Storm Prediction Center Day 2 Fire Weather Outlook

Created: Wed Dec 6 07:20:02 UTC 2017 (20171206 1200Z Day 2 FireWX shapefile | 20171206 1200Z Day 2 FireWX KML)

Day 2 Fire Weather Forecast graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
Extreme 8,483 8,692,856 Santa Ana, CA...Anaheim, CA...Riverside, CA...Glendale, CA...San Bernardino, CA...
Critical 5,959 11,379,949 Los Angeles, CA...San Diego, CA...Long Beach, CA...Chula Vista, CA...Huntington Beach, CA...

Click for Day 2 FireWX Areal Outline Product (KWNSPFWFD2)

   FNUS22 KWNS 060718

   Day 2 Fire Weather Outlook  
   NWS Storm Prediction Center Norman OK
   0118 AM CST Wed Dec 06 2017

   Valid 071200Z - 081200Z


   Dangerous and extremely critical fire weather conditions are
   expected across a greater portion of southern CA on Day 2/Thursday
   compared to Day 1/Wednesday.

   Within large-scale upper troughing over much of the central/eastern
   CONUS, an embedded positively tilted upper trough will develop
   south-southeastward over the Rockies/Plains by 12Z Thursday.
   Enhanced north/northeasterly low- and mid-level flow around 30-40 kt
   on the western periphery of this upper trough will overspread the
   Southwest and southern CA Thursday morning and early afternoon.
   Highly amplified upper ridging will remain over the eastern Pacific
   and West Coast.

   At the surface, a broad area of high pressure over the northern
   Rockies and Great Basin will restrengthen late from Wednesday night
   into Thursday morning. A corresponding increase in offshore winds
   will occur across much of coastal southern CA through Thursday
   evening, supporting high-end critical to extremely critical fire
   weather conditions.

   ...Portions of Southern CA...
   Given the strengthening surface pressure gradient plus the enhanced
   low- and mid-level flow mentioned above, sustained northeasterly to
   easterly winds of 30-40 mph will likely occur across much of the
   higher terrain of southern CA from Thursday morning through at least
   the evening hours. This includes the mountains/foothills and
   adjacent areas of Ventura, Los Angeles, Orange, southwestern San
   Bernardino, western Riverside, and central/eastern San Diego
   counties. Stronger gusts of 50-70 mph will likely occur in favored
   higher terrain and passes where flow channeling will be maximized.
   RH values will easily fall/remain in the 5-10% range due to diurnal
   heating and low-level downslope warming/drying effects. Coupled with
   very dry/receptive fuels, these expected meteorological conditions
   support an extremely critical fire weather area. Large fire spread
   and extreme fire behavior will occur with any new/ongoing fires.

   Surrounding the extremely critical designation, critical fire
   weather conditions are anticipated. Here, sustained winds of 20-30
   mph, with gusts to 40-50 mph, and RH values of 5-15% will be common.
   Both downtown Los Angeles and the LA basin along with San Diego have
   been included in a critical delineation. These dangerous fire
   weather conditions are forecast to continue through the entire Day
   2/Thursday period, although the surface pressure gradient should
   relax slightly from late Thursday night into Friday morning. This
   should act to lessen winds somewhat across southern CA late in the

   ..Gleason.. 12/06/2017

   ...Please see for graphic product...


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