FXUS64 KOUN 232004

Area Forecast Discussion
National Weather Service Norman OK
304 PM CDT Sat Jun 23 2018

There are several short term concerns, followed by a transition
to a calmer, drier, and hotter pattern late in the forecast
period. The most impactful weather may be localized flooding this
evening into tonight, and again Sunday night. Severe thunderstorms
are possible this evening again possible late Sunday and Sunday

Significant convective overturning was evident in this morning's 12z
sounding at KOUN in the wake of last night's MCS, resulting in a
drier low-level air mass than is depicted in model forecast
soundings. Special 19z sounding shows some boundary layer
moistening, but capping is still quite extensive. Several residual
boundaries are present across the area early this afternoon,
including; 1.) a surface composite front/outflow boundary oriented
east to west from just north of Seminole, to near Chickasha, to
Cheyenne, 2.) another outflow boundary evident in satellite
extending from the east-central Texas Panhandle eastward across
southern Oklahoma and shows little movement, 3.) an outflow boundary
from Truscott to Archer City, 4.) a synoptic front from near DFW
westward into west Texas.

Gravity waves have been evident in visible satellite all the way
down to the synoptic front in north Texas. Patches of mid-level
clouds remain across the area, typical of these post-MCS scenarios.
This has tempered diabatic heating somewhat, and slightly cooler
temperatures coupled with depleted low-level moisture should limit
diurnal convective development some this afternoon. Current thinking
is aforementioned boundaries should become more diffuse with time
this afternoon but should still focus isolated to scattered
development by late afternoon as surface heating and mid-level
cooling continues. At least moderate instability and enough deep
layer shear for storm organization could result in a few instances
of very large hail until upscale growth continues this evening and
wind becomes the dominate threat. The tornado potential is low
given weak low-level shear, though some enhancement near
boundaries leads to a small chance with the most intense/organized
supercells through mid evening.

Although Corfidi vectors suggest convection should propagate fast
enough to preclude significant flood/flash flood concerns,
localized flooding/flash flooding threat may occur given the
moistening environment. This is especially true for areas where
heavy rainfall amounts have occurred (i.e., from near Velma to
Sulphur, to Atoka).

Additional convection, or potentially a convective complex, may move
into northwest/north-central Oklahoma later this evening and
overnight from the initial diurnal development later today in the
Colorado Plains. We have increased rain chances across the northern
half of the area later tonight and into tomorrow morning.

A deepening mid-upper trough in the central High Plains tomorrow
will strengthen our low-level southerly flow and continue to
transport deeper moisture northward. Meanwhile, west-southwesterly
mid-level flow will strengthen and advect steep mid-level lapse
rates eastward resulting in moderate to strong instability late in
the day. This will be another scenario where initial development
during the afternoon will have the greatest hail threat, with
significant hail sizes possible, followed by upscale growth and a
potentially significant wind swath across northern portions of the
area and especially in Kansas. Veering/strengthening low level
flow resulting in more favorable Corfidi vectors for backbuilding
and locally heavy rain/flooding threat could evolve Sunday night.

Some convection may continue until the trough pulls northeast late
Monday. Then a warm/dry pattern will occur through the end of the
forecast period.



Oklahoma City OK 70 94 74 89 / 40 40 40 30
Hobart OK 72 98 73 92 / 40 10 10 20
Wichita Falls TX 73 101 78 98 / 60 20 0 10
Gage OK 70 95 67 86 / 50 40 80 10
Ponca City OK 71 92 72 86 / 40 20 70 40
Durant OK 76 94 77 92 / 60 40 0 10




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