SPC MD 213


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Mesoscale Discussion 0213
NWS Storm Prediction Center Norman OK
0258 PM CDT Thu Mar 14 2019

Areas affected...Northern Alabama

Concerning...Tornado Watch 25...

Valid 141958Z - 142130Z

The severe weather threat for Tornado Watch 25 continues.

SUMMARY...Several supercells have developed within tornado watch 25.
The highest tornado threat will be over north central Alabama for
the next several hours.

DISCUSSION...A line of supercells has continued into northern
Alabama. These storms have exhibited good mid-level rotation, but
low-level rotation has been limited. The 18Z Birmingham sounding
showed a small inversion between 850mb and 700mb which has likely
limited more robust updraft development up to this point. Farther
north, the 18Z Huntsville Vortex-SE sounding showed limited
instability. Given extensive cloud cover which has now overspread
this area and northward moisture transport which is becoming
increasingly cut off with northward extent, expect the severe threat
has decreased significantly in the northern half of tornado watch
25. This is further supported by the 18Z HRRR which shows convection
intensity decreasing across far northern Alabama and central

The best region for a continued severe and tornado threat will
likely be from areas south and east of Columbus, MS to areas near
Tuscaloosa and north of Birmingham over the next 2 hours. In this
area, instability has increased with MLCAPE in excess of 1000 J/kg
and low-level shear remains moderate to strong (>250 m2/s2 0-1 SRH
according to 18Z BMX sounding and 19Z BMX VWP). In addition, the
storms in Kemper County, MS and Lamar County, AL have shown
considerable updraft strengthening in the last 30 minutes suggesting
that this region is starting to feel the effects of better buoyancy.

..Bentley.. 03/14/2019

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


LAT...LON   36498659 36668616 36198585 35018612 33878672 33138716
            32698790 32488873 32468931 32678967 33878910 35418767

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