Fire Weather Outlook Discussion
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FNUS21 KWNS 161636
FWDDY1

Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1136 AM CDT Mon Oct 16 2017

Valid 161700Z - 171200Z

...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF SOUTHEASTERN
WYOMING...

The critical area has been expanded slightly across southeastern WY
based on 16Z surface observations and latest short-term model
guidance. Across this region, sustained winds of 20-25 mph and RH
values of 10-15% are either ongoing or are expected to develop for
at least a few hours this afternoon. The surrounding elevated area
has also been expanded to include more of south-central WY,
northeastern CO, and western NE. Although fuels become more marginal
with westward extent into south-central WY, latest guidance suggests
fine fuels should be marginally receptive to large fire starts
across this area with elevated to locally critical meteorological
conditions expected. Confidence in strong/gusty winds occurring over
an even greater portion of the northern/central High Plains remains
too low to delineate a larger critical area. See the previous
discussion below for more information.

..Gleason.. 10/16/2017

.PREV DISCUSSION... /ISSUED 0206 AM CDT Mon Oct 16 2017/

...Synopsis...
A weak mid/upper-level ridge is forecast to remain centered over the
Desert Southwest through much of today, before flattening late in
the period as a large-scale trough approaches the Pacific Northwest.
Meanwhile, a subtle mid-level shortwave trough is expected to round
the crest of the ridge over portions of the Northern Rockies. At the
surface, the persistent area of high pressure over the Great Basin
is forecast to weaken further.

...Portions of Southeast Wyoming, North-central Colorado, and
Western Nebraska...
Strong downslope winds in the lee of the Laramie Range are expected
to develop today, as enhanced mid-level flow associated with
aforementioned shortwave trough passes overhead. Despite relatively
cool temperatures, heating of a very dry airmass will keep minimum
RH values at or below 15% while fostering efficient deep-layer
mixing. A Critical fire weather area has been introduced across
portions of Albany, Laramie, Platte, and Goshen Counties, as latest
high-resolution deterministic/ensemble guidance suggest a sufficient
duration of sustained winds greater than 20 mph coupled with
critical RH values and increasingly receptive fuels (especially fine
fuels) in these areas. Only minor adjustments were made to the
surrounding Elevated area, where surface winds around 15-20 mph and
RH values at or below 15% are expected.

...Southern California...
While a weakening pressure gradient will allow surface winds to
weaken considerably today, warm and dry conditions combined with
lingering offshore breeziness will create near elevated fire weather
conditions (especially Monday/Tuesday morning). The limited duration
of the stronger winds precludes an Elevated fire weather area at
this time.

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

$$



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