Fire Weather Outlook Discussion
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FNUS21 KWNS 171653

Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1052 AM CST Sun Dec 17 2017

Valid 171700Z - 181200Z


The overall forecast philosophy remains unchanged from the previous
outlook.  Near-critical conditions (gusty northerly winds especially
in terrain-favored areas and 20-30% RH values) will persist for at
least a few more hours across the northern/central California
critical area.  Surface winds should decrease some throughout the
day today as stronger mid-level flow migrates away from the region.
Elevated fire weather conditions will persist throughout the
afternoon and into the evening.

Farther south, elevated to critical conditions will persist along
coastal ranges of southern California throughout the day and into
the overnight hours.  Gusty offshore winds were already observed
this morning within the critical area and have exceeded 30-40 mph at
times.  RH will continue to fall through the afternoon as well,
creating a dangerous environment conducive to rapid fire spread and
unpredictable fire behavior.

See the previous discussion below for more information.

..Cook.. 12/17/2017

.PREV DISCUSSION... /ISSUED 0111 AM CST Sun Dec 17 2017/

...Portions of Central into Northern CA this Morning...

Strong north to northeast winds were ongoing as of 07z, and a few
hours of critical fire weather conditions are possible through about
midday. RH values in the 15-25 percent range will be common with
sustained wind speeds around 15-25 mph and higher gusts. Deep-layer
northerly flow will weaken through the day and conditions should
improve by afternoon. Overnight recovery will be good, with RH
values rebounding to around 40 percent or greater.

...Portions of Southern CA...

Gusty winds were ongoing this morning and should continue into at
least this evening. Strong deep-layer northerly flow will persist
longer across the southern portion of the state as the upper trough
only slowly progresses eastward. The surface pressure gradient
across the region is forecast to remain favorable for moderate to
strong offshore winds through at least this evening but could
stretch into early Monday morning. Sustained winds of 15-30 mph with
higher gusts are expected. RH values of 15-25 percent early this
morning will fall to around 10-15 percent during the afternoon.
Overnight recovery should be better tonight compared to recent days,
with values climbing into the 25-45 percent range and even higher
values near the coast.

...Please see for graphic product...

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