ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 191702
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1202 PM CDT Thu Jun 19 2025
Valid 191700Z - 201200Z
...CRITICAL FIRE WEATHER AREA FOR NORTHWESTERN NEVADA...
...CRITICAL FIRE WEATHER AREA FOR PARTS OF EASTERN NEVADA...WESTERN
UTAH...AND NORTHWESTERN ARIZONA...
Only minor changes to previous forecast were needed. A broad
upper-level trough and associated stronger southwest flow pattern
will bring widespread Elevated to Critical fire weather conditions
to much of the Great Basin today. Dry fuels, low humidity and
expansive area of 20-25 mph from the southwest will contribute to
wildfire spread potential. Latest model guidance suggests fast
moving showers and isolated thunderstorms with minimal rainfall
across southeastern Oregon late today into this evening but cooler
temperatures following a cold front passage, cloud cover and
isolated showers Friday preclude introduction of Isolated Dry
Thunderstorm highlights.
..Williams.. 06/19/2025
.PREV DISCUSSION... /ISSUED 0206 AM CDT Thu Jun 19 2025/
...Synopsis...
Within the base of a large-scale trough moving into the western
CONUS, a swath of moderate-strong deep-layer southwesterly flow will
overspread central CA into the Great Basin today. In response,
surface low pressure will deepen over the northern Great Basin and
separately over the Lower CO River Valley.
...Great Basin...
Deep boundary-layer mixing is expected across the Great Basin during
the afternoon, with surface temperatures climbing into the 90s to
100 F and RH falling into the single digits. The deep boundary-layer
mixing into the strong flow aloft, coupled with a tightening
regional pressure gradient, will contribute to an expansive area of
20-25 mph sustained southwesterly surface winds (with higher gusts).
The greatest overlap of these strong surface winds and low RH is
expected over northwestern NV and western UT into eastern NV and far
northwestern AZ. Given dry/receptive fuels over these areas,
critical fire-weather conditions are expected.
...San Joaquin Valley and vicinity...
Hot and dry conditions will combine with 15-20 mph sustained
northwesterly surface winds during the afternoon into the evening.
This will promote elevated fire-weather conditions where fuels are
receptive to fire spread.
...Dry Thunderstorms...
Large-scale forcing for ascent preceding the midlevel trough will
favor isolated dry thunderstorms across parts of southeastern OR
into central ID during the evening hours. However, current
indications are that fuels are only modestly receptive to
lightning-induced ignitions -- precluding Dry Thunderstorm
highlights at this time.
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 182158
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0458 PM CDT Wed Jun 18 2025
Valid 201200Z - 261200Z
...Day 3-4/Friday-Saturday...
An upper-level low entering the Pacific Northwest on Day 3/Friday
with accompanying strong mid-level jet and tightening surface
pressure gradient will promote strong southwest surface winds across
much of the Great Basin, Four Corners and parts of the Upper
Colorado Basin. 70 percent probabilities for Critical fire weather
conditions were maintained for northwestern Nevada as well as much
of southern Utah, northern Arizona and far western Colorado.
Confidence remains quite high for an expansive fire weather threat
amid an increasingly dry fuelscape. A cold front ushering in cooler
temperatures and higher relative humidity will mitigate fire weather
concerns across northwestern Nevada but mid-level jet positioning
will continue to promote strong southwest winds across northern
Arizona and much of Utah into western Colorado Day 4/Saturday. In
addition, dry, post-frontal winds in the Central Valley and adjacent
foothills combined with dry fuels will support some fire weather
threat on Day 4/Saturday.
...Day 5-8/Sunday-Wednesday...
Upper-level trough is expected to remain over the western U.S.
through early next week keeping at least modest southwest flow over
much of northern Arizona, southern Utah and Four Corners area. A
very dry boundary layer along with dry fuels will maintain elevated
wildfire spread potential early next week. Ensemble model guidance
suggests a transition to a muted zonal flow pattern by midweek
across CONUS, mitigating fire weather concerns in terms of winds
across the much of the Western U.S. beginning midweek.
..Williams.. 06/18/2025
