Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 152024
SWOMCD
SPC MCD 152023
ARZ000-MOZ000-OKZ000-152230-

Mesoscale Discussion 1501
NWS Storm Prediction Center Norman OK
0323 PM CDT Tue Aug 15 2017

Areas affected...Central and northeast Oklahoma

Concerning...Severe potential...Watch unlikely

Valid 152023Z - 152230Z

Probability of Watch Issuance...20 percent

SUMMARY...Showers and thunderstorms are developing across the area.
Strong gusty winds and hail will be possible with the strongest
thunderstorms.

DISCUSSION...Surface dewpoint temperatures in the 70s combined with
strong diurnal heating has resulted in a very unstable airmass
across the southern Plains, with most-unstable CAPE values greater
than 4000 J/kg found across northeast Oklahoma. Ongoing elevated
convection across central Oklahoma should eventually transition to
surface-based convection by later this afternoon as remaining
surface-based convective inhibition erodes.

Although the overall deep-layer shear is modest (around 30 knots),
the 17Z Lamont, OK, sounding denotes a maximum low-to-mid-level
lapse rate of almost 8 C/km between 850-600 mb. Given precipitable
water values around 2 inches, the presence of steep low-to-mid-level
lapse rates, and large CAPE values, an isolated strong downburst and
hail may be possible with the strongest thunderstorms. This activity
is expected to move east-northeast during the late afternoon with a
primary threat gradually transitioning to gusty outflow.

..Marsh/Weiss.. 08/15/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...SGF...TSA...OUN...

LAT...LON   34969849 35819835 36589703 36899474 36349431 35819459
            35119543 34459696 34439797 34969849




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