Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 180417

Area Forecast Discussion
National Weather Service Norman OK
1117 PM CDT Sat Mar 17 2018



For the 06z TAFs:

First round of showers will reach southwest TAF sites early-mid
morning and move northeast toward OKC/OUN. This round should move
out by mid-afternoon. Showers and storms should develop over
northwest Oklahoma during the evening impacting GAG/WWR/OUN. Winds
will generally be light and southerly. A period of MVFR stratus
may occur at most TAF sites from early-mid morning through much of
the afternoon but confidence is not high at this time.


.PREV DISCUSSION... /issued 1016 PM CDT Sat Mar 17 2018/

Removed thunder and shifted the chance of rain eastward for

Also updated temperatures and dew points based on current
observations/short-term models.

Showers continue to shift eastward across southeast Oklahoma this
evening. Opted to remove thunder based on the lack of progged
elevated instability. These showers are associated with a mid-
level jet that will continue to move eastward tonight. As this
mid-level jet exits the region, expect relatively quiet weather
for tonight.

For tomorrow, it still appears there will be two rounds of
showers/storms. The first round of thunderstorms will be
associated with a lead shortwave trough/mid-level jet that will
approach mid to late tomorrow morning. This convection is expected
to be primarily elevated (with a threat for hail); however some
of the convective-allowing models (such as the 18/00Z 4 KM NAM and
to a lesser extent the 17/18Z HRRRX) do suggest more intense
(suggested by progged updraft helicity), surface-based convection
could develop near the Red River tomorrow afternoon. This trend
will have to be monitored.

A second round of thunderstorms is expected tomorrow evening into
the overnight hours (~8 PM to 3 AM) as another shortwave trough
approaches behind this wave. The primary threat will be large hail
with steep mid-level lapse rates; however, strong ascent may allow
for line segments that could allow for damaging wind gusts. The
highest risk for storms with the second round will generally be
from I-40 northward.


PREV DISCUSSION... /issued 354 PM CDT Sat Mar 17 2018/

Moisture is returning already from the south, resulting in a few
showers and isolated thunderstorms in southern Oklahoma and
western north Texas. Disorganized convection is expected to
continue through Sunday afternoon, until a much more substantial
wave aloft arrives by Sunday evening. This will bring an increased
chance of stronger storms, particularly over northwest Oklahoma,
where elevated storms will be supported by strong vertical shear.
For a few hours, this area will have an increased risk of hail,
and possibly strong winds.

At the same time, much drier air will sweep east into the
southwest and west-central parts of Oklahoma, along with western
north Texas. The dry, windy conditions will result in a rapid
deterioration in fire weather conditions. A Fire Weather Watch is
included in this forecast, and it tentatively goes through the
night. There is a possibility that relative humidities will
increase enough to mitigate the risk, and winds may not be quite
strong enough to warrant the fire headlines, which is why this is
a Watch, and not a Warning.

After the storm system moves away late Sunday night/early Monday,
cooler and breezy conditions will arrive in Oklahoma and north
Texas. We will reevaluate fire weather conditions for that event
tomorrow, and it is possible that fire weather headlines will be
needed again...although the expected temperatures and relative
humdities will limit the fire weather potential quite a bit.

A quiet period will follow from Tuesday through Thursday, with
mild temperatures and little chance of precipitation.

Another strong storm system is forecast to approach from the west
on Friday, followed by cooler conditions on Saturday, and perhaps
a return of moisture/storm chances on Sunday. That far out, the
model discrepancies make a very large difference in the forecast
of actual weather conditions, meaning we could see anything from
nothing of consequence to a fairly substantial severe weather
event Friday and Sunday. It appears at this time that the most
likely outcome is a modest amount of convection, similar to what
is expected tomorrow.



Oklahoma City OK  67  45  67  48 /  10  10  40  20
Hobart OK         66  44  71  49 /  10  10  20  10
Wichita Falls TX  71  49  76  51 /  10  10  20   0
Gage OK           67  40  69  44 /   0   0  30  30
Ponca City OK     64  40  60  45 /   0   0  60  60
Durant OK         74  53  72  51 /  20  40  50  20


OK...Fire Weather Watch from Sunday afternoon through Monday morning
     for OKZ009-014-016-021-022-033>037.

TX...Fire Weather Watch from Sunday afternoon through Monday morning
     for TXZ083>089.



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