Fire Weather Outlook Discussion
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FNUS28 KWNS 212201

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0400 PM CST Tue Feb 21 2017

Valid 231200Z - 011200Z

Prolonged period of elevated-to-critical fire-weather conditions
appears likely into next week.

A broad mid-upper-level trough will slowly deepen as it moves east
through the end of the week. As this occurs, strong mid-level winds
will overspread the southern Rocky Mountains. This enhanced
mid-level flow is expected to persist into early next week, when yet
another trough will move east into the central United States.
Persistent westerly flow across the Rocky Mountains will result in
downslope flow keeping the boundary layer dry nearly every day
across the southern Plains.

...Day 3: Thursday...
As the first mid-upper-level trough moves east into the central
United States, downslope flow will aid surface cyclogenesis in the
vicinity of southeast Colorado and southwest Kansas. This resulting
increase in the surface-pressure gradient will allow for westerly
surface winds to increase into the 30-40 miles per hour range across
much of the southern Plains. The westerly surface winds will help
push a dryline east into central Oklahoma. This will allow for the
surface-thermal ridge to orient itself from the Big Bend of Texas
northward into western Oklahoma. Within and to the west of the
surface-thermal ridge, direct numerical output would suggest that
relative-humidity values will fall into the low-to-mid teens.
However the strength of the westerly flow the resultant mixing, feel
that single digit relative-humidity values are quite possible. At
the very least, this will result in widespread critical fire-weather
conditions across much of the southern Plains. Furthermore, if it
becomes apparent that single digit relative-humidity values will be
likely, the strength of the wind field suggests that extremely
critical fire-weather conditions may be realized across parts of
eastern New Mexico, Texas/Oklahoma panhandles, and far southwest

Overnight Thursday into Friday, a surface cold front should push
southward across at least the northern portions of the critical
fire-weather area. This will result in winds taking on more of a
northwestward component, with a slight increase in relative-humidity
values as slightly cooler air filters in to the area.

...Day 4: Friday...
In the wake of the aforementioned cold front, west-northwest winds
will develop across the southern High Plains on Friday. The airmass
behind the surface cold front will be dry. This will allow for
afternoon temperatures to warm into the 50s and 60s under full
sunshine, despite gusty northwest winds. Thus, another day of
elevated-to-critical fire weather appears likely.

...Days 5-6: Saturday-Sunday...
The overall fire-weather threat appears to be less during the
upcoming weekend, although it does not appear to be zero. A dry
airmass will remain across the southern Plains and southern Rocky
Mountains areas. At this time, downslope flow across this area
appears to weaken somewhat, tempering the overall fire-weather
threat slightly. By late in the weekend, latest ECMWF model suggests
a rapid uptick in surface winds, which would increase the
fire-weather risk. However, given run-to-run inconsistencies in the
ECMWF regarding the Sunday threat, and little support from the GFS,
have not added any probabilities at this time. However, Sunday will
need to be watched closely across eastern New Mexico.

...Days 7-8: Monday-Tuesday...
Latest guidance continues to come into better agreement in depicting
yet another widespread critical fire-weather event. Strong
west/southwest mid-level flow will overspread a warm, dry boundary
layer. Relative-humidity values should easily fall into the teens in
the presence of surface winds between 20-30 miles per hour, with
stronger gusts. Given the long-lead time and run-to-run and
model-to-model inconsistencies regarding the placement of key
features, have held off on higher probabilities.

..Marsh.. 02/21/2017

...Please see for graphic product...

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