Mesoscale Discussion 1861

Issued

Oct 14, 2021, 9:46 PM CDT (02:46 UTC)

Expired

Oct 15, 2021, 12:15 AM CDT

In force

2 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

Counties Caddo County, OK, Canadian County, OK, Cleveland County, OK, Creek County, OK, Grady County, OK, Lincoln County, OK, McClain County, OK, Okfuskee County, OK, Oklahoma County, OK, Okmulgee County, OK, Pottawatomie County, OK, Seminole County, OK

The Norman radar (KTLX), 25 km from the middle of the area, began a volume at 02:46 UTC, the scan nearest the moment this went out.

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198 
ACUS11 KWNS 150246
SWOMCD
SPC MCD 150246 
OKZ000-150515-

Mesoscale Discussion 1861
NWS Storm Prediction Center Norman OK
0946 PM CDT Thu Oct 14 2021

Areas affected...Much of central Oklahoma

Concerning...Severe potential...Watch unlikely 

Valid 150246Z - 150515Z

Probability of Watch Issuance...20 percent

SUMMARY...An area of increasing thunderstorm activity may evolve
into a small organizing cluster near the Interstate 40 and 44
corridors, across and east-northeast of the Oklahoma City
metropolitan area, through Midnight-2 AM CDT.

DISCUSSION...Ahead of a southward advancing cold front, large-scale
ascent driven by lower/mid-tropospheric warm advection appears to be
in the process of strengthening across southwestern into central
Oklahoma.  Latest model output suggests that, as this continues to
develop east-northeastward through late evening, it may become
augmented by forcing for ascent associated with a focused area of
increasingly divergent upper flow, between a pair of coupled,
cyclonic upper jets across the central and southern Great Plains.

The primary mid-level short wave impulse, and colder mid-level air,
may pass to the northwest of the region, and an initially warm,
subsident layer, based near or below 500 mb, may hinder
destabilization.  However, deepening low-level moisture return,
above a boundary-layer stabilizing with the loss of daytime heating,
is expected to become sufficient to support the initiation of an
upscale growing cluster of thunderstorms near the Oklahoma City
metropolitan area by 04-06Z.

Due to the weak mid-level lapse rates, supportive of only weak to
perhaps modest CAPE (generally on the order of 500-750 J/kg), and
stable near-surface layer, potential for severe hail and wind seems
low, but remains uncertain.  Much may depend on strengthening of
low-level flow and the extent of low-level hodograph enlargement in
the vicinity of the developing cluster.  Most model output has
suggested that this will remain relatively modest, but with perhaps
a mesoscale area of strengthening that could support substantive
updraft rotation and storm organization, particularly east-northeast
of the Oklahoma City overnight.

..Kerr/Guyer.. 10/15/2021

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

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

LAT...LON   35379873 35949733 36179631 35519561 34979712 34999859
            35379873

Mesoscale Discussions in Oklahoma, 2021Every mesoscale discussion in 2021

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.