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    Day 2 FW Outlook >
Jun 26, 2017 Day 1 Fire Weather Outlook
Updated: Mon Jun 26 16:57:02 UTC 2017 (Print Version | 20170626 1700Z Day 1 FireWX shapefile | 20170626 1700Z Day 1 FireWX KML)
Day 1 Fire
 Population  Cities/Towns  CWAs  Interstates  Counties  FEMA Regions  Day 1 Surface Analysis

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...
   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...

   CLICK FOR DAY 1 FIREWX AREAL OUTLINE PRODUCT (KWNSPFWFD1)
      
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Page last modified: June 26, 2017
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