Fire Weather Outlook Discussion
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000
FNUS22 KWNS 261743
FWDDY2

Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1242 PM CDT Mon Jun 26 2017

Valid 271200Z - 281200Z

...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHERN AZ AND
NORTHWEST NM...

Primary changes to the Day-2 Fire Weather Outlook are as follows:

1. The northern AZ Critical area has been expanded eastward into
northwest NM and has been expanded slightly westward, based on the
latest model guidance`s depiction of enhanced low/midlevel flow
overlapping with a deep boundary layer characterized by hot surface
temperatures and 3-11 percent RH. West-southwesterly surface winds
of 20-25 mph are expected across the Critical area.

2. The northern part of the Elevated area surrounding the Critical
area has been expanded eastward into extreme southwest SD and far
western parts of the NE Panhandle. The latest model guidance
suggests that a deep boundary layer with adequately low surface RH,
coinciding with enhanced winds, will materialize west of a
sharpening lee trough amid sufficiently dry fuels. Confidence in
critical winds/RH occurring on any more than a brief/spotty/marginal
basis is too limited for Critical designation at this time.

3. The Isolated Dry Thunderstorm area has been expanded eastward
into extreme southwest SD and far western parts of the NE Panhandle,
with the anticipation that thunderstorm activity will spread farther
east amid the deep boundary layer and produce minimal precipitation
before reaching richer moisture.

4. An Elevated area has been added across portions of the southern
CA mountains and adjacent foothills, where lingering enhanced winds
are expected to combine with low RH. Poor RH recovery is expected in
many areas for Tuesday night, resulting in a long-duration period of
enhanced fire-weather potential.

No other changes have been made to the ongoing forecast.

..Cohen.. 06/26/2017

.PREV DISCUSSION... /ISSUED 0258 AM CDT Mon Jun 26 2017/

...Synopsis...
Shortwave trough over the northern Rockies at the beginning of the
period -- 12Z Tuesday -- will progress eastward through the northern
Plains, reaching the upper MS Valley early Wednesday morning.
Farther east, a pair of phased shortwave troughs will move through
the upper trough initially over the eastern CONUS. Progression of
these shortwave troughs will act to deamplify the parent upper
trough. As a result, a largely zonal pattern is anticipated across
the CONUS by 12Z Wednesday. At the surface, high pressure will shift
eastward into OH and TN valleys while a low moves eastward across
the Dakotas. Cold front attendant to this low will move across the
northern and central High Plains.

...Southwest...Great Basin...Central Rockies...
Another day of above-average temperatures and afternoon RH values in
the single digits is anticipated across much of the western CONUS,
including portions of the Southwest, Great Basin, and central
Rockies. Some breezy winds are also anticipated, primarily a result
of the enhanced mid-level flow coupled with deep boundary-layer
mixing. Best combination of windy and dry conditions with dry fuels
is expected across portions of the central/north-central AZ.
Critical fire weather conditions are expected here with elevated to
locally critical conditions anticipated across the remainder of the
region.

...Southwest WY...
Thunderstorms are expected across much of the northern Rockies
during the afternoon. However, high storm coverage, modest storm
motions, and high PWs suggest mainly wetting rains with much of this
activity. The only exception appears to be across southwest WY where
a deep mixed boundary layer will support high cloud bases and ample
sub-cloud precipitation evaporation. Mean storm motion is this area
is also expected to be around 35-40 kt. These meteorological
conditions support increased fire danger due to isolated dry
thunderstorms.

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

$$



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