File:Day2otlk fire sep 6.gif

English: ZCZC SPCFWDDY2 ALL

  FNUS22 KWNS 061959

  Day 2 Fire Weather Outlook  
  NWS Storm Prediction Center Norman OK
  0259 PM CDT Sun Sep 06 2020

  Valid 071200Z - 081200Z

  ...EXTREMELY CRITICAL FIRE WEATHER AREA FOR PARTS OF NORTHWEST
  OREGON FROM THE CASCADES TO THE COASTAL RANGES...
  ...CRITICAL FIRE WEATHER AREA FOR EASTERN WASHINGTON TO NORTHWESTERN
  OREGON FROM THE COLUMBIA BASIN TO THE OREGON SHORELINE...
  ...CRITICAL FIRE WEATHER AREA FOR MUCH OF THE CENTRAL AND EASTERN
  GREAT BASIN INTO THE CENTRAL ROCKIES...
  ...CRITICAL FIRE WEATHER AREA FOR SOUTHERN CALIFORNIA ALONG THE LEE
  OF THE SANTA YNEZ AND TEHACHAPI MOUNTAINS...

  An Extremely Critical risk was added for parts of northwest Oregon,
  encompassing the Coastal Ranges to the western slopes of the
  Cascades. Global/regional models and high-resolution guidance depict
  unseasonably strong offshore flow from roughly 06-12Z Monday
  night/Tuesday morning, supported by a strong pressure gradient
  associated with an approaching surface cold front and passing
  mid-level wind maximum. Easterly winds gusting to 50+ mph and RH
  dropping below 20% will foster very favorable wildfire-spread
  conditions given very dry fuels between the Coastal Ranges/Cascades
  (ERCs exceeding the 90th percentile in spots).

  A Critical area was also added for areas in close proximity to the
  Santa Ynez/Tehachapi Mountain Ranges. During the late
  afternoon/early evening hours, a tightening pressure gradient along
  with boundary-layer mixing/downslope flow are expected to contribute
  to 20-25 mph northwesterly surface winds amidst critically low RH
  per consensus of the latest regional/high-resolution guidance. 

  From central California to central Oregon, surface northwesterly
  winds are expected to remain somewhat weaker compared to areas
  farther east-northeast, in closer proximity to a deepening trough
  aloft. Nonetheless, while an Elevated area remains in place, locally
  critical conditions may occur, especially by afternoon peak heating.

  The Elevated area across the Four Corners was extended into parts of
  the southern High Plains, where 15 mph westerly winds and 15-20% RH
  may occur by afternoon peak heating, and where the finer fuels are
  marginally supportive of fire spread. Otherwise, the forecast
  remains on track for the Great Basin into the central Rockies, and
  for the Pacific Northwest (outside of the Extremely Critical Risk
  area). Please see the previous forecast for more details involving
  the Great Basin/Inter-mountain West areas.

  ..Squitieri.. 09/06/2020

  .PREV DISCUSSION... /ISSUED 0130 AM CDT Sun Sep 06 2020/

  ...Synopsis...
  A large-scale pattern shift will continue to unfold across the
  western U.S. D2/Mon as a vigorous mid/upper trough digs southward
  across the interior West and a ridge initially over the western
  Great Basin weakens and retreats westward.  Additionally, a very
  strong surface ridge will build southward across the northern
  Rockies as surface lows remain located along the West Coast, near
  the Lower Colorado River Valley, and across New Mexico.  The
  resultant pressure gradient will set up an abnormally strong
  offshore flow regime across the Pacific Northwest along with areas
  of very strong surface flow across dry areas of the Great Basin. The
  overall pattern requires broad areas of elevated to critical fire
  weather highlights encompassing much of the western U.S.

  ...Northern Oregon and southern Washington State...
  The aforementioned synoptic setup will foster development of a
  significant offshore flow pattern across the region that will result
  in strong easterly surface winds throughout the forecast period. 
  Wind speeds will likely exceed 30 mph in most areas, with gusts
  perhaps exceeding 50 mph especially in terrain-favored areas.  Low
  RH values (around 15-25%) and very dry fuels across the region will
  support rapidly spreading fires potentially exhibiting extreme
  behavior.  Poor overnight recovery and continued strong surface
  winds will result in fire-weather threats continuing through the
  overnight hours as well.

  ...Much of Nevada eastward into northwestern Colorado...
  The combination of strengthening flow aloft and a tightening
  pressure gradient will result in broad areas of 20-35 mph surface
  winds - especially within the critical delineation encompassing
  these regions through peak heating hours.  Meanwhile, insolation
  (especially away from any clouds or precipitation near the region)
  will result in very warm surface temperatures (reaching the 90s F)
  and low RH values falling into the single digits.  Winds near the
  approaching cold front (across Idaho/northern Nevada) will shift to
  northerly and remain strong (around or above 20 mph) overnight,
  which may complicate any ongoing fire suppression efforts in these
  areas.

  ...California...
  Much of the state will remain displaced from any direct influence
  from the approaching mid/upper trough across the northern Rockies. 
  However, tightening of the surface pressure gradient across the
  state may combine with localized terrain influences to promote
  elevated to locally critical fire-weather at times.  Most interior
  areas will remain very warm and dry, with afternoon RH values
  falling 7-15% and fuels remaining very dry across the state.  The
  overall regime will support continued plume-dominated fire activity
  along with localized fire spread where surface winds can increase
  due to terrain.

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

  CLICK FOR DAY 2 FIREWX AREAL OUTLINE PRODUCT (KWNSPFWFD2)

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Page last modified: September 06, 2020