Storm Prediction Center
Day 1 and Day 2 Fire Weather Outlooks

Day 1 Fire Weather Forecast graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast

Click for Day 1 FireWX Areal Outline Product

   ZCZC SPCFWDDY1 ALL
   FNUS21 KWNS 181541

   Day 1 Fire Weather Outlook  
   NWS Storm Prediction Center Norman OK
   1041 AM CDT Fri Aug 18 2017

   Valid 181700Z - 191200Z

   ...NO CRITICAL AREAS...

   No changes are needed to Day 1/Friday forecast.

   Morning water vapor imagery and objective analysis depicts
   mid/upper-level ridging quickly translating eastward across MT as a
   upper-level trough continues to progress eastward across far
   northern BC/AB.  

   While the strongest flow is forecast to generally remain north of
   the Canadian border, belt of 15-20 mph sustained surface winds is
   expected to sag across portions of the Pacific Northwest into the
   northern Rockies this afternoon along base of the aforementioned
   trough. Gusty afternoon winds coupled with low afternoon RH values
   and relative dry fuels across this region support continuation of
   the elevated fire risk. Some locally-critical fire weather
   conditions may briefly develop in the lee of the Cascades this
   afternoon where terrain induced channeling enhances low-level flow.
   Locally-critical conditions may also develop closer to the stronger
   mid-level flow across far northern MT.

   Please see previous forecast below for more detailed evolution of
   the fire weather threats.

   ..Elliott/Picca.. 08/18/2017

   .PREV DISCUSSION... /ISSUED 0150 AM CDT Fri Aug 18 2017/

   ...Synopsis...
   An upper trough will move eastward from BC to AB/SK today, while a
   related weak surface low likewise develops eastward across southern
   AB/SK through this evening. A surface trough will extend southward
   from this low across parts of the northern Rockies/High Plains.
   Enhanced mid-level westerly winds associated with the upper trough
   will overspread parts of the Pacific Northwest and northern
   Rockies/High Plains, elevating fire weather concerns across these
   regions.

   ...Portions of the Pacific Northwest into the Northern Rockies/High
   Plains...
   Low-level winds will strengthen to the lee of the Cascades and
   northern Rockies this afternoon as the enhanced mid-level westerly
   winds mentioned previously become diurnally mixed to the surface.
   Sustained west-southwesterly surface winds around 15-20 mph appear
   likely across parts of the interior Pacific Northwest into the
   northern Rockies/High Plains. Diurnal heating of a dry airmass and
   downslope warming/drying will act to lower RH values generally into
   the 15-25% range across these regions this afternoon and early
   evening. This combination of strong/gusty winds, lowered RH values,
   and dry to very dry fuels supports the continuation of an elevated
   delineation. Locally critical conditions may be realized across
   parts of eastern WA into north-central OR (within the Columbia River
   Gorge) where winds may exceed 20 mph on a brief/spotty basis.
   However, confidence in sustained winds in excess of 20 mph for
   multiple hours this afternoon is too low to include a critical area.

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

      
Day 2 Fire Weather Forecast graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast

Click for Day 2 FireWX Areal Outline Product (KWNSPFWFD2)

   ZCZC SPCFWDDY2 ALL
   FNUS22 KWNS 181940

   Day 2 Fire Weather Outlook  
   NWS Storm Prediction Center Norman OK
   0240 PM CDT Fri Aug 18 2017

   Valid 191200Z - 201200Z

   ...NO CRITICAL AREAS...

   No changes needed to Day 2/Saturday forecast, with elevated fire
   weather conditions developing over portions of the northern Great
   Basin/Rockies into the northern Plains owing to the combination of
   sustained surface winds of 15-20 mph, RH values of 15-20%, and very
   dry fuels. While critical conditions may briefly develop across the
   northern Great Basin -- particularly where terrain-induced
   channeling is enhanced through the Snake River Valley -- 
   probabilities of sustained surface wind speeds exceeding 20 mph over
   a sufficiently large area remain too low to delineate a critical
   area at this time. If future trends in model guidance suggest an
   increase in wind speeds, then a critical area may be needed in
   future outlooks. 

   Elsewhere, diurnally-driven thunderstorm activity is forecast to
   develop during the afternoon across much of central NV. While fuels
   are somewhat receptive across this area, recent bouts of at least
   some wetting rainfall combined with weak steering flow is expected
   to keep probabilities of dry thunderstorms below 10%.

   ..Elliott/Picca.. 08/18/2017

   .PREV DISCUSSION... /ISSUED 0150 AM CDT Fri Aug 18 2017/

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

   ...Portions of the Northern Great Basin/Rockies into the Northern
   Plains...
   Strong/gusty low-level winds should develop both along and ahead of
   the surface cold front Saturday afternoon across eastern MT into
   western ND and northwestern SD. Consensus of short-term guidance
   suggests sustained west-northwesterly winds of 15-20 mph will likely
   occur 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 at this time.

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

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

      

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