Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 160222

Area Forecast Discussion
National Weather Service Norman OK
822 PM CST Fri Dec 15 2017

A moderate south wind will keep temperatures from falling
quickly this evening. The exception will be far southeast
Oklahoma where the wind will remain light through at least
the evening hours. Lowered temperatures a few degrees across
southeast Oklahoma, otherwise no changes are anticipated.


.PREV DISCUSSION... /issued 517 PM CST Fri Dec 15 2017/

VFR conditions to continue through the forecast period. Southwest
wind will remain up in the 12-14kt range across parts of western
into central Oklahoma overnight. Gusts over 20kts expected at all
sites by late morning with some gusts over 30kts possible by
afternoon. Will also see increase in high/mid clouds after 18Z.


PREV DISCUSSION... /issued 330 PM CST Fri Dec 15 2017/

Main focus for impactful weather continues to be fire weather
conditions. Temperatures will be near to slightly above normal for
the next several days until a much colder pattern settles in late
next week. Rain chances increase tomorrow evening/night with light
amounts, primarily across the eastern two-thirds of the area.
Otherwise dry conditions are expected until low probabilities
return in the south late next week.

Latest visible satellite imagery shows clear skies across the
region. Temperatures are mild and near normal for mid-December.
Slightly warmer weather will return tomorrow as most locations
make it to the lower 60s for high temperatures. Strengthening
southerly winds are expected as western trough deepens. Mid-upper
low over the Gulf of California will open and move quickly
northeast into the area providing ascent to increasingly moist
environment. This will result in some rain across the area
tomorrow evening into the night, with the best chances being
across eastern Oklahoma. Models diverge early next week in the
degree to which western trough closes off and its timing as it
moves east. This will probably necessitate mainly minor
adjustments in the forecast as the time nears and models come into
better agreement.

Large trough to our west will force a strong cold front through
Thursday bringing much colder air to the area. There`s general
agreement in the synoptic scale pattern in medium range guidance
which shows a deep closed off southern stream system to our west.
At this time southerly warm/moist advection atop the cold front
looks to yield a minor precipitation event at best, and primarily
to our south. Nevertheless, preliminary thoughts are that some
wintry precipitation may occur across the southeast portions of
the area by Friday. Details with regard to amounts and
precipitation type will be better resolved in the coming days.


Despite fairly deep mixing and low RH values this afternoon, winds
are fairly light limiting the potential for significant fire
spread. Nonetheless, some initial attack fire activity may occur
through the rest of the afternoon.

Bigger (albeit somewhat conditional) concerns arise tomorrow as
southerly winds increase markedly in response to deepening western
trough. 20-30 knot southerly winds with gusts approaching 40 will
be possible over far western Oklahoma. RH values stand the best
chance of dropping to near critical or critical levels in
northwest Oklahoma if cirrus is a little slower to increase over
the area than currently expected. Current indications are that the
timing/position of the ejective shortwave trough should support
fairly thick cirrus and eventually mid-level deck by afternoon
across especially western north Texas and southern Oklahoma,
spreading into northern Oklahoma by early afternoon. This would
limit fuel heating and temper mixing depth some. Another mitigating
factor will be lack of anomalous temperatures (lower 60s for
highs). Nevertheless, potential for initial attack fire activity
will increase, and conditions could briefly reach critical levels
in northwest Oklahoma tomorrow afternoon.

The next potential fire weather day may be Thursday as
warm/downsloping southwesterly winds occur ahead of a cold front.
Strong northerly winds will occur with the frontal passage late
Thursday or Thursday night.



Oklahoma City OK  31  60  44  56 /   0   0  50  10
Hobart OK         28  60  41  55 /   0   0  20   0
Wichita Falls TX  31  61  44  62 /   0  10  40   0
Gage OK           27  61  36  48 /   0   0  20   0
Ponca City OK     30  60  44  51 /   0   0  60  10
Durant OK         33  61  44  61 /   0  10  70  10



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