ZCZC SPCFWDDY1 ALL
   FNUS21 KWNS 201637

   Day 1 Fire Weather Outlook  
   NWS Storm Prediction Center Norman OK
   1137 AM CDT Fri Jun 20 2025

   Valid 201700Z - 211200Z

   ...CRITICAL FIRE WEATHER AREA FOR FOUR CORNERS AND GREAT BASIN...

   No changes are needed to the current D1 Fire Weather Outlook.
   Morning satellite analysis shows mostly sunny skies across the
   Critical area, with relative humidity ranging from 15-20 percent and
   winds gusting 20-30 mph. HREF guidance continues to indicate that
   several hours of Critical conditions are likely from the Great Basin
   to the Four Corners and into portions of the High Plains through
   this afternoon. See previous discussion below for more information.

   ..Thornton.. 06/20/2025

   .PREV DISCUSSION... /ISSUED 0132 AM CDT Fri Jun 20 2025/

   ...Synopsis...
   Widespread critical fire weather conditions are expected today
   across parts of the Greater Four Corners region and the Great Basin.
   Early-morning water vapor imagery shows a dominant upper ridge over
   the central CONUS with shortwave troughing over the western Great
   Basin and northeastern Pacific. The Great Basin shortwave is
   forecast to move into the northern High Plains through the
   afternoon, which will facilitate surface low development across
   eastern WY by late afternoon. Strengthening low-level winds in
   response to the deepening low will promote a widespread swath of
   20-30 mph winds within a very dry air mass and across a region with
   receptive fuels. 

   ...Four Corners into the High Plains...
   The axis of the mid-level jet associated with the leading shortwave
   is forecast to reside from southeast UT into southern WY by peak
   heating. This will maximize the potential for 20+ mph winds at the
   surface, and will likely support wind gusts between 30-45 mph. RH
   values in the single digits to low teens coupled with antecedent dry
   fuels (active fires were recently noted across southern UT in GOES
   IR imagery) will support widespread and prolonged critical
   conditions with periods of extremely critical wind speeds possible -
   especially across south-central WY. Elevated to critical fire
   weather conditions will likely extend well to the northeast into the
   central High Plains, and possibly as far east and western South
   Dakota behind an eastward surging dry line. However, fuel conditions
   generally improve with eastward extent due to recent rainfall. Fire
   risk highlights have been expanded northeast to account for the
   strong wind/RH signal, but Critical highlights were focused across
   areas with dry, receptive fuels. 

   ...Nevada into adjacent portions of Idaho and Utah...
   Southwesterly flow over the southern to central Sierra Nevada will
   induce strong downslope flow into western and central NV, spreading
   into southeast ID and western UT by late afternoon. Guidance
   continues to show a strong signal for 20-25 mph winds through much
   of the afternoon, and single-digit RH values should support
   widespread critical fire weather conditions. 

   ...Southern California into the San Joaquin Valley...
   A strong onshore pressure gradient will support increasing downslope
   winds on the leeward side/eastern slopes of the coastal ranges
   across southern California this afternoon. Relative humidities
   values falling into the teens within the downslope regime, coupled
   with dry grasses, will support a fire weather concern.