Storm Prediction Center Fire Weather Outlook

• Day 1 fire weather outlook and map
• Day 2 fire weather outlook and map

Day 1 Fire Weather Outlook

	    
   NWS Storm Prediction Center Norman OK
   1140 AM CDT Sat Aug 19 2017

   Valid 191700Z - 201200Z

   No changes have been made to the existing elevated areas. 

   Across portions of eastern MT/western ND, elevated conditions are
   already being observed at some locations and these conditions will
   persist through the afternoon. Critical RH/wind criteria may be
   reached concurrently for a brief period this afternoon, but the
   potential for a sufficient duration of critical conditions at any
   given location appears too limited for an upgrade.

   Further west, elevated to locally critical conditions still appear
   likely across portions of ID/southwest MT/WY, and also across
   portions of northern CA/southwest OR. See the previous discussion
   below for additional information.

   ..Dean.. 08/19/2017

   .PREV DISCUSSION... /ISSUED 0144 AM CDT Sat Aug 19 2017/

   ...Synopsis...
   An upper trough over AB/SK will progress eastward towards MB today.
   30-40 kt of mid-level westerly winds attendant to this upper trough
   will overspread eastern MT into ND by this afternoon. At the
   surface, a low over southern SK will also develop eastward into MB
   by this evening, with a trailing cold front advancing southeastward
   across the northern Plains.

   ...Portions of the Northern Great Basin into the Northern/Central
   Rockies and Northern Plains...
   Strong/gusty low-level winds should develop both along and ahead of
   the surface cold front this afternoon across eastern MT into western
   ND and northwestern SD. Short-term guidance shows sustained
   west-northwesterly winds of 15-20 mph occurring in conjunction with
   RH values lowering into the 15-25% range with diurnal heating of a
   relatively dry boundary layer, supporting an elevated fire weather
   threat. RH values are forecast to increase behind the front,
   although strong surface winds approaching 20 mph and veering to
   northwesterly may allow for continued elevated fire weather concerns
   into the evening hours. Locally critical conditions may be realized
   briefly across a small part of the elevated delineation, but
   confidence in widespread winds in excess of 20 mph remains too low
   to include a critical area.

   Elevated fire weather conditions should also develop this afternoon
   across part of the northern Great Basin into portions of the
   northern/central Rockies, as the southern fringe of enhanced
   mid-level westerlies overlies this region. Localized enhancement to
   the low-level winds appears likely across part of the Snake River
   Valley and vicinity into western/southern WY, with sustained
   west-southwesterly winds of 15-20 mph combining with RH values of
   10-20% and dry fuels to support an elevated fire weather threat. The
   lack of even stronger forecast low-level flow precludes a critical
   designation across this region.

   ...Southwestern OR/Northern CA...
   A strengthening surface pressure gradient to the west of the
   Cascades will encourage increasing northeasterly to northwesterly
   winds across southwestern OR/northern CA this afternoon and evening.
   Sustained winds of 15-20 mph appear likely at lower elevations, with
   stronger gusts possible at mid/high elevations. RH values will
   easily lower into the 15-25% range by afternoon given the dry
   airmass in place, and overnight RH recovery is expected to remain
   poor, particularly at higher elevations. This expected combination
   of strong/gusty winds with lowered RH values, very dry fuels, and
   numerous ongoing large fires necessitates the introduction of an
   elevated area across this region.

   ...Please see www.spc.noaa.gov/fire for graphic product...

      

Day 2 Fire Weather Outlook

 Storm Prediction Center Norman OK
   0157 PM CDT Sat Aug 19 2017

   Valid 201200Z - 211200Z

   Elevated wind/RH conditions are still expected on Sunday afternoon
   across portions of southern ID and adjacent southwest MT/western WY,
   as modest low/midlevel flow persists across the area. Locally
   critical conditions will be possible in terrain-favored locations,
   but confidence in a sufficient duration of such conditions is too
   low for any upgrade at this time. See the previous discussion below
   for more details.

   ..Dean.. 08/19/2017

   .PREV DISCUSSION... /ISSUED 0145 AM CDT Sat Aug 19 2017/

   ...Synopsis...
   A large-scale trough will continue moving eastward across central
   Canada Sunday, with a belt of enhanced mid-level westerly winds
   remaining confined to the north-central CONUS. An upper ridge is
   forecast to amplify over the eastern Pacific and western CONUS,
   while a weak upper low remains just off the coast of southern CA. At
   the surface, a cold front will advance eastward across the northern
   Plains and Upper Midwest, with its trailing portion becoming
   stationary and ill-defined across the northern High Plains into the
   northern Rockies/Great Basin.

   ...Portions of the Northern Great Basin/Rockies...
   Although the strongest mid-level flow will remain displaced to the
   north of this region, around 20-25 kt of westerlies at 500 mb will
   likely reach the surface as the boundary layer warms/mixes by Sunday
   afternoon and early evening. Localized enhancement to the low-level
   west-southwesterly flow appears likely across eastern portions of
   the Snake River Valley into western WY, where sustained winds of
   15-20 mph should occur. Some higher gusts will be possible. RH
   values will once again become lowered into the 10-15% range across
   this region as both the low-level airmass and available fuels remain
   quite dry. These expected meteorological and fuel conditions support
   the introduction of an elevated area across southern ID into far
   southern MT and western WY. Locally critical conditions may occur
   where winds exceed 20 mph, but this is currently expected on just a
   brief and spotty basis.

   ...Please see www.spc.noaa.gov/fire for graphic product...

      

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