On December 1 the Predictive Services section at the National Interagency Fire Center issued their Wildland Fire Potential Outlook for December through March. The data represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit.
If their predictions are correct, the elevated wildfire danger that has plagued the southern states for weeks will be returning to normal. From January through March their analysis shows no areas with above normal wildfire potential.
Continue reading “Wildfire potential, December through March”
On November 1 the Predictive Services section at the National Interagency Fire Center issued their Wildland Fire Potential Outlook for November through February. The data represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit.
If their predictions are correct, firefighters in the southeast and in southern California could see significant wildfire activity in November and December.
Scroll down to see additional wildfire potential maps, the drought monitor, and the 90-day temperature and precipitation outlooks, but immediately below are highlights from the wildfire potential outlook.
November significant wildland fire potential is generally very minimal throughout the northern tier of the U.S. as conditions transition out of normal fire season. Areas of the Great Basin and Rocky Mountains that are currently seeing increased levels of fire activity are likely to see much of that activity diminish and transition to out of season conditions through early November.
Exceptions will continue in Southern California where long term drought is still in place. Conditions in this area will slowly transition to normal from north to south through the Outlook period. Normal implies a significant reduction in fire activity, but some fires should still be expected. Also, the southeastern U.S. will continue to see a large area of above normal significant fire potential for November and December that will slowly transition back to normal through the Outlook period as well. This condition is also largely due to long term drought that is going to be exacerbated by dry leaf litter falling on top of already dry fuels and also occasional dry and windy periods. For the southern Plains there is a plentiful grass crop that presents the potential for occasional dry and windy periods to increase fire activity.
Normal winter conditions will prevail across the U.S. in January and February. There will be occasional periods of increased fire activity, but these will be infrequent and difficult to predict accurately. During this outlook period winter precipitation and snowpack development will be a critical situation to monitor as the 2017 fire season becomes the focus of many fire managers.
Continue reading “Wildfire potential, November through February”
On October 1 the Predictive Services section at the National Interagency Fire Center issued their Wildland Fire Potential Outlook for October through January. The data represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit.
If their predictions are correct, firefighters in the mountains of central and southern California could be busy through November, at least, while most of the Southeast is coming into what could be a very active fall fire season.
Scroll down to see 6 to 14-day temperature and precipitation outlooks, and Red Flag Warnings for October 2, but immediately below are highlights from the wildfire potential outlook.
“October represents a significant shift in fire activity in the United States. Shorter days, cooler nights and generally moister conditions reduce wildfire activity across the northern tier of the U.S., taking much of this area out of season or at least to very low fire activity conditions.
“October does represent the beginning of the primary time of concern for offshore flow across California. These dry windy conditions can lead to very significant fire events in areas with high populations. This year the forecasts indicate that offshore wind events may be less frequent than usual. However during even light wind periods fires will occur and they will have the potential to spread extremely quickly with extreme fire behavior. Fuels continue to be very dry in California due to long term drought and increased vegetation stress and mortality. Under windy conditions these fuels will become extremely volatile and can support extreme fire behavior.
“October also marks the start of the fall fire season across the eastern U.S. Leaf drop begins and adds a new dry layer of fuel. In seasons such as this one where leaf drop occurs on already dry fuels, fire activity can be amplified. Expect this to lead to increased initial attack activity and probably a slight increase in large fires. Fire activity occurs year round in the southeastern U.S. so the most likely scenario is to see an increase in frequency and the potential for more control problems than usual on fires this fall.
Continue reading “Wildfire potential, October through January”
On September 1 the Predictive Services section at the National Interagency Fire Center issued their Wildland Fire Potential Outlook for September through December, 2016. The data represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit. Below are highlights from the outlook.
September is typically a month of significant change in fire conditions, especially across the northern tier of the United States. Days shorten, lessening available solar radiation to dry and heat fuels; longer nights are cooler with generally higher humidity. These conditions slowly reduce fire activity and typically end normal fire season activity throughout the month. This is expected to be the trend this season as well.
Throughout the northern portions of the Great Basin including portions of the Northwest, Northern Rockies and Rocky Mountain Areas above normal conditions will transition through the month to normal conditions and by the end of September normal conditions indicate minimal fire activity throughout this area. Occasional dry cold fronts during September and possibly October will present the potential for large fires on the landscape to grow rapidly; however, these conditions will be short in duration followed by opportunities for successful firefighting efforts. California will remain at above normal levels of fire activity throughout much of the state as dry conditions will continue and fall will bring the increased potential for offshore flow events.
In October, November and December diminishing activity in the northern tier will transition to heightened activity across the southern tier; especially in central and southernCalifornia and the Southeast. California is not expected to see any significant events that will alleviate long term drought and very dry fuels. This will come with enhanced potential for offshore flow, increasing the potential for very dry and windy conditions. The southeastern United States is a significant wildcard moving into the fall months.
Tropical systems the Atlantic Ocean and Gulf of Mexico could provide substantial relief to some if not all of the area.
If this dry area remains, fall fire activity in the Southeast will be amplified and could become significant throughout the fall and winter. It is possible significant changes will occur, but the current conditions dictate elevated potential is likely.
The U.S. Forest Service produced this map showing wildfire potential in the lower 48 states. Higher resolution versions are available.
Here is how the USFS describes this map:
“The wildland fire potential (WFP) map is a raster geospatial product produced by the USDA Forest Service, Fire Modeling Institute that is intended to be used in analyses of wildfire risk or hazardous fuels prioritization at large landscapes (100s of square miles) up through regional or national scales. The WFP map builds upon, and integrates, estimates of burn probability (BP) and conditional probabilities of fire intensity levels (FILs) generated for the national interagency Fire Program Analysis system (FPA) using a simulation modeling system called the Large Fire Simulator (FSim; Finney et al. 2011).
The specific objective of the 2012 WFP map is to depict the relative potential for wildfire that would be difficult for suppression resources to contain, based on past fire occurrence, 2008 fuels data from LANDFIRE, and 2012 estimates of wildfire likelihood and intensity from FSim. Areas with higher WFP values, therefore, represent fuels with a higher probability of experiencing high-intensity fire with torching, crowning, and other forms of extreme fire behavior under conducive weather conditions.
Using the FPA FSim products as inputs, as well as spatial data for vegetation and fuels characteristics from LANDFIRE and point locations of fire occurrence from FPA (ca. 1992 – 2010), we used a logical series of geospatial processing steps to produce an index of WFP for all of the conterminous United States at 270 meter resolution.”
On August 1 the Predictive Services section at the National Interagency Fire Center issued their Wildland Fire Potential Outlook for August through November, 2016. The data represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit. Below are highlights from the outlook.
“For August, significant wildland fire potential will continue to be focused in the finer fuel and brush areas of California and the Great Basin with some expansion into Oregon, Montana and Wyoming. Primary concerns continue to focus on the abundant fine fuels and their ability to carry fires more effectively than in a typical year. Additionally significant mortality will increase heavy fuel availability throughout the mountains of California, while typical summer dryness will bring fire activity in the heavier fuels of the Northwest, Northern Rockies, Rocky Mountains and Great Basin up to normal levels. Furthermore, the Southwest, Rocky Mountains and southern Great Basin will see an intermittent monsoon which will continue some level of fire activity in those areas.
“As fall begins, days shorten, temperatures cool and frontal systems become more common. This typical transition will return much of the Northwest, Northern Rockies, Rocky Mountains and Great Basin to normal fire activity through September. California will continue to see elevated potential due to long term dryness. This will occasionally be amplified through the fall and early winter as offshore flow events become more common. The southern U.S. will also see an increase to above normal significant fire potential as long term dryness couples with leaf drop and dormancy of live fuels to create a receptive environment for fall fire activity.
“By October and November much of central California will transition to normal fire potential as is seasonally expected. Southern California will continue to see elevated significant fire potential and will also see the persistent threat of offshore wind events. The southeastern states will see a broad area of increased potential as a result of long term dryness and the introduction of La Niña conditions which typically bring warmer and drier-than-normal conditions to the southern tier of states.”