Statewide Discussion: A dynamic weather pattern today will thrust both critical fire weather and severe storm potential into Oklahoma as a bi-modal threat – fire-effective west of the dryline ahead of a frontal boundary while rain and storms are possible east of the dryline. A Red Flag Warning is in effect today until 8:00 PM for the western tier of Oklahoma counties and until 10:00 PM for the Oklahoma Panhandle Counties. The footprint of realized rainfall following today’s storms will be key to discerning the extent of fire danger on Wednesday as much drier air spreads across the state in the postfrontal environment. By Wednesday evening, rain/storm chances begin to expand and by Friday evening widespread rain chances with some promise for statewide wetting amounts that will spur green-up in most areas.
**A Fuels & Fire Behavior Advisory has been issued for most of the northern half of Oklahoma -Available HERE
Today: Low to moderate significant fire potential overlays the current warned area, identifying where the fire environment (fuels/weather/topography) will support the possibility of a fire burning 5,000 acres or greater. Within this warned area, initial attack activity is expected to increase, and wildfires will present suppression difficulty including rapid to extreme rates of fire spread, high resistance to control and problematic fire behavior including torching and spotting. The most fire-effective weather will set up along and west of the dryline that is expected to stall around the 100th Meridian and this area is also where fuels will support concerning fire behavior potential. One beneficial hindrance to this will be some cloud cover and blowing dust that will limit fuel heating. East of the dryline, higher relative humidity values and heavier sky cover will serve to limit fine-dead fuel receptiveness although any wildfire that becomes established will be subjected to strong winds support rapid rates of fire spread and erratic fire behavior.
Fire Behavior:
- Warned Area: The dryline is expected to push from west to east into the area across the Oklahoma Panhandle and into the western tier of counties presenting powerful fire environment alignment with critical fire weather and fuels that will support potential for extreme rates of fire spread and high resistance to control. Of note, there will be a limiting factor with sky cover (clouds and blowing dust) that will limit insolation, lowering fuel heating and the resulting fine-dead fuel moisture. Respectable overnight moisture recovery will quickly wane the dryline ushers in temperatures 77°-90° under partly-cloudy skies with afternoon relative humidity values 14-18%, yielding fine-dead fuel moisture at 3%. Southwest winds will increase to 23-35 mph, gusting 40-50 mph during peak heating. Rangeland fuels will have the potential to exhibit extreme rates of spread on any established wildfire. Head fire rates of spread of 280-370 ft/min (3.0-4.2 mph) with flame lengths 15-20 ft should be expected. This will be coupled with problematic fire behavior in brush fuel types including torching and crowning with spotting distances +/- 0.25 miles. The dryline will regress westward after sunset and conditions will gradually improve although winds will also shift to a more westerly direction as a frontal boundary edges into the area. While some storm chances develop late, the Warned area is likely to remain dry.
- Western Oklahoma: Areas east of the dryline will present challenges as well on any new wildfire that becomes established given current fuel condition and strength of the wind field, noting that the development of fire danger concern is conditional today. Any going fire in the vicinity of a storm developing along the dryline will likely exhibit erratic fire behavior with shifting spread direction and surging rates of spread. Temperature in the upper-70°s to mid-80°s under mostly-cloudy skies with min relative humidity values 28-40% will yield fine-dead fuel moisture at 6% (east edge of the dryline) to 8% (nearer to central Oklahoma). Southwest winds will ratchet up to 23-30 mph, gusting to around 45 mph. Rangeland fuels where grazing or other manipulation has been absent will support head fire rates of spread 210-300 ft/min (+/- 2.9 mph) and flame lengths 12-17 ft. Shorter grass stands will exhibit ROS 115-140 ft/min and flame lengths 8-9 ft. Brush fuel will support problematic fire behavior, including single/group tree torching and some short-range spotting. Wildfire concern moderates as the dryline regresses west with rain/storm chances introduced late afternoon and overnight.
- North-Central/Northeastern Oklahoma: Recent rainfall, in areas, combined with higher dew point temperature today will serve to hold relative humidity levels at much higher observations than in days past limiting fine-dead fuel moisture from nearing critical threshold. New wildfire activity today, while possibly challenging, has good probability of successful initial attack. Temperature in the 70°s under cloudy skies with relative humidity values +/-50% will hold fine-dead fuel moisture around 8-9% limiting receptiveness. Southwest winds will increase to 17-28 mph with higher gusts. Wildfires today will likely exhibit erratic fire behavior given improved fuel moisture. Grass-dominated fuels will exhibit head fire rates of spread 90-135 ft/min and average flame lengths +/- 9 ft on fully established wildfires. Rain/storm chances begin to ratchet up late afternoon and evening.
- South-Central/Southeastern Oklahoma: Limited fire danger today with improved fuel moisture and much higher relative humidity values today limiting potential for new fire starts. Fires that do occur today will provide very good opportunity for successful initial attack. Increasing rain/storm chances will likely halt fire danger concern by late afternoon.
Outlook: Wednesday will bring much drier air into Oklahoma in the wake of a stalling cold front with single-digit relative humidity observations west and teens central. The areal coverage of rainfall from overnight will be key to determining the extent of fire danger tomorrow. Fortunately, winds will be comparatively lighter, offering good opportunity for initial attack success noting that large fire potential will remain in the drier west. Thursday heading into the weekend brings an increasing promise of statewide wetting rainfall. The amounts forecasted coupled with increasing soil temperature will spur herbaceous green-up and declining fuel availability to support significant wildfire potential. Nonetheless, a pause in concerning fire danger is expected, and it cannot come anytime soon enough.
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