3/4/20 1130AM UPDATE: Severe Thunderstorm Watch possibly extended into south Mississippi

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Latest Mesoscale Discussion // Courtesy: spc.noaa.gov

The Storm Prediction Center issued a Mesoscale Discussion regarding extending the current Severe Thunderstorm Watch, currently in parts of Texas and Louisiana, into Mississippi.

Here is a look at the current Radar/Satellite imagery:

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11:30am Satellite / Radar composite imagery with ProbSevere // Courtesy: CIMMS

As of now, the only ‘game in town’ is a thunderstorm riding along/near I-20 between Jackson and Meridian. But the SPC notes that there may soon be a potential increase in activity.

From the SPC:

A 500 mb cutoff low and subsequent modest upper-level support will gradually drift eastward across TX this afternoon. In response, strong 850-700 mb WAA has promoted both deep-layer ascent and elevated buoyancy (1000+ J/kg MUCAPE per 16Z Mesoanalysis) to support sustained elevated convection north of a quasi-stationary surface baroclinic zone. Over the past few hours, a few areas of organized, marginally severe hail-producing convection have been noted, including elevated bowing segments in central MS and in the Houston/Walker County TX vicinity.

These storms are rooted along the 850 mb baroclinic zone, and given the approach of the upper-low and constant feed of low-level moist/unstable air, these segments are expected to continue for the next few hours. With strong deep-layer shear also in place, these segments may also remain organized and intense enough to promote isolated damaging wind gusts as well marginally severe hail. In addition, strong low-level shear (200+ m2/s2 effective SRH) coincides with an unstable surface airmass along the surface baroclinic zone across portions of southern LA into southern MS, and any storm that root in the boundary layer and latch unto the boundary may produce a tornado.

Later into the afternoon though, the upper-low and associated associated mid-level ascent will lag the eastward movement of the WAA axis, suggesting a gradual west-to-east weakening trend in convection, as supported by 12Z HREF and the latest 12Z HRRR runs. As such, convective trends will continue to be monitored for the need of additional watch issuance later this afternoon.

The Latest run of the HRRR model, at 16z, shows a few Updraft Helicity Streaks across the region.

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16z HRRR computer weahter model showing Updraft Helicity Streaks // Courtesy: Pivotal Weather

These would – most likely – be elevated storms but, as the SPC noted in their discussion, any strongly rotating storm that can get rooted would have the potential to produce a tornado.





Author of the article:


Nick Lilja

Nick is former television meteorologist with stints in Amarillo and Hattiesburg. During his time in Hattiesburg, he was also an adjunct professor at the University of Southern Mississippi. He is a graduate of both Oregon State and Syracuse University that now calls Houston home. Now that he is retired from TV, he maintains this blog in his spare time.