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Day 2 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0204 PM CDT Thu Sep 01 2022

Valid 021200Z - 031200Z

...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF CENTRAL AND SOUTHERN
OREGON INTO EXTREME NORTHEASTERN CALIFORNIA AND EXTREME NORTHWESTERN
NEVADA...

Critical highlights have been added to portions of the southern
Cascades for tomorrow/Friday afternoon. Model guidance consensus,
including high-resolution ensemble guidance, depicts an increasing
chance for widespread 20+ mph sustained south-southwesterly surface
winds during the mid to late afternoon hours. While the surface wind
field is still relatively marginal for Critical standards, RH may
dip into the 10-15 percent range by afternoon peak heating, with
fuels reaching near-record levels of dryness in some spots. The
anticipated wind field may encourage sufficient spread of new
wildfires as well as potential significant growth of pre-existing
fires given very favorable fuels/RH, necessitating Critical
highlights. It is also possible that a brief thunderstorm could
develop and produce a couple of strikes to support new ignitions,
though the threat is too sparse to introduce highlights this
outlook.

Otherwise, the previous forecast (see below) remains on track for
portions of the Central Plains.

..Squitieri.. 09/01/2022

.PREV DISCUSSION... /ISSUED 0155 AM CDT Thu Sep 01 2022/

...Synopsis...
Fire weather concerns will return to the Pacific Northwest and
portions of the central Plains on Friday. A dominant Great Basin
ridge will largely remain in place over the next 48 hours, but will
deamplify slightly as a shortwave trough impinges on its
northwestern periphery, strengthening flow over the northern Sierra
Nevada in the process. To the east, a departing upper wave over the
Canadian Prairies will help push a weak cold front into the Plains.
Breezy post-frontal conditions will support fire weather concerns
outside of pockets of recent rainfall.

...Northern Sierra Nevada into Southern Oregon...
An upper-level shortwave trough, noted over the eastern Pacific in
water-vapor imagery, is forecast to move ashore into the Pacific
Northwest Friday. Increasing mid-level flow along the northern
Sierra Nevada will yield dry and breezy downslope winds across
northeast CA/northwest NV into central OR. RH reductions into the
teens are likely, and may reach as low as near 10% per drier/windier
solutions. Elevated conditions are expected prior to the passage of
a cold front during the evening hours, and several ensemble members
suggest critical conditions are probable during peak heating.
However, considerable spread among deterministic guidance is noted
and limits confidence in the coverage of critical conditions.
Critical highlights may be needed in future forecast updates as
guidance co*es into better agreement.

...Central Plains...
A cold front associated with a surface low over the Canadian
Prairies is expected to push south into the Plains through the day
Friday. Cold advection behind this front will be modest and allow
diurnal RH reductions into the 20-25% range. Breezy post-frontal
winds between 15-20 mph are expected, resulting in elevated fire
weather conditions from northeast CO into north-central NE. MRMS
rainfall estimates from the past 24 hours reveal pockets of heavy
rain through this corridor, though many locations received limited
rainfall. Dry conditions through Friday afternoon will maintain ERC
values near the 90th percentile and support a fire weather risk
outside of the pockets of heavier rainfall. The spatial coverage of
the fire weather risk may be conditional on the placement of the
front by late afternoon. Furthermore, isolated to scattered
thunderstorms are possible along the boundary and may support strong
to severe outflow winds (see the latest Day 2 convective outlook for
additional details).

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