U.S. Day 1 Fire Weather Outlook
ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 221641
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1141 AM CDT Fri Sep 22 2023
Valid 221700Z - 231200Z
...17z Update...
No major changes will be assessed to the currently valid outlook.
Dry and breezy downslope flow is probable along the I-25 Corridor
and the eastern San Luis Valley of southeastern CO this afternoon.
Probabilities were nudged slightly eastward across parts of the
OK/TX Panhandles where dry and breezy conditions appear possible
this afternoon. However, fuels across much of the area are only
marginally receptive to fire spread given recent rainfall lending
lower confidence in widespread fire-weather concerns. Please see the
previous forecast for more information.
..Lyons.. 09/22/2023
.PREV DISCUSSION... /ISSUED 1249 AM CDT Fri Sep 22 2023/
...Synopsis...
Areas of elevated fire weather conditions are probable this
afternoon across a broad swath of the Four Corners region and into
the Front Range of southern CO and northeast NM, though fuel status
will be a limiting factor across much of this region. Early-morning
low-level water vapor imagery depicts a plume of drier low to
mid-level air from southern CA to northeast AZ on the southern
periphery of a upper low over the northern Great Basin. 00Z
soundings within this dry plume sampled average RH in the 850-700 mb
layer around 20-30%. This dry air mass is expected to spread north
across much of the Four Corners over the next 12-24 hours, and
should mix to the surface amid deep diurnal heating/mixing. The
combination of dry air advection, diurnal warming, and downslope
warming/drying in the lee of terrain features will support
widespread RH reductions into the low teens with 15-20 mph winds.
Recent ensemble guidance shows reasonably good consensus for this
scenario, but latest ERC analyses suggests that fuels across much of
the region are not currently receptive. Local fuel reports from
northeast NM into southeast CO suggest that fuels are regionally
drier and may support a fire weather concern. Consequently,
highlights are maintained across this region where the fire weather
threat is higher.
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U.S. Day 2 Fire Weather Outlook
ZCZC SPCFWDDY2 ALL
FNUS22 KWNS 221941
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0241 PM CDT Fri Sep 22 2023
Valid 231200Z - 241200Z
...NO CRITICAL AREAS...
...20z Update...
No changes will be made to the current outlook. Overall fire-weather
concerns are expected to remain below Elevated criteria and
localized across the lee of the Rockies and northern Great Basin.
See the previous discussions for more information.
..Lyons.. 09/22/2023
.PREV DISCUSSION... /ISSUED 0130 AM CDT Fri Sep 22 2023/
...Synopsis...
Fire weather concerns should remain fairly localized for Saturday
along the High Plains. A surface low and an attendant surface trough
are forecast to deepen as they migrate east across the Plains on
Saturday. This will establish a zonal flow regime across much of the
Rockies and High Plains by late morning. Downslope warming/drying
along the CO Front Range and in the lee of the Sangre de Cristo and
Sandia/Manzano Mountains, augmented by diurnal heating, should
promote areas of 15-25% RH as winds increase to 15-20 mph (with
locally drier/windier in terrain-favored locations). Somewhat meager
mid to upper-level winds should confine the strongest surface winds
close to terrain features - with the exception of southeast WY into
adjacent portions of NE/northeast CO where surface gradient winds
will be stronger. This, combined with somewhat marginal fuel status
outside of far northeast NM and southern CO, will limit the coverage
of elevated conditions and the overall fire weather threat.
U.S. Day 3-8 Fire Weather Outlook
ZCZC SPCFWDD38 ALL
FNUS28 KWNS 222102
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0402 PM CDT Fri Sep 22 2023
Valid 241200Z - 301200Z
Shortwave ridging over the western US will quickly breakdown ahead
of a Pacific trough moving onshore late this weekend into early next
week. As the upper ridge breaks down and strong flow aloft moves
overhead, localized dry and breezy conditions are possible across
parts of the Northwest, Great Basin, and Rockies. By mid week next
week, rain chances are forecast to increase limiting fire-weather
concerns over much of the Northwest. Some fire concerns may linger
over the Great Basin and Rockies, but confidence is low.
...Northern Great Basin and Rockies...
Early next week, enhanced mid-level flow associated with the Pacific
trough will begin to overspread much of the western CONUS including
the Great Basin and northern Rockies. While temperatures and
humidity are not expected to be overly warm/dry, the increase in
southwesterly flow aloft may support localized pockets of dry and
breezy conditions (winds 15-20 mph and RH below 25%) as early as
D3/Sunday, continuing trough midweek. Fuels across much of the
region have not been overly favorable for fire spread in recent
weeks from precipitation and cooler temperatures. Further
uncertainty exists regarding the chance for additional precipitation
with the trough as it continues to move eastward through the week.
However, the introduction of gusty winds may allow for some drying
of fine fuels enough to support a low chance for fire-weather
conditions through the forecast period. Ensemble and deterministic
guidance suggest the most likely corridors for low-end fire-weather
conditions will exist across portions of northern CA/NV into
southern ID, and across parts of the Rockies in northern CO/southern
WY, and western MT. However, with the uncertainties regarding fuel
availability and precipitation chances, confidence in sustained
critical fire-weather conditions is low.
Towards the end of the extended forecast period, model guidance
diverges on the overall amplification of the upper-level flow
pattern and the subsequent risk for critical fire-weather
conditions. Some indications for a return to strong ridging may
favor a slow increase in fire-weather concerns late in the month.
Conversely, a cut-off low or persistent troughing, as indicated by
some ensemble guidance, may also allow for cooler and wetter
conditions across the western US into October.
..Lyons.. 09/22/2023
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