Category: Wildfire

7:51 a.m. PDT August 26, 2021

The northeast side of the 136,000-acre Caldor Fire 12 miles southwest of Lake Tahoe was active Wednesday night. The fire added about 10,000 acres over the last 24 hours. The spot fire north of Highway 50 has continued to spread east, growing to approximately 2,600 acres. The photo below was taken in that area.

To see all articles on Wildfire Today about the Caldor Fire, including the most recent, click HERE.

The weather forecast for Thursday predicts 7 to 8 mph winds out of the southwest and northwest with relative humidity in the teens. Friday will be about the same but with lower humidity. These conditions will allow the fire to keep spreading.

Resources assigned as of Wednesday evening included 243 fire engines, 27 water tenders, 21 helicopters, 80 hand crews, and 51 dozers for a total of 2,897 personnel.

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Firefighters on the 126,000-acre Caldor Fire are hoping to slow the spread with extensive use of dozers. They are constructing firelines out ahead from which they plan to ignite backfires or other burning operations. This will remove the available fuel so that when the fire reaches those barriers it will stop, at least at those locations.

The fire is still about 14 miles southwest of Lake Tahoe.

On the map below produced by the Incident Management Team the “xxxxxx”  indicates dozer lines completed at the end of the day August 24. Crews are working on extending these lines and tying in the various segments. Air tankers are slowing the spread on the northeast side in Division J to give the dozers time to complete the lines.

On Wednesday the fire primarily spread to the northeast along Highway 50 toward Twin Bridges. Firing operations continued on the southwest side but were slowed by numerous small spot fires that were quickly extinguished. The north side of the fire is backing downhill to the north toward Highway 50 achieving results not unlike a well-planned prescribed fire.

The spot fire across Highway 50 has grown to about 2,000 acres and spotted to the east across Wrights Lake Road.

The weather conditions recorded at Barney Ridge were moderate in the afternoon with 5 to 8 mph winds gusting at 12 to 16 mph out of the southwest while the relative humidity was around 20 percent. The forecast for Thursday is for 8 to 11 mph winds out of the west with humidity in the mid-teens.

The fire has destroyed 465 residences and 178 other structures. The El Dorado County Sheriff in collaboration with CAL FIRE has released a map displaying properties that have been inspected for any damage or that have been destroyed by the Caldor Fire.

Continue reading “Firefighters on Caldor Fire concentrating on dozers and firing operations”

In order for the spread of the 117,000-acre Caldor Fire to stop or to be suppressed by firefighters, something will have to change — either the weather or the fuel.

If the relative humidity stayed above 40 percent and the wind speed was less than five mph, it might lose enough intensity to allow firefighters on the ground and in the air to take direct action on the flanks. But there is no sign of that happening this week.

To see all articles on Wildfire Today about the Caldor Fire, including the most recent, click HERE.

Let’s look at the fuel, which is the primary driver of this fire.

From the Incident Management Team:.

There is a heavy dead and down component with drought-stressed fuels. Live fuels are cured to levels normally seen in late September, and fuels are extremely receptive to spotting. Fuel moistures are historically low. Northern California remains under a Fuels and Fire Behavior Advisory. ERC’s are above the 97th percentile. 100 hr and 1000hr fuels are below [3 percent fuel moisture].

The predominant direction of spread has been to the northeast or east-northeast. If it continues in that direction for the next 10 miles it will not encounter the footprints of any fires that have burned in the last 21 years large enough to have a significant effect on the spread. Just beyond that distance on the north side of Highway 50 is the 2007 Angora Fire southwest of South Lake Tahoe.

North of Highway 50 four miles northeast of the location of the fire Monday night there is a large rocky area several miles across with sparse fuel. It is north of Twin Bridges and west of Fallen Leaf and could slow the fire in that location, but there’s no guarantee that it can’t find a way to burn around, through, or over it. Spot fires have been igniting a mile out in front; one was 1.8 miles.

Another fuel-related factor to consider is the fuel treatments that have been accomplished over the years, shown in green on the map above. The Caldor Fire has already burned across dozens, and it will be interesting to find out if they had the intended effect. There has been a great deal of fuels work in the South Lake Tahoe area.

A reduction in the volume of vegetation resulting from a fuels project in most cases is not expected to stop a high-intensity wildland fire. At best in those areas the fire may spread more slowly and perhaps throw out fewer burning embers.

But by far the best protection for structures is make them as fire resistant as possible, including the envelope of the structure itself — the roof, vents, siding, doors, windows, foundation, fences, eaves, and decks. A FEMA publication (13 MB) has excellent detailed recommendations. And in the Home Ignition Zone the NFPA and FireWise programs recommend reducing flammable material within 100 feet of structures and spacing the crowns of trees at least 18 feet apart that are within 30 feet of the home, 12 feet apart at 30 to 60 feet, and 6 feet apart at 60 to 100 feet. Another house that is 15 to 50 feet away is also fuel, and if it ignites will be a serious threat.

The LA Times (subscription) published an excellent article August 21 about rethinking forest management — the effects of logging and prescribed fire, and learning to live with fire.

10:21 a.m. PDT August 24, 2021

The Caldor Fire grew by about 10,000 acres Monday under the influence of a 6 mph wind gusting out of the south, southwest, and west at 8 to 15 mph while the relative humidity was in the high 20s. Most of the activity was on the southeast and northeast sides. So far crews have been able to keep it south of Highway 50 except for a spot fire near Granite Springs Road that has burned several hundred acres. During a Monday night mapping flight the fire was about two miles southwest of Sciots Camp and 14 miles southwest of Lake Tahoe.

The fire was mapped Monday night at 117,000 acres.

Monday night fire activity moderated overall, but with some small spot fires and significant terrain-driven runs on the southeast side. Humidity recovery allowed crews to engage in direct control tactics and to continue indirect line construction.

To see all articles on Wildfire Today about the Caldor Fire, including the most recent, click HERE.

The Incident Management Team (IMT) reported Monday that in three or more days the following areas have the potential to be threatened: Silver Lake, Kit Carson, Plasse, Kirkwood, Twin Bridges, Sierra-at-Tahoe, Caples Lake, and the Lake Tahoe Basin.

Monday the IMT identified a long list of “critical resource needs” requested by today, Monday, including 330 engines, 60 hand crews, 17 Division Supervisors, and 40 other overhead personnel.

The weather forecast predicts very challenging conditions for firefighters over the next two days — strong winds Tuesday afternoon, 13 mph gusting out of the south-southwest at 20 mph, with 30 percent relative humidity and 70 degrees. Overnight the wind will slow to 6 mph from the southwest, then increase again Wednesday, 14 to 17 mph gusting up to 26 mph from the southwest with the RH in the low 20s.

This weather combined with the historically low fuel moistures could result in very significant growth of the fire Tuesday and Wednesday.

Damage inspections are in progress with approximately 40 percent of the current fire perimeter having being inspected. Crews have documented the destruction of 455 residences and 11 commercial structures. On the list of structures destroyed are one school, a church, a post office, and two fire stations (Grizzly Flats Forest Service and Pioneer Fire Dept. Station 35). PG&E currently has about 3,000 customers without power.

The El Dorado County Sheriff in collaboration with CAL FIRE has released a map displaying properties that have been inspected for any damage or that have been destroyed by the Caldor Fire.