Tag: weather

Simulation shows winds near origins of Oct. 8 fires in Northern California may have been 75-90 mph

wind simulation october 8 fires northern california

“Hurricane force” winds, according to the National Weather Service, are sustained winds or frequent gusts of 74 mph.

Triple-digit temperatures in Southern California

Extreme temperatures Southern California

Above: Extreme temperatures in Southern California Tuesday afternoon, October 24, 2017.

(Originally published at 2:05 p.m. PDT October 24, 2017)

Weather conditions appear conducive to wildland fires in Southern California today. The temperature even reached 96 degrees on San Clemente Island, and triple digits in some inland areas. Meanwhile, it’s only 93 in Phoenix.

red flag weather conditions — Weather conditions at 2:27 p.m. PDT October 24, 2017 in Southern California.

Red Flag Warnings and Fire Weather Watches , October 24, 2017.

Traffic sits at a stand still on the 210 east at the 15 as firefighters battle a brush fire northwest of the interchange. pic.twitter.com/tNmq90E1kR

— Jennifer Maher (@JCMaherPhoto) October 24, 2017

Red Flag Warning weather

Spectacular weather, time-lapsed

This film can be a learning opportunity for firefighters.

Arizona weather

Officials investigating the roles of wind and power lines in Northern California wildfires

There is no doubt that after numerous wildfires started Sunday night October 8 north of San Francisco the very strong winds caused them to spread so rapidly that there is no way firefighters could put them out before they grew large. There are reports that the Tubbs Fire between Santa Rosa and Napa burned about 20,000 acres in a few hours.

Many power lines blew down or sparked as electrical conductors brushed together in Sonoma and Napa Counties.

According to the Mercury News:

Emergency dispatchers in Sonoma County received multiple calls of power lines falling down and electrical transformers exploding. In all, according to a review of emergency radio traffic by the Bay Area News Group, Sonoma County dispatchers sent out fire crews to at least 10 different locations across the county over a 90-minute period starting at 9:22 pm to respond to 911 calls and other reports of sparking wires and problems with the county’s electrical system amid high winds.

Officials have not released the causes of most of the fires, but the stock price of Pacific Gas and Electric which supplies electrical power to much of the area dropped 22 percent last week.

Stock price of PG&E, last two years. CNBC graphic.

On Monday the Cliff Mass Weather and Climate Blog, an excellent source for in-depth analysis of weather events, looked at the conditions that led to the extreme winds when the fires started. Here is an excerpt:

…Although there have been a lot of media reports about windy conditions, few have described the extreme, often unprecedented, nature of the winds on Sunday night and Monday morning (October 8/9th). Some have even mocked PG&Es claims of hurricane-force winds, suggesting wind speeds of 30-40 mph.

Let’s clarify a few things. There was a wide range of winds that night, with the strongest winds on ridge tops and on the upper lee slopes of terrain. Some winds was startling.

For example, at 10:30 PM on 9 Oct 2017 the wind gusted to 96 mph on a 3400 foot peak NE of Geyersville, about 20 miles NNW of downtown Santa Rosa. They reported sustained 74 knots (85 mph). Those are hurricane force winds (sustained of 64 knots or more).

At the Santa Rosa RAWS station (U.S Forest Service and Bureau of Land Management) at 576 ft elevation, the wind accelerated rapidly Sunday night to 68 mph.

wind forecast northern california fires — Desert Research Institute’s forecast model (WRF) at very high resolution (2-km grid spacing). This is their 6-hour forecast for sustained surface winds at 11 PM Sunday October 8. Click to enlarge.

San Diego Gas and Electric (SDG&E) is still battling over who will pay for the destruction, the company or their customers, caused by the Witch Creek, Guejito, and Rice Canyon fires in 2007 that started from issues with their power lines. The fires destroyed more than 1,300 homes in southern California, killed two people, and caused massive evacuations. The Witch Creek Fire alone, which started near Santa Ysabel, burned 197,990 acres.

In 2009 SDG&E proposed to implement a system of completely turning off power preemptively to areas where very strong winds are predicted.

California PG&E power line SDG&E tubbs fire weather

Wildfire potential, October through January

On October 1 the Predictive Services section at the National Interagency Fire Center issued their Wildland Fire Potential Outlook for October through January. The data represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit.

If the prediction is accurate, October should see higher than normal wildfire activity in the northern Rockies and along the California coast.

Below are:

The highlights of the NIFC report;
NIFC’s graphical outlooks for September through November;
NOAA’s long range temperature and precipitation forecasts; and
Drought Monitor

“Abundant rain and mountain snowfall across the Pacific Northwest, Northern Rockies, and Great Basin in mid-September ended the record dry conditions and brought fire danger indices down to seasonal levels entering October. While drought conditions continue across these areas, short-term fire impacts have been minimized. The Southeast continued to receive sufficient moisture, keeping the region at low potential for wildfire. Temperatures were above average for the month across the West. However, there was a significant cooling occurred with the mid-month rain and snow. By month’s end, temperatures had returned to average levels. In the East, temperatures were generally below average.

“Three historically significant weather events occurred during the month. Hurricane Harvey made landfall on the Texas Coast, dropping 45 to 50 inches of rain and producing catastrophic flooding in southeast Texas, including the Houston area. Hurricane Irma battered the U.S. Virgin Islands and Puerto Rico before making landfall in Florida as a major hurricane. Hurricane Maria crossed Puerto Rico with strong winds and considerable flooding, causing catastrophic damage to the island.

“Weather patterns along the West Coast allowed fuels to dry and become receptive to fire should events arise. October marks the beginning of the fall fire season in California as the state becomes susceptible to offshore winds. Events are typically multi-day in duration and vary in intensity. Indicators suggest that this could be an active season for the development of these events during October and November before the state exits its season in December. The fall is also typically a peak in fire activity for the Southeast. While normal significant fire potential is expected for most areas during this outlook period, the Southeast will need to be monitored for above normal conditions and activity in November.”

potential weather

Rain and snow affect some fires in the Northwest — but not all

Wildfires are still active in California, Oregon, Washington, and northwest Montana. Red Flag Warning for northern Nevada.

Blacktail Fire Crucifixion Creek Fire Montana Oregon Red Flag Warning weather

Looking back at NIFC’s June prediction for August-September wildfire activity

At the beginning of the month here on Wildfire Today we usually summarize the National Interagency Fire Center’s (NIFC) monthly prediction of wildfire potential for the next three to four months. Their analysis represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit.

The primary variable factors that affect large scale wildfire activity are the condition of the fuel (vegetation) and the weather when the fires ignite and continue to burn. In the western United States the amount of the lighter fuels available, such as grass, is affected by the precipitation in the winter and spring. That same precipitation also affects the amount of moisture in the live fuels as well as the dead and down duff and woody material.

Another factor that we have often said is even more important than conditions in the winter and spring is the weather DURING the fire season. In the West if the summer is relatively cool and wet, the fire activity will be less intense than average. On the other hand, a hot, dry summer can lead to more acres burned than normal — in spite of the winter/spring weather.

When someone asks me during the first six months of the year for my prediction of the coming Western fire season, I will tell them to ask me again in August.

This year many areas in the West had unusually high amounts of rain and snow over the winter which might have led some prognosticators to assume there would be fewer fires in the summer. But that has not been the case.

Nationally, according to NIFC, 8.4 million acres have burned so far this year, which is 47 percent higher than the 10-year average to this date. Montana, which accounts for 1.2 million of those blackened acres, has been a focal point for seemingly endless fires producing staggering quantities of smoke. Combined with the smoke created by other fires in Idaho, Oregon, Washington, and northern California, the fouled air has affected residents across large sections of the country.

A spokesperson for Montana’s Department of Natural Resources and Conservation, Angela Wells, said “the period from June to August was the hottest and driest on record in Montana, and our fire season started about a month earlier than it usually does.”

It is extremely difficult to accurately predict the weather more than three or four days in advance. Attempting to forecast wildfire activity three or four MONTHS out, takes audacity. On June 1 NIFC produced the following graphic as part of their monthly report, illustrating their prediction for “normal” fire potential in Montana, Idaho, Washington, Oregon, and extreme northwest California.

As we now know, those areas had a very active summer fire season. The map below shows in red, heat on fires detected by a satellite on August 31, 2017.

wildfires map satellite heat — Fires detected by a satellite on August 31, 2017.

Here is an excerpt from NIFC’s analysis that was published on June 1, 2017:

Above normal precipitation and soil moisture is leading to a robust green-up across the West. Overall cooler than average temperatures and a heavy snowpack have led to slower than normal melting of the mountain snowpack in nearly all locations across the West. This should lead to a delayed start to the fire season in the higher elevations which may, in turn lead to a compressed season…

Above normal large fire potential will continue across southeastern Georgia and Florida into mid-June before the cumulative effects of precipitation events begin to take hold. Below Normal potential is expected across most of the remainder of the southeast through July before returning to Normal for August and September. Recent dry conditions across the southwest will lead to Above Normal potential across southeastern Arizona and Southern California. Below Normal to Normal large fire potential is also expected in the a majority of the higher elevations across the West in June and July.

July and August may be periods of concern. Above Normal potential is expected across the western portion of the Great Basin and across the middle elevations in California in July and August after the abundant grass crop cures. Fire activity will be mostly driven by short term weather events.

Below is the Drought Monitor from August 29, 2017: