Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 181730 AAC
AFDOUN

Area Forecast Discussion...UPDATED
National Weather Service Norman OK
1230 PM CDT Sun Jun 18 2017

.AVIATION...
18/18Z TAFs. MVFR conditions expected to continue through the
afternoon across far southern Oklahoma and KSPS terminals with
brief light rain showers possible. TSRA will be included at KSPS
in the 03Z to 09Z time frame but bulk of activity expected south
and east of KSPS. Cigs expected to rise across the region through
the evening and tonight and northerly winds will subside quickly
toward and after 00Z.

&&

.PREV DISCUSSION... /issued 1054 AM CDT Sun Jun 18 2017/

DISCUSSION...
Shallow convective showers continue to develop mainly along and
north of a frontal boundary in southern Oklahoma and western
north Texas this morning. RAP model soundings suggest scattered
showers will remain possible into the early/mid afternoon.

Clouds have decreased across parts of northern Oklahoma but
additional mid level clouds may move back into the area by
afternoon. Enough elevated instability across mainly north
central Oklahoma may allow for a few showers/storms during the
afternoon.

Several models indicate that thunderstorms may develop by
late afternoon/early evening over south central and southeast
Oklahoma. A few strong to severe storms will be possible with
areas of heavy rain.

PREV DISCUSSION... /issued 637 AM CDT Sun Jun 18 2017/

.Aviation Discussion...

AVIATION...

For the 12z TAFs:

MVFR ceilings are possible at most TAF sites this morning,
especially across central and southwest Oklahoma into north Texas.
A return to VFR is expected by late morning. Gusty northeast winds
should subside later in the day. Additional thunderstorm
development near the front will occur later this afternoon/evening
but should generally be east of SPS. MVFR stratus may return to
SPS and possible other sites further north later tonight.

PREV DISCUSSION... /issued 226 AM CDT Sun Jun 18 2017/

DISCUSSION...
The focus is primarily in the short term with frontal passage
tonight and ongoing convection. Cooler weather will arrive today,
followed by a gradual warm up and a return of thunderstorm

Latest water vapor imagery shows a fairly sharp shortwave trough
traversing southern Minnesota and northern Iowa. This has forced a
cold front southward into Oklahoma. Latest surface observations
shows the front along a line from just south of Stillwater to near
Cheyenne. Frontal lift of a still moderately unstable environment
with at least a couple thousand Joules of MUCAPE has resulted in
some thunderstorms. Although the stronger ascent will stay to the
north and thus the more widespread convection should occur over
Kansas, a couple of clusters and bowing segments are ongoing across
north-central Oklahoma. These should continue to move southeast for
the next few hours in a moist and unstable environment. Westward
extent/growth should be tempered by warm capping mid-level layer as
700 mb temperature gradient is fairly steep east-to-west across the
area.

A marginal low-end severe threat will continue for the next few
hours, although growing MLCIN should lessen the wind threat some,
and storm mode generally won`t favor significant hail sizes.

Despite stronger forcing remaining north of the area, a couple of
factors led us to retain at least low precipitation probabilities
across the eastern portion of the area this morning. 1.) a very
moist environment (nearly 2.0 inches PWAT) that is still modestly
unstable, and 2.) outflow/cold pool strengthening as storms track
southeast along periphery of ridge and edge of stronger mid-level
capping.

Thunderstorms should reform near the slowing cold front across south-
central and southeast Oklahoma later today. Marginal deep layer
shear for storm organization should preclude a higher end severe
threat, but given magnitude of instability that should form as
diabatic heating occurs late in the day, some severe thunderstorms
will be possible. Convection should diminish and/or shift southeast
by the early morning hours on Monday.

For later in the week, we continue to be on the northeast side of
mean ridging with occasional shortwaves moving through the northern
and central Plains. Periodic thunderstorm chances are expected and
timing of these will be refined in later forecasts. As it appears
now, the best chance of storms should be across northern and perhaps
eastern portions of the area on Wednesday night and late Friday into
Saturday.

BRB

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  76  63  87  65 /  20  10   0   0
Hobart OK         78  62  88  65 /  10   0   0   0
Wichita Falls TX  85  65  87  69 /  10  20   0   0
Gage OK           79  59  86  60 /   0   0   0   0
Ponca City OK     77  61  85  60 /  30   0   0   0
Durant OK         87  67  87  68 /  50  60  20  10

&&

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

$$

06/11



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