Storm Prediction Center
Day 1 and Day 2 Fire Weather Outlooks

Day 1 Fire Weather Forecast graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
Critical 81,556 3,501,220 Las Vegas, NV...Henderson, NV...Paradise, NV...Sunrise Manor, NV...North Las Vegas, NV...
Dry Tstm 26,083 748,920 Nampa, ID...Meridian, ID...Caldwell, ID...Eagle, ID...La Grande, OR...

Click for Day 1 FireWX Areal Outline Product

   ZCZC SPCFWDDY1 ALL
   FNUS21 KWNS 261653

   Day 1 Fire Weather Outlook  
   NWS Storm Prediction Center Norman OK
   1153 AM CDT Mon Jun 26 2017

   Valid 261700Z - 271200Z

   ...CRITICAL FIRE WEATHER AREA FOR SCATTERED DRY THUNDERSTORMS ACROSS
   PORTIONS OF EASTERN OR AND SOUTHWEST ID...
   ...CRITICAL FIRE WEATHER AREA FOR STRONG WINDS/LOW RH ACROSS
   PORTIONS OF THE SOUTHERN CA MOUNTAINS AND ADJACENT FOOTHILLS...
   ...CRITICAL FIRE WEATHER AREA FOR STRONG WINDS/LOW RH ACROSS
   PORTIONS OF NORTHWEST NV...
   ...CRITICAL FIRE WEATHER AREA FOR STRONG WINDS/LOW RH ACROSS
   PORTIONS OF SOUTHERN/EASTERN NV...WESTERN UT...NORTHWEST AZ...

   The primary changes to the forecast involve categorical upgrades
   across parts of southern/eastern CA.

   A Critical area for strong winds/low RH has been added across
   portions of the southern CA mountains and adjacent foothills --
   especially those foothills toward the general direction of the
   desert (eastward). The VAD wind profiles at Sulphur Mountain (VTX)
   and Santa Ana Mountains (SOX) are indicating relatively enhanced
   (20-40 mph) westerly winds around 3.5-6.5 kft above ground. This is
   highlighting the strong flow aloft that will be manifested at the
   surface by vertical mixing across the added Critical area. Across
   this area, westerly surface winds of 20-30 mph with higher gusts are
   expected to combine with RH of 3-10 percent as hot surface
   temperatures materialize and fuels remain dry. Poor RH recovery and
   continued strong winds are expected to support critical conditions
   into tonight.

   Elevated areas over portions of the Great Basin / AZ and southern CA
   have been connected -- adding areas along and east of the crest of
   the southern Sierra mountains to Elevated designation. This is where
   enhanced downslope winds are expected to combine with reduced RH.

   Also, the southern CA Elevated area has been expanded westward
   toward the coast, especially in Santa Barbara, Ventura, and Los
   Angeles Counties. Diurnally enhanced vertical mixing into the dry
   air aloft (e.g., PW around one-half inch per Vandenberg Air Force
   Base 12Z sounding) will support minimum RH around 8-15 percent
   inland and removed from the marine layer, amid modestly enhanced
   winds.

   The remainder of the forecast is unchanged.

   ..Cohen.. 06/26/2017

   .PREV DISCUSSION... /ISSUED 0245 AM CDT Mon Jun 26 2017/

   ...Synopsis...
   Shortwave trough currently off the northern CA coast will continue
   progressing east-northeastward, reaching central OR by the early
   afternoon and southern ID by the evening. Continued eastward
   progress of this shortwave trough will take it through much of the
   northern Rockies by 12Z Tuesday. Overall progression of this system
   will result in the breakdown of the upper ridge which has remained
   in place across much of the Intermountain West for the past week.
   Additionally, the passage of the this shortwave trough will result
   in both wind-driven and lightning-caused fire weather threats today
   from the Pacific Northwest south into AZ today. Farther east, upper
   troughing covering much of the central/eastern CONUS at the
   beginning of the period will shift eastward as several shortwave
   troughs track quickly through its base.

   ...Great Basin...AZ...
   Strengthening mid-level flow coupled with deep boundary-layer mixing
   and a tightening surface pressure gradient will support gusty winds
   from southern OR across much of the Great Basin and into central AZ.
   The strongest winds (i.e. sustained 20-25 mph) are anticipated
   across northeast NV, where the mid-level flow is the strongest, and
   across southern/eastern NV and adjacent southwest UT and northwest
   AZ where the surface pressure gradient is the tightest.
   Above-average temperatures are anticipated areawide with minimum RH
   values ranging from the mid-teen to upper single-digits. As a
   result, critical fire weather conditions are expected in those areas
   where the winds are strongest. 

   ...Pacific Northwest...Northern Rockies...
   Mid-level moisture associated with the approaching shortwave trough
   will advect into the Pacific Northwest/northern Rockies atop a very
   dry antecedent airmass. Forecast soundings across much of the region
   reveal deeply mixed inverted-v profiles by the early afternoon.
   During the afternoon, PW values will likely range from around 1"
   across central OR to closer to 0.60" across south-central ID. This
   gradient in moisture combined with a deeply mixed boundary layer and
   at least moderately fast storm motions (around 30 kt) will result in
   an environment supportive of dry thunderstorm. The highest coverage
   of dry storms is expected across east-central OR and southwest ID. A
   more hybrid storm mode is anticipated across the remainder of Oregon
   and into WA. Less storm coverage is anticipated across the remainder
   of ID, with most of this storms expected to be on the drier side.

   ...Mountains and Western/desert Foothills of Southern CA...
   Strong onshore flow is expected across much of the interior portions
   of southern CA today. Best overlap of the windy and dry conditions
   with receptive fuels will be across the higher elevations and
   western/desert foothills during the afternoon and evening. Elevated
   to locally critical fire weather conditions are anticipated across
   these areas.

   ..Central/Eastern MT...
   A strong surface pressure gradient will exist over the region
   between the lower pressures to west (associated with the
   aforementioned shortwave trough) and remnant high pressure across
   the northern Plains/upper MS valley. This gradient will support
   breezy southeast surface winds (i.e. 15-20 mph) from the early
   afternoon through the evening. Above-average temperatures (i.e.
   highs in the 90s) amidst a dry airmass will support afternoon RH
   values from 15 to 20 percent. Guidance still suggests some
   dissociation between the strongest winds (over north-central MT) and
   the lowest RH (over southeast MT). Resulting conditions support an
   elevated fire weather threat but the dissociation between the
   strongest winds and lowest RH values currently precludes a critical
   delineation.

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

      
Day 2 Fire Weather Forecast graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
Critical 60,699 725,955 Flagstaff, AZ...Farmington, NM...Prescott, AZ...Prescott Valley, AZ...Gallup, NM...

Click for Day 2 FireWX Areal Outline Product (KWNSPFWFD2)

   ZCZC SPCFWDDY2 ALL
   FNUS22 KWNS 261742

   Day 2 Fire Weather Outlook  
   NWS Storm Prediction Center Norman OK
   1242 PM CDT Mon Jun 26 2017

   Valid 271200Z - 281200Z

   ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHERN AZ AND
   NORTHWEST NM...

   Primary changes to the Day-2 Fire Weather Outlook are as follows:

   1. The northern AZ Critical area has been expanded eastward into
   northwest NM and has been expanded slightly westward, based on the
   latest model guidance's depiction of enhanced low/midlevel flow
   overlapping with a deep boundary layer characterized by hot surface
   temperatures and 3-11 percent RH. West-southwesterly surface winds
   of 20-25 mph are expected across the Critical area.

   2. The northern part of the Elevated area surrounding the Critical
   area has been expanded eastward into extreme southwest SD and far
   western parts of the NE Panhandle. The latest model guidance
   suggests that a deep boundary layer with adequately low surface RH,
   coinciding with enhanced winds, will materialize west of a
   sharpening lee trough amid sufficiently dry fuels. Confidence in
   critical winds/RH occurring on any more than a brief/spotty/marginal
   basis is too limited for Critical designation at this time.

   3. The Isolated Dry Thunderstorm area has been expanded eastward
   into extreme southwest SD and far western parts of the NE Panhandle,
   with the anticipation that thunderstorm activity will spread farther
   east amid the deep boundary layer and produce minimal precipitation
   before reaching richer moisture.

   4. An Elevated area has been added across portions of the southern
   CA mountains and adjacent foothills, where lingering enhanced winds
   are expected to combine with low RH. Poor RH recovery is expected in
   many areas for Tuesday night, resulting in a long-duration period of
   enhanced fire-weather potential.

   No other changes have been made to the ongoing forecast.

   ..Cohen.. 06/26/2017

   .PREV DISCUSSION... /ISSUED 0258 AM CDT Mon Jun 26 2017/

   ...Synopsis...
   Shortwave trough over the northern Rockies at the beginning of the
   period -- 12Z Tuesday -- will progress eastward through the northern
   Plains, reaching the upper MS Valley early Wednesday morning.
   Farther east, a pair of phased shortwave troughs will move through
   the upper trough initially over the eastern CONUS. Progression of
   these shortwave troughs will act to deamplify the parent upper
   trough. As a result, a largely zonal pattern is anticipated across
   the CONUS by 12Z Wednesday. At the surface, high pressure will shift
   eastward into OH and TN valleys while a low moves eastward across
   the Dakotas. Cold front attendant to this low will move across the
   northern and central High Plains.

   ...Southwest...Great Basin...Central Rockies...
   Another day of above-average temperatures and afternoon RH values in
   the single digits is anticipated across much of the western CONUS,
   including portions of the Southwest, Great Basin, and central
   Rockies. Some breezy winds are also anticipated, primarily a result
   of the enhanced mid-level flow coupled with deep boundary-layer
   mixing. Best combination of windy and dry conditions with dry fuels
   is expected across portions of the central/north-central AZ.
   Critical fire weather conditions are expected here with elevated to
   locally critical conditions anticipated across the remainder of the
   region.

   ...Southwest WY...
   Thunderstorms are expected across much of the northern Rockies
   during the afternoon. However, high storm coverage, modest storm
   motions, and high PWs suggest mainly wetting rains with much of this
   activity. The only exception appears to be across southwest WY where
   a deep mixed boundary layer will support high cloud bases and ample
   sub-cloud precipitation evaporation. Mean storm motion is this area
   is also expected to be around 35-40 kt. These meteorological
   conditions support increased fire danger due to isolated dry
   thunderstorms.

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

      

Fire Weather/Forecast Products/Home