Fire Weather Outlook Discussion
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FNUS28 KWNS 252125
FWDD38

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0325 PM CST Sat Feb 25 2017

Valid 271200Z - 051200Z

A moderately deep, positively titled upper trough is expected to
extend from the northern Rockies southwestward to off the central CA
coast at the beginning of the extended period (12Z Monday), while
southwesterly/westerly upper flow extends eastward across the
remainder of the CONUS. This upper trough will likely deepen and
attain a more neutral tilt as it slowly shifts eastward across the
intermountain West on D4/Tuesday and across the plains on
D5/Wednesday. As the trough moves eastward, the southwesterly flow
aloft ahead of it is expected to strengthen across the southern
Plains/southern High Plains on D4/Tuesday across the middle MS and
OH valleys on D5/Wednesday. Deep cyclogenesis is expected across the
central High plains on D3/Monday and again farther south (near the
TX/OK/NM border intersection) on D4/Tuesday. Combination of enhanced
flow aloft, a strong surface pressure gradient, and a dry airmass
will result in several days of favorable fire weather conditions
across the southern Plains/southern High Plains.

...D3/Monday-D5/Wednesday: Southern Plains/Southern High PLains...
Guidance has trended towards better agreement regarding the strength
and speed of the upper trough, leading to a higher overall forecast
confidence than yesterday.

Cyclogenesis on D3/Monday is expected over the central High Plains,
which will tighten the surface pressure gradient across the
central/southern High Plains. This tight gradient coupled with
modest southwesterly flow aloft and deep boundary-layer mixing will
support gusty winds (i.e. 20-30 mph) across the southern High
Plains. Temperatures will likely reach the mid 60s to lower 70s (5
to 10 degrees above-average) with minimum RH values in the teens.
Highest likelihood of critical conditions exists from southeast CO
southward along the TX/NM border and into the Permian Basin, with
confidence in critical conditions high enough to delineate a
70-percent area.

For D4/Tuesday, model guidance has trended back to more a southerly
and stronger cyclogenesis (i.e. far northeast NM) with strong
southwesterly flow aloft ahead of the upper trough. This is in sharp
contrast to the trend within the guidance over the past two days,
which had been trending weaker and more northerly with the
cyclogenesis and towards more modest flow aloft. Now forecast deep
cyclogenesis combined with deep boundary-layer mixed and strong flow
aloft would support strong southwesterly winds with sustained speeds
from 30 to 40 mph with gusts over 50 mph. Minimum RH values in the
teens and single-digits are possible. As a result, the 70-percent
area was expanded to cover a large portion of the southern High
Plains. Some high-end critical conditions are possible if the
currently progged scenario is realized.

A dry and breezy post-frontal environment is expected across the
region on D5/Wednesday with breezy northerly winds occurring amidst
minimum RH values in the teens and low 20. Some fire weather
conditions are possible within this environment from western OK
southward into deep south TX.

...D6/Thursday - Southeast and Carolinas...
Dry post-frontal environment may result in some fire weather
conditions across the region but low confidence in minimum RH values
precludes introducing any probabilities with this forecast.

...D7/Friday - Southern High Plains...
Lee troughing may contribute to a tight surface pressure gradient
across the Plains. Tight gradient and resulting breezy winds coupled
with the warm and dry conditions anticipated across the southern
High Plains may result in more fire weather conditions across the
region. The strength of the winds will likely be tempered by the
lack of stronger flow but confidence in some fire weather conditions
is high enough to introduce a 40-percent delineation.

..Mosier.. 02/25/2017

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

$$


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