Fire Weather

by Phillip Manuel

The drought, which persisted through the winter months, brought some attention to our fire weather program in February. On Sunday, February 10th, there was a high wind event that triggered an onslaught of fire activity across the Mid-Atlantic Region. Before going into any grave detail about the event, I would like to first introduce you to our Fire Weather Program, since its something that we have not written about in our past NOAA ‘Bout Weather articles.

The National Weather Services (NWS) Fire Weather Services Program is managed under its Office of Climate, Water and Weather Services, Fire Weather Services Branch. The Program objective is to provide fire weather products and services to the fire and land management community for the protection of life and property, promotion of firefighter safety, and stewardship of America’s public wildlands. The program is recognized at all National Weather Service offices, including Blacksburg, but is more publicly known in the Western United States, where fires grow extremely large and affect a lot of communities.

Fire behavior, like the weather, can be hard to predict, and for good reason. Fire behavior is highly dependant on the weather, especially when it is windy and dry, like it was this past February. As a result, the land management agencies depend on our weather forecasts in order to make accurate fire behavior forecasts. With this information, a prediction can be made where an existing fire will burn today, tomorrow, or the next day. A lot of fire management planning revolves around the fire weather forecasts that are provided by this office.

When is fire activity the highest in the Mid Atlantic Region? To answer this, I reference you to a graph showing the number of specialized fire forecasts that we have created over the last 4 years (figure 1). The graph clearly shows a large number of site specific forecasts generated during the spring, and a secondary flurry of activity in the fall.  From this it can be said that most of our wildland fire activity occurs in the spring (February 15 - May 15), with a secondary peak in the fall (October 15 - December 15). These are the dates that we speak of when we refer to our spring and fall fire seasons.  Keep in mind that wildfires can occur anytime of the year, but their occurrence is more frequent during the transitional seasons. An example of high fire activity occurring outside of these normal seasons occurred this past year (2007), when fires were observed during the late summer. Lightning from thunderstorms sparked fires which persisted for several weeks due to the ongoing drought.

 

Graph showing a monthly depiction of site specific forecasts (SPOT forecasts) for the Blacksburg Service area for the years 2004 through 2007.
Figure 1. Graph showing a monthly depiction of site specific forecasts
(SPOT forecasts) for the Blacksburg Service area for the years 2004 through 2007.

 

The spring fire season typically begins with the increasing sun angle and warming temperatures, and ends with “greenup,” when the grass turns green and the trees become full with foliage. The fall fire season typically begins with leaf fall in mid October, and ends with the first snow or long duration rain event that saturates the ground. During drought years, these seasons can be extended. Drought results in drying of forest fuels that would not normally burn during a normal fire season. These fuels include large downed limbs, logs, and subsurface fuels such as roots and duff of the forest floor. Live fuels can also readily burn during a drought, such as mountain laurel and pine. As a result, crown fires can occur, where fire spreads through the crowns of the trees. An example of this occurred in Pittsylvania County on September 12, 2007 (figure 2).

 

This fire (known as the Woodview Fire) was started around 1300 LST on 9 September, 2007, by a land owner burning brush
Figure 2. This fire (known as the Woodview Fire) was started around 1300 LST on 9 September, 2007,
by a land owner burning brush. The fire escaped into an 8-12 year old pine plantation. This picture was taken
by a local news crew at around 1600 LST. Note the active Crown Fire.


For our local region, the drought which began in early 2007, persisted through the fall and into the winter months of 2008. This put our local fire weather program in the lime light in February when we experienced a long duration high wind event on February 10th.

On that Sunday, sustained winds of 25 to 40 miles an hour with gusts of 60 to 70 mph were observed for a 6 to 8 hour period of time. These strong winds downed power lines which sparked numerous fires across the region. In Virginia alone, the Virginia Department of forestry responded to 387 fires, which burned around 16,000 acres, damaged or destroyed 9 homes and 21 other structures. These numbers are still preliminary and do not include local response from the Volunteer Fire Departments.

 

On February 10th, and the days that followed, fire fighters responded from multiple states to combat the fires. Federal and State incident management teams were formed to combat the larger fires, some of which grew several thousand acres in size. These larger fires persisted for 4 to 10 days before they could be contained. A rain and freezing rain event that occurred on February 12th and 13th aided in the containment efforts.

During this week of fire activity, the Blacksburg NWS, provided numerous fire weather site specific forecasts. Onsite weather support was provided to the federal teams, where we sent an incident meteorologist to work as a weather specialist to support the planning for the fire fighting efforts.

Photo was taken from Montvale, Virginia, of the Blackhorse fire
Figure 3. Photo was taken from Montvale, Virginia, of the Blackhorse fire which grew to 1488
acres, threatening homes and resulting in evacuations ( 2/12/2007). The top of the ridgeline
in the background is the Blue Ridge Parkway.

 

 

Incident Command Post Photo
Figure 4.  Photo was taken from inside of the incident command post that was set up in the
old Montvale elementary school, used to coordinate the fire fighting efforts of the Blackhorse
Fire (2/13/2007).  The fellow in the white ball cap sitting next to the back wall is a National
Weather Service Incident Meteorologist, working from a laptop to obtain weather information
used by the incident management team.

 

In closing, I would like to invite anyone who is interested in fire weather to check out our Fire Weather Web Page.

 

Phillip Manuel
Fire Weather Program Leader
NWS Blackburg