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000
FXUS64 KOUN 171703
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
1103 AM CST Thu Jan 17 2019

.AVIATION...
18Z TAFs - Skies will continue to gradually clear from west to
east although ceilings may be in and out for a brief time in a few
places due to a few holes in the overall cloud cover. Some MVFR
ceilings could return overnight/Friday morning in a few locations.
Winds will gradually shift towards the south this afternoon and
tonight. Breezy southerly winds are expected Friday morning. It
currently looks like any precipitation will wait until after 18Z
tomorrow before beginning so TAFs are dry through the TAF period
for now.

&&

.PREV DISCUSSION... /issued 533 AM CST Thu Jan 17 2019/

DISCUSSION...
The 12Z aviation discussion follows....

AVIATION...
Patches of fog, and a large area of low clouds, cover most of
Oklahoma and north Texas early this morning. Forecast models
suggest that subsidence above the cloud layers will help clear
the clouds by about 18Z at most sites. Given that models have a
strong tendency to clear skies too rapidly (sometimes when
clearing doesn`t happen at all), we have elected to delay the
clearing by a few hours--both to account for this tendency, and to
fit better with the overall situation. Assuming the sky does
clear by mid or late afternoon, it should remain generally clear
(below cirrus level) through tonight. Rapid deterioration appears
likely to begin around the end of this TAF period as an
approaching storm system will likely bring lowering ceilings and
chances of showers and thunderstorms to the region Friday morning
and beyond.

CmS

PREV DISCUSSION... /issued 422 AM CST Thu Jan 17 2019/

DISCUSSION...
A weak cold front from east-central to south-central Oklahoma this
morning was accompanied by patches of dense fog, especially
earlier this morning. Since the fog has become less dense and less
widespread, we have elected to cancel the Dense Fog Advisory
early.

Patches of fog are nevertheless expected to continue through mid-
morning, with a general improving trend. Cloud cover will also be
slow to diminish across most of Oklahoma, which will blunt the
warmup that we would otherwise have this afternoon (and
tomorrow).

By Friday afternoon, a strong upper-level wave will approach from
the west, with an associated surface low deepening over the Texas
Panhandle. This will result in warm-air advection showers, and
perhaps a few thunderstorms out ahead of the low. In this area,
instabilities will not be overly strong, but sufficient wind shear
will exist for perhaps a few strong storms, mainly near the Red
River east of I-35.

The low will then move fairly quickly to the east, followed by
much colder air. A tight pressure gradient will result in strong
north winds overnight Friday into Saturday. While this will be an
abrupt drop in apparent temperatures, it appears that our forecast
area will remain above levels needed to warrant a Wind Chill
Advisory. A Wind Advisory, however, appears more likely to be
needed.

Rain should change over to snow rather quickly as the storm
system moves east. There may be a brief period of sleet or
freezing rain in the transition zone, but ice accumulation should
be minimal. Some modest snow accumulation is likely. Given the
trajectory of the system and its speed, it is improbable that
heavy snow will occur in our forecast area.

Another storm system will arrive about Tuesday, bringing another
chance for snow. With a limited amount of available moisture, and
another fairly quick passage, snowfall amounts should be
relatively light.

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  53  40  55  25 /   0   0  20  50
Hobart OK         56  41  61  28 /   0   0  10  30
Wichita Falls TX  56  43  66  32 /   0   0  20  30
Gage OK           59  41  58  22 /   0   0  20  50
Ponca City OK     49  36  52  23 /   0   0  30  70
Durant OK         56  39  58  32 /   0   0  40  70

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&

$$

25/06/99