Fire Weather Fire

Fire Weather Fire weather depends on a combination of wildland fuels and surface weather conditions. Dead and live fuels are assessed weekly from a satellite that determines the greenness of the landscape. Surface weather conditions are monitored every 5-minutes from the Oklahoma . This fire weather help page highlights the surface weather ingredients to monitor before wildfires and also includes several products to monitor once wildfires are underway.

Fire Weather Ingredients: WRAP While the presence of wildland fuels is one necessary component for wildfires, weather conditions ultimately dictate whether or not a day is primed for wildfires to occur. There are four key fire weather ingredients and they include: high , low Relative humidity, high Air temperature, and no/minimal recent (WRAP).

High Winds are the second most critical weather ingredient for wildfires. In general, winds of 20 mph or greater 20+ mph winds increase spot fires and make for most of the containment considerably more difficult. state

Low Relative humidity is the most 30-40+ critical weather ingredient for wildfires mph winds and is most common in the afternoon when the air temperature is at its warmest. When relative humidity is at or below 20% extreme fire behavior

can result and spot fires become frequent. Watch out for areas of 20% or below relative humidity and 20 mph or higher winds à 20/20 rule! Extremely low relative humidity Warm Air temperatures are another values key weather ingredient for wildfires as warming can lower the relative humidity, reduce moisture for smaller dead fuels, and bring fuels closer to their ignition point.

No or minimal recent Precipitation is the final wildfire weather ingredient. Rainy conditions keep the relative humidity at levels unsupportive of Warmest air wildfires while also limiting the ability of temperatures dead fuels to burn.

In the examples to the right from 2PM on 6 March 2017, a dangerous combination of very high winds (30+ mph), very low relative humidity (less than 20%), warm temperatures (upper 70s to mid 80s F), and no recent precipitation (not shown) contributed to extreme fire weather conditions that resulted in an outbreak of wildfires throughout Northwest Oklahoma, the Texas Panhandle, and southwest Kansas.

Monitoring Wildfires with Weather Satellite & Once wildfires are underway, it is important to continue monitoring Oklahoma Mesonet data – especially data for early cues of possible wind shifts. However, other datasets – namely weather satellite and radar – are better suited for confirming the presence of on-going fires as well as their changing coverage.

GOES-16 Channel 2 – Visible GOES-16 Channel 7 – A significant upgrade in Shortwave Window Infrared weather satellite technology arrived in late 2016 with the launch of the new GOES-16 weather satellite (officially Fire Weather commissioned as the new Hot spots GOES-East in late 2017). The satellite boasts 3x more channels, 4x better resolution, and 5x faster scans than the satellite it replaced. Among the 16 available channels on the satellite are several that are useful for wildfire monitoring, Smoke plumes including Channel 2 (visible channel) and Channel 7 (shortwave window infrared). The visible channel is effective in capturing the presence of smoke plumes (see above example), however, it is limited to daytime use only. The shortwave window infrared channel is the ideal GOES-16 channel for wildfire detection due to its sensitivity to increases in temperature. These increases appear as dark “hot spots” at the location of fires amongst cooler surrounding temperatures (see above example, which also includes colorized enhancement). Channel 7 can be used day or night and tends to detect hot spots before smoke plumes are apparent in the visible channel during daytime wildfires.

Weather radar is another good tool for monitoring wildfires, which are observed as smoke plumes in Base Reflectivity. The example at the right shows a series of smoke plumes observed in reflectivity from the Dodge City, KS radar during the early portion of the 6-7 March 2017 Smoke plumes wildfire outbreak. Smoke plumes align with the winds in the atmosphere and appear on radar as a streak of reflectivity with an anchored end (fire side of the plume). However, unlike satellite monitoring of wildfires, radar cannot observe all wildfires nor does it provide accurate location information of the fire itself. Radar often misses smoke plumes that are low in the sky or located far from the radar (smoke stays “under the radar”). Radar is an important detection tool but keep in mind these limitations.