USFS (Los Padres) Fire weather indicies

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SLOweather

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I'm looking for the definitions of the actual fire weather indicies that LPNF dispatch reads off during the afternoon update. I have an interest in weather and fire weather indexes, and would like to know which ones these refer to, and their meanings.

Does anyone have any pointers?
 

SCPD

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A summary of all the fire weather observation sites nationwide can be found at this link: http://www.fs.fed.us/land/wfas/fdr_fcst.dat

With the definitions in the link Selgaran provided you and the summary, you should be set. These induces are part of the data used to forecast fire behavior, which is a very complicated science. The daily "adjective rating" of fire danger into low, moderate, high, very high, and extreme is not a seat of the pants estimate. It is based on a lot of data gathering.

One thing you might notice is that a particular burning index may lead to an adjective rating of moderate in one location and another rating, perhaps low or high, in another location. This is because of differences in what is called the fuel model. Fuel models are general in nature and are an attempt to categorize areas into a set number of models based on vegetation type and the typical fuel loading (how much fuel is present). So you might have a "Ponderosa pine/grassland" fuel model or an "oak/chemise" fuel model. It takes a higher number to reach a given fire danger adjective in the lower elevation, lighter fuel models. For example a burning index of 75 might only rank as a moderate in grassland fuels, but could rank as a very high in higher elevation forest fuels.

Here are some additional sites to look at for fire weather information:

http://gacc.nifc.gov/oscc/predictive/weather/index.htm

This first one gives you a lot of information specific to weather forecasting in the Southern California Geographic Area Coordinating Center (GACC). There are 11 GACC's around the country whose function is to coordinate all the use of wildland fire resources in the area. Weather forecasting is organized within each GACC.

http://gacc.nifc.gov/oscc/predictive/weather/California_2008_AOP.pdf

It is impossible to decipher what is being said about the weather and the various indicies unless you know what weather zone is involved. The link above has maps on pages 7 and 8 that shows these zones statewide. Someplace in each GACC site for California are maps that show these zones in more detail. I can't find that link right now. This operating plan also contains quite a bit of information that helps in understanding what is involved in making assessments of fire weather and it is conveniently in one document.

http://gacc.nifc.gov/

This is the index for the 11 GACC's nationwide. As you can see California is the only state with two GACC's. Most of the remaining GACC's cover more than one state, the exceptions being Alaska and Nevada where there is one GACC for each state.

http://www.wfas.net/

This is another site you might want to look over. It is the home site of the Wildland Fire Assessment System.

Are the other National Forests broadcasting a project activity and sale activity level rating where they pronounce the project rating with the international phonetic alphabet and the sale activity level with a number? They do so for each zone on both the Inyo and Sierra National Forests, both of which I can monitor from my location. You might hear them say "Project Activity for Area 532 Echo Victor/Echo Victor, 534 Charlie/Delta" and "Sale Activity Level for Jerseydale" (a fire station) is a 3." This is done during the reading of the afternoon weather, that is usually done around 4 p.m.

http://www.fs.fed.us/r5/sanbernardino/conditions/

At the bottom of this page there is a very brief explanation of what the various levels are.

http://www.fs.fed.us/r5/eldorado/documents/dispatch/pal_level.pdf

This document shows the project activity levels in more detail.

For those of you that have been hearing these levels being broadcast and had no idea who to ask about deciphering them, you have been provided with all the information you need. I think I will start a separate thread on this topic to see if other National Forests are broadcasting this information during the 1600 weather.

SLOweather, this should give you enough reading to last for quite some time. Fire weather is a fascinating topic, just one topic of many in the field of fire behavior.
 

SLOweather

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Thanks for all that, Exsmokey. That's exactly what I was looking for. I will be exploring all of it. Being interested in weather (running www.sloweather.com for 10 years), and living in a wildfire prone area, I've developed an interest in fire weather indicies and forecasting. And then hearing the morning and afternoon briefigs on the scanner additionally piqued my interest.

I've written PHP scripts to calculate and display my local Chandler, Fosberg, and Angstrom indicies, Equilibrium Moisture Content, Keetch-Byram Drought Index, and, for fun, the Nesterov index. I'd forgotten about the various fuel models.

Also been working on the Canadian Fire Weather Index, but it's really involved (35 equations or so).

Thanks again!
 
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