Fire Weather

SPC Day 1 Fire Weather Outlook

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook Image
Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0155 AM CDT Thu Jun 20 2019

Valid 201200Z - 211200Z

A mid-level shortwave trough will amplify across the western CONUS
through the period, with a surface low-pressure trough developing
across the Great Basin, and a cold front moving southward across the
central Rockies regions to the southern Great Basin. Behind the cold
front, cool surface temperatures and relatively higher relative
humidity values are expected despite windier conditions. With
surface high pressure building in from off the Pacific Coast, a
modest pressure gradient will become established across portions of
northern California, promoting dry, breezy conditions across parts
of the Sacramento Valley, where some potential will exist for
wildfire spread.

...Northern California...
During the afternoon hours, deep mixing of the boundary layer will
result in downslope flow along the southern extent of the Klamath
Mountains. Winds out of the north at 15-20 mph amidst 15-25% RH are
expected up until sunset, when nocturnal cooling and diminished
boundary layer mixing will temper the wildfire threat. An elevated
area was delineated to account for this scenario.

...Southern Great Basin/Four Corners regions...
Stronger mid-level flow at the base of the trough will overlap a
deeply mixed boundary layer, promoting widespread 20+ mph sustained
west-southwesterly surface winds and RH in the 10-20% range by peak
heating of the afternoon. Currently, fuels are modestly (at best)
receptive to wildfire spread given recent rainfall over the past few
days. As such, no areas were delineated at this time, though
meteorological conditions will support wildfire spread potential
over any isolated patches of fuels that have cured sufficiently
after the most recent rainfall. In addition, the lack of forecast
rainfall and aforementioned dry/windy conditions will prime the
finer fuels across lower elevations for Day 2/Friday.

..Squitieri.. 06/20/2019

...Please see for graphic product...

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SPC Day 2 Fire Weather Outlook

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook Image
Day 2 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0158 AM CDT Thu Jun 20 2019

Valid 211200Z - 221200Z


A mid-level shortwave trough will continue to deepen across the
western CONUS while very slowly advancing eastward. At the surface,
high pressure will dominate much of the Great Basin and Four Corners
regions. Meanwhile, surface low pressures will develop to the
south/east of the aforementioned high pressure, across portions of
the southern High Plains and southern Great Basin, promoting dry and
strong westerly surface flow across the southwest CONUS, along with
wildfire spread potential. In addition, mid-level winds associated
with the backside of the shortwave trough will better coincide the
axis of the Sacramento Valley, promoting more efficient downward
transport of higher momentum air aloft via a well-mixed boundary
layer. As such, wildfire spread potential will become a concern for
portions of northern California.

...Northern California...
A critical delineation was maintained for portions of the northern
Sacramento Valley. While the magnitude of the flow aloft will be
weaker compared to the previous day, the better alignment of the
mid-level flow to the axis of the Sacramento Valley suggests a
greater chance for sustained northerly surface winds to exceed 20
mph amidst 15-20% RH by mid-late afternoon. After sunset, a cooling
boundary layer will gradually diminish the wildfire spread threat
with time.

...Portions of the southern Great Basin/Four Corners regions...
By peak heating of the afternoon, boundary layer mixing will result
in widespread west-southwesterly surface winds of 25+ mph amidst
10-20% RH across much of central/eastern Arizona and nearly all of
New Mexico. Though fuels overall are slightly below critical
thresholds, a few areas of finer fuels should at least be modestly
supportive of wildfire spread. A critical delineation was added
where fuels will most likely be receptive to fire spread, and where
sustained wind speeds will most likely exceed 25 mph for the longest
period of time. Widespread critical wind/RH conditions will also be
likely east/north of the current critical delineation, but the
marginal receptiveness of fuels warrants an elevated at this time.
West of the current critical delineation, fuels are modestly
receptive to fire spread, though confidence is slightly lower in
widespread critical wind/RH conditions becoming sustained across
central Arizona, with an elevated area being delineated. By evening,
RH recovery and calming winds will result in the wildfire spread
threat gradually subsiding with time.

..Squitieri.. 06/20/2019

...Please see for graphic product...

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