ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 201637
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1137 AM CDT Fri Jun 20 2025
Valid 201700Z - 211200Z
...CRITICAL FIRE WEATHER AREA FOR FOUR CORNERS AND GREAT BASIN...
No changes are needed to the current D1 Fire Weather Outlook.
Morning satellite analysis shows mostly sunny skies across the
Critical area, with relative humidity ranging from 15-20 percent and
winds gusting 20-30 mph. HREF guidance continues to indicate that
several hours of Critical conditions are likely from the Great Basin
to the Four Corners and into portions of the High Plains through
this afternoon. See previous discussion below for more information.
..Thornton.. 06/20/2025
.PREV DISCUSSION... /ISSUED 0132 AM CDT Fri Jun 20 2025/
...Synopsis...
Widespread critical fire weather conditions are expected today
across parts of the Greater Four Corners region and the Great Basin.
Early-morning water vapor imagery shows a dominant upper ridge over
the central CONUS with shortwave troughing over the western Great
Basin and northeastern Pacific. The Great Basin shortwave is
forecast to move into the northern High Plains through the
afternoon, which will facilitate surface low development across
eastern WY by late afternoon. Strengthening low-level winds in
response to the deepening low will promote a widespread swath of
20-30 mph winds within a very dry air mass and across a region with
receptive fuels.
...Four Corners into the High Plains...
The axis of the mid-level jet associated with the leading shortwave
is forecast to reside from southeast UT into southern WY by peak
heating. This will maximize the potential for 20+ mph winds at the
surface, and will likely support wind gusts between 30-45 mph. RH
values in the single digits to low teens coupled with antecedent dry
fuels (active fires were recently noted across southern UT in GOES
IR imagery) will support widespread and prolonged critical
conditions with periods of extremely critical wind speeds possible -
especially across south-central WY. Elevated to critical fire
weather conditions will likely extend well to the northeast into the
central High Plains, and possibly as far east and western South
Dakota behind an eastward surging dry line. However, fuel conditions
generally improve with eastward extent due to recent rainfall. Fire
risk highlights have been expanded northeast to account for the
strong wind/RH signal, but Critical highlights were focused across
areas with dry, receptive fuels.
...Nevada into adjacent portions of Idaho and Utah...
Southwesterly flow over the southern to central Sierra Nevada will
induce strong downslope flow into western and central NV, spreading
into southeast ID and western UT by late afternoon. Guidance
continues to show a strong signal for 20-25 mph winds through much
of the afternoon, and single-digit RH values should support
widespread critical fire weather conditions.
...Southern California into the San Joaquin Valley...
A strong onshore pressure gradient will support increasing downslope
winds on the leeward side/eastern slopes of the coastal ranges
across southern California this afternoon. Relative humidities
values falling into the teens within the downslope regime, coupled
with dry grasses, will support a fire weather concern.
U.S. Day 2 Fire Weather Outlook
ZCZC SPCFWDDY2 ALL
FNUS22 KWNS 201946
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0246 PM CDT Fri Jun 20 2025
Valid 211200Z - 221200Z
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE EASTERN GREAT
BASIN...
No changes are needed to the D2 Fire Weather Outlook. See previous
discussion below for more information.
..Thornton.. 06/20/2025
.PREV DISCUSSION... /ISSUED 0208 AM CDT Fri Jun 20 2025/
...Synopsis...
Another day of widespread fire weather concerns is expected across
the eastern Great Basin Saturday afternoon. The primary upper-level
low, currently off the Pacific Northwest Coast, is forecast to shift
east into the northern Great Basin through late Saturday. As this
occurs, a belt of strong low to mid-level flow will overspread much
of the Great Basin ahead of a southeastward moving cold front. Dry,
windy conditions ahead of the front will promote widespread fire
weather concerns over a region with ongoing active fires.
...Eastern Great Basin...
Early-morning surface observations show a very dry air mass in place
across much of the Southwest/Great Basin (overnight RH values remain
in the single digits to low teens). Continued dry/windy conditions
today will maintain this dry air mass through Saturday. A
combination of very dry low-level conditions and abundant daytime
heating will promote deep boundary-layer mixing across the region,
which will facilitate downward transport of 30-40 knot mid-level
flow. Latest high-res ensemble guidance continues to show a strong
signal for 20-25 mph winds from southern NV/northern AZ northward
into southern WY. With afternoon RH minimums in the single digits,
critical conditions appear likely. Winds gusting up to 35-45 mph
will support periods of extremely critical conditions. Winds are
forecast to shift from southwesterly to northwesterly with the
passage of the cold front during the late evening/overnight hours,
but dry post-frontal conditions may support additional fire spread.
...CA Central Valley...
Northerly winds are forecast to increase to 15-20 mph through the
day within the Central Valley. Some degree of downslope warming will
promote RH reductions into the teens to low 20s by late afternoon.
With dry grasses already in place, the dry/windy conditions will
likely pose a fire weather concern.
...High Plains...
West to southwesterly winds are forecast to increase to 15-25 mph
behind a surface trough/dryline draped along the High Plains. Most
forecast guidance suggests that somewhat widespread elevated fire
weather conditions will emerge within this regime from northeast NM
into eastern CO, southeast WY, and adjacent portions of western SD,
NE, and KS. Despite the potential for widespread dry/windy
conditions, recent rainfall has mitigate fuel status for the time
being and has promoted widespread green up of most grasses. Because
of this highlights were withheld, though fuel trends will continue
to be monitored.
U.S. Day 3-8 Fire Weather Outlook
ZCZC SPCFWDD38 ALL
FNUS28 KWNS 202157
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0457 PM CDT Fri Jun 20 2025
Valid 221200Z - 281200Z
Several periods of Elevated to near Critical fire weather conditions
are possible 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/Sunday...
A cold front will move in across the Southwest and usher in cooler
temperatures and higher relative humidity across much of the Great
Basin on Day 3/Sunday. As a result, fire weather concerns will shift
eastward into the Four Corners region. Farther west, dry northerly
flow in the wake of a cold front will continue to support at least
an Elevated fire weather threat across the California Central Valley
and into portions of the Sierra Madre and San Rafael Mountains
D3/Sunday.
...Day 4-5/Monday-Tuesday...
An upper-level trough will persist over the western U.S. early next
week, with occasional daytime elevated winds across portions of the
Upper Colorado River Basin and northern Arizona. Dry and breezy
conditions will persist, with dry fuels aiding in increased wildfire
spread potential. Moisture will steadily increase into western New
Mexico and southern Arizona as early as Day 4/Monday and D5/Tuesday.
...Day 6-8/Wednesday-Friday...
The upper-level will weaken by mid-week with primarily weak mid and
upper-level flow, leading to more localized terrain driven breezes.
A shortwave 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.
Monsoonal moisture will steadily increase across New Mexico. Dry
thunderstorm threats may increase on the periphery of this deep
moisture but confidence remains low, precluding introduction of dry
thunderstorm probabilities at this time.
..Thornton.. 06/20/2025
