Tag: weather

On September 1 the Predictive Services section at the National Interagency Fire Center issued their Wildland Fire Potential Outlook for September through December. The data represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit.

Below are:

• the highlights of the NIFC report;
• NIFC’s graphical outlooks for September through November;
• NOAA’s long range temperature and precipitation forecasts; and
• Drought Monitor

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“The Western fire season is reaching its peak for 2017 as it enters September. While an active southwestern monsoon has curtailed activity in the Southwest and across portions of the central Rockies, above normal significant fire activity continues to be observed across portions of the Pacific Northwest, Northern Rockies, northern Great Basin and northern California. Fuel moisture levels and fire danger indices in these areas are at near-record to record levels for severity. While the frequency and density of lightning occurrence has begun its seasonal decline, occasional lightning bursts are still being observed. Most of the new lightning-caused fire starts are being effectively handled with initial attack, but a few are still developing into larger incidents that require additional resources. Drier and warmer than average conditions across the central Great Basin and Southern California are allowing for the fine fuels to become more receptive to fire activity. A slight upturn in initial attack activity is being observed in both areas. Cool and wet conditions have arrived in Alaska. Its season has effectively ended.

Precipitation received was generally well below average across the Pacific Northwest, Northern Rockies, Great Basin and California in August as most areas received less than 25 percent of normal rainfall. Once exception to this was the Sierra Mountains in California where several episodes of wet convection produced rainfall amounts that were above average. Across the central Rockies and the Southwest, precipitation amounts were near average. Temperature extremes were less frequent in August than in July. For the month, average temperatures were only a few degrees above average.

Fire season will peak by mid-September as the fuels remain much drier than average and as existing precipitation trends continue. By mid-September decreasing solar radiation received and longer nights will allow for fuel moistures to begin recovering. Should a season-slowing weather event not occur, this will be sufficient to allow for the fire activity across the northwestern states to begin to decrease significantly late in the month. Significant large fire activity will remain possible in foehn wind-prone areas like the Rocky Mountain Front and across Southern California through November and will be event-driven should they occur.”

On August 1 the Predictive Services section at the National Interagency Fire Center issued their Wildland Fire Potential Outlook for August through November. The data represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit.

It revises the outlook that was issued for August a month ago, adding to the “Above Normal” category Northern Idaho, the eastern halves of Oregon and Washington, and Western Montana. Many of the August “Above Normal” areas will carry over into September except for the areas in Oregon and Washington.

Below are:

• the highlights of the NIFC report;
• NIFC’s graphical outlooks for September through November;
• Drought Monitor, and;
• NOAA’s long range temperature and precipitation forecasts.

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The seasonal transition of the western fire season north has occurred. A strong southwestern monsoon has developed over the Southwest and has reduced the significant large fire potential and activity across the Four Corners Region. Significant lightning activity associated with the monsoon has spread north creating numerous incidents across the northern Great Basin, Northern California, Pacific Northwest, and the Northern Rockies. With the fine fuels now fully cured and with larger fuels now receptive, even at the higher elevations, fire activity is increasing as it nears its seasonal peak in August. While the northwestern states have shown a significant upturn in activity, fire activity in Alaska has begun to wane with the arrival of the late summer rains across the Alaskan Interior. The eastern and southeastern states have seen and will continue to experience overall limited activity as the regions remain largely out of season.

Precipitation received was generally well below average across the western half of the country in July. With the occurrence of three significant heat wave events, fuels dried quickly and became receptive to fire earlier than in most years. By month’s end, the previous winter’s record snowpack and above average spring rainfall was a distant memory. Drought was beginning to reemerge in the Rockies and across portions of the Pacific Northwest. Across the northern Great Plains, the established long term drought conditions continued to worsen. Large fire activity became problematic across eastern Montana, Wyoming and the Dakotas.

Looking forward to the peak of the western fire season in August and September, conditions are expected to remain favorable for the Above Normal significant fire activity to continue. Areas with the greatest potential for significant large fire activity will be the grasses and rangelands of the Pacific Northwest east of the Cascades, the lower and middle elevations across California, most of the Northern Rockies region. The grass and rangelands across the northern Great Basin will also continue to demonstrate Above Normal significant large fire potential and activity.

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