Fire Weather Outlook Discussion
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FNUS28 KWNS 212056
FWDD38

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0256 PM CST Wed Feb 21 2018

Valid 231200Z - 011200Z

An upper trough over the Great Basin on Day 3/Friday will eject
northeastward across the Plains and to the Great Lakes/Upper Midwest
vicinity by Day 5/Sunday. Another shortwave trough should move
southeastward from the West Coast to the southern Plains from
Saturday afternoon to Sunday evening. Large-scale upper troughing
may redevelop across the western CONUS around Day 7/Tuesday.
Potentially critical fire weather conditions should remain confined
to portions of the southern High Plains though the extended forecast
period.

...Day 3/Friday - Day 5/Sunday: Portions of the Southern High
Plains...
A lee surface trough should form over the southern High Plains by
Friday afternoon, and the pressure gradient should become modestly
enhanced in the same time frame. The 40%/marginal area for Day
3/Friday has been confined to the southern High Plains where the
best potential for strong/gusty southwesterly low-level winds and
near-critical RH values should exist. Areas to the west (across
southern/central NM and far southeastern AZ) will likely have
unreceptive fuels due to prior precipitation. Confidence is not high
enough in a prolonged overlap of sub-15% RH values with strong
surface winds to warrant a 70%/critical area at this time.

An enhanced surface pressure gradient will likely be present across
the southern High Plains as an area of low pressure moves eastward
across KS on Day 4/Saturday. A cold front should extend southward
from this low across the southern Plains. Strong/gusty post-frontal
west-northwesterly winds will likely occur from parts of eastern NM
into west TX Saturday afternoon, and RH values may fall near
to/below critical thresholds. The 40%/marginal area for Day
4/Saturday has been maintained with only minor changes. Antecedent
precipitation across central/north TX should limit the eastward
extent of fire weather concerns.

As a second shortwave trough mentioned above moves across the
southern High Plains on Day 5/Sunday, another afternoon of
strong/gusty downslope winds appears probable across portions of
this region. RH values may become critically reduced mainly due to
low-level downslope warming/drying processes. Have therefore
introduced a 40%/marginal area for Day 5/Sunday to account for this
threat.

There may be some potential for critical fire weather conditions
around Day 7/Tuesday into Day 8/Wednesday for part of the southern
High Plains as large-scale upper troughing potentially redevelops
over the western CONUS. However, too much uncertainty exists
regarding the strength/placement of low-level winds and the degree
of lowered RH values to introduce any probabilities at this time.

..Gleason.. 02/21/2018

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

$$



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