Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 191756

Area Forecast Discussion
National Weather Service Norman OK
1156 AM CST Thu Jan 19 2017

The 18Z aviation discussion follows....


The low clouds will continue to erode from SW to NE through the
early/mid afternoon. It is possible that clearing may not reach
the Kansas border (and possibly not KPNC, other than "TEMPO"
periods). Toward, and after, midnight, clouds and/or fog are
expected to form again over all but far SW Oklahoma and north
Texas. Winds will increase quickly Friday morning from the west or
southwest, especially across north Texas and southwest Oklahoma,
as a low pressure system briefly intensifies over the Oklahoma
Panhandle. Any fog or low clouds that form overnight should
quickly dissipate during mid-morning, except in northern Oklahoma,
where low clouds are expected to last into the afternoon.


.PREV DISCUSSION... /issued 1046 AM CST Thu Jan 19 2017/

Visibilities have improved substantially in the past couple of
hours, and all the remaining fog should be gone by noon. Southwest
flow will bring a general clearing trend, although clearing may
not make it all the way to north-central Oklahoma, particularly
near the Kansas border.

There are hints of fog again tomorrow morning, but there is not
enough confidence yet in probability or location to warrant
inclusion in the forecast.

Have made mostly minor adjustments to the forecast to account for
current and forecast conditions, including a few adjustments to
the extended portion of the forecast to align a little better with
surrounding offices.

PREV DISCUSSION... /issued 547 AM CST Thu Jan 19 2017/

The January 19-20, 2017 12 UTC TAF discussion follows:

IFR to LIFR flight conditions due to stratus and/or fog/mist are
expected to continue at most terminals through at least mid-
morning. Flight conditions are expected to improve from southwest
to northeast this morning into the early afternoon. Currently
expect all terminals to become VFR by 19Z.

Stratus and/or fog will be possible again tonight, especially
across northern Oklahoma. Included tempos at KGAG/KWWR/KPNC toward
the end of the TAF period to account for this possibility.

Otherwise, south to southwest winds are expected to continue
through this afternoon. Winds could become gusty across southwest
Oklahoma and western north Texas. A weak northerly windshift may
enter northwest Oklahoma tonight; however, wind speeds are
expected to be very light (<5 knots). Therefore, did not mention
the wind shift in the KGAG and KWWR TAFs.


PREV DISCUSSION... /issued 357 AM CST Thu Jan 19 2017/

Areas of fog have been present across southwest Oklahoma this
morning. Opted not to issue a dense fog advisory for now as most
stations have been >= 1/2 SM; however, intermittent areas of
dense fog will possible. Most high resolution guidance suggests
fog may continue to develop northeastward into central Oklahoma
the next few hours. Otherwise, low cloud cover is forecast to
decrease from southwest to northeast today with seasonably warm

On Friday, even warmer weather is forecast as both the 19/00Z GFS
and ECMWF have 850 mb temperatures ranging from 8-10C with south
to southwest low-level flow. As a result, high temperatures are
forecast to be in the 60Fs and to near 70F (~15F above average).
Opted to increase wind speeds slightly above blended guidance for
Friday afternoon as 925 mb winds are progged to be 25-30 knots. As
a result, near critical fire weather conditions are forecast across
southwest Oklahoma and adjacent western north Texas.

Seasonably warm weather will continue in Saturday. Increasing
ascent with the approach of the next shortwave trough will be
sufficient for isolated showers across southwest Oklahoma/western
north Texas Saturday afternoon. Added a mention of thunder as the
GFS has progged MUCAPE of 150-200 J/kg.

By Saturday night/early Sunday, the trough is forecast to evolve
into a closed mid/upper level low as it approaches the Southern
Plains. The outlier is the NAM12, which keeps the wave open with
minimal precipitation. Opted to disregard the NAM for now as the
GFS and ECMWF have been consistent with their solutions the last
several days.

The low is forecast to track across southern Oklahoma/near the
Red River. This would place the northern half of Oklahoma in the
deformation zone within an area of rain. Additional showers would
be possible across southeast Oklahoma in a region of DPVA and
isentropic ascent. Lowest chances will be across southwest
Oklahoma/western north Texas with this area potentially dry
slotted. Isolated thunder will also be possible as some elevated
instability will be present--especially across southeast Oklahoma.
Breezy northwest winds are forecast in the system`s wake, which
may result in near critical fire weather conditions.

For Monday, both the ECMWF and GFS indicate a 925-850 mb thermal
ridge with veering low-level flow with height. Therefore, raised
high temperatures above blended guidance for Monday.

On Tuesday, a closed-low is forecast to track north of Oklahoma,
keeping the primary ascent for precipitation to the north;
however, veering surface winds/dry air advection as an associated
Pacific front/dryline pass may result in near-critical fire
weather conditions--perhaps as far east as central Oklahoma.
Increased wind speeds for Tuesday afternoon beyond blended
guidance based on 925-950 mb winds.

The airmass behind this system is progged to be colder than
Sunday`s, which will result in at least slightly below average on



Oklahoma City OK  60  40  67  41 /   0   0   0   0
Hobart OK         59  38  68  38 /   0   0   0   0
Wichita Falls TX  65  42  71  44 /   0   0   0   0
Gage OK           55  35  63  32 /   0   0   0   0
Ponca City OK     55  41  61  37 /  10   0   0   0
Durant OK         62  46  71  48 /  10   0   0   0




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