Storm Prediction Center Day 1 Fire Weather Outlook

Created: Fri Jul 20 16:28:02 UTC 2018 (20180720 1700Z Day 1 FireWX shapefile | 20180720 1700Z Day 1 FireWX KML)

Day 1 Fire Weather Forecast graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast

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   FNUS21 KWNS 201626

   Day 1 Fire Weather Outlook  
   NWS Storm Prediction Center Norman OK
   1126 AM CDT Fri Jul 20 2018

   Valid 201700Z - 211200Z

   An elevated area was added for portions of far southwest
   Oregon/northwest California where gusty north-northeast winds
   (sustained 15-20 mph) will overlap with RH values of 15-25% this
   afternoon/evening. The elevated area over central Oregon was
   expanded farther south as a dry cold front should increase winds
   this evening as it passes through the region. The ongoing fire
   activity within these two elevated areas are likely to be
   exacerbated by these dry/windy conditions and antecedent dry fuels.
   The isolated dry thunderstorm area was expanded southward as
   monsoonal moisture continues slowly moving northward via latest
   surface/upper-air observations and water vapor imagery.

   Overall, the forecast looks on track and please see discussion below
   for more details.

   ..Nauslar.. 07/20/2018

   .PREV DISCUSSION... /ISSUED 0204 AM CDT Fri Jul 20 2018/

   A long-wave upper-level trough will move into the Pacific Northwest
   today. In the meantime, an upper-level ridge will build across the
   Front Range of the Rockies. An area of enhanced 40 to 50 knot
   mid-level flow will develop across much of the Pacific Northwest and
   could lead to several areas of elevated fire weather concern. In
   addition, thunderstorms will develop across much of the Desert
   Southwest, Great Basin, and Colorado Rockies. Some of these
   thunderstorms will be on the drier side along the northern and
   western periphery of the richer moisture.

   ...Columbia River Basin...
   Downslope flow and deep mixing will lead to sustained winds around
   15 mph across much of the Columbia River Basin. These winds,
   combined with RH values of 15 to 20 percent, will lead to elevated
   fire weather conditions. Wind speeds may be slightly higher in some
   of the gaps in the Cascades, but the marine influence west of the
   Cascades will lead to slightly higher RH values (25 to 30 percent)
   in these locations.

   ...Southern Idaho...
   Sustained winds will approach 15 mph during the afternoon today as
   deep mixing transports stronger mid-level winds towards the surface
   across much of the Snake River Valley into portions of the
   Bitterroot Mountains. RH values will be 10 to 15 percent across much
   of this area leading to elevated fire weather conditions.

   ...Northern Montana...
   Downslope flow and deep mixing will lead to increasing surface winds
   into the afternoon east of the Lewis Range. In addition, RH values
   will drop to the 15 to 20 percent range. This will lead to elevated
   fire weather conditions for at least a few hours on Friday.

   ...Eastern California into the northern Great Basin...
   An area of dry thunderstorms is possible along the periphery of the
   greater monsoon moisture from far eastern California across northern
   Nevada and Utah and into far southwest Wyoming. Kept the isolated
   dry thunderstorm delineation to areas which have seen mostly limited
   rainfall (< 0.25") over the past 7 days where PWAT values are less
   than an inch and storms are expected.

   ...Southern Plains...
   A heat wave in the southern Great Plains will lead to dry conditions
   during the afternoon hours for much of west eastern New Mexico, West
   Texas, and western and central Oklahoma. RH values are expected to
   drop into the 15 to 20 percent range during the afternoon with an
   increasing surface wind. Southerly surface winds will strengthen to
   around 15 mph. This combination of gusty surface winds and low
   relative humidity values warrants elevated fire weather concerns
   across much of the southern High Plains into western and central
   Oklahoma. While some of this area has seen significant rainfall over
   the past 7 days, coverage of these storms has been spotty, and hot
   weather the past few days has led to significant drying of fine

   ...Please see for graphic product...


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