Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 182000

Area Forecast Discussion
National Weather Service Norman OK
300 PM CDT Sun Mar 18 2018

A strong storm system moving into the southern Plains will bring
rain and thunderstorms to Oklahoma and north Texas though Monday
night. There is a complex mix of elevated instability and vertical
wind shear this afternoon, and it will remain complicated into
tonight. Based on the forecasts of these parameters, plus the
output of Convection-Allowing Models (CAMs), it appears that the
most likely scenario consists of at least three separate
areas/times of convective development.

First, the existing storms over central and north-central Oklahoma
are likely to remain non-severe, as they continue to travel to the
northeast this afternoon and perhaps early evening.

Second, there is a possibility of storm development in
northeast/north-central Texas this afternoon or early evening. Any
storms that can develop in this environment would have a solid
chance of becoming a supercell storm. The risk of supercell storms
diminishes quickly with northward extent, as the surface warm
front over north Texas is unlikely to move much farther north, and
the relatively cooler/drier air under the elevated frontal surface
will adversely affect storm development. In addition, short-wave
subsidence is probably occurring in the region, which will further
limit the likelihood of storm development.

Finally, the most likely area of severe weather will be over
northwest and north-central Oklahoma late this evening and
overnight, as elevated storms are likely to develop closer to the
upper-level circulation. Wind shear will be very strong, and the
modest amounts of instability should be enough to support elevated
supercell storms. This situation would most strongly favor large
hail, but strong winds reaching the surface can`t be ruled out.

As the system moves off to the east tomorrow, brisk west winds
will turn generally northerly during the day, as cooler air moves
into the region. Sufficient moisture will continue rain chances in
northern Oklahoma into tomorrow night. A few thunderstorms will
be possible with the cool air aloft, but severe storms will be
unlikely after tonight.

A mild and "quiet" period will extend from Tuesday into early
Friday, before the next storm system arrives. There is still a lot
of difference between the medium-range forecast models, so it is
hard to say exactly what will happen from Friday into the
weekend. A "chance of thunderstorms" seems most appropriate for
most of our forecast area for most of the Friday night through
Sunday periods. As is usually the case, the rain chances are
higher east/lower west.


Oklahoma City OK  45  53  38  58 /  10  10  10   0
Hobart OK         46  57  36  62 /   0   0   0   0
Wichita Falls TX  50  63  39  63 /   0   0   0   0
Gage OK           41  48  31  60 /  60  10  10   0
Ponca City OK     47  53  36  56 /  70  20  30   0
Durant OK         50  67  43  62 /  20   0  10   0




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