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Saturday, May 2, 2015

The First Fire Weather Forecast issued by the National Interagency Fire Center

The National Interagency Fire Center in Boise, ID issued their first fire forecast for 2015 on May 1st.

June: 

Above normal wildland fire potential will expand across California, into SW Arizona and the pacific NW as fire season develops in earnest.

July & August:

Above normal wildland fire potential will persist across the pacific coast states and expand into the northern Great Basin and northern Rocky Mountains during the summer months.

The Northwest is facing a complicated set up to the fire season. Precipitation deficits and warm weather left the area with little snowpack. This will allow fuels to dry earlier than usual and leaves carry-over fine fuels standing tall. During the spring the warmth continued; however, some precipitation entered the Area. This did little to quell the drought or add to the anemic snowpack. It did provide inputs of precipitation that was well timed for adding additional grass growth through the growing season. It is likely the combination of these conditions will lead to an earlier than usual onset of both range and timber fires and that this will extend the length of the fire season in the Northwest.

Drought across California will continue to have a major impact on fuel conditions. Drought stressed heavy fuels will have lower live fuel moistures and will have a higher likelihood of insect and disease damage, leading to increased combustibility. Expect fine fuels in lower elevations to cure more than a month early. Higher elevations will also become susceptible to ignitions earlier than usual, due to green-up six to eight weeks earlier than normal. 

Significant wildland fire potential typically remains low over northern Idaho and western Montana through the spring as snowpack melts and green-up slowly commences in the lower elevations in mid to late April and to sub-alpine biomes by early June. This year, however, the very warm February and March period has led to a three to four week early green-up in the lower elevations west of the Continental Divide, and a loss of snow cover over large areas below 6000 feet, especially on south through west aspects. This will likely lead to an earlier than usual onset of fire season in these areas of the Northern Rockies.

Northern Rockies: 

Significant wildland fire potential is expected to return to normal in May for southeast Montana and eastern North Dakota. Elsewhere, potential will be near normal in May.

For June all of the geographic Area is expected to see normal potential for significant wildland fires. North central Idaho and portions of Montana will increase to above normal significant wildland fire potential in July and August, while the remainder of the area will continue to see normal potential. Precipitation over the past 60 days has been very low over the region with the exception of far northern Idaho and northwestern Montana and part of northeastern Montana.

Above normal temperatures have continued during this time over Idaho and Montana, so lower to mid-elevation mountain snowpack has decreased markedly or completely melted off three to four weeks earlier than average. Current snow water equivalent measurements from SNOTEL sites are showing only  to 63 percent of normal in Idaho and far western Montana, and 39 to 80 percent of normal over the rest of Montana.

May and June typically are the wettest months climatologically in the lower elevations of Idaho and western Montana.

NOAA's CPC outlooks show near to above normal precipitation through May-June and Above normal temperatures.

The CPC outlooks depict above normal temperatures continuing through July and August over Idaho into western Montana, with above normal precipitation for the period.