Scientific Forecaster Discussion
fxus64 koun 222329
Area forecast discussion
National Weather Service Norman OK
629 PM CDT Sat Jul 22 2017
isolated showers and thunderstorms with gusty winds are expected
to dissipate by 9 PM this evening with the loss of daytime
heating. Severe potential remains low due to weak shear (0-6 km
bulk shear generally below 20 kt) and due to weak mid level lapse
rates (generally around 6 c/km). Cannot completely rule out a
rogue wind gust around 60 mph due to steep low level lapse rates
(9-9.8 c/km) with ongoing activity mainly northwest of Oklahoma
City near Kingfisher up towards Seiling and Alva.
Aviation discussion for the 00 UTC tafs is below.
VFR conditions are expected to continue.
Kept vcsh mention in a few locations across central and
northwestern Oklahoma before -shra dissipates around 01 UTC.
Although isolated-scattered rain showers/thunderstorms and rain are possible after 01 UTC, did not
mention at any site due to low confidence of occurrence.
A weak front/surface outflow boundary will move south and likely
bring a surface wind shift to the north/northeast across northern
Oklahoma 03-12 UTC. Exact timing remains uncertain.
Previous discussion... /issued 259 PM CDT Sat Jul 22 2017/
isolated showers and storms will be possible across mainly western
Oklahoma and perhaps western North Texas into early evening but
threat should decrease quickly toward and after sunset. Some
activity could approach far northern Oklahoma late tonight as weak
frontal boundary slowly approaches. This front will be the focus
for scattered storms tomorrow through late Monday. High-res model
suite suggests that most of the storms tomorrow will be near and
ahead of the frontal boundary, where the moisture will be
consolidated, giving higher pops to areas near and south of I-40.
Damaging downbursts are possible with any storm that can mature
tomorrow afternoon into early evening. As frontolysis takes place
late tomorrow into Monday, best focus for convective activity will
on Monday may be outflow boundaries so relatively low pops were
spread over a larger area.
We elevated the heat advisory to an excessive heat warning for
Sunday across portions of central and southeast Oklahoma where
dewpoints are expected to pool near and ahead of the the weak
frontal boundary that will progress into Oklahoma tomorrow. Heat
indices in excess of 110 are expected east and southeast of the
okc Metro. Addition of cloud cover and storm development will
complicate the temperature forecast for tomorrow, but we allowed
for only minimal cooling behind the dying frontal boundary.
Currently expect a near or below head advisory day Monday and
Tuesday but upper ridge builds back over the region and resumes
the typical Summer heat. Another slight cool down and chance for
showers and storms possible by Friday into next weekend given
latest trends of medium range models.
Preliminary point temps/pops...
Oklahoma City OK 76 100 74 95 / 10 30 40 30
Hobart OK 76 100 74 97 / 10 30 30 20
Wichita Falls Texas 76 100 75 98 / 10 20 20 20
gage OK 72 96 70 96 / 20 30 40 20
Ponca City OK 76 97 72 95 / 20 30 40 20
Durant OK 76 97 75 94 / 0 20 30 30
OK...heat advisory until 8 PM CDT this evening for okz007-008-012-013-
Heat advisory from noon to 8 PM CDT Sunday for okz008-013-019-
Excessive heat warning from noon to 8 PM CDT Sunday for okz020-