Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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000
FXUS64 KOUN 231710
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
1210 PM CDT Sun Apr 23 2017

.AVIATION...
Light north winds will shift to the southeast this afternoon and
then to the south overnight before increasing into Monday morning
from west to east. Gusts above 30kts likely across western TAF sites
by end of forecast. Otherwise, VFR conditions to continue.

30

&&

.PREV DISCUSSION... /ISSUED 610 AM CDT Sun Apr 23 2017/

.DISCUSSION...
Aviation discussion for the 12 UTC TAFs is below.

&&

.AVIATION...
VFR conditions are expected to continue.

Light surface winds at all sites will become southerly at all
locations by 01 UTC. These winds will then increase across
western Oklahoma after 01 UTC.

MBS

&&

.PREV DISCUSSION... /issued 354 AM CDT Sun Apr 23 2017/

DISCUSSION...
The forecast challenges revolve around severe thunderstorm
potential Tuesday night as well as severe thunderstorm and heavy
rainfall/flooding potential Thursday through next weekend.

Today, sunny and warmer weather with lighter surface winds will
occur. Any patchy frost from chilly conditions this morning will
quickly dissipate by 9 am. Model guidance highs in the upper 60s
and lower 70s appeared to be reasonable.

Tonight through Monday night, dry and mostly clear conditions
will continue. Warmer and breezy conditions will occur on Monday.

Tuesday will likely be the warmest day of the week. Went above
model guidance highs in most areas as 00 UTC MOS numbers appeared
to be too cool. Many areas in southwestern Oklahoma and western
north Texas should reach the 90s south of a weak cold front and
west of a developing dryline where fire weather concerns may be
elevated due to dry and hot conditions. Temperatures may not be
too far from record highs (91 at Oklahoma City set in 1939 and 98
at Wichita Falls set in 2012). Capping appears to be too strong
for any storm development before 7 pm.

Tuesday night, will monitor for a few severe thunderstorms mainly
along and east of a cold front and dryline, roughly near and east
of I-35 as a mid/upper disturbance moves across the Plains to
weaken a cap. Strong 0-6 km shear 40-60 kt and MUCAPE 1000-3000
J/kg would support mainly elevated supercells and multicells with
large hail as the main hazard. Locally heavy rainfall and damaging
wind gusts may be possible as well. The greater storm potential
may stay across northeastern Oklahoma. Additional weaker storms
may form near and slightly behind the surface cold front in parts
of western and northern Oklahoma. Cooler air will move behind the
cold front.

Wednesday, chances for showers and weak thunderstorms may linger
mainly during the morning hours across northern and eastern
Oklahoma. Cooler conditions are expected.

Wednesday night, removed rain chances as most models have depicted
a drier, cooler, and more stable solution during this time.

Thursday through Saturday, some uncertainty remains during this
time frame, though severe thunderstorms and heavy rain/flooding
will likely be possible sometime during this time frame across
Oklahoma and north Texas.

Most models (the 00 UTC GFS/ECMWF) have been depicting a cooler
solution Thursday and Thursday night which may lower the severe
thunderstorm potential during this time frame. Mainly elevated
thunderstorms with some hail and heavy rainfall may be possible,
particularly Thursday night into early Friday as the low level jet
increases. The 00 UTC GEM model, which appeared to be an outlier
and was not preferred, suggested a greater potential for severe
storms Thursday and Thursday night.

Friday and Saturday, severe thunderstorm and heavy rainfall
potential will likely increase on these days, though the exact
details and impacts remain uncertain. The 00 UTC GFS model run
favored Friday through early Saturday as the main time frame for
active weather while the 00 UTC ECMWF model run depicted two
rounds of severe storms Friday into Friday night and again
Saturday through early Sunday. Strong atmospheric winds and
unseasonably high potential instability/moisture with surface
dewpoints climbing well into the 60s and possibly lower 70s (near
climatological maximums for late April) support that significant
severe storms with very heavy rainfall and flooding could occur
sometime during this time frame.

MBS

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  70  45  77  58 /   0   0   0   0
Hobart OK         70  45  80  59 /   0   0   0   0
Wichita Falls TX  72  45  81  61 /   0   0   0   0
Gage OK           70  49  84  56 /   0   0   0   0
Ponca City OK     70  48  77  56 /   0   0   0   0
Durant OK         71  42  77  57 /   0   0   0   0

&&

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

$$

10/17/17



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