ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 211640
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1140 AM CDT Sat Jun 21 2025
Valid 211700Z - 221200Z
...CRITICAL FIRE WEATHER AREA FOR EASTERN GREAT BASIN...
Morning satellite imagery shows mainly clear conditions across much
of the southwest into southern California, with the exception of a
notable marine layer inland across the LA Basin. Surface
observations show warming and mixing well underway, with relative
humidity in the teens from southern Nevada north into Arizona/Utah
and southern Wyoming. Several hours of Critical fire weather
conditions are expected within these regions, with winds increasing
through the afternoon with the cold front passage and deeper mixing.
A small extension was made to the Elevated in New Mexico to account
for latest trends with increasing wind speeds amid critical fuels.
See previous discussion below for more information concerning
Elevated conditions expected in the Central Valley and Santa Barbara
Coast in California.
..Thornton.. 06/21/2025
.PREV DISCUSSION... /ISSUED 0122 AM CDT Sat Jun 21 2025/
...Synopsis...
Widespread elevated to critical fire weather conditions are expected
again this afternoon across a large swath of the eastern Great Basin
and Four Corners region. An upper ridge is evident across the
central CONUS in early-morning water-vapor imagery. Across the
Pacific Northwest, an upper wave continues to slowly amplify as a
low/mid-level cold front pushes southeast into the western Great
Basin. A belt of strong southwesterly flow will remain in place
across the eastern Great Basin and greater Four Corners region
through peak heating ahead of the front. Strong winds within the
pre-frontal regime, combined with antecedent dry conditions and
receptive fuels, will promote widespread fire weather concerns.
...Southern Nevada into southern Wyoming...
Little to no appreciable moisture recovery is expected over the next
12-24 hours across the eastern Great Basin and parts of the Four
Corners. The very dry conditions sampled by 00 UTC RAOBs and
early-morning surface obs should largely remain in place with
another day of RH minimums in the single digits expected. A deep,
dry boundary layer will promote efficient downward mixing of the
stronger mid-level winds. Similar conditions yesterday (Friday)
resulted in widespread sustained winds between 20-25 mph with
frequent gusts between 35-50 mph. Similar wind speeds are expected
today, albeit within a more confined corridor given the impingement
of the cold front from the northwest. Active fires are noted in GOES
IR imagery across the region, which indicates that fuels remain very
supportive of fire spread. The passage of the cold front later this
evening/tonight will result in a wind shift from southwest to
northwesterly, which could result in additional fire spread.
...CA Central Valley...
Northerly down-valley winds are expected to strengthen to 15-20 mph
within the Sacramento/San Joaquin Valley this afternoon within the
post-frontal regime. Despite an influx of cooler air, downslope
warming/drying should promote areas of 15-20% RH by peak heating.
Elevated to locally critical fire weather conditions are expected,
and dry grasses within the valley should support the fire concern.
...Santa Barbara Coast...
Northerly downslope winds are expected to increase off the Sierra
Madre and San Rafael mountains as the cold front passes later this
afternoon/tonight. This will promote elevated to locally critical
fire weather conditions along the Santa Barbara coast where fuels
have sufficiently dried in recent days to support fire spread.
...Central High Plains...
15-25 mph southwesterly winds are expected this afternoon behind a
surface trough/dryline. Trajectories emanating off the higher
terrain, coupled with ample daytime heating, will promote sufficient
drying for RH minimums in the teens. Somewhat widespread elevated to
critical fire weather conditions are expected; however, spring green
up of grasses and recent rainfall should modulate the overall fire
potential.
U.S. Day 2 Fire Weather Outlook
ZCZC SPCFWDDY2 ALL
FNUS22 KWNS 211902
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0202 PM CDT Sat Jun 21 2025
Valid 221200Z - 231200Z
No changes are needed to the D2 Fire Weather Outlook. See previous
discussion below for more information.
..Thornton.. 06/21/2025
.PREV DISCUSSION... /ISSUED 0201 AM CDT Sat Jun 21 2025/
...Synopsis...
Fire weather concerns are expected to persist across portions of the
Intermountain West through the end of the weekend, and may emerge
within parts of the High Plains.
...Intermountain West...
The base of the upper trough currently amplifying over the Pacific
Northwest is forecast to pivot into the Four Corners/central Rockies
through the day Sunday. As this occurs, a belt of moderate mid-level
flow will overspread a region with active ongoing fires. Limited
precipitation through the next 48 hours will maintain very dry
fuels, but the passage of cold front today into early Sunday will
help modulate diurnal RH reductions to some degree for Sunday
afternoon. Although areas of sub-15% RH are expected, slightly
improved RH coupled with weaker low-level winds should result in an
overall reduced fire weather concern compared to previous days.
Nonetheless, areas of elevated fire weather conditions are probable,
and isolated pockets of critical conditions are possible.
...Central High Plains...
Latest guidance shows the greatest potential for sustained 20+ mph
winds and 15-20% RH across eastern CO into adjacent portions of far
southwest NE and northwest KS behind a sharpening dryline. Despite
fairly high confidence in critical conditions, green up of grasses
across the region should largely mitigate a more robust fire weather
threat. However, preceding days of hot/dry/windy conditions should
yield at least pockets of dry fuels that may support a low-end fire
weather concern.
U.S. Day 3-8 Fire Weather Outlook
ZCZC SPCFWDD38 ALL
FNUS28 KWNS 212019
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0319 PM CDT Sat Jun 21 2025
Valid 231200Z - 291200Z
Periods of Elevated to near Critical fire weather conditions are
possible early next week as weak troughing remains across the
western US through the period. A high amplitude ridge building
across the eastern US will bring very warm temperatures and drying
across much of the central/southern Plains into the East before
precipitation potential returns late in the period.
...Day 3-4/Monday-Tuesday...
An upper-level trough will persist over the western U.S. D3/Monday
and D4/Tuesday, with occasional daytime elevated winds across
portions of the Upper Colorado River Basin and northern Arizona.
This will extend as far north as southeastern Wyoming on D4/Tuesday
as an upper-level jet streak traverses the northern Rockies. Dry and
breezy conditions will persist, with dry fuels aiding in increased
wildfire spread potential.
...Day 5-8/Wednesday-Saturday...
The upper-level low will weaken by mid-week with winds becoming more
localized terrain driven breezes. A series of shortwaves late in the
period may bring an increase in winds across the Snake River Plain
in Idaho, with potential for highlights to be included if confidence
increases.
...Dry Thunderstorms...
Moisture will steadily increase into western New Mexico and southern
Arizona as early as Day 3/Monday and D4/Tuesday. Dry thunderstorm
threats may increase on the periphery of this deeper moisture but
confidence remains low on coverage, precluding introduction of dry
thunderstorm probabilities at this time.
..Thornton.. 06/21/2025
