Fire Weather Outlook Discussion
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FNUS28 KWNS 182154

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0453 PM CDT Mon Sep 18 2017

Valid 201200Z - 261200Z

A broad area of deep cyclonic flow is forecast to persist across the
western United States through Day 8/Monday, with troughing
continually being reinforced by impulses progressing through the
larger-scale flow. Strong tropospheric flow -- associated with the
impulses -- will foster periodic heightened fire weather concerns,
as strong/gusty winds overlap areas of reduced RH values and
increasingly receptive fuels.

...Day 3/Wednesday...
A transition day is expected Day 3/Wednesday, as troughing begins to
re-amplify across the Pacific Northwest. While strong winds are
anticipated across portions of the Great Basin into eastern WY, cool
temperatures -- owing to recent frontal intrusion -- are expected to
hinder RH reductions. Strong winds may also develop over portions of
AZ as the pressure gradient tightens. However, uncertainty in RH
reductions and fuel receptiveness is currently too great for
critical fire weather probabilities.

...Day 4/Thursday...
Greatest potential for critical fire weather during the extended
exists on Day 4/Thursday, as West Coast trough continues to amplify
and lee surface troughing over the central/southern High Plains
strengthens. As this occurs, increasing low-level mass response will
promote strong/gusty winds over broad areas of the Great Basin,
southwest United States, and Central Plains. However, the degree of
low-level drying and receptiveness of fuels continues to remain too
uncertain for 70% critical fire weather probabilities. Thus, 40%
probabilities have been maintained with only slight modifications to
the areal extent.

...Day 5/Friday through Day 8/Monday...
Episodic near-critical conditions -- owing to strong tropospheric
flow near the base of the large-scale trough -- may occur from Day
5/Friday through Day 8/Monday. However, low predictability in the
areal extent of RH reductions and strong-wind potential coupled with
uncertainty in antecedent fuel receptiveness currently precludes
introduction of any critical fire weather probabilities.

..Elliott.. 09/18/2017

...Please see for graphic product...

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