Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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172
FXUS64 KOUN 300243
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
943 PM CDT Sat Apr 29 2017

.DISCUSSION...
Heavy rain has ended across all but the far eastern parts of our
forecast area. So...we are canceling the Flood Watch for the area
west of Holdenville to Lake Texoma. Additional rain is expected
overnight across much of our forecast area, as another arm of the
upper low passes across Oklahoma and north Texas, but flooding
with this rain area is unlikely.

Short-range model data shows a rather high degree of certainty
that some snow will occur in our far northwest (generally
northwest of the Antelope Hills to Freedom). Most likely, it will
be rain mixed with snow, but may be all snow at times. With the
warm ground, and above-freezing temperatures, we do not expect
any accumulation east of the Panhandles.

We may be able to cancel the remainder of the Flood Watch around
midnight if current trends (in eastward progress of the heavy rain
area) continue.

CmS
&&

.PREV DISCUSSION... /issued 658 PM CDT Sat Apr 29 2017/

DISCUSSION...
The 00Z aviation discussion follows....

AVIATION...
The large storm system affecting most of the central United States
will continue to advance east-northeast over the next 24 hours. A
surface low will form near the Kansas/Missouri/Oklahoma/Arkansas
border area tonight, and will move to near Kansas City by midday
on Sunday. In general, low ceilings will shift slowly to the
northeast, resulting in a very gradual improvement trend, over
the course of the next 24 hours, with VFR conditions across
southern Oklahoma/north Texas by late afternoon. Of greater
importance for many aircraft, however, will be the strong west
winds on Sunday, especially over the western 1/3 of Oklahoma and
adjacent parts of Texas. Even in central Oklahoma, most small
aircraft will be grounded by the strong crosswinds (at airports
with only a north-south runway). There may be occasional patches
of drizzle or light rain overnight/early Sunday that will cause
short periods of much lower visibilities/ceilings than what is
shown in the TAFs.

CmS

PREV DISCUSSION... /issued 256 PM CDT Sat Apr 29 2017/

DISCUSSION...
Primary forecast focus is on continued thunderstorm chances through
this afternoon and overnight, as well as additional heavy rainfall
and severe chances in south central and southeastern Oklahoma.

Currently, to put it lightly, it`s been an active day, with showers
and thunderstorms continuing this afternoon across central and
eastern Oklahoma. Currently GOES 16 low level water vapor shows some
slight increase in moisture streaming north and northeast across
western Oklahoma, with dry air still impinging into central
Oklahoma, helping with the north and northeastward push of remaining
convection.

19z Surface analysis reveals the leading edge of the warm front has
pushed as far south as Ardmore, with a broad shield of strato-cu
spread across the remainder of Oklahoma and the vast majority of the
plains, for good measure. Partly cloudy conditions, with flattened
Cumulus across far south central/southeastern has allowed for
sunshine and steamy conditions, Durant is 84/70 at the moment,
soupy. Watching this area closely, especially with the front pushing
in, but 18z sounding from FWD reveals a minor capping inversion in
place. However, radar and GOES 16 Channel 2 loops reveal some
attempts at convective initiation, with orphan anvils showing up
from isolated stronger updrafts on satellite.

Expect the cap to diminish over the next few hours, and aided by
forcing for ascent provided by the front, to begin seeing more
sustained updraft development across south central/southeastern
Oklahoma. No shortage of instability and shear, any strong updrafts
should be capable of large hail, up to golf balls and damaging wind
gusts.

Elsewhere, to the west and and north, rainfall chances will
continue, increasing across western and northwestern Oklahoma this
evening and overnight as the 500mb low lifts northeast across the
Panhandles. Kept out any mention of snow for the far northwest
overnight, as the consensus from bufr profiles would suggest rain is
the primary precipitation type and surface temperatures are not
expected to dip any lower than the mid 30s. So, even if a few flakes
develop, the impacts would be minor and likely to visibilities for a
short while.

Rainfall chances will persist through Sunday morning, primarily
across northern Oklahoma, with the best chance for rain along the
Oklahoma/Kansas border region.

Additional rainfall from this afternoon through tomorrow morning will
be greatest across southeastern Oklahoma, between 1 to 2 inches
possible, primarily from thunderstorms this afternoon and evening.
The heaviest area of rainfall from last night/early this morning
fell along a sizable swath beginning near Clinton, continuing to
Kingfisher up to Stillwater, with amounts varying between 2 to 5
inches on average. Flooding of roads and urban areas, creeks and
streams, will persist from this rainfall through the evening and
overnight. Luckily, any additional heavy rainfall over this region
will be isolated, and should be brief. Talked about dropping
counties from the Flood Watch, especially those on the south and
southeast tier of the watch area. However, given the messaging and
impacts to current areas of the watch, decided to hold off on any
changes to keep consistency and avoid confusion given continued
flooding and the additional minor rainfall this afternoon and
evening across portions of the watch area. With that said, flooding
could still become an issue with additional rainfall from
thunderstorms this evening and afternoon across southeastern/south
central Oklahoma.

Kurtz

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  43  54  41  72 /  40  20   0   0
Hobart OK         39  54  39  73 /  30  20   0   0
Wichita Falls TX  43  61  41  77 /  30  10   0   0
Gage OK           35  47  36  70 /  80  50   0   0
Ponca City OK     42  50  40  69 /  60  50  10   0
Durant OK         49  62  44  75 /  60  10   0   0

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Flood Watch until 7 AM CDT Sunday for OKZ032-043-048-052.

TX...None.
&&

$$

23/09



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