Fire Weather Outlook Discussion
Issued by NWS
FNUS28 KWNS 242049
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0249 PM CST Fri Feb 24 2017
Valid 261200Z - 041200Z
Broad upper troughing will cover the U.S. at the beginning of the
extended period (12Z Sunday) with moderate to strong mid-level flow
extending across the entire southern third of the CONUS. A shortwave
trough embedded within this belt of enhanced flow is expected to
move eastward across the Southwest states and southern Plains. At
the same time, another shortwave trough will drop through the
Pacific Northwest and northern Great Basin. As the lead shortwave
trough continues northeastward through the middle MS valley, the
second shortwave trough will continue eastward towards the central
Plains while yet another shortwave trough approaches the West Coast.
By 12Z D5/Tuesday, this last shortwave is expected to extend from
the Pacific Northwest southward into southern CA. It will likely
continue eastward across the intermountain West on D5/Tuesday and
into the Plains late D5/Tuesday or early D6/Wednesday. However,
there are some differences amongst guidance regarding the strength
and speed of this shortwave trough, leading to some uncertainty with
the overall eastward progression of the system. Even so, the train
of shortwave troughs and strong flow aloft will result in a pattern
favorable for a period of elevated to critical fire weather
conditions across the southern High Plains/southern Plains from
D3/Sunday through at least D6/Wednesday.
...D3/Sunday-D6/Wednesday: Southern Plains/Southern High Plains...
On D3/Sunday, a tight surface pressure gradient between the
anticipated lee troughing and eastern CONUS high coupled with deep
boundary-layer mixing and strong flow aloft will support windy
conditions across the southern High Plains. Downslope effects amidst
an antecedent dry airmass will also contribute to warm and dry
conditions. Resulting overlap between these dry and windy conditions
will result in favorable fire weather threat with confidence in
critical conditions now high enough to introduce a 70-percent
delineation across far southeast NM and the Trans-Pecos of TX.
Deep cyclogenesis is expected across the central High Plains on
D4/Monday, shifting the strong surface pressure gradient
northwestward to over much of eastern NM. Widespread elevated
conditions are expected with some critical conditions possible.
However, uncertainty regarding the duration of critical conditions
precludes introducing a 70-percent delineation with this forecast.
For D5/Tuesday, guidance continues to trend towards a weaker
pressure gradient and correspondingly weaker surface winds. Elected
to shrink the current 70-percent area to where guidance suggests the
best overlap between gusty winds and warm/dry conditions exists. If
guidance continues to trend away from strong winds, confidence in
critical conditions in subsequent outlooks may drop below the
threshold needed to maintain the 70-percent delineation.
Breezy and dry post-frontal environment across the southern Plains
will likely result in some fire weather conditions on D6/Wednesday,
particularly across the Edwards Plateau southward into deep south
...Please see www.spc.noaa.gov/fire for graphic product...