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FNUS28 KWNS 202022

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0322 PM CDT Wed Sep 20 2017

Valid 221200Z - 281200Z

Most of the extended period will feature a deep/amplified trough
across the western US, with a ridge anchored over the Great Lakes,
Ohio Valley, and Northeast. By the middle of the next week, the
trough should slowly progress eastward to the central US, as heights
rise along the West Coast in its wake.

...D3/Friday: Central High Plains...
Along the southeastern fringe of the western trough, a corridor of
enhanced southwesterly flow aloft will overlie a zone of dry
tropospheric air across the central High Plains. The combination of
downward mixing and a tightened surface gradient from lee troughing
will encourage breezy winds. Additionally, RH values should fall to
around 15-25%, if not lower, during the day. Continued curing of
fine fuels will maintain a threat of rapid fire spread, enhanced by
the aforementioned meteorological conditions. Considering the
potential for at least elevated/locally critical concerns, a 40%
area has been added.

...D5/Sunday - D7/Tuesday: California...
Following the eastward advance of the deep western trough, surface
high pressure will build into the Pacific Northwest and Great Basin.
An offshore pressure gradient will increase north/northeasterly
winds across parts of California, especially southern California,
during the first half of next week. Lowering RH values and drying
fuels will likely support at least pockets of elevated concerns.
However, deterministic/ensemble guidance currently suggest the
gradient strength may not be particularly strong. As such, no 40%
areas have been introduced; however, they could be needed in later

..Picca.. 09/20/2017

...Please see for graphic product...

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