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Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0150 AM CDT Mon Sep 02 2024

Valid 021200Z - 031200Z

...CRITICAL FIRE WEATHER AREA FOR SOUTHERN OREGON INTO FAR NORTHEAST
CALIFORNIA AND FAR NORTHWEST NEVADA...
...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON INTO SOUTHWEST
IDAHO...NORTHEAST NEVADA...AND FAR NORTHWEST UTAH...
...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO WESTERN
SOUTH DAKOTA...

...Synopsis...
An active fire weather day is anticipated across the High Plains and
Pacific Northwest/northern Great Basin. Fire weather concerns across
the West will be associated with a progressive upper wave currently
moving onshore along the northern CA coast, which is forecast to
migrate into the interior Pacific Northwest over the next 24 hours.
As this occurs, strengthening low-level winds will support dry/windy
conditions, and lift ahead of the wave will promote isolated to
scattered thunderstorms. To the east, flow across the northern to
central Rockies is forecast to strengthen slightly within the apex
of an upper ridge. This will result in modest surface pressure falls
along the High Plains, which when juxtaposed with a building surface
high over the Midwest will yield strong southerly winds and dry
conditions. Fuels across both regions remain very dry (ERCs at or
above the 90th percentile) after multiple days of dry conditions,
which will support the fire weather concerns.

...Pacific Northwest/Great Basin...
Regional VWPs along the West Coast are beginning to observe the
influence of the approaching wave with winds in the lowest few
kilometers slowly strengthening since 00 UTC. Further
intensification of the low-level wind field is anticipated, which
will strengthen downslope flow off the central to northern Sierra
Nevada. Dry conditions are already in place and will be maintained
within the augmented downslope regime. Latest ensemble guidance
continues to show a strong signal for afternoon RH values to fall
into the teens with 15-25 mph winds. The strongest winds (and
highest probability for sustained critical conditions) are expected
from northeast CA into southern OR and far northwest NV as the
mid-level jet max passes overhead around peak heating. 

Over the past several days, a plume of monsoonal moisture has been
tracked from southern AZ into northern NV and central to eastern OR.
The 00 UTC MFR sounding sampled this air mass well, which is
characterized by sufficient mid-level moisture to support weak
convection, but a very dry boundary layer favorable for dry
thunderstorms. Over the past two days, thunderstorms within this air
mass across the Great Basin have been predominantly dry, and are
expected to mainly be dry once again today for much of the region
(one exception is from the Blue Mountains in northeast OR to the
Salmon River Mountains in central ID where orographic ascent should
support more prolonged convection with a higher probability for
wetting rainfall). Stronger synoptic-scale forcing for ascent should
result in greater thunderstorm coverage co*pared to previous days,
warranting a scattered dry thunderstorm risk area from eastern OR
into ID, northeast NV, and far northwest UT where latest CAM
guidance shows the best convective signal.

...High Plains...
A recent frontal intrusion into the Plains/Midwest has shunted
seasonally rich moisture southward into the southern Plains. A
strong surface high in the wake of the front will shift east through
the day concurrent with the deepening of a weak lee trough. A dry
return flow regime will beco*e established through the day as winds
beco*e more southerly. Latest deterministic and ensemble solutions
show a fairly strong signal for 20-25 mph winds (gusting to 35 mph)
across western NE into western SD with RH values falling into the
low 20s to teens. Consequently, confidence in sustained critical
conditions over an appreciable area has increased enough to warrant
introducing a Critical risk area.

..Moore.. 09/02/2024

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