Mesoscale Discussion 855

Issued

Jun 24, 2018, 7:17 AM CDT (12:17 UTC)

Expired

Jun 24, 2018, 9:15 AM CDT

In force

118 min

Issued by

the Storm Prediction Center

Chance of a watch

40%

The Dodge City radar (KDDC), 163 km from the middle of the area, began a volume at 12:16 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

592 
ACUS11 KWNS 241217
SWOMCD
SPC MCD 241217 
OKZ000-KSZ000-TXZ000-241415-

Mesoscale Discussion 0855
NWS Storm Prediction Center Norman OK
0717 AM CDT Sun Jun 24 2018

Areas affected...southwest Kansas...Texas and Oklahoma
Panhandles...and western Oklahoma

Concerning...Severe potential...Watch possible 

Valid 241217Z - 241415Z

Probability of Watch Issuance...40 percent

SUMMARY...Thunderstorms developing across southwest Kansas southeast
into central Oklahoma will continue to pose an isolated risk for
large hail. Additionally, a strong wind threat may develop from
southwest Kansas into the Texas and Oklahoma Panhandles. The area
will be monitored for possible watch issuance.

DISCUSSION...Persistent warm-air advection atop congealing outflow
boundaries in the wake of early morning MCS (now over eastern
Oklahoma and western Arkansas) has promoted the development of a
line of thunderstorms stretching from central Oklahoma northwest
into southwest Kansas. Additionally, early morning thunderstorms
from northeast Colorado moved into western Kansas and then turned
southward along the western periphery of the warm-air advection
storms -- directly into the instability axis. 

Latest IR imagery indicates cooling cloud tops across southwest
Kansas, and the radar presentation suggests this cluster of
thunderstorms has developed a cold pool. This would suggest storms
should maintain intensity or intensify further, and continue their
southward movement into the Oklahoma and Texas Panhandles -- and
potentially as far east as the ongoing line of thunderstorms across
western Oklahoma -- through the morning. Northerly deep-layer shear
vectors on the order of 50 knots and most-unstable CAPE values
ranging from 3000 J/kg immediately ahead of the ongoing
thunderstorms to upward of 4000 J/kg across the Texas Panhandle,
suggest environmental conditions are favorable for maintaining this
mesoscale convective system. Additionally, latest mesoanalysis
indicates maximum 2-6 kilometer lapse rates on the order of 9 C/km
exists within the region ahead of the southward moving MCS.

The eastern extent of the severe threat will be demarcated by the
thin, but occasionally severe, line of thunderstorms stretching from
central Oklahoma northwestward into southwest Kansas. Westerly lower
tropospheric flow will continue to advect the unstable airmass
across the Texas Panhandles atop the cooler boundary layer left over
in the wake of the earlier morning MCS. 

Given the degree of instability, deep-layer shear, and steep lapse
rates, hail will be possible with any vigorous, sustained updraft.
Additionally, as the developing cold pool across southwest Kansas
continues to organize, a strong wind threat may also materialize.
One potential negative to a longer-lived severe threat will be the
tendency for the warm-air advection to weaken through the morning.
Trends will continue to be monitored for a potential watch.

..Marsh/Guyer.. 06/24/2018

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

ATTN...WFO...OUN...DDC...AMA...

LAT...LON   37750155 37659948 36289746 35579702 35089746 35019955
            35180149 35830190 36880197 37750155

Mesoscale Discussions in Oklahoma, 2018Mesoscale Discussions in Texas, 2018Mesoscale Discussions in Kansas, 2018Every mesoscale discussion in 2018

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.