 15 miles north of Grand Junction, Colorado created its own weather very early this morning. It took a combination of several factors, including low relative humidity, an unstable atmosphere, plenty of available fuels (vegetation), and strong outflow winds from a thunderstorm to the north that blew through the fire area between 10:20-10:30 p.m. This caused the fire to increase in intensity and the development of a very large pyrocumulus cloud over the smoke column that created lightning.

Here is the tweet from the National Weather Service that accompanied the image above:

lightning fire Grand Junction Pine Gulch

The Weather Service said the lightning lasted for hours and Grand Junction residents could hear the thunder.

Below is map of the fire showing the perimeter at 1:49 a.m MDT August 19, 2020.

map Pine Gulch Fire
The red line on the map was the perimeter of the Pine Gulch Fire at 1:58 a.m. MDT August 19, 2020. The white line was the perimeter three days before.

The Pine Gulch Fire grew by 37,899 acres on August 18, bringing size up to 125,108 acres.

The Garfield County Sheriff issued new evacuation orders for the northwest side of the Pine Gulch fire August 19.

  • From the Mesa County line north to the east/west Colorado Highway 256 (Four A Ridge Road) including north/south CO Hwy 256. 256/205 moving from pre-evacuation to full evacuation.
  • From Highway 139 Douglas Pass road east to the preexisting evacuation order for Carr Creek Road (207).
  • This includes CO Hwy 205 Salt Wash and Kimball Creek Road (202) on Kimball Mountain.
  • CO Hwy 258/King Road is evacuated.
Pine Gulch Fire
Pine Gulch Fire Tuesday night, August 18, 2020. InciWeb.

Lightning ignites fires in San Francisco Bay Area

August 18, 2020  |  6:14 p.m. PDT

Map of the LNU Complex of fires
Map of the LNU Complex of fires at 2:06 p.m. PDT August 18, 2020.

Most of the wildfires in the LNU Complex were very active Tuesday. Based on data from a satellite at 2:06 p.m. the Del Puerto Fire especially increased in size.

(To see all of the articles on Wildfire Today about the lightning-caused wildfires in California, including the most recent, click HERE.)

Waddle, 5-14, 5-15, and 5-18 fires
Photo from the Black Mountain camera looking southwest, in the general direction of the Waddle, 5-14, 5-15, and 5-18 fires at 5:46 p.m. PDT August 18, 2020.

August 18, 2020  |  7:43 a.m. PDT

map fires bay area california
The map shows heat detected by a satellite on wildfires in the San Francisco South Bay Area at 2:48 a.m. PDT August 18, 2020. The names of some of the fires have changed.

Most of the wildfires that started in the San Francisco Bay area in the last three days that escaped initial attack and were already large by Monday evening continued to grow into Monday night, according to heat data collected by a satellite at 2:48 a.m. PDT Tuesday.

At least 16 fires north and south of Livermore are being managed as one “complex”, the SCU Lightning Complex. SCU is the CAL FIRE unit responsible for the counties of Santa Clara, Alameda, Contra Costa, western Stanislaus, and San Joaquin. Some of the names of the individual fires have changed in the last 24 hours, but the largest blazes in the complex are Marsh, Ohlone, Reservoir, and Del Puerto.

Very little detailed information is available about the individual fires.

The Del Puerto Fire, formerly part of the Canyon Zone Fires, is about 10 miles west of Patterson and about three miles northwest of Diablo Grande. With all the name changes the size is not clear, but it is likely 5,000 to 15,000 acres.

The Ohlone and Reservoir Fires southeast of Fremont are adjacent to the Calaveras Reservoir three to seven miles east of the 680 freeway.

Fires that have been grouped into the CZU August Lightning Complex include the Waddle, 5-14, 5-15, and 5-18 Fires, plus other smaller fires. CAL FIRE says they total about 1,000 acres.

Outside of the South Bay area there are many other fires. Further north there are more than 60 fires combined in Butte and Napa Counties, for example.

There are reports that competition for firefighting resources is intensifying as requests placed by some incident commanders are unable to be filled (UTF). Firefighters in some cases are being asked to work double shifts. This situation is unlikely to improve soon, based on the extraordinary heat predicted for this week.


August 17, 2020  |  7:21 p.m. PDT

map fires bay area california
The map shows some of the significant wildfires that have started in the last few days in the Bay Area. Updated August 17, 2020 with satellite heat data from 2:24 p.m.

The map above is an updated version of the one below. The satellite heat data from 2:24 p.m. August 17 shows that the Canyon Zone Fires are growing rapidly toward the southeast and the west.

The Deer Zone Fire west of Los Vaqueros Reservoir was also active on the south side, but not to the same degree. It was mapped at 1,161 acres.

The Marsh Fire east of Milpitas was active at 2:24 p.m. Monday and has burned 1,775 acres.

The three fires oddly named 5-14, 5-15, and 5-18 did not create enough heat to be picked up during the latest satellite overflight at 2:24 p.m. Monday. They are about 5 miles east of Pescadero.


August 17, 2020 | 4:14 p.m. PDT

map fires bay area california
The map shows some of the significant wildfires that have started in the last few days in the Bay Area. Updated August 17, 2020. Red and yellow dots indicate heat detected by a satellite.

A rare series of intense summer thunderstorms passed through the San Francisco Bay Area Sunday morning and Monday morning. Some of the cells passed through so quickly there was little chance for precipitation.

lighting strikes 48-hour period california bay area
Lightning strikes during the 48-hour period ending at 12:59 p.m. PDT August 17, 2020. The yellow strikes are the most recent.

Numerous wildfires ignited and while not all of them have been investigated, lightning is the likely cause for many. Combined with winds that accompanied the storms with gusts of 50 to 70, very high temperatures, and a Red Flag Warning, there are so many fires now that they are difficult to track, at least from this writer’s vantage point.

The southern Bay Area has quite a few and there are others in the North Bay and Napa area.

There is competition for firefighting resources. Some of the incident commanders placing orders for aircraft, dozers, engines, or crews are at times being told that a particular order can’t be filled at that time, or there may be a lengthy delay.

From the Washington Post:

In California, the heat resulted in scores of record highs over the weekend including around Los Angeles, the San Francisco Bay area and Sacramento. Early Sunday morning, a bizarre “heat burst” raised the temperature 20 degrees in two hours in Fairfield, about 40 miles northeast of San Francisco. The temperature shot from around 80 to 100 degrees in the hours around sunrise.

The National Weather Service in San Francisco issued an unusually large severe thunderstorm warning that covered more than 7,000 square miles from Monterey Bay to the Bay Area and north into Napa Valley. The office warned of “erratic outflow wind gusts of 50 to 70 mph wind gusts, [and] frequent lightning.” The warning, the largest ever issued by that office, was six times larger than the state of Rhode Island.

“This 20-year forecaster cant recall such a widespread [thunderstorm] event on the heels of such a heat wave,” wrote one meteorologist in the office forecast discussion late Sunday.

We will add to this post later with more details about individual fires.

Almost a dozen new lightning-caused fires on the Modoc National Forest

Originally published at 4:38 p.m. PDT July 23, 2020

Modoc Lightning Fires
Modoc Lightning Fires; satellite heat data from 12:05 p.m. PDT July 23, 2020.

In the last 48 hours firefighters have discovered at least 11 lightning-caused fires on the Modoc National Forest in northeast California.

The Caldwell Fire close to Tionesta and southeast of Lava Beds National Monument, has burned 1,500 acres. It was growing rapidly Wednesday afternoon while pushed by winds associated with a thunderstorm.

(To see all articles on Wildfire Today about the Caldwell Fire, including the most recent, click here.)

The Allen Fire in a difficult to access area near Allen Butte was last reported at 800 acres. Smoke jumpers and other crews are working to keep it south of County Road 85.

The Canyon Fire near Canby Bridge has been contained at 234 acres.

At least eight other fires started by lightning have each burned 0.1 to 3.8 acres.

From the Modoc National Forest:

Quick response from firefighting resources in difficult conditions allowed great progress toward containment and control on fires that have been kept small.

The primary fire response strategy for 2020 in Region 5 [California] continues to be aggressive initial attack, to include using local resources from partners. The primary firefighting goal is rapid containment to minimize the number of large wildfires.

Caldwell Fire Modoc National Forest
Caldwell Fire on the Modoc National Forest, posted to InciWeb July 23, 2020.

Recent lightning could lead to new wildfires in several northwestern states

Originally published at 3:18 p.m. PDT July 23, 2020

lightning 48 hour period map
Lightning during the 48-hour period ending at 2:29 p.m. PDT July 23, 2020. The red areas are the most recent.

During the last 48 hours thunderstorms with lightning moved across several states in the northwest leading to the possibility of new wildfire ignitions. Most heavily affected were northern and northeast California, southeast Oregon, the south half of Idaho, and western Montana. Precipitation accompanying the cells was spotty.

precipitation 48 hour period
Precipitation during the 48-hour period ending at 2 p.m. PDT July 23, 2020. NWS.