Fire Weather Outlook Discussion
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FNUS28 KWNS 242151
FWDD38

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0450 PM CDT Mon Apr 24 2017

Valid 261200Z - 021200Z

Enhanced mid-level winds over the western CONUS should foster
increased fire weather concerns across portions of the Southwest and
southern Plains through much of the extended forecast period.
Elevated to critical conditions will be possible most afternoons
from Day 3/Wednesday through at least Day 6/Saturday across parts of
these regions.

...Day 3/Wednesday - Day 8/Monday: Portions of the Southwest and
Southern Plains...
On Day 3/Wednesday, an upper trough is forecast to move eastward
across the Plains, with enhanced northwesterly flow continuing
across the Southwest and parts of the southern Plains. The
40%/marginal area has been extended southeastward along the Rio
Grande in TX for strong/gusty downslope winds along/behind a
dryline. Confidence in critically lowered RH values across the
40%/marginal area remains too low for higher probabilities at this
time.

A mid-level jet axis will remain centered over the Southwest and
southern High Plains on Day 4/Thursday. Latest guidance is in better
agreement with the placement of strong low-level winds across NM
into west TX, and critically lowered RH values now appear likely to
overlap with these strong winds. Therefore, a 70%/critical area has
been introduced across parts of central/southern NM into far west
TX, where fuels are expected to remain favorable for large fire
starts.

Medium-range guidance is consistent in showing amplification of an
upper trough/low over the western CONUS on Day 5/Friday. A
40%/marginal area has been maintained across parts of the southern
High Plains to account for the possibility of a sufficient overlap
of strong/gusty winds and lowered RH values. A separate 40%/marginal
area has also been introduced across the lower CO River Valley where
strong northwesterly mid-level winds should translate to the surface
and combine with RH values approaching critical levels.

For Day 6/Saturday, the strongest mid-level winds associated with an
eastward-moving upper trough/low may become removed from the dry
low-level airmass across the Southwest and southern High Plains.
While some increase in fire weather concerns may be possible across
far southern NM/far west TX Saturday afternoon, confidence in the
placement of enhanced mid-level winds is too low to delineate a
40%/marginal area for now. By Day 7/Sunday and continuing into Day
8/Monday, it appears that the potential critical fire weather
conditions may lessen across the Southwest and southern High Plains,
as enhanced mid-level flow remains displaced to the north and east
of these regions.

...Day 5/Friday - Day 6/Saturday: Portions of Southern CA...
Strong northwesterly winds associated with a mid-level jet should
overspread portions of central/southern CA Friday afternoon. A
strengthening surface pressure gradient across the Great Basin and
CA may also lend some support to gusty offshore northerly to
northeasterly winds across portions of southern CA from Day 5/Friday
into Day 6/Saturday. At this time, confidence in RH values becoming
sufficiently lowered and fuels being receptive is high enough to
introduce a 40%/marginal area across portions of southern CA for
both days. Mid-level flow and the surface pressure gradient are
forecast to weaken by Day 7/Sunday, which should lessen the fire
weather threat.

...Day 3/Wednesday - Day 6/Saturday: Portions of the FL Peninsula...
A relatively dry low-level airmass is forecast to remain across much
of the FL peninsula through at least Day 6/Saturday in the wake of a
prior frontal intrusion. RH values may fall near to/below critical
thresholds each afternoon across interior portions of the FL
peninsula. However, forecast wind speeds do not appear sufficiently
strong to support a critical fire weather threat any day, precluding
the introduction of 40%/marginal probabilities.

..Gleason.. 04/24/2017

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

$$


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