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000
FXUS64 KOUN 231056
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
556 AM CDT Sat Sep 23 2017

...Aviation Discussion...

&&

.AVIATION...
For the 12z TAFs:

Latest 10.3-3.9 satellite imagery shows low stratus moving
northward from the Permian Basin region of Texas. Short term
guidance has this advecting/developing further north into the
Panhandles this morning. Further east across our area we`ll be
moist in the low levels, but not saturated except for perhaps far
western Oklahoma. We have included a TEMPO for MVFR ceilings at
Gage, Woodward, and Clinton. Elsewhere, as mixing increases,
cumulus is expected to form and southerly winds will become
increasingly gusty. Stratus is possible again toward the end of
the TAF period particularly across western Oklahoma.

&&

.PREV DISCUSSION... /issued 301 AM CDT Sat Sep 23 2017/

DISCUSSION...
Not much change to the previous forecast. A cooler and wetter
pattern will begin this weekend and continue into the middle of next
week. Forecast confidence remains fairly high through at least early
next week. The main change was to decrease rain chances from mid-
late week.

Models are in good agreement with the amplified synoptic scale
pattern featuring a deep western trough and a couple periphery
shortwave troughs. The first shortwave rounds the base of the
longwave trough tonight and continues northeastward across the
central High Plains late Sunday. A second one will take a similar
track on Monday. Both should act to enhance convective coverage
within a band of deep moisture.

We`ve adjusted temperatures downward from the model blend early next
week to account for expected clouds and precipitation. Upper 60s and
low 70s across western portions of the area may still be too warm
for highs on Monday and Tuesday for areas that receive prolonged
rainfall.

Once the second wave lifts northeast, weak ridging and mid-level
height rises should result in lower precipitation chances. This
decreasing trend should start Tuesday afternoon and be in the slight
chance range by late Wednesday as cool/stable post-frontal
northeasterly flow builds in. Medium range deterministic and
ensemble guidance is now in better agreement with holding deep
closed low far enough west until possibly sometime next weekend as
it opens up and progresses eastward.

Typical of these deep moist meridional flow patterns, instability
will be meager at best and severe thunderstorms are unlikely. The
main threat will be heavy rain and some flooding potential given
anomalous PWAT values (at or above the 90th percentile). The
greatest potential for heavy rainfall amounts will be in western
Oklahoma and portions of western north Texas.

BRB

FIRE WEATHER...
Persistent lee surface troughing in response to western system
will support south winds continuing, peaking around 20-25 mph this
afternoon with gusts around 30-35 mph possible. Low level moisture
is considerably higher in the last 24-36 hours and this will keep
minimum relative humidity values at or above 40 percent at most
locations, perhaps slightly lower across north Texas counties.
Since RH values are relatively high and ERC-G values are barely
above 50th percentile, a Fire Danger Statement will not be needed
for this afternoon. Although the winds may support an increase in
fire activity. Fire concerns will decrease markedly Sunday into
next week as a wetter cooler pattern arrives.

BRB

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  88  69  87  68 /   0   0   0  10
Hobart OK         88  70  86  69 /  10  10  10  40
Wichita Falls TX  91  70  90  69 /   0   0  10  20
Gage OK           87  69  81  64 /  10  10  50  70
Ponca City OK     90  69  90  70 /   0   0  10  10
Durant OK         91  70  91  69 /  10  10  10  10

&&

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

$$

03/12