Space WX Alerts: SUMMARY:  X-ray Event exceeded M5 ( Latest Alert ) - Issue Time: 2024 Apr 11 1727 UTC
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Live FWI10: 2.5
Current Conditions for Foresthill, CA.
Updated4/12/24  8:19am
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This map is not a source of official information. Do not use this map to make important decisions that could result in harm to life or property. Always follow the instructions of local law enforcement and officials. This map is intended only to provide a general awareness of wildfire activity. For official information regarding the incidents shown on the map, please visit VCEmergency.com.


Fire Information - National Fire News

Northern California Preparedness Level 1  

National Preparedness Level 1   

Updated Time: April 5, 2024

Currently, three uncontained large fires are burning in Alabama, Missouri and Florida. Wildland firefighters and support personnel contained 23 large fires this week. 

To date, 8,433 wildfires have burned 1.7 million acres in the United States. The number of wildfires is slightly below the 10-year average, while the number of acres burned more than triple the average. 

The National Interagency Coordination Center predictive services staff released the National Significant Wildland Fire Potential Outlook on April 1. Parts of the Eastern, Rocky Mountain and Southwest areas could see above normal wildfire potential this month

A fuels and fire behavior advisory is still in effect for Northwest Texas, western Oklahoma, southwest Kansas, southeastern Colorado and far eastern New Mexico. Wildland fire personnel should expect extreme to unprecedented fire growth and intensity in these areas. 

Wildfire has shaped out wildland for ages and the animals and plants have adapted to these cycles. People in the wildlands need to understand the natural role of fire and adapt as well. Be Firewise by building homes with fire resistance materials, especially on the roof, and remove flammable materials from around your home. Create fire breaks with lawns, driveways and walkways and stack firewood away from your home. Finally, make sure you address is visible from the road so emergency responders can see it and ensure you have a plan for your family and pets to evacuate when needed. Check out Ready.gov and ReadyForWildfire.org  to help you prepare.

    Please check the IMSR for more information.
    National Weather: April 5, 2024

    Breezy sustained winds of 20-35 mph and gusts of 30-55 mph amid relative humidity of 7-20% will develop across the central and southern High Plains today and Saturday with widespread elevated to critical conditions. Winds will be southerly today and westerly Saturday, with the westerly winds and low relative humidity continuing across portions of the southern High Plains Sunday. A large upper low will move through the southern half of the West this weekend, with widespread showers for much of the West and snow in the mountains. Breezy and dry northwesterly winds are forecast for the Southeast today into Saturday, but concerns will be mitigated due to green-up and recent precipitation. The upper low in the West will move onto the southern Plains early to mid-next week, with widespread rainfall from the southern Plains into the Southeast, including wetting rain for much of the southern High Plains bringing some relief. Periods of light precipitation are forecast next week from the northern Plains to the Northeast as well, but northern Minnesota and North Dakota are likely to remain dry. 

    Local Weather: Friday, April 12, 2024 - 2:30am PDT

    Lightning Ignited Fires

    National Interagency Fire Center statistics show that in 2002-2006, an average of 12,000 (16%) of the wildland fires were started by lightning per year. These fires burned an average of 5.2 million acres per year.

       Two-thirds of lightning fires occur June-August. lightning fires peak in the late afternoon and early evening. Three-fifths (61%) of all fires started by lightning occurred between 2:00 and 10:00 p.m.

       55% of lightning fires occur outdoors, and 41% occur in structures. Deaths and injuries occur mostly in structures (89% and 86%, respectively).

       Because most lightning fires occur outdoors, the most prominent form of material ignited is "growing living form," which includes trees, brush, and grass. Materials found on residential structures that are commonly ignited include roofs, sidewalls, and framing. Electrical wiring is another material often ignited, as the electrical current in lightning is drawn to electrical wires.

       Civilians suffer more injuries than fatalities in lightning fires each year. Most casualties result from lightning structure fires rather than outside or other types of lightning fires. 89% of lightning fire civilian fatalities and 86% of injuries occur in structure fires.

    Potential Outlook Maps

    Fire Potential Outlook

    Significant Fire Potential Outlooks
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    Lightning Probability Forecast Map
    Thunderstorm Probability
    Current Lightning Efficiency Map
    (click to enlarge)

    Lightning Ignition Efficiency

    Lightning fires are started by strikes to ground that have a component called a continuing current. All positive discharges have a continuing current, and about 20% of negative discharges have one. Ignition depends on the duration of the current and the kind of fuel the lightning hits. Ignition in fuels with long and medium length needle cast, such as Ponderosa pine and Lodgepole pine, depend on the fuel moisture. Ignitions in short- needled species, such as Douglas fir depend far more on the depth of the duff layer than on the moisture. Spread of the fire after ignition usually depends on fuel moisture in all cases.

    The ignition efficiency on a 1 km pixel is given on a per discharge basis. That is, if the efficiency is high, then about 9 discharges will result in one ignition; if the efficiency is extreme, about 5 or fewer discharges will result in an ignition. The ratio of positive and negative discharges is built into the calculation. (Latham and Schlieter 1989) document the algorithm.

    The fuel type and depth are conversions of the 1 km resolution current cover type (Hardy and others 1999) for this specific calculation. The moisture input is the 100-hr dead fuel moisture.

    August 2002 - The lightning ignition efficiency algorithm has been corrected due to discovery of an error. The resulting maps reflect higher lightning efficiency than previously.

    Current Lightning Efficiency Map
    Current Lightning Efficiency Map

    Haines Index (Wildfire Potential)

    Haines (1988) developed the Lower Atmosphere Stability Index, or Haines Index, for fire weather use. It is used to indicate the potential for wildfire growth by measuring the stability and dryness of the air over a fire. It is calculated by combining the stability and moisture content of the lower atmosphere into a number that correlates well with large fire growth. The stability term is determined by the temperature difference between two atmospheric layers; the moisture term is determined by the temperature and dew point difference. This index has been shown to be correlated with large fire growth on initiating and existing fires where surface winds do not dominate fire behavior.

    Haines Index is computed from the morning (12Z) soundings from RAOB stations across North America.

    The Haines Index can range between 2 and 6. The drier and more unstable the lower atmosphere is, the higher the index.

    • 2 : Very Low Potential -- (Moist Stable Lower Atmosphere)
    • 3 : Very Low Potential
    • 4 : Low Potential
    • 5 : Moderate Potential
    • 6 : High Potential ------ (Dry Unstable Lower Atmosphere)
    Current Haines Index Map
    Haines Index Map

    Fire Danger Maps

    Each day during the fire season, national maps of selected fire weather and fire danger components of the National Fire Danger Rating System are produced by the Wildland Fire Assessment System (WFAS-MAPS), located at the USDA Forest Service Rocky Mountain Research Station in Missoula, Montana.

    Current Observed Fire Danger Map
    Observed Fire Danger Map
    Current Forecast Fire Danger Map
    Forecast Fire Danger Map
    Current Observed Relative Humidity
    Observed Relative Humidity
    Current Observed Dew Point Levels
    Observed Dew Point Levels
    Current Observed Temperature
    Observed Temperature
    Forcast Wind Speed
    Forcast Wind Speed

    Keetch-Byram Drought Index

      Keetch and Byram (1968) designed a drought index specifically for fire potential assessment. It is a number representing the net effect of evapotranspiration and precipitation in producing cumulative moisture deficiency in deep duff and upper soil layers. It is a continuous index, relating to the flammability of organic material in the ground.

      The KBDI attempts to measure the amount of precipitation necessary to return the soil to full field capacity.

    It is a closed system ranging from 0 to 800 units and represents a moisture regime from 0 to 8 inches of water through the soil layer. At 8 inches of water, the KBDI assumes saturation. Zero is the point of no moisture deficiency and 800 is the maximum drought that is possible. At any point along the scale, the index number indicates the amount of net rainfall that is required to reduce the index to zero, or saturation.

      The inputs for KBDI are weather station latitude, mean annual precipitation, maximum dry bulb temperature, and the last 24 hours of rainfall. Reduction in drought occurs only when rainfall exceeds 0.20 inch (called net rainfall). The computational steps involve reducing the drought index by the net rain amount and increasing the drought index by a drought factor.

    Current - Keetch-Byram Drought Index
    Keetch-Byram Drought Index

     

    • KBDI = 0 - 200: Soil moisture and large class fuel moistures are high and do not contribute much to fire intensity. Typical of spring dormant season following winter precipitation.
    • KBDI = 200 - 400: Typical of late spring, early growing season. Lower litter and duff layers are drying and beginning to contribute to fire intensity.
    • KBDI = 400 - 600: Typical of late summer, early fall. Lower litter and duff layers actively contribute to fire intensity and will burn actively.
    • KBDI = 600 - 800: Often associated with more severe drought with increased wildfire occurrence. Intense, deep burning fires with significant downwind spotting can be expected. Live fuels can also be expected to burn actively at these levels.

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