Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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402
FXUS64 KOUN 211746
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
1246 PM CDT Thu Sep 21 2017

.AVIATION...
Continued VFR conditions will prevail across the area through the
forecast period. Only possible exceptions may occur at the western
terminals, including: KGAG, KWWR, KHBR where a low probability of
showers/thunderstorms will occur after 21/21-22z through roughly
22/00z. Otherwise, breezy south to southwesterly winds will be the
primary aviation concern.

Lindley

&&

.PREV DISCUSSION... /issued 401 AM CDT Thu Sep 21 2017/

DISCUSSION...
Once again this afternoon, isolated to scattered thunderstorms
will be possible in a weakly forced environment. Subtle height
falls (most evident on progged 500 mb analyses) are expected to
enter the Texas panhandle/western Oklahoma late this afternoon.
BUFKIT soundings indicate limited convective inhibition (<30 J/kg)
near the Oklahoma/Texas border. Due to the weak capping, the
subtle ascent should provide enough lift for at least isolated
thunderstorms this afternoon.

The 21/00Z suite of convective-allowing models vary on how
aggressive they are with convective initiation, but the majority
do indicate CI will be possible near the Oklahoma/Texas border.
The 3 KM NAM and the NCAR Ensemble are the most aggressive with
convection, with the potential for storms as far north as the
Oklahoma/Kansas border. This doesn`t seem out of the question
based on forecast soundings. Therefore, opted to place a slight
chance of showers/storms across the western 2 to 2 1/2 row of
counties in Oklahoma and adjacent parts of north Texas for late
afternoon/evening.

If thunderstorms develop, environmental conditions will be
favorable for strong to severe thunderstorms. Damaging wind gusts
will be the primary hazard with large DCAPE (>=1500
J/kg)/inverted-V soundings and steep low-level lapse rates. Hail
will be the secondary hazard with any stronger updrafts.

Fire weather will also be an issue this afternoon. Breezy
southerly winds, hot temperatures, and low relative humidity will
result in elevated fire weather conditions across northwest and
north central Oklahoma. A Fire Danger Statement was issued for
this afternoon based the elevated fire weather conditions.

For Friday and Saturday, very warm and dry conditions are
expected as we will be on the southwestern periphery of a mid-
level ridge centered across the Midwest. This should keep the
affects of a longwave trough across the western contiguous United
States to the west of our area. High temperatures will continue to
be above average in the upper 80Fs to low 90Fs. Elevated fire
weather conditions will still be possible--primarily across
northwest Oklahoma--these two days.

By late Sunday into Monday, the trough/closed-low across the west
is forecast slowly to shift eastward. As it shifts eastward, part
of the trough is forecast to eject northeastward into the
Northern Plains while a closed low remains across the southwest
U.S.

The closed-low across the southwest will provide continued
synoptic-scale ascent, which will be a favorable pattern for
widespread showers/storms through the middle of next week. Locally
heavy rainfall/flooding may become a hazard during this period.

The northern trough`s associated cold front will advect much
cooler (below average) temperatures by Tuesday. Abundant cloud
cover/precipitation will limit insolation, which will also
contribute to cooler temperatures.

The unsettled weather will likely continue through at least
Wednesday as the ECMWF,GFS, and all the GEFS members keep the
closed-low across the southwest U.S.

Mahale

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  92  72  89  69 /  10  10   0   0
Hobart OK         95  73  90  71 /  10  20   0   0
Wichita Falls TX  95  73  92  71 /  10  10   0   0
Gage OK           96  71  90  69 /  20  20   0  10
Ponca City OK     94  73  92  70 /  10  10   0   0
Durant OK         92  72  91  69 /  10  10   0   0

&&

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

$$

20/23/20



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