Storm Prediction Center Day 1 Fire Weather Outlook
Created: Thu Oct 24 16:39:03 UTC 2019 (
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Storm Prediction Center Day 1 Fire Weather Outlook
Created: Thu Oct 24 16:39:03 UTC 2019 (
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Click for Day 1 FireWX Areal Outline Product
ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 241638
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1138 AM CDT Thu Oct 24 2019
Valid 241700Z - 251200Z
...EXTREMELY CRITICAL FIRE WEATHER AREA FOR PARTS OF THE VENTURA
VALLEY TOWARDS THE SAN GABRIEL MOUNTAINS AND THE SANTA ANA
MOUNTAINS...
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE TRANSVERSE
RANGES...
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE NORTH SIERRA...
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE NORTHERN COAST
RANGES...
The previous forecast remains on track. Extremely critical
fire-weather conditions are developing and will continue to develop
by early afternoon along/near portions of the San Gabriel/Santa Anna
Mountain ranges. Sustained winds near or exceeding 30 mph are being
reported across the region. RH values are in the single digits now
and should remain that way throughout the day. Likewise, critical
fire-weather conditions are developing in adjacent areas where
sustained winds of 20-25 mph are expected. Winds along/near the
Laguna Mountains will become more easterly and increase overnight,
resulting in conditions approaching and perhaps briefly exceeding
extremely critical criteria by the end of the forecast period.
Meanwhile, critical fire-weather conditions will continue this
morning into the afternoon across portions of the North Sierra and
northern Coast Ranges. Sustained winds exceeding 30-40 mph are still
being observed along terrain-favored crests/ridge tops amidst RH
values in the teens. Although winds will continue to subside
throughout the day, a warm/dry airmass will remain in place that
will not inhibit any ongoing fire activity.
..Karstens.. 10/24/2019
.PREV DISCUSSION... /ISSUED 0216 AM CDT Thu Oct 24 2019/
...Synopsis...
A positively tilted mid-level trough situated across the western
CONUS will eject into the Plains states, with surface high pressure
gradually drifting from the Great Basin towards the central Rockies
and southern High Plains. A gradual weakening of the California
pressure gradient will ensue, with northerly downslope flow in
northern California, and offshore flow in southern California slowly
weakening with time. Nonetheless, volatile wildfire-spread
conditions should be in place across the southern Transverse Ranges
through at least the afternoon hours. Similarly, at least modest
wildfire-spread potential will persist in proximity to the
Sacramento Valley through at least the afternoon hours. Lastly,
strong mid-level northerly flow associated with the departing trough
will overlap a well-mixed boundary layer in place across the lower
Colorado River Valley, supporting an elevated fire-weather threat.
...Southern California...
Elevated to locally critical conditions will be in place at the
start of the period across the majority of the Transverse Ranges. By
early afternoon, extremely critical conditions are expected,
primarily across eastern Ventura County (Ventura Valley area),
eastward to the higher terrain north of Los Angeles,
east-southeastward to the Santa Ana Mountain Ranges. Sustained
northeasterly surface winds of at least 30 mph are expected, with
higher gusts. RH is also expected to drop to at least 10-15%, with
some single digits possible (along with the strongest gusts) in
terrain-favoring locations. Later in the evening, a stronger
easterly component of downslope flow may promote critical, to
locally extremely critical conditions across the Santa Ana to Laguna
Mountain Ranges towards the end of the period (per latest
high-resolution model guidance).
...Northern California...
Elevated to critical conditions (15-25 mph sustained
north-northeasterly flow and 15-20% RH) will be ongoing at the start
of the period across the northern Coast Ranges. However, as
upper-level support begins to wane, critical conditions are expected
to subside during the afternoon hours. Downslope flow (and
associated critical conditions) may persist along the northern parts
of the Sierra, into the northern Sacramento Valley into the early
evening hours per latest high-resolution model guidance. Later in
the evening, these critical conditions are expected to gradually
subside.
...Lower Colorado River Valley...
15-25 mph sustained northerly winds amidst 10-20% RH are expected
across the Lower Colorado River Valley during peak afternoon
heating/boundary-layer mixing, necessitating the need for an
elevated area given dry fuels. By evening, boundary-layer decoupling
and the departing trough will cause some weakening of the winds and
subsequently tempering the wildfire-spread threat to a degree.
...Please see www.spc.noaa.gov/fire for graphic product...