Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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350
FXUS64 KOUN 242112
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
412 PM CDT Wed May 24 2017

.DISCUSSION...
The primary forecast issue is the potential for severe weather on
Saturday.

A rapid warming trend is expected to commence by Thursday and
Friday as a low-level thermal ridge develops across the southern
Plains. Model consensus indicates 850 mb temperatures to near ~30C
across parts of western north Texas by Thursday afternoon.
Consequently, high temperatures will likely warm into the low
100Fs across parts of north Texas.

Late Thursday night into Friday, a cold front is expected to
shift southeastward and stall near the Red River by Friday
afternoon. Opted to lower temperatures below blended guidance
across northern Oklahoma, where cooler air may advect southward.
Hot temperatures are still expected across southern Oklahoma and
adjacent north Texas Friday afternoon.

A strong cap is expected to be in place with very warm 800-700 mb
temperatures aloft with 800 mb temperatures near >=22C.
Therefore, expect the cap to suppress convection for Friday
afternoon. The cold front is expected to lift northward as a warm
front Friday night.

There is a signal that an MCS will develop in the upslope flow
across eastern Colorado/western Kansas Friday afternoon. This MCS
may affect northern Oklahoma Saturday morning and result in a
remnant boundary located somewhere across northern Oklahoma.

By Saturday afternoon, a complex mesoscale pattern is expected to
develop across Oklahoma. Currently, the greatest uncertainties
are 1) the location of a potential triple point and 2) the
strength of the cap.

A dryline is expected to be situated somewhere in vicinity or
perhaps just east of I-35 Saturday afternoon. In addition, a cold
front will enter northwest Oklahoma Saturday afternoon. The
remnant boundary from the aforementioned MCS may begin to lift
northward Saturday afternoon--becoming an effective warm front.
The location of any remnant boundary and its intersection with the
dryline and cold front would result in a triple point with an
enhanced potential for severe weather in its vicinity.

The cap is expected to be weaker Saturday afternoon with at least
isolated storms possible. Both the 24/12Z ECMWF and GFS do
initiate convection along the dryline. The NAM does not initiate
convection; however, this is a known bias due to the BMJ
convective parameterization scheme.

The atmosphere south and east of these boundaries will be at
least moderately unstable with progged MLCAPE >=3500 J/kg as a
very moist airmass (dewpoints >=70F) is forecast in the warm
sector. Effective bulk shear is also progged to be >= 50 knots.
Therefore, the parameter space will be sufficient for severe
thunderstorms, including supercells. Large to giant hail will be
possible with significant CAPE in the hail-growth zone.

There is some uncertainty on the exact location of the
aforementioned mesoscale features (and the attendant triple
point). For example, the ECMWF is the farthest west with the
dryline while the 24/06Z NAM is the fastest with the cold front.
The location of these features will modulate where the greatest
risk for severe weather will be Saturday afternoon. The bottom
line: Saturday will have to be monitored carefully as there will
be the potential for very intense storms if they form.

Thunderstorms will remain possible across southeast Oklahoma as
the cold front passes by Saturday night.

Beyond Saturday, the Plains are expected to transition into
northwest flow aloft. This will allow cooler temperatures across
the area. In addition, there is a chance MCSs could affect parts
of the area (especially northern Oklahoma) by the middle of next
week.

Mahale

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  53  86  66  87 /   0   0   0   0
Hobart OK         55  91  63  91 /   0   0   0   0
Wichita Falls TX  56  94  74  97 /   0   0   0   0
Gage OK           54  91  59  83 /   0   0   0   0
Ponca City OK     51  82  62  84 /   0   0   0   0
Durant OK         54  87  72  94 /   0   0   0   0

&&

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

$$

06/10



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