ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 200632
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0132 AM CDT Fri Jun 20 2025
Valid 201200Z - 211200Z
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE FOUR CORNERS AND
GREAT BASIN...
...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.
..Moore.. 06/20/2025
U.S. Day 2 Fire Weather Outlook
ZCZC SPCFWDDY2 ALL
FNUS22 KWNS 191958
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Thu Jun 19 2025
Valid 201200Z - 211200Z
...CRITICAL FIRE WEATHER AREA FOR MUCH OF THE GREAT BASIN INTO THE
SOUTHWEST...
...Great Basin into the Southwest...
A prominent low pressure system and associated 60-70 mph mid-level
jet entering the northwestern U.S. will promote an expansive area of
critical fire weather conditions across much of the Great Basin,
northern Arizona and Four Corners area on Friday. The pronounced
juxtaposition of a mid-level jet maxima, a deep and well-mixed
boundary layer and surface relative humidity of 10 percent or below
is expected across eastern Utah and western Colorado. The
combination of sustained winds of 25-30 mph and very dry surface
layer could yield locally extremely critical fire weather conditions
across western portions of the Colorado Plateau Friday.
...Southern California into the San Joaquin Valley...
Enhanced west-northwest flow and within a dry boundary layer will
support an elevated fire weather threat mainly leeward of interior
mountain ranges across Southern California Friday. Previous forecast
(see below) remains on track.
..Williams.. 06/19/2025
.PREV DISCUSSION... /ISSUED 0209 AM CDT Thu Jun 19 2025/
...Synopsis...
A robust midlevel low will advance eastward across the Northwest
during the day, while a swath of strong deep-layer westerly flow
overspreads much of the western CONUS. In response, surface low
pressure will deepen over the northern Great Basin, promoting a
tightening pressure gradient across the Great Basin into the
Southwest. This large-scale pattern will support widespread critical
fire-weather conditions across the Great Basin into the Southwest.
...Great Basin into the Southwest...
Strong diurnal heating amid a dry antecedent air mass will support
another day of widespread single-digit RH across the region. At the
same time, deep boundary-layer mixing into the strong flow aloft,
combined with the tightening pressure gradient, will yield an
expansive area of 20-30 mph sustained southwesterly surface winds.
Given increasingly dry fuels across much of the Great Basin into the
Southwest, widespread critical fire-weather conditions are expected,
with localized extremely critical conditions possible over
terrain-favored areas.
...Southern CA into the San Joaquin Valley...
Deep-layer west-northwesterly flow on the upstream-side of the
midlevel low will overspread central and southern CA, where the
tight regional pressure gradient will be in place. This will promote
breezy/gusty surface winds primarily over the interior mountains and
valley -- where 15-20 percent RH is expected. These dry/breezy
conditions will favor elevated fire-weather conditions where fuels
are receptive to wildfire spread.
U.S. Day 3-8 Fire Weather Outlook
ZCZC SPCFWDD38 ALL
FNUS28 KWNS 192153
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0453 PM CDT Thu Jun 19 2025
Valid 211200Z - 271200Z
...Day 3-4/Saturday-Sunday...
Elevated mid-level flow ahead of a an upper-level trough moving
through the Northern Rockies will linger over the Intermountain West
through the weekend. This will interact with a deep and well-mixed
boundary layer over the Southwest to bring breezy winds amid low
relative humidity amid dry fuels to support an ongoing fire weather
threat across the region. A cold front will usher in cooler
temperatures and higher relative humidity across much of the Great
Basin on Day 4/Sunday, translating fire weather concerns eastward
into the greater Four Corners region. Farther west, dry northerly
flow in the wake of a cold front still supports a fire weather
threat across the California Central Valley on Day 3/Saturday.
...Day 5-6/Monday-Tuesday...
An upper-level trough will persist over the western U.S. early next
week reinforcing 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.
...Day 7-8/Wednesday-Thursday...
Synoptically driven dry and breezy conditions will wane across the
western U.S. as the upper-level trough becomes more diffuse with
weak mid and upper-level flow in its wake by midweek. In addition,
model guidance consensus suggests moisture beginning to intrude into
western New Mexico and southern Arizona as early as Day 5/Monday.
Initial surge of moisture could bring a dry thunderstorm threat to
the area where fuels are very dry but confidence remains low,
precluding introduction of dry thunderstorm probabilities at this
time.
..Williams.. 06/19/2025
