Fire Weather Outlook Discussion
Issued by NWS
FNUS21 KWNS 211652
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1051 AM CST Tue Feb 21 2017
Valid 211700Z - 221200Z
...CRITICAL FIRE WEATHER AREA FOR COLORADO FRONT RANGE...
Critical fire-weather conditions are expected across much of the
front range of eastern Colorado. Surrounding the critical, elevated
fire-weather conditions are expected across much of the central
Observations suggest that overnight relative humidity recovery was
poor across much of the Colorado Front Range. This coupled with
downslope flow will allow for warm/dry conditions in the presence of
gusty surface winds. As such, only slight changes were made to the
previous critical area.
To the north of the critical, stronger low-level winds are expected.
However, relative-humidity values are only expected to fall into the
15-30% range, which should temper the magnitude of the fire-weather
threat. Given the combination of strong, gusty winds and dry fine
fuels an elevated fire-weather threat is expected.
To the east of the critical, across portions of Nebraska and Kansas,
minimum relative-humidity values are expected to also fall into the
15-25% range. Winds should be weaker across this area as compared to
areas to the north and west, but the ongoing dry conditions and
potential for gusty surface winds will support at least elevated
To the south of the critical, across southern Colorado and far
northeast New Mexico, minimum relative-humidity values should fall
into the upper-single digits to low teens. Although relative
humidity will be well within critical thresholds, surface wind
should be somewhat less as compared to farther north. This should
temper the overall fire-weather threat, although elevated
fire-weather conditions are still expected.
.PREV DISCUSSION... /ISSUED 0156 AM CST Tue Feb 21 2017/
An extensive midlevel wind-speed maximum is forecast to overlie
areas from coastal CA to the upper MS Valley, while mean troughing
is reinforced over the Pacific Northwest and adjacent east Pacific.
A surface trough will deepen over portions of the northern and
central High Plains. Two separate regions of fire-weather highlights
are in effect, as subsequently discussed, while recent precipitation
between and north of these areas may limit the fire-weather risk.
...Portions of southeast WY, northeast CO, western NE...
Enhanced downslope winds extending off the central Rockies will
support warming/drying over the adjacent High Plains. Westerly winds
of 15-25 mph with higher gusts are forecast to combine with RH
around 12-20 percent in support of elevated to critical fire-weather
The latest short-range, high-resolution model guidance suggests that
overlap of critically strong winds (speeds of 20-25 mph) and low RH
(12-15 percent) will be most likely for the following areas: the
vicinity of the CO Front Range and surrounding foothills, eastward
across portions of the northeastern CO High Plains, extreme
southeast WY, and extreme southern parts of the NE Panhandle. Given
relatively limited precipitation across these areas, sufficiently
dry fuels exist for Critical designation.
For locations surrounding the Critical area, elevated to
borderline-critical fire-weather conditions will be possible,
warranting Elevated designation. However, the strongest winds are
forecast to remain displaced to the north of the lowest RH, limiting
the critical fire-weather potential.
...Portions of southwest KS northeastward to south-central NE...
A modestly enhanced low-level pressure gradient east of the lee
trough is forecast to support southwesterly to west-northwesterly
surface winds of 15-18 mph. With a warm air mass in place and a
dearth of moisture return, vertical mixing will encourage RH values
falling to around 12-20 percent. While elevated fire-weather
conditions are expected, critically strong winds are unlikely.
...Please see www.spc.noaa.gov/fire for graphic product...