Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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130
FXUS64 KOUN 231633
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
1033 AM CST Thu Feb 23 2017

.DISCUSSION...
Temperatures, relative humidities, etc., seem to be rising/falling
about as planned. Current guidance suggests that our forecast high
temperatures are reasonable (albeit slightly above said guidance).
There doesn`t appear to be a need to update any forecast
parameters at this time, but we will keep a close eye on
conditions, particularly those that affect the ability of fires to
spread quickly.

&&

.PREV DISCUSSION... /issued 546 AM CST Thu Feb 23 2017/

DISCUSSION...
The February 23-24, 2017 12 UTC TAF discussion follows:

AVIATION...
No ceiling or visibility restrictions are expected through the TAF
period. Light winds this morning will become gusty this afternoon,
especially across terminals in western Oklahoma. Across western
Oklahoma, the wind direction will become predominantly west-
southwest. Farther east, south to southwest winds are expected
(albeit lighter).

Winds should weaken after sunset; however, a cold front will
shift the winds to the northwest through the evening/overnight
hours.

Mahale

PREV DISCUSSION... /issued 435 AM CST Thu Feb 23 2017/

DISCUSSION...
Unseasonably warm temperatures are expected this afternoon. Last
night`s OUN 00Z sounding indicates the boundary layer had mixed to
~850 mb with a temperature of 17C. Anticipate at least similar
mixing heights today with slightly warmer 850 mb temperatures
(~20C). Therefore, opted to raise high temperatures a few degrees
above blended guidance. The only potential caveat is what impact
high clouds overhead will have on mixing; however, most guidance
(HRRRX/NAM12) indicates decreasing high clouds this afternoon.

A dryline is expected to rapidly shift eastward as a surface low
lifts northeastward across Kansas. Deep mixing behind the dryline
will result in gusty southwest to west winds across western
Oklahoma and far western north Texas. Farther east, mixing will
not be as deep; however, a secondary area of gusty surface winds
will be possible from near I-44 to the south and east. These gusty
winds are associated with a veered low-level jet that is progged
to develop in response to a lead wave aloft. The veered flow just
above the surface is expected to mix drier air to the surface.
Therefore, lowered dewpoints farther east toward the more
aggressive RAP/HRRR.

For tonight, a cold front is expected to veer the winds to the
northwest. The airmass behind the front is much cooler, with more
seasonable temperatures expected Friday. A widespread freeze is
expected Friday night into Saturday morning. A secondary surge of
low-level cold air advection will result in below average
temperatures for Saturday afternoon.

On Sunday, increasing isentropic ascent will result in a chance
of showers and thunderstorms. The 23/00Z GFS is faster/more
aggressive with the ascent than the ECMWF. For now, trended toward
the more consistent ECMWF with the greatest ascent Sunday night
into Monday morning. Sufficient elevated instability is progged
for at least a slight chance of thunder.

On Tuesday, another significant mid/upper level trough is
expected to approach the Plains. Another significant dryline push
eastward is currently forecast with unseasonably warm
temperatures. There will be a low chance of showers/storms,
primarily east of I-35. Cooler, seasonable weather is expected in
the system`s wake for Wednesday.

Mahale

FIRE WEATHER...
Critical to extreme fire weather conditions are expected this
afternoon across western Oklahoma and far western north Texas. A
dryline will move into western Oklahoma/north Texas and surface
winds will veer to the west-southwest as the dryline passes by.
Deep mixing will allow for sustained wind speeds at 20 to 25 mph
with gusts to 45 mph. Very low relative humidity values (~10%)
will be possible near the 100th meridian.

Though relative humidity values are forecast to be higher to the
east (especially across southeast Oklahoma), a secondary wind
maxima is forecast this afternoon for areas near I-44 to the
south and east (in association with a low-level jet), which could
result in near-critical fire weather conditions. This is
coincident with a low-level thermal ridge aloft.

Across the entire area, temperatures are forecast to warm into
the mid-80Fs to near 90F--around 30F above climatological
averages.

A cold front will pass by tonight, which will result in winds
veering to the northwest. Though much cooler air is expected on
Friday, gusty northwest winds will maintain at least elevated
fire weather conditions Friday afternoon--especially across parts
of western north Texas (where the warmest temperatures are
forecast).

By Tuesday, near-critical to critical fire weather conditions are
possible as another mid/upper level trough approaches the Plains.
This system is forecast to bring gusty southerly winds and
unseasonably warm temperatures. In addition, this trough may
result in a dryline entering western Oklahoma and parts of
western north Texas--resulting in very low relative humidities.

Mahale

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  86  41  55  28 /   0   0   0   0
Hobart OK         85  38  56  26 /   0   0   0   0
Wichita Falls TX  88  43  62  30 /   0   0   0   0
Gage OK           85  33  49  21 /   0   0   0   0
Ponca City OK     83  38  50  25 /   0   0   0   0
Durant OK         85  50  65  34 /   0   0   0   0

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Red Flag Warning until 9 PM CST this evening for OKZ004>048-
     050>052.

TX...Red Flag Warning until 9 PM CST this evening for TXZ083>090.

&&

$$

23/26



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