ZCZC SPCFWDD38 ALL
   FNUS28 KWNS 092049

   Day 3-8 Fire Weather Outlook  
   NWS Storm Prediction Center Norman OK
   0349 PM CDT Fri Apr 09 2021

   Valid 111200Z - 171200Z

   A split-flow regime in the mid levels will begin with northwesterly
   flow dominating much of the western CONUS in the wake of a strong
   upper low across the central US. A shortwave trough embedded within
   the flow will drive a cold front south across the central Plains
   Day4/Monday, before a second upper low across the West Coast digs
   into the Great Basin by mid week. Elevated/critical fire weather
   conditions are expected periodically across portions of the Great
   Basin and Southwest. 

   ...Great Basin into the Southwest...
   Ahead of the cold front Day3/Sunday, widespread dry and windy
   conditions are forecast from the Four Corners into eastern New
   Mexico. Northwesterly flow aloft on the backside of the central US
   trough will encourage westerly boundary-layer flow of 15-20 mph. The
   modified continental airmass should support humidity of 10-20% which
   will be more than sufficient for elevated fire weather conditions
   given cured fuels and ongoing drought. 

   A brief break from active weather conditions is expected late
   Day3/Sunday through Day4/ Monday as a cold front swings south
   through eastern New Mexico toward the Mexican border. Locally
   elevated fire weather conditions may exist with strong winds behind
   the front, though widespread conditions appear unlikely at this time
   due to cooler temperatures and higher RH. 

   Lee cyclogenesis ahead of the next West Coast trough is expected to
   begin across the Great Basin late Day4/Monday into Day5/Tuesday. The
   increasing southwesterly flow aloft and surface pressure falls
   should support widespread winds of 15-25 mph. Surface RH should fall
   to near critical along a wide swath from the southern Great Basin,
   the Four Corners, and into central New Mexico. The GFS remains drier
   and stronger with the low-level flow (a well known bias) suggesting
   the potential for more widespread critical conditions. A 40%
   probability of critical area will be maintained for now.

   ...Central High Plains...
   Periodic downslope flow and a localized risk for elevated fire
   weather conditions is expected behind the southward moving cold
   front Day4/Monday. The dry nature of westerly low-level flow
   supporting RH of 20-30% and surface winds of 20-30 mph will support
   locally elevated fire weather conditions given the ongoing drought
   and pre-green up dry fuels. Widespread precipitation from the
   ejecting Great Basin low/trough should keep the threat confined to
   Day4/Monday before cooler and wetter conditions prevail through the
   rest of the extended. 

   ...California...
   Dry down-valley winds across central and southern California
   associated with the southern Great Basin low may support elevated
   fire weather potential through the day. Surface Rh of 10-20% and
   adequate fuels would be sufficient for locally elevated conditions,
   though the longevity of the stronger flow and attendant fire weather
   threat remains uncertain.

   ..Lyons.. 04/09/2021

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

   $$

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