FNUS21 KWNS 131649

Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1149 AM CDT Sat Jul 13 2024

Valid 131700Z - 141200Z

Only minor adjustments were made to the isolated dry thunderstorm
area in alignment with recent trends and coordination with local
partners. Otherwise, the D1 Fire Weather Outlook remains on track
with no changes needed to the Elevated risk areas. See previous
discussion below for more information.

..Thornton.. 07/13/2024

.PREV DISCUSSION... /ISSUED 1250 AM CDT Sat Jul 13 2024/

Fire weather concerns will continue today across the western CONUS
with dry lightning as the primary threat. Multiple days of very hot
and dry conditions have cured fuels across much of the Great Basin
and Pacific Northwest with ERC values well above the 90th percentile
for most locations. Preconditioned fuels coupled with the potential
for dry lightning may pose a considerable fire weather risk this
afternoon and evening. A persistent upper ridge over the lower CO
River Valley will continue to promote weak gradient winds for much
of the Great Basin, though breezy conditions are anticipated across
the Pacific Northwest/northern Rockies.

...Dry Thunder - CA into the Great Basin...
00 UTC soundings across the Southwest and West Coast sampled steep
mid-level lapses and cool temperatures between 500-600 mb as well as
appreciable mid-level moisture atop very dry conditions within the
lowest 3 km. Thunderstorms ongoing at the time of the soundings were
producing pockets of wetting rainfall - likely due to slow storm
motions near 10 knots - but many areas received limited
precipitation per MRMS QPE. GOES precipitable water imagery
continues to show the northward expansion of 0.5-1.0 inch PWAT
values into central NV. Although forcing for ascent will be fairly
weak through the day, deep mixing will quickly erode any nocturnal
MLCIN as ascent increases ahead of a weak mid-level perturbation.
Thunderstorm development will likely begin across southern CA/NV and
western AZ before spreading north through the afternoon, possibly
reaching into southeast OR by the 22-02 UTC period. Likewise,
thunderstorm coverage is expected to be greatest across the lower CO
River Valley, but higher PWAT values and a higher probability for
wetting rainfall in ensemble guidance limits confidence in the
potential for a more widespread dry-lightning risk. Further north
into central and northern NV (and adjacent states), storm coverage
should be more sparse, but lower PWAT values, faster storm motions,
the potential for strong convective outflows, and very receptive
fuels should support a robust fire weather concern where storms

...Pacific Northwest/northern Sierra and northern Rockies...
Dry/windy conditions over the past 24-48 hours continue to promote
active fire behavior east of the Cascades and into the northern
Rockies per recent reports. A belt of stronger mid-level flow on the
northern periphery of the upper ridge will support another day of
breezy conditions as 20-30 knot flow between 700-500 mb is
transferred downward amid deep diurnal mixing. Widespread RH
reductions into the single digits and low teens are anticipated, and
localized elevated fire weather conditions will be common; however
confidence in a more prolonged, wind-driven fire weather threat
remains highest across southeast OR and over portions of eastern
ID/southwest MT. A more narrow zone of prolonged elevated fire
weather conditions is anticipated in the lee of the northern Sierra
Nevada within a modest downslope flow regime.

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