U.S. Day 1 Fire Weather Outlook
ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 270634
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0134 AM CDT Fri Jun 27 2025
Valid 271200Z - 281200Z
...Synopsis...
Sub-tropical high pressure is forecast to intensify across much of
the southern US as flow aloft lifts to the north. Across the
northern edge of the building high, a low-amplitude midlevel trough
with embedded speed maxima will move eastward from the northern
Rockies to the northern High Plains through tonight. At the
surface, lee cyclogenesis is expected this afternoon in the vicinity
of northeast WY, with a weak lee trough extending south across the
High Plains. Increasing westerly flow aloft and warm temperatures
suggest increased fire-weather concerns are likely.
...Southwest WY and central ID...
Moderate westerly flow at the base of the upper trough will begin to
overspread ID and southwest WY early today as lee troughing develops
to the east. Dry downslope winds are expected across southwest WY
with surface winds to near 20 mph. Deep mixing will also promote
frequent gusts to 25-30 mph, as RH values fall into the teens this
afternoon. Several hours of elevated conditions appear likely,
coincident with dry fuels and ongoing drought.
Farther west, slightly weaker surface flow should develop through
the eastern Snake River Plain and central ID. Deep mixing and the
approach of the upper trough will promote surface gusts of 15-20
mph, along with relative humidity below 20%. This could support a
few hours of elevated fire-weather conditions amid drying fuels.
..Lyons.. 06/27/2025
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U.S. Day 2 Fire Weather Outlook
ZCZC SPCFWDDY2 ALL
FNUS22 KWNS 270636
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0136 AM CDT Fri Jun 27 2025
Valid 281200Z - 291200Z
...Synopsis...
Low-amplitude mid-level troughing over the Northern Rockies will
begin to shift eastward Saturday as high pressure over the southern
US continues to build. A belt of stronger mid-level flow will remain
in place over parts of the Intermountain West, supporting dry
downslope flow ahead of a weak cold front over the Northwest.
...ID into southwest WY...
Gusty surface winds through central ID and southwest WY could
support a few hours of elevated fire-weather potential Saturday. In
the wake of the departing upper trough, continued mid-level zonal
flow will linger over central ID. Confidence is highest that 15-20
mph surface winds will occur across portions of the central and
eastern Snake River Plain Saturday afternoon. Coincident with RH
below 20%, elevated fire-weather conditions are probable amid fuels
that continue to dry.
Farther east into WY, less confidence exists in sustained surface
winds greater than 15 mph occurring on a widespread basis through
the day. However, a very warm and dry air mass will remain in place.
This could support some localized fire-weather concerns, especially
where terrain-augmented winds may occasionally gust to 15-20 mph.
..Lyons.. 06/27/2025
U.S. Day 3-8 Fire Weather Outlook
ZCZC SPCFWDD38 ALL
FNUS28 KWNS 262151
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0451 PM CDT Thu Jun 26 2025
Valid 281200Z - 041200Z
...Day 3-4/Saturday-Sunday...
Stronger westerly mid-level winds under a largely zonal flow pattern
will remain across the Pacific Northwest and Northern Tier states
through the weekend. This will support breezy valley winds within
the Snake River Plain on Day 3/Saturday. These winds will overlap
within a dry boundary layer/low relative humidity environment where
fuels continue to dry, becoming more receptive to wildfire spread.
...Day 5-7/Monday-Wednesday...
Increasing mid-level lapse rates, moisture and elevated instability
along with supportive dynamics from incoming upper-level trough will
promote shower and thunderstorm development across northern
California and along and just east of the Oregon Cascades beginning
as early as Day 4/Sunday, heading into the Day 5/Monday time frame.
The initial build up of mid-level moisture and convection over a
dry, sub-cloud layer will inhibit higher rain amounts under nascent
thunderstorms. Fuels will undergo further drying through the weekend
with above normal temperatures and dry conditions. ERC values near
the 90th percentile are expected by early next week, increasing
ignition potential. Increasing atmospheric moisture Day 6/Tuesday
should promote higher rainfall amounts, limiting dry thunderstorm
threat across the Cascades and portions of central Oregon. A drier,
downslope flow pattern returns to the Cascades Day 7/Wednesday as
the leading mid-level trough axis shifts east into the Great Basin
and Northern Rockies. This would allow potential holdover ignitions
to be exposed to an environment more favorable to fire spread.
...Day 8/Thursday...
Long term ensemble guidance indicates a weak mid-level trough
lingering across the Western U.S. However, forecast signal remains
muted, introducing enough uncertainty to preclude introduction of
any critical fire weather probabilities.
..Williams.. 06/26/2025
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