Fire Weather Outlook Discussion
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FNUS21 KWNS 251649

Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1148 AM CDT Tue Apr 25 2017

Valid 251700Z - 261200Z


The ongoing critical area has been expanded westward to include
parts of central of southern AZ. Across this region, confidence has
increased that RH values will fall into the 10-15% range for a few
hours this afternoon in combination with strong/gusty winds of 20-25
mph. Otherwise, only a small southward extension has been made to
the critical area in Presidio/Brewster counties in west TX where
fuels are dry.

An elevated area has been introduced for parts of the FL peninsula,
where a dry low-level airmass is in place due to a cold front
passage. 12Z sounding from Tampa Bay FL indicated a PWAT value of
just 0.42", and RH values should fall into the 30-40% range this
afternoon across interior portions of the central/southern FL
peninsula. Although low-level flow is not expected to be overly
strong through the day, sustained west-northwesterly winds around 10
mph and continued dry fuels in many locations will support an
elevated fire weather threat. Locally critical conditions may be
realized where winds approach 15 mph, but this is expected to occur
on just a brief/spotty basis.

..Gleason.. 04/25/2017

.PREV DISCUSSION... /ISSUED 1247 AM CDT Tue Apr 25 2017/

An upper trough will progress eastward across the Four Corners
region today and into the adjacent High Plains during the overnight
hours. This will bring a band of enhanced deep-layer westerly flow
across much of AZ/NM into western TX and northeast toward the mid-MS
Valley. At the surface, a broad area of low pressure will be
centered over NM into the TX Panhandle and OK. Strong winds and very
dry conditions will combine across parts of the region, leading to
elevated and critical fire weather conditions during the afternoon.

...Southern AZ/NM into Western TX...

Widespread breezy conditions are expected across the region today as
mid/upper level height fall accompany the eastward-advancing trough.
A band of strong surface winds and low RH conditions are expected to
develop across portions of southern and central AZ. Northwest winds
around 15-25 mph with higher gusts are forecast while RH values fall
into the 12-20 percent range. This will lead to several hours of
elevated to critical fire weather conditions.

Further east, surface winds are expected to be even stronger as
surface low pressure deepens modestly through the day. Widespread
west/southwest winds of 20-30 mph with higher gusts are expected
across much of southern and central NM into the TX Panhandle and far
western TX. Above-normal high temperatures are also expected across
southern NM into west TX as highs top out in the mid 80s to low 90s.
Temperatures will warm quickly due to downsloping off the central NM
mountains. This will result in deep boundary-layer mixing through
the morning, and wind speeds will increase quickly while RH values
plummet. Expect the lowest RH values across southern NM into far
western TX where values from 7-13 percent will be common. Where
fuels are dry, this will result in several hours of critical
conditions. There is some uncertainty in the eastward extent of the
critical area due to recent green-up of fuels across parts of the
Trans-Pecos to the TX South Plains, so portions of this area remain
in the elevated delineation, but likely will experience critical
meteorological conditions.

Further north across central NM into the TX Panhandle, RH values
will be higher, in the 18-30 percent range but wind speeds will
remain quite gusty. However, given the marginality of RH values,
only elevated conditions are expected.

...Please see for graphic product...

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