Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 261745
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
1245 PM CDT Wed Jul 26 2017

.AVIATION...
VFR conditions will prevail through at least the early evening
hours. High clouds associated with convection in Kansas should
gradually decrease/thin this afternoon. Widely scattered showers
and storms may form close to northwest Oklahoma late this
afternoon and evening as a surface front approaches. Perhaps
better chances will arrive overnight into early Thursday as
the front continues to move south and precipitation moves east
from the higher terrain.



&&

.PREV DISCUSSION... /issued 959 AM CDT Wed Jul 26 2017/

UPDATE...
Isolated showers have affected NW portions of the fa this morning.
This activity is expected to diminish/end over the next hour or
two. Additional showers/storms will be possible later this
afternoon in NW OK as a cold front gets closer to the fa. A few
isolated showers may also be possible this afternoon in southern
portions of the fa. However, chances are very low (10-15%).

Hot and humid conditions will continue today with heat index
values of 105+ possible in many locations. Did not make any
changes to the current heat advisory. Made some adjustments to
dewpoints, especially in SE portions of the fa, where slowed the
decrease in dewpoints this afternoon.

PREV DISCUSSION... /issued 431 AM CDT Wed Jul 26 2017/

AVIATION...26/12Z TAF Issuance...
A few isolated showers this morning may impact airfields across
far northwestern and northern Oklahoma, but coverage should be
limited, will leave out of the KGAG/KWWR TAFs for now. For the
rest of the period, expect VFR conditions to prevail. Winds will
remain out of the south, increasing, at most sites, through the
mid to late morning, through the afternoon. Winds will be greatest
for aerodromes across western and central Oklahoma, where gusts
just over 20kts are possible. A frontal boundary will push into
northwestern Oklahoma through the later half of the period.
Increasing mid-level clouds and a more westerly component to the
winds are possible. Low chances for showers and thunder, but
confidence in coverage and timing, so will keep out of the
northwestern TAFs for now.

Kurtz

PREV DISCUSSION... /issued 310 AM CDT Wed Jul 26 2017/

DISCUSSION...
Primary forecast focus is on hot temperatures today and Thursday,
then showers and thunderstorms to close out the week into the
weekend.

This morning, quiet, but still hot and humid. Even at 2 AM, dew
points remain in the low 70s across most of Oklahoma and north
Texas. These dew points will stick around, increasing and expanding
north and northwestward through the day as warm, moist, southerly
flow continues to advect northward ahead of the approaching surface
trough to the northwest. In response, it will continue to hot and
humid, with maximum heat index values across central and eastern
Oklahoma between 105 and approaching 110. Stay safe and stay cool
out there.

Additionally, one or two diurnally driven showers may develop across
portions of north Texas into far southern Oklahoma.

Through the evening and overnight, the chance for showers/thunder
will increase across northwestern Oklahoma as the frontal boundary
begins to push into the region. Chances will continue through
sunrise, Thursday, as the front continues to slowly move
south/southeast into Oklahoma. Given the upper level dynamics, the
parent 500mb shortwave displaced over the lower Missouri Valley by
morning, and exiting east/southeast across the Ohio Valley through
the day; agree with the slower surface boundary movement of the
latest ECMWF.

In response to this slower frontal evolution, two things will
happen. First, rain chances will linger across the central and
northern half of the state through the day. Second, and more
importantly, this will allow for greater low level moisture
advection and higher heat index values farther north, through the
afternoon. Therefore, with heat index values now forecast reaching
105 to 108 as far north as the OKC metro and Stillwater, expanded
the Heat Advisory for Thursday to encompass these areas. We`re not
out of the furnace, yet.

Expect the effective front to push to the Red River by late
Thursday/early Friday morning, with low chances for scattered
showers and thunderstorms continuing. Through Friday, low
precipitation chances will persist, focused loosely along the more
diffuse frontal boundary, which will linger across north
Texas/southern Oklahoma to the Panhandles, as the short wave
continues to push towards the Atlantic and the 500mb ridge axis
builds along the Rockies.

Precipitation chances will persist into the weekend, a rather tricky
forecast, as continued low level theta-E advection will build across
the Panhandles and western Oklahoma on the backside of an expansive
surface ridge and developing surface trough along the Front Range
southward along the Llano Estacado. This pattern will keep a rather
focused area of isentropic ascent for development over the
Panhandles and western Oklahoma into western north Texas, persisting
into early next week, as the 500mb ridge builds and stands pat over
the entire western half of the U.S.

Kurtz

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  78  98  74  92 /  10  20  40  30
Hobart OK         78  99  74  94 /  20  20  40  30
Wichita Falls TX  79 101  76  97 /   0   0  10  10
Gage OK           76  90  69  90 /  40  40  40  30
Ponca City OK     78  93  72  90 /  30  30  30  20
Durant OK         78  99  76  95 /   0   0  20  30

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Heat Advisory until 8 PM CDT Thursday for OKZ013-019-020-024>032-
     039>043-045>048-050>052.

     Heat Advisory until 8 PM CDT this evening for OKZ007-008-012-018.

TX...None.
&&

$$


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