Fire Weather Outlook Discussion
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FNUS22 KWNS 201844
FWDDY2

Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0143 PM CDT Wed Sep 20 2017

Valid 211200Z - 221200Z

...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE CENTRAL HIGH
PLAINS...

No changes have been made to the ongoing critical area across
eastern Colorado, western Kansas, and far southwest Nebraska.
Sustained winds around 20-30 mph will combine with RH values around
10-15% to increase concerns across parts of the central High Plains.
Fine fuels will be sufficiently dry, such that these meteorological
conditions will support a critical threat Thursday.

Elsewhere, the elevated area has been expanded, mainly to account
for breezy/windy conditions across much of the region, in response
to strong southwesterly mid-level flow along the periphery of an
amplified trough across the West. Fuels in some locations are only
marginally receptive to rapid fire spread; however, the strength of
flow, combined with curing of fine fuels and RH values near 20%,
will likely support elevated concerns.

..Picca.. 09/20/2017

.PREV DISCUSSION... /ISSUED 0207 AM CDT Wed Sep 20 2017/

...Synopsis...
A deep upper-level trough is expected to move slowly eastward across
the West on Thursday, while an upper ridge amplifies from the Ozarks
region northeastward into the eastern Great Lakes. A surface low
will deepen in the lee of the Rockies as the trough approaches from
the west.

...Southern/Central High Plains...
Strengthening low-level southwesterly flow in conjunction with
strong heating/mixing of a dry airmass will result in an increasing
fire weather threat on Thursday, and a critical area has been
introduced across eastern CO, western KS, and far southwest NE.
Across this area, sustained winds are expected to increase into the
20-25 mph range during the afternoon as RH values fall below 15%.
The northern extent of the critical area is constrained by weaker
wind speeds in closer proximity to the surface low, while the
southern and eastern extent are constrained by uncertainty regarding
the critical RH potential, and also by increasingly marginal fuel
conditions.

...Four Corners region into eastern UT/western CO...
Elevated to locally critical conditions are expected across
northeast AZ, eastern UT, western CO, and northwest NM on Thursday,
as sustained winds increase into the 20-25 mph range and RH values
drop to near 15%. At this time, the best chance for critical wind/RH
appears to be displaced to the west of the drier fuels, so no
upgrade has been made for this region.

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

$$



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