Storm Prediction Center Day 1 Fire Weather Outlook

Created: Tue Jul 17 15:31:03 UTC 2018 (20180717 1700Z Day 1 FireWX shapefile | 20180717 1700Z Day 1 FireWX KML)

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

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   FNUS21 KWNS 171529

   Day 1 Fire Weather Outlook  
   NWS Storm Prediction Center Norman OK
   1029 AM CDT Tue Jul 17 2018

   Valid 171700Z - 181200Z

   Forecast looks on track and only minor changes were made. Please see
   the forecast discussion below for more details.

   ..Nauslar.. 07/17/2018

   .PREV DISCUSSION... /ISSUED 0209 AM CDT Tue Jul 17 2018/

   A weak 500 mb shortwave trough will pass over the northern Great
   Basin during the afternoon. Mid-level moisture will also move
   eastward in association with the shortwave trough. At the surface, a
   thermal trough will develop east of the Cascades down into far
   northern Nevada. 

   ...Central Washington/Oregon...
   A thermal low will become established along the lee of the Cascades
   during peak heating of the afternoon, as temperatures are expected
   to reach up to 100F in some locales. The thermal low induced
   pressure gradient will generate downslope sustained surface winds of
   at least 15-20 mph in tandem with 10-20% RH. Fuels are receptive in
   this area, with elevated RH/wind criteria being met for fire spread
   potential. Stronger surface winds (20-25 mph) may occur along the
   immediate eastward facing slopes of the Cascades along with
   critically low RH. The brevity of the critical conditions warrant
   only an elevated delineation at this time.  
   ...Southern Idaho...
   Strong surface heating during the mid-late afternoon may induce a
   weak pressure gradient in the Snake River Plain. Sustained surface
   winds of 15-20 mph are expected along with critical RH. An elevated
   delineation was added given the receptive nature of fuels in this

   ...Southwest Wyoming...
   A weak thermal low and associated pressure gradient may develop in
   the Green River Basin. 15-20 mph sustained surface winds are
   expected along with 15-20% RH. Though the RH is marginally low and
   recent rainfall from scattered storms has recently occurred, 10-hr
   fuels remain receptive to the spread of grass fires. An elevated
   delineation was added to account for the stronger surface winds
   overlapping rebounding finer fuels.  

   ...Idaho/Montana border into far western Wyoming...
   As the aforementioned mid-level shortwave trough progresses
   eastward, deep-layer ascent and at least marginal buoyancy will
   foster the development of isolated thunderstorms across the area.
   Precipitable water values of 0.5-0.75 inches and a relatively deep
   sub-cloud layer suggests that dry lightning will be possible. Modest
   mid-level flow will also allow faster storm motions (above 20
   knots), reducing accumulating rainfall atop fuels receptive for fire
   weather spreads.

   ...Please see for graphic product...


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