Mesoscale Discussion 0869
NWS Storm Prediction Center Norman OK
0308 PM CDT Mon Jun 07 2021
Areas affected...Far east Texas and northern Louisiana
Concerning...Severe Thunderstorm Watch 242...
Valid 072008Z - 072215Z
The severe weather threat for Severe Thunderstorm Watch 242
SUMMARY...Recent intensification has occurred with a line of
thunderstorms in portions of northwest/west-central Louisiana. The
downstream environment will continue to support isolated to
widely-scattered damaging wind gusts. As shear decreases to the
east, some weakening may occur later this afternoon. The need for
additional watches is uncertain. Trends will be monitored.
DISCUSSION...Recent radar trends have shown and increase in 50 dBZ
cores on 7 and 9 km MRMS CAPPI data with the convective line
entering northwestern Louisiana. This is coincident with storm
encountering an increasingly unstable airmass with temperatures in
the mid/upper 80s F and dewpoints in the mid/upper 70s F. Wind gusts
thus far have been sub-severe over the past couple of hours.
Effective shear is only 20-30 kts across the area, with the greatest
values in close proximity to the well-developed MCV in
north-central/northeast Texas. However, KSHV VAD data has recently
observed 40-50 kts of flow in the lowest 2-3 km. Given the large
buoyancy downstream, strong to severe wind gusts will remain
possible with north-south oriented portions of the line.
There is some question how intense the line will remain as it moves
towards the Mississippi River. Given decreasing shear to the east,
it seems probable some weakening will occur as it moves across
northern Louisiana/southern Arkansas. While local areal extensions
of the watch may be needed this afternoon, the need for a new
downstream watch is not clear. Trends will continue to be monitored.
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