Fire Weather Outlook Discussion
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000
FNUS22 KWNS 222000
FWDDY2

Day 2 Fire Weather Outlook CORR 1
NWS Storm Prediction Center Norman OK
0159 PM CST Wed Feb 22 2017

Valid 231200Z - 241200Z

CORRECTED FOR INCORRECT GRAPHIC

...EXTREMELY CRITICAL FIRE WEATHER AREA FOR THE PLAINS OF EASTERN
NEW MEXICO NORTHEAST INTO NORTHWEST OKLAHOMA AND FAR SOUTHWEST
KANSAS...
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF SOUTHEAST ARIZONA
NORTHEAST INTO SOUTHEAST COLORADO AND SOUTHWEST KANSAS...INCLUDING
MUCH OF WEST TEXAS AND PARTS OF WESTERN OKLAHOMA...

Potential remains for a very active fire-weather day on Thursday.

Latest guidance continues to indicate a deepening surface low will
move east out of southeast Colorado into southwest Kansas during the
afternoon. As this occurs, a strengthening 850-millibar low will aid
the rapid increase of westerly low-level flow across much of New
Mexico, west Texas, far western Oklahoma, southeast Colorado, and
southwest Kansas. This strong westerly low-level flow will help mix
a dryline east into western/central Oklahoma. To the west of the
dryline, the low-level thermal ridge should become established from
the Big Bend area of Texas northward to very near the Oklahoma-Texas
Panhandle border. Along and west of the low-level thermal ridge,
afternoon relative humidity should fall below 15% across much of the
critical area.

Within the broader critical area, a belt of enhanced
850-700-millibar flow will become established along the general
corridor from eastern New Mexico north-northeast into far southeast
Colorado and southwest Kansas. Within this broader zone, vertical
mixing will allow this 850-700-millibar flow to mix down to the
surface, supporting wind speeds potentially in excess of 35 miles
per hour with gusts locally approaching 50-60 miles per hour.
Therefore, after collaborating with the local National Weather
Service Forecast Offices across the southern Plains, have opted to
expand the extremely-critical area to the south toward Midland,
Texas; northwest into southeast Colorado; and northeast into far
northwest Oklahoma and southwest Kansas.

In addition to the critical and extremely critical fire-weather
areas to the west, another region of concern may develop across
portions of eastern Oklahoma. Numerical guidance suggests a very
strong southerly low-level jet may develop by late afternoon.
Although minimum relative-humidity values may only fall between
30-40%, the strength of the low-level flow may support strong, gusty
surface winds. Since fuels in this area are very dry given the
long-term drought have pulled the elevated fire-weather area east
across Oklahoma to encompass this potential threat.

..Marsh.. 02/22/2017

.PREV DISCUSSION... /ISSUED 0156 AM CST Wed Feb 22 2017/

...Synopsis...
An extensive zone of broadly cyclonic and strong midlevel flow will
overlie the Southwest and South-Central States, which will be
reinforced by multiple shortwave impulses advancing through the
flow. A surface cyclone is forecast to deepen on its track along a
frontal zone from eastern CO to KS, before it advances to the middle
Mississippi Valley. A dryline extending south of the cyclone will
sharpen and move eastward over parts of the Great Plains. A cold
front trailing to the west/southwest of the low will spread
southeastward across parts of the Plains during the evening and
overnight hours. Deep vertical mixing into the strong flow aloft
west of the dryline and south of the front, along with ample
downslope-flow-enhanced warming/drying, will greatly increase
fire-weather potential across portions of the Southwest States to
the central and southern Great Plains.

...Portions of the Southwest States to the central and southern
Great Plains...
Across the Extremely Critical area, west-southwesterly to westerly
winds of 30-35 mph are forecast to combine with RH of 8-10 percent
during the afternoon as temperatures rise into the upper 60s to the
70s. These very strong downslope winds will support the very low RH
given the dry antecedent upstream air mass over the southern Rockies
(observed precipitable water around 0.25 inch), and especially given
poor RH recovery Wednesday night. Critical conditions could develop
by late morning on Thursday, before extremely critical conditions
develop during the afternoon. The presence of very dry fuels further
supports the Extremely Critical designation.

Across the surrounding Critical area, southwesterly to westerly
winds of 20-30 mph are forecast to combine with RH of 10-15 percent
(except 15-20 percent across far eastern parts of the Critical
area).

Within the surrounding Elevated area, elevated to borderline-
critical fire-weather conditions are expected. However, critical
fire-weather conditions are not expected to occur on any more than a
brief/spotty basis.

Across portions of the central/southern Plains, a wind shift to
northwesterly is forecast to occur in association with the passage
of the cold front during the evening and overnight hours, which
could re-direct any ongoing fires.

Uncertainty regarding the eventual positions of the aforementioned
dryline and front attendant to the surface cyclone extend to the
northern and eastern bounds of, especially, the Critical area. The
progressive wave pattern aloft should tend to be associated with an
overall eastward advance of the dryline, though adjustments to areal
delineations of fire-weather highlights may be necessary in
subsequent outlooks.

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

$$


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