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FNUS28 KWNS 191950

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0149 PM CST Thu Jan 19 2017

Valid 211200Z - 271200Z

A large-scale trough will develop in the Western U.S. at the
beginning of the forecast period as a powerful (120 kt) mid-level
jet develops eastward into far Southern California and Northern
Mexico.  With time, this belt of stronger flow will migrate eastward
along the southern tier of the U.S. as a significant shortwave
develops over the Southern Rockies/Plains.  The longer wave trough
over the West will only make slow eastward progress with time, and
very strong mid/upper flow will persist with this slowly evolving
synoptic feature.

At the surface, periods of cyclogenesis across the Plains and
Lower/Mid Mississippi Valley will foster substantial downslope flow
and reinforce a generally dry pattern (especially across portions of
the Plains and southward to the Rio Grande Valley), which will
foster period of elevated to critical fire weather conditions.

...D3/Sat through D6/Tue - Portions of the Southern Plains...
The aforementioned favorable synoptic pattern will foster multiple
days of dry downslope flow in portions of Eastern New Mexico and
West/South Texas during the period.  On D3/Sat, a lee cyclone over
northeastern New Mexico will foster areas of 30-40 mph surface winds
(with higher gusts) and 25-30% RH values in southeastern New Mexico,
along with gradually drying fuels.  Winds will be somewhat weaker in
South Texas along the Rio Grande Valley, although the airmass and
underlying fuels will be somewhat drier.  Have added 40%/elevated
areas to address elevated to locally critical fire weather potential
in these areas.

On D4/Sun, the northeastern New Mexico low will deepen and move to
the Memphis, Tennessee vicinity by afternoon.  As this occurs, a
favorable pressure gradient and some vertical mixing will foster
northwesterly low-level flow in much of the Southern Plains -
strongest in central and south Texas.  Pronounced drying will also
occur, with RH values falling below 15% in portions of eastern New
Mexico and south Texas by afternoon.  Areal adjustments have been
made to the ongoing 40%/elevated area and a 70%/critical area has
been introduced for much of south Texas after some coordination with
local offices in the affected areas.

On D5/Mon and D6/Tue, another deepening low will reinforce the
westerly downslope flow pattern across portions of the southern and
central Plains, although confidence is a bit low regarding the
extent of low-level drying, especially D5/Mon afternoon.
Nevertheless, a favorable synoptic pattern for continued dry
atmospheric conditions and drying fuels suggests enough of a fire
weather risk to introduce 40%/elevated areas during this time
period, with the associated threat spreading eastward into central
Oklahoma and north central Texas on D6/Tue.  The threat appears to
be somewhat more substantial on D6/Tue, and critical upgrades may be
needed in later outlooks once details on the fire weather threat
become clearer.

Latest guidance suggests that the fire weather threat will lessen
some from D7/Wed onward.

..Cook.. 01/19/2017

...Please see for graphic product...

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