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FNUS28 KWNS 232118

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0318 PM CST Thu Nov 23 2017

Valid 251200Z - 011200Z

Temporary re-amplification of the mid-level ridge -- centered over
the Southwest -- is forecast Day 3/Saturday before the ridge axis
slides eastward over the Rockies into Day 4/Sunday coincident with a
mid/upper-level trough moving inland over the West Coast. As the
trough shifts inland, an attendant cold front will move through much
of the western half of the United States Day 4-6/Sunday-Tuesday.
Meanwhile, high pressure is expected to build into the Great Basin
in the wake of the front Day 5-7/Monday-Wednesday.

...Day 5-6/Monday-Tuesday: Portions of The Southern/Central High
Plains and vicinity...
Westerly/southwesterly low-level flow is expected to increase Day
5/Monday, as a mid-level speed maxima impinges on the area and a lee
trough develops/strengthens. Meanwhile, downslope winds are expected
to enhance warming/drying with RH values approaching critical
criteria. The 40% Critical probabilities for Day 5/Monday have been
maintained, with no upgrade due to large timing uncertainties
regarding the aforementioned speed maxima (which would impact the
strength of the low-level wind field).

The aforementioned cold front is expected to continue to move across
the area Day 6/Tuesday. While there is some potential for lingering
near critical fire weather conditions in the pre-frontal regime
(mainly over the Southern Plains), large timing differences in
frontal passage preclude introduction of any fire weather highlights
at this time.

...Day 5-7/Monday-Wednesday: Southern California...
The 40% probabilities for Critical fire weather conditions have been
maintained across the area for Day 6/Tuesday for a potential
moderate/strong Santa Ana wind event. Offshore winds are expected to
develop perhaps by late Day 5/Monday, but more likely Day 6/Tuesday,
as the aforementioned surface high builds into the Great Basin. At
this time, model spread regarding the evolution, intensity, and
placement of the surface high and upper-level support as well as the
degree of low-level drying is too large for an upgrade.
Additionally, while near critical conditions could linger into Day
7/Wednesday, model dispersion is too large to introduce any fire
weather highlights at this time.

..Elliott.. 11/23/2017

...Please see for graphic product...

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