Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 271757 AAA
AFDOUN

Area Forecast Discussion...UPDATED
National Weather Service Norman OK
1257 PM CDT Tue Jun 27 2017

.UPDATE...
Added 10% isolated thunderstorm wording now through 7 pm across
parts of southern Oklahoma (south of a Waurika to Pauls Valley to
Atoka line) and north central Oklahoma (near Enid, Medford, Ponca
City, and Perry).

&&

.DISCUSSION...
Made the changes mentioned above based on latest radar imagery as
well as latest HRRR guidance. A few showers have formed near Madill
and Petersburg Oklahoma (near the Red River) in the past hour.
Apparently the cap is just weak enough to allow for a few showers
and thunderstorms to form near a precipitable water maxima
1.5-1.6" that stretched across the central third of Oklahoma. For
now, did not include central Oklahoma in the 10% isolated area due
to lower confidence of storm occurrence in this location. Severe
potential remains very low due to weak shear and weak mid level
lapse rates. Any shower or storm will move slowly and may produce
heavy rain in a short period of time.

MBS

&&

.PREV DISCUSSION... /issued 1221 PM CDT Tue Jun 27 2017/

DISCUSSION...
The 18Z aviation discussion follows....

AVIATION...
A tightening surface pressure gradient will cause wind speeds to
increase over the next 24 hours, albeit with the usual diurnal
weakening overnight. We can`t completely rule out a few SHRA or
TSRA, especially over northern Oklahoma this afternoon, but
chances are far too low to mention in the forecasts.

CmS

PREV DISCUSSION... /issued 1034 AM CDT Tue Jun 27 2017/

UPDATE...
Reduced/removed rain chances in central and northern Oklahoma
today. Made minor adjustments to temperatures, dewpoints, sky
cover, and surface winds today.

DISCUSSION...
Seasonably hot and increasingly humid conditions with stronger
surface winds can be expected for the rest of today.

A few thunderstorms have dissipated northeast of Ponca City in
the past hour due to increased capping/mid level temperatures. As
a result, it is unlikely that additional storms will form today
anywhere in the NWS Norman forecast area, including northwest and
north central Oklahoma.

Surface dewpoints have increased into the upper 60s and lower 70s
across much of the area and made this adjustment in the forecast.

Hotter temperatures will occur today which should be close to
average for this time of year, mainly in the upper 80s and
lower 90s.

Products have been updated.

MBS

PREV DISCUSSION... /issued 542 AM CDT Tue Jun 27 2017/

AVIATION...
Isolated thunderstorms across northern Oklahoma should
gradually decrease through 14-15Z. Some light fog may
reduce visibility around HBR/LAW early this morning, otherwise
VFR conditions are expected with a breezy south wind.

PREV DISCUSSION... /issued 355 AM CDT Tue Jun 27 2017/

DISCUSSION...
A few strong to occasionally severe storms are moving southward
across southern Kansas and northern Oklahoma early this morning.
Storms appear to be developing along a nose of slightly stronger
85h winds/warm air advection. Although storm motion is enhancing
inflow, storms are dissipating as they move southward into central
Oklahoma. At this time will keep low chances for storms across
northern Oklahoma early this morning.

A shortwave trough will move across the northern and central
Rockies today which will help flatten the upper ridge over
the western states.  This will also bring much warmer 7h temperatures
eastern into the southern Plains. Therefore, warmer temperatures
and rather low rain chances can be expected for much of today
through the first half of Thursday.

Late Thursday into early Friday, a cold front is expected to approach
northern Oklahoma, as another trough moves across the Rockies and
northern Plains. Better rain chances Thursday night will be north
and east of the area, but some storms may develop or move into
northern Oklahoma mainly during the overnight period. The front
may push far enough south to reach southern Oklahoma and north
Texas by late Friday afternoon. This frontal timing may favor
higher rain chances for southern Oklahoma Friday night into
Saturday. Will continue higher POPs farther north at this time as
the EC model develops storms in central Oklahoma near an elevated
frontal boundary. Regardless, it does appear the front will bring
much needed rain to at least parts of Oklahoma. Some of the rain
will likely be heavy which may cause some flooding concerns.

The trend going into next week is for more hot and dry weather.

Fire Weather...
A gusty southerly wind is expected Wednesday and Thursday
afternoon. The wind will combine with rather low humidity in
western Oklahoma and north Texas to elevate fire weather
conditions during the afternoon/early evening.

&&

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

$$

17/23



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