Day 3-8 Fire Weather Forecast Issued on Dec 7, 2017

Updated: Thu Dec 7 21:15:03 UTC 2017

Day 3-8 Fire Weather Forecast Graphic Issued on Dec 7, 2017
 
Day 3 Probabilistic Dry Thunder/Strong Wind FireWX Forecast Graphic Issued on Dec 7, 2017

Day 3 Experimental Probabilistic Fire Weather Outlooks:
Probability of dry thunderstorms with dry fuels within 12 miles of a point denoted by scalloped lines for
- Critical Area - 40% (blue)
- Marginal Area - 10% (brown)
Probability of strong winds, low RH, and warm temperatures concurrent for at least 3 hours with dry fuels within 12 miles of a point denoted by solid lines for
- Critical Area - 70% (red)
- Marginal Area - 40% (orange)


Day 4 Probabilistic Dry Thunder/Strong Wind FireWX Forecast Graphic Issued on Dec 7, 2017

Day 4 Experimental Probabilistic Fire Weather Outlooks:
Probability of dry thunderstorms with dry fuels within 12 miles of a point denoted by scalloped lines for
- Critical Area - 40% (blue)
- Marginal Area - 10% (brown)
Probability of strong winds, low RH, and warm temperatures concurrent for at least 3 hours with dry fuels within 12 miles of a point denoted by solid lines for
- Critical Area - 70% (red)
- Marginal Area - 40% (orange)


Day 5 Probabilistic Dry Thunder/Strong Wind FireWX Forecast Graphic Issued on Dec 7, 2017

Day 5 Experimental Probabilistic Fire Weather Outlooks:
Probability of dry thunderstorms with dry fuels within 12 miles of a point denoted by scalloped lines for
- Critical Area - 40% (blue)
- Marginal Area - 10% (brown)
Probability of strong winds, low RH, and warm temperatures concurrent for at least 3 hours with dry fuels within 12 miles of a point denoted by solid lines for
- Critical Area - 70% (red)
- Marginal Area - 40% (orange)


Day 6 Probabilistic Dry Thunder/Strong Wind FireWX Forecast Graphic Issued on Dec 7, 2017

Day 6 Experimental Probabilistic Fire Weather Outlooks:
Probability of dry thunderstorms with dry fuels within 12 miles of a point denoted by scalloped lines for
- Critical Area - 40% (blue)
- Marginal Area - 10% (brown)
Probability of strong winds, low RH, and warm temperatures concurrent for at least 3 hours with dry fuels within 12 miles of a point denoted by solid lines for
- Critical Area - 70% (red)
- Marginal Area - 40% (orange)


Day 7 Probabilistic Dry Thunder/Strong Wind FireWX Forecast Graphic Issued on Dec 7, 2017

Day 7 Experimental Probabilistic Fire Weather Outlooks:
Probability of dry thunderstorms with dry fuels within 12 miles of a point denoted by scalloped lines for
- Critical Area - 40% (blue)
- Marginal Area - 10% (brown)
Probability of strong winds, low RH, and warm temperatures concurrent for at least 3 hours with dry fuels within 12 miles of a point denoted by solid lines for
- Critical Area - 70% (red)
- Marginal Area - 40% (orange)


Day 8 Probabilistic Dry Thunder/Strong Wind FireWX Forecast Graphic Issued on Dec 7, 2017

Day 8 Experimental Probabilistic Fire Weather Outlooks:
Probability of dry thunderstorms with dry fuels within 12 miles of a point denoted by scalloped lines for
- Critical Area - 40% (blue)
- Marginal Area - 10% (brown)
Probability of strong winds, low RH, and warm temperatures concurrent for at least 3 hours with dry fuels within 12 miles of a point denoted by solid lines for
- Critical Area - 70% (red)
- Marginal Area - 40% (orange)


Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
D3 16,185 20,224,823 Los Angeles, CA...San Diego, CA...Long Beach, CA...Santa Ana, CA...Anaheim, CA...
D4 10,776 7,408,933 Riverside, CA...Glendale, CA...San Bernardino, CA...Ontario, CA...Fontana, CA...
D3Sat, Dec 09, 2017 - Sun, Dec 10, 2017 D6Tue, Dec 12, 2017 - Wed, Dec 13, 2017
D4Sun, Dec 10, 2017 - Mon, Dec 11, 2017 D7Wed, Dec 13, 2017 - Thu, Dec 14, 2017
D5Mon, Dec 11, 2017 - Tue, Dec 12, 2017 D8Thu, Dec 14, 2017 - Fri, Dec 15, 2017
(All days are valid from 12 UTC - 12 UTC)
   ZCZC SPCFWDD38 ALL
   FNUS28 KWNS 072113

   Day 3-8 Fire Weather Outlook  
   NWS Storm Prediction Center Norman OK
   0313 PM CST Thu Dec 07 2017

   Valid 091200Z - 151200Z

   The primary synoptic-scale feature contributing to fire weather
   concerns through D8/Thu Dec 14 will be an expansive and nearly
   stationary surface ridge across the Intermountain West and Great
   Basin.  The resulting offshore gradient in portions of southern
   California will persist throughout the forecast period, with
   elevated to critical fire weather conditions most probable in the
   D3/Sat through D6/Tue time frame.

   Elsewhere, areas of breezy northwesterly surface flow (particularly
   on D5/Mon) will lead to locally elevated fire weather conditions
   across portions of the central Plains, although borderline RH and
   uncertainty on specific corridors of higher winds preclude
   probabilities for this outlook.

   ...Southern California...
   The aforementioned surface pressure gradient will continue across
   the area through the end of the forecast period resulting in gusty
   offshore flow.  A gradual weakening of this pressure gradient (and
   attendant winds) is expected however - especially from around D5/Mon
   onward.  More widespread critical wind fields are expected on D3/Sat
   and D4/Sun especially in terrain-favored canyons and higher
   elevations.  Critically low RH will exist on a widespread basis
   throughout the forecast period as a dry airmass remains in place. 
   Meanwhile, poor overnight recovery of this airmass will result in
   areas of critically low RH values (hovering around 10-20%) well into
   the overnight hours.  

   Because a greater confidence of critically strong surface winds
   exists on D3/Sat and D4/Sun, 70%/critical probabilities will be
   maintained across the region.  Rapid fire spread will remain likely
   on these days.  From D5/Mon into D6/Tue, the slackening gradient and
   resultant weaker winds suggests lends less confidence in critical
   fire weather thresholds being achieved on a widespread basis,
   although localized areas may experience critical wind/RH.  40%
   probabilities may eventually be needed after D7/Wed if greater
   confidence in areas of gusty winds are achieved in later model
   cycles.

   ..Cook.. 12/07/2017

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

   $$

   CLICK TO GET FNUS38 KWNS PFWF38 FIRE WEATHER OUTLOOK DAY 3-8 AREAL OUTLINE PRODUCT