Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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000
FXUS64 KOUN 210804
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
304 AM CDT Mon Aug 21 2017

.DISCUSSION...
Overnight, convection moved northeast out of the Texas Panhandle
into northwest Oklahoma. Early this morning, much of this has
shifted into southern Kansas with some southward development to
near Alva and Woodward. Some lightning has been detected with
this, but overall meager instability has tempered thunderstorm
intensity. Meanwhile, weaker convection with little/no lightning
was moving north-northeastward through the Texas Panhandle and far
west-central Oklahoma. This is tied to a mid-level shortwave
moving out of northeast New Mexico.

Aforementioned mid-level shortwave trough will attempt to phase
with transient northern stream wave today while elongating and
continuing to provide some forcing for ascent for northwest
portions of our area. We have retained low probabilities for
showers and thunderstorms through the morning to account for this
evolution. Convection may grow in coverage/intensity some this
afternoon as modest destabilization occurs. Overall weak
instability and deep layer shear should be unsupportive of severe
thunderstorms.

The above described pattern is supporting a mid-level moisture
plume across at least the northwest third of our area. Mid-high
clouds from this monsoon moisture as well as convective debris
will result in considerable mid-high level cloud cover for
eclipse watchers later today. Further east across central
Oklahoma, mid level clouds will be less extensive but some thin
cirrus may be present during viewing time. Also, some cumulus
development may begin around that time. So, not optimal viewing
conditions central and eastern Oklahoma, although not as
unfavorable as across northwest Oklahoma into Kansas.

The mid-level wave will continue to elongate with stronger forcing
shifting east tonight. Showers and thunderstorms should be limited
to about the northeast third of the area overnight. The large
scale pattern will amplify considerably through Tuesday and a cold
front will move south into the area. Most models have some subtle
ascent from shearing out but diminishing mid-level wave and
frontal convergence focusing convective development in a west to
east oriented band across the central portion of our area. ECMWF
is the faster outlier and has the front near the Red River by the
end of the day. So, there is some uncertainty in how this will
play out but Tuesday/Tuesday night still seem to be the best
opportunity for precipitation this week. The main change that we
made was to lower precipitation chances for Wednesday and shift
them further southward. This is more in line with the ECMWF/EPS
and accounts for the often overzealous QPF behind cold fronts. If
the GFS is right and the front slows and becomes diffuse near the
Red River, then decent coverage of convection may occur Wednesday
afternoon across southern portions of the area, but this is an
outlier scenario at the moment.

Medium range deterministic and ensemble guidance are all in
reasonable agreement with timing/placement of central Rockies
shortwave trough emerging onto the Plains on Friday and increasing
our chances for showers and thunderstorms. A fairly active
northwesterly flow pattern next weekend may bring periodic chances
of convection, although ensemble spread and deterministic
differences don`t allow us to provide much detail at this time
range.

BRB

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  93  74  94  70 /  10  10  50  50
Hobart OK         95  75  95  71 /  10  10  50  50
Wichita Falls TX  95  76  97  74 /  10   0  20  50
Gage OK           92  71  87  65 /  30  40  30  20
Ponca City OK     95  75  88  66 /  10  30  50  20
Durant OK         92  74  94  73 /  10  10  20  60

&&

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

$$

03/12



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