Fire Weather Outlook Discussion
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FNUS21 KWNS 201611
FWDDY1

Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1111 AM CDT Thu Jul 20 2017

Valid 201700Z - 211200Z

...CRITICAL FIRE WEATHER AREA FOR PARTS OF NORTHERN MONTANA...

A critical designation is introduced across north-central Montana,
where enhanced westerly winds are forecast to develop behind a cold
front this afternoon and evening. Sustained westerly winds around
20-25 mph will combine with RH values below 20% and very dry fuels
to promote critical fire-weather concerns. Elsewhere across the
northern Rockies region, locally critical conditions may develop
later today, but confidence in sufficiently strong winds remains too
low for the introduction of a critical area.

Additionally, an isolated dry-thunderstorm area is introduced across
northern Montana. With a mid-level impulse skirting the region (and
the aforementioned passage of the cold front), isolated storms may
develop late today. Weak mid-level buoyancy, a deep/dry boundary
layer, and quick storm motions will support a potential for a few
dry lightning strikes.

..Picca.. 07/20/2017

.PREV DISCUSSION... /ISSUED 0158 AM CDT Thu Jul 20 2017/

...Synopsis...
Upper ridging will remain prominent across the central/southern
Plains today, while an upper trough moves slowly northeastward from
BC and the Pacific Northwest over the northern Rockies and adjacent
Canadian provinces. Enhanced mid-level winds attendant to this
trough should elevate fire weather concerns this afternoon and
evening across parts of the interior Pacific Northwest, northern
Great Basin/Rockies, and northern High Plains.

...Portions of the Interior Pacific Northwest...
Behind a surface cold front, temperatures will be slightly cooler
than yesterday across interior portions of the Pacific Northwest.
Regardless, strong/gusty west-southwesterly winds around 15-20 mph
will likely develop this afternoon as downslope trajectories act to
warm/dry the low levels. RH values will become lowered into
generally the 20-25% range, supporting the ongoing elevated fire
weather delineation.

...Portions of the Northern Great Basin/Rockies into the Northern
High Plains...
A corridor of enhanced mid-level southwesterly winds will remain
over parts of the northern Great Basin/Rockies into the northern
High Plains. As diurnal mixing of the boundary layer occurs, these
mid-level winds will reach the surface and promote strong sustained
winds of 15-20 mph. RH values will also likely become lowered into
the 10-20% range from the Snake River Valley of ID and vicinity
northeastward into parts of the northern Rockies/High Plains. Dry
fuels will exist across a majority of these regions, supporting an
elevated fire weather threat. Locally critical conditions may be
realized across a subset of the Snake River Valley in ID, where
sustained winds may exceed 20 mph on a brief/spotty basis.

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

$$



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