Fire Weather Outlook Discussion
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000
FNUS21 KWNS 281521
FWDDY1

Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1020 AM CDT Fri Apr 28 2017

Valid 281700Z - 291200Z

...CRITICAL FIRE WEATHER AREA FOR MUCH OF ARIZONA AND A SMALL PART
OF ADJACENT SOUTHEASTERN CALIFORNIA ALONG THE LOWER COLORADO RIVER
VALLEY...

Ongoing forecast is generally on track with no changes needed.
Critical conditions remain likely in much of Arizona and adjacent
southeastern California today as northwesterly low-level flow
increases and temperatures warm into the 70s and 80s F in the
afternoon.  Wind gusts may exceed 45 mph in a few locations in
central Arizona today.

Farther east, locally critical atmospheric conditions are likely
from south-central New Mexico into far west Texas this afternoon,
although the overlap of sufficiently low RH, warm surface
temperatures, and critically dry fuels should be mostly insufficient
for any categorical upgrade with this outlook.  Elevated (perhaps
locally critical) fire weather conditions are also possible in the
Florida Peninsula today.

See the previous discussion below for more information.

..Cook.. 04/28/2017

.PREV DISCUSSION... /ISSUED 0200 AM CDT Fri Apr 28 2017/

...Synopsis...
In the mid levels, a broad area of cyclonic flow will extend across
portions of the western and central States toward the Great Lakes
region. Embedded within this flow, a wind-speed maximum is forecast
to progress across parts of CA and the southwest States, in
association with an amplifying trough embedded within the broadly
cyclonic flow. Meanwhile, mid-level ridging will occur across the
Southeast.

...Portions of the lower CO River Valley eastward across portions of
AZ into southern NM and southwest TX...
Deep vertical mixing during the afternoon, into the enhanced flow
aloft accompanying the aforementioned wind-speed maximum, is
forecast to support surface wind speeds of 15-25 mph with higher
gusts across the region. Wind directions are generally forecast to
be southwesterly to westerly, except westerly to northerly within
the Critical area across portions of the lower CO River Valley into
AZ.

Across the Critical area, the influx of a dry air mass is expected
to support minimum RH around 7-15 percent, while sustained wind
speeds of 20-25 mph are expected.

Farther east, across portions of far southeast AZ into southern NM
and southwest TX, the relatively stronger winds are forecast to be
displaced to the west of the critically low RH confined to the TX
Trans-Pecos and Permian Basin vicinity. This should minimize the
overlap of critically strong winds and low RH, though elevated
fire-weather conditions are anticipated.

...Portions of the central FL Peninsula...
Easterly to southeasterly winds of 10-15 mph are forecast to combine
with minimum RH around 35-40 percent this afternoon, as the boundary
layer diurnally deepens in response to strong surface heating. Given
the presence of dry fuels across the region, elevated fire-weather
conditions are expected. However, without stronger winds and lower
RH, the critical fire-weather risk should be mitigated.

...Southern CA coastal ranges and adjacent foothills...
In association with the aforementioned mid-level wind-speed maximum,
areas of enhanced northerly surface winds (15-25 mph and locally
stronger) are forecast to combine with critically low RH (upper
single digits to around 15 percent). Despite the anticipated
elevated to critical meteorological conditions, fuels are not
forecast to be sufficiently dry for elevated or critical
designation.

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

$$


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