Fire Weather Outlook Discussion
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FNUS21 KWNS 231649
FWDDY1

Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1149 AM CDT Sun Apr 23 2017

Valid 231700Z - 241200Z

...CRITICAL FIRE WEATHER AREA FOR NORTHERN ARIZONA...FAR SOUTHWEST
COLORADO...AND NORTHWEST NEW MEXICO...

Several changes have been made to the current forecast.

1. Added southwest Colorado to the ongoing critical area. Several
hours of relative humidity less than 15% and winds in excess of 20
mph are expected this afternoon.

2. Added the Lower Colorado River Valley into the ongoing elevated
area. Several hours of sub-15% relative humidity will occur this
afternoon. Some uncertainty in the strength of the low-level flow
will preclude adding this area to the critical, but several hours of
gusty surface winds may occur during the afternoon.

3. Added a large elevated area for much of the Central Plains.
Expectation is that several hours of sub-30% relative humidity will
occur with winds gusting to greater than 20-30 mph. Despite greening
of some fuels, some of the warm-season grasses remain dead and thus
susceptible to fire starts.

Lastly, there will be the potential for new fire starts this
afternoon due to lightning across portions of the Florida peninsula
on the northern periphery of the better moisture/precipitation
shield. This will be of particular concern with any lightning
strikes outside thunderstorm cores. A dry thunderstorm area has not
been added as this threat will not meet dry thunderstorm criteria,
but given the ongoing drought conditions wanted to draw attention to
this potential.

..Marsh.. 04/23/2017

.PREV DISCUSSION... /ISSUED 1158 PM CDT Sat Apr 22 2017/

...Synopsis...
An upper trough over the Four Corners region will shift east into
the Plains this afternoon. Meanwhile, a shortwave trough will
migrate across the Great Basin to the Rockies. This will lead to
enhanced westerly deep-layer flow across much of the Great Basin and
southwestern deserts. Furthermore, strengthening surface low
pressure from the northern High Plains to the Four Corners will
allow for increasing southwesterly low level winds. Where fuels are
dry, elevated to critical conditions are expected across parts of
the southwestern U.S.

...Far southern NV, far southern UT, far southwest CO, northwest NM,
and northern AZ...

As temperatures climb into the 80s to near 90 degrees in lower
elevations, RH values will drop into the 7-15 percent range. As this
occurs, southwesterly surface winds will increase to 20-25 mph with
higher gusts. Where fuels are dry, this will lead to several hours
of elevated to critical fire weather conditions from late morning
through the afternoon. Wind speeds should decrease during the
evening hours and RH values will recover to the 20-40 percent range
overnight.

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

$$


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