NWS Storm Prediction Center - Day 1-2 Fire Weather Outlook
Updated: Thu Apr 22 15:57:03 UTC 2021
Apr 22, 2021 Day 1 Fire Weather Outlook
Day 1 Fire
 Pop.  Cities  CWAs  RFCs  Interstates  Counties  ARTCC  FEMA  Tribal  Day 1 Surface Analysis 

Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
Critical 144,947 2,899,169 El Paso, TX...Albuquerque, NM...Las Cruces, NM...Rio Rancho, NM...Grand Forks, ND...
   FNUS21 KWNS 221556

   Day 1 Fire Weather Outlook  
   NWS Storm Prediction Center Norman OK
   1056 AM CDT Thu Apr 22 2021

   Valid 221700Z - 231200Z


   The primary change to the outlook is to shift the eastern edge of
   the elevated/critical areas in the southern High Plains westward.
   Morning observed soundings in the region indicate relatively moist
   layer up to 1-1.5 km or so with an isothermal/slight temperature
   inversion layer above that to near 2 km. These factors coupled with
   the surface low's position generally remaining northwest of this
   area for a majority of the day does not bode well for this region
   deeply mixing and drying this afternoon. Nevertheless, perhaps up to
   1-2 hours of near-critical to critical conditions are still possible
   late this afternoon conditional on greater eastward progression of
   the surface trough/dryline. As such, the westward shift was
   relatively conservative.

   Within the northern Plains, morning surface observations show
   near-elevated to elevated conditions now occurring in southwestern
   Minnesota. Given these trends, ensemble guidance, and EACC showing
   dry fuels, it seems likely several hours of elevated conditions are
   probable this afternoon and the elevated area has been expanded
   southeastward. A weak mid-level shortwave trough/cloud cover is
   evident on visible satellite in Nebraska/South Dakota. Timing this
   feature suggests that cloud cover will not impact southwestern
   Minnesota until very late in the afternoon, beyond peak heating.

   ..Wendt.. 04/22/2021

   .PREV DISCUSSION... /ISSUED 1153 PM CDT Wed Apr 21 2021/

   ...Southern High Plains...
   Strong lee cyclogenesis is forecast in southeastern Colorado through
   the day as a mid-level shortwave trough traverses the Rockies.
   Moderate to strong mid-level southwesterly flow will accompany this
   mid-level trough and overspread portions of the Southwest and
   Southern Plains. Surface winds are expected to increase through the
   day as the pressure gradient tightens. Deep mixing in excess of 3km
   will help to transport some of the stronger mid-level flow to the
   surface where relative humidity of 8 to 13 percent is forecast.

   ...Northern Plains...
   Very dry and breezy conditions are expected in the northern Plains
   this afternoon. Sustained winds are expected to be around 15 mph
   across much of north Dakota and northwest Minnesota, but some
   sustained winds may exceed 20 mph, especially across eastern North
   Dakota. Forecast wind speeds are borderline for critical conditions,
   but relative humidity is forecast to be between 10 and 15 percent
   and this specific region has seen very little precipitation in the
   past month with record low fuel moisture observed. Therefore, the
   extreme dryness from fuels and relative humidity supports the need
   for a critical delineation. 

   ...Southeast Oregon into southwest Idaho and northern Nevada...
   A mid-level shortwave trough will dig southeastward through the
   Pacific Northwest today. Some surface cyclogenesis is expected in
   the Columbia Basin and northern Great Basin. This will strengthen
   the pressure gradient across Oregon. Surface winds will increase as
   a result of the tightening pressure gradient. In addition, deep
   mixing in excess of 3 km will transport stronger mid-level flow
   downward and aid in strengthening northwesterly surface flow.
   Critical meteorological conditions will likely be met across a large
   portion of the elevated area, but fuels in this region are currently
   only marginally dry. Therefore, no critical delineation has been

   ...Mid Atlantic into the Carolinas...
   Dry and breezy conditions are expected in the post frontal airmass
   along the East Coast. However, the large-fire threat should be
   mitigated as the strongest winds and lowest relative humidity are
   expected in areas which received precipitation today with weaker
   winds expected farther south across the Carolinas where fuels remain
   more dry.

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


   Source:  NWS Fire Weather Outlook
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