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FNUS28 KWNS 162200

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0500 PM CDT Wed Aug 16 2017

Valid 181200Z - 241200Z

Multiple subtle mid-level impulses will progress eastward across the
northwestern CONUS in quasi-meridional flow through the weekend,
with mid-level flow remaining strongest near/north of the
US/Canadian border. A mid/upper-level low will develop over the
weekend across southern CA with ridging building across the
Intermountain West into early next week. Breakdown of the ridge is
expected early/middle next week with an increase in thunderstorm
coverage (including some possibly dry thunderstorms) across parts of
the Pacific Northwest into the northern Rockies/Great Basin owing to
increased deep-layer moisture. However, current timing differences
amongst operational guidance in the progression of an upper trough
over the Pacific Northwest limits predictability for both an
isolated dry thunderstorm and critical wind/RH threat from Day
6/Monday through Day 8/Wednesday.

...Day 3/Friday: Northern Rockies into the Northern Great Basin and
Pacific Northwest...
Better predictability exists Day 3/Friday as a shortwave trough with
relatively strong mid-level winds traverses eastward across the
northern Rockies. Downslope westerly winds east of the higher
terrain will create at least some critical fire potential as the
strongest winds overlap an area of lowered RH values and dry fuels.
This combination of near-critical winds and relative dryness
supports the introduction of 40%/marginal probabilities across part
of north-central MT.

Locally critical conditions may also develop farther west/south
across the Pacific Northwest and northern Great Basin. Current
guidance suggests probability of sustained winds above critical
thresholds is too low for probabilistic delineation at this time.

..Elliott/Gleason.. 08/16/2017

...Please see for graphic product...

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