U.S. Day 1 Fire Weather Outlook
ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 051631
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1131 AM CDT Fri Sep 05 2025
Valid 051700Z - 061200Z
...Update...
No changes were required for today's forecast. Expect increasing
chances of lightning beginning late this afternoon across
southeastern OR, peaking by this evening over central OR.
..Barnes.. 09/05/2025
.PREV DISCUSSION... /ISSUED 0137 AM CDT Fri Sep 05 2025/
...Synopsis...
A mid-level trough will traverse the Midwest/Great Lakes Regions as
upper ridging remains in place over the Interior West, but with a
small but pronounced mid-level impulse impinging on the northern
California coastline today. This impulse, in tandem with adequate
instability, will provide enough lift to support at least scattered
thunderstorms to portions of the Pacific Northwest this afternoon
into the overnight hours. These storms will move atop a modestly dry
boundary layer, with wet and dry storm modes both possible.
Nonetheless, these storms will overspread dry fuel beds, especially
from the central/northern Cascades and points east. Dry thunderstorm
highlights remain in place for the possibility of lightning strikes
(some dry) posing a hazard for fuel ignition.
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U.S. Day 2 Fire Weather Outlook
ZCZC SPCFWDDY2 ALL
FNUS22 KWNS 051915
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0215 PM CDT Fri Sep 05 2025
Valid 061200Z - 071200Z
...Update...
Some minor changes were made to the Isolated Dry Thunderstorm area
for Saturday. The latest model trends regarding the track and ascent
associated with the initial mid-level shortwave trough moving
onshore suggest additional lightning strikes may occur further west
over the Cascades of WA. Farther south, into portions of the
northern Great Basin and far southeastern OR, fuels appear far less
receptive. Therefore, some of this region was trimmed out of the
isolated area. Please see the previous discussion below for
additional details.
..Barnes.. 09/05/2025
.PREV DISCUSSION... /ISSUED 0152 AM CDT Fri Sep 05 2025/
...Synopsis...
A mid-level trough will continue to approach the East Coast as upper
ridging builds over the Rockies and a mid-level trough remains in
place along the Pacific Northwest coast tomorrow (Saturday). A
mid-level impulse will pivot around the northwestern trough,
providing locally stronger upper support for dry and breezy
conditions across northern California into southern Oregon. At the
moment, the overlap of 15+ mph sustained southwesterly surface winds
amid 15-20 percent RH seem to be too localized to warrant Elevated
highlights at this time.
Of greater concern is the development of scattered thunderstorms
ahead of the mid-level trough over parts of the Pacific Northwest
into the northern Rockies. Here, a mix of wet and dry storm modes
will overspread a dry boundary layer, as well as dry fuel beds.
Storm motions will be relatively slow. However, the high
receptiveness of the fuels may compensate for possible wet, slow
moving storms to support lightning-induced ignitions, warranting the
introduction of isolated dry thunderstorm highlights.
U.S. Day 3-8 Fire Weather Outlook
ZCZC SPCFWDD38 ALL
FNUS28 KWNS 042034
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0334 PM CDT Thu Sep 04 2025
Valid 061200Z - 121200Z
A negatively-tilted upper-level shortwave trough will continue to
track slowly northward across the Northwest Day 3/Saturday into Day
4/Sunday. A larger upper low will move into the Northwest late Day
4/Sunday through Day 6/Tuesday, with upper-level troughing likely
deepening over the West Coast through mid-next week. Upper-level
troughing may develop over most of the West mid to late next week,
but forecast uncertainty remains high on the progression of the
upper-level trough over the West/West Coast.
Isolated to scattered mixed wet/dry thunderstorms are likely in
portions of the Northwest and northern Rockies/Great Basin on Day
3/Saturday - Day 4/Sunday, with the Cascades having the best
chances. Onshore flow will bring showers, higher RH, and cooler
temperatures to the Northwest and eventually the northern Rockies
and northwest California beginning late Day 4/Sunday and likely
lasting through much of the outlook period. This pattern change and
potential preceding wetting rain in areas on Day 1/Thursday - Day
2/Friday will limit the impacts of potential ignitions on Day
3/Saturday - Day 4/Sunday and slow fire activity across the
northwestern US. However, if the upper-level trough slows or changes
track in the coming days, areas may need to be introduced.
Dry/windy conditions are likely to develop across portions of the
central/southern Intermountain West on Day 4/Sunday - Day
7/Wednesday as upper-level troughing moves into the West. Fuel
conditions are vastly improved after the last monsoonal surge.
However, the environment will be monitored, especially in areas that
received less wetting rain with the last monsoon surge, for
potential overlap of critical winds/RH and receptive fuels.
..Nauslar.. 09/04/2025
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