|Mesoscale Discussion 846|
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Mesoscale Discussion 0846
NWS Storm Prediction Center Norman OK
0750 PM CDT Sat Jun 23 2018
Areas affected...Parts of western and central OK and extreme
Concerning...Severe Thunderstorm Watch 207...
Valid 240050Z - 240145Z
The severe weather threat for Severe Thunderstorm Watch 207
SUMMARY...Storm development remains possible yet this evening across
western and central Oklahoma and adjacent extreme northwest Texas,
though current thinking suggests severe potential may be isolated.
An additional severe-weather threat is being monitored for later
tonight (after 2 AM CDT) for much of western, northern, and central
Oklahoma, as the potential exists for a fast-moving line of storms
(producing damaging winds) to track southeast from western Kansas.
DISCUSSION...Trends in early evening local radar imagery and
lightning data indicated a couple of storms forming across southwest
OK (Greer and Jackson Counties) where the environment remained very
unstable (MLCAPE exceeding 3000 J/kg) and effective bulk shear was
increasing with time to at least 40 kt. This CAPE/shear parameter
space in addition to steep lapse rates and vertically veering winds
per 00Z OUN sounding and an expected increase in southerly low-level
winds across western OK suggest all severe hazards will be possible
during the early evening. A lack of discernible low-level
convergence in the eastern part of WW 207 to focus storm development
suggests this part of the watch could be canceled early.
The latest runs of the operational HRRR indicated a
forward-propagating MCS advancing to the southeast from eastern
CO/western KS and reaching northwestern OK around 07Z (2 AM CDT),
and into central OK by 10-11Z (5-6 AM CDT). Given the reservoir of
instability across the southern Plains and expected strengthening
southerly low-level jet tonight, the short-term forecast confidence
continues to increase with this scenario.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 33829894 33889946 34249999 35969995 35839873 36129849
36089742 35859662 35119647 34619642 34189643 34019762
33919796 34079834 34189899 33829894
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