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FNUS28 KWNS 142123
FWDD38

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0322 PM CST Thu Dec 14 2017

Valid 161200Z - 221200Z

An active pattern for fire weather concerns will continue across the
CONUS through D8/Thu Dec 21.  Low-level cyclogenesis will occur
across the Plains downstream of a strong mid-level trough that will
decelerate over the Southwest through D5/Mon.  Meanwhile, periodic
surges of high pressure in the Great Basin will heighten fire
weather concerns across California throughout the extended period,
with greatest potential occurring around the D3/Sat-D4/Sun
timeframe.

...Central and Southern California...
Aforementioned high pressure will settle into the Great Basin and
remain there through early D4/Mon, setting up a strong offshore
pressure gradient.  Periods of gusty northeasterly/easterly surface
flow will once again persist especially in terrain-favored areas of
southern California amidst a pre-existing dry airmass.  A
70%/critical area remains in place on D4/Sun across Ventura and Los
Angeles counties where greatest confidence exists of critical
wind/RH amidst dry fuels.  Critical upgrades may also be needed on
D3/Sat and also for part of D5/Mon in later outlooks if guidance
trends lower in its depiction of surface RH.

For this update, an expansive area of 40% probabilities have been
extended northward to include areas along the California coast and
into the San Francisco Bay and Sacramento Valley areas.  Dry
northerly flow will increase to around 30 mph in terrain-favored and
higher elevation areas in conjunction with falling RH values (around
20-25%).

Late in the forecast period (around D7/Wed onward), models hint at
another potential Santa Ana event developing as the offshore
pressure gradient restrengthens over southern California.  Specific
timing regarding the onset of elevated to critical fire weather is
still in question at this time frame, although probabilities will
likely be needed in later outlooks given the synoptic scenario and
minimal precipitation chances in the coming week.

...D3/Sat - Portions of the central and southern Great Plains...
Southerly to southwesterly surface flow will increase in many areas
in response to a deepening surface low over southeastern Colorado.
The region will reside on the northern periphery of deeper boundary
layer moisture advection across the western Gulf of Mexico, with
insolation and mixing promoting widespread areas of 20-25% RH values
during peak heating hours.  At this time, it appears that the
greatest chance of critical fire weather conditions will exist in
portions of eastern New Mexico (where RH values will approach
critical thresholds) and also across the Oklahoma and Texas
Panhandles (where surface wind speeds will be the strongest).  40%
probabilities remain in place for this region, however, as guidance
continues to depict RH values a bit too high to justify upgrades at
this time.

..Cook.. 12/14/2017

...Please see www.spc.noaa.gov/fire for graphic product...

$$



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