Fire Weather Outlook Discussion
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FNUS28 KWNS 202158

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0358 PM CST Tue Feb 20 2018

Valid 221200Z - 281200Z

A long-wave western U.S. trough is forecast to generally remain in
place through the extended fire weather forecast, with occasional
pieces of mid-level energy rotating around its base over the
southwestern CONUS. The most intense of these shortwave troughs is
forecast to eject out over the southern High Plains Day 4/Friday
into Day 5/Saturday, with associated lee surface cyclogenesis
occurring near the NM/CO border.

...Day 4/Friday through Day 6/Sunday - Portions of the southern High
Low-level downslope westerly flow is expected to intensify Day
4/Friday, as the aforementioned lee cyclone develops to the north of
the area and as the mid-level speed maxima -- associated with the
aforementioned shortwave trough -- passes overhead. The downslope
flow will encourage low-level drying, with near critical RH values
possibly developing. While the timing and positioning of the
shortwave trough has become clearer, fairly large spread regarding
the magnitude of the shortwave trough and subsequent strength of the
lee cyclone remains in the ensemble/deterministic guidance. This
leads to uncertainty in both the degree of drying and strength of
the low-level flow. Have maintained (with slight modification) the
40% probabilities for Critical fire weather conditions for Day
4/Friday and also introduced 40% probabilities for Day 5/Saturday,
as any fire weather conditions would spread slightly eastward with
the shortwave trough. Also, considering the ongoing drought
situation, Critical fire weather conditions could arise even with
marginally Critical meteorological conditions.

Critical fire weather conditions may also arise Day 6/Sunday as
another shortwave trough passes nearby and lee cyclogenesis is
induced. However, uncertainty is currently too large to introduce
Critical fire weather probabilities.

..Elliott.. 02/20/2018

...Please see for graphic product...

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