Mesoscale Discussion 0383
NWS Storm Prediction Center Norman OK
1026 AM CDT Mon Apr 08 2024
Areas affected...parts of the mid/upper Texas coastal plain and
adjacent western Louisiana
Concerning...Severe potential...Watch possible
Valid 081526Z - 081800Z
Probability of Watch Issuance...40 percent
SUMMARY...Widely scattered strong thunderstorms may begin to form
across and inland of mid/upper Texas and southwest Louisiana coastal
areas by early afternoon. This may be accompanied by at least some
risk for severe hail, and perhaps a tornado, before storms increase
and intensify with a more notable increase in severe weather
potential later this afternoon, as activity spreads toward
central/northern Texas.
DISCUSSION...An initial influx of low-level moisture, which
accompanied a significant cyclone now weakening over the Upper
Midwest vicinity, lingers along and south of a stalling/weakening
boundary now extending across the lower Mississippi Valley into
southeastern Texas. This includes surface dew points ranging from
the lower 70s across the northwestern Gulf into immediate Texas Gulf
coastal areas, and upper 60s F further inland across the coastal
plain, which will begin to advect northwestward and northward
through the day, downstream of a significant short wave trough
turning eastward across the Southwest.
Beneath the northeastern periphery of a plume of elevated
mixed-layer air advecting across the lower Rio Grande Valley, this
moisture already appears to be contributing to sizable CAPE on the
order of 2000 J/kg. This probably will increase at least a bit
further through the day, as thin spots and breaks in the overcast
allow for some insolation.
At the same time, models indicate strengthening of southwesterly
flow into mid-levels (30-50+ kts in the 700-500 mb layer), beneath a
strong upper jet emanating from the subtropical eastern Pacific, and
by early afternoon the environment will become increasingly
conducive to potential for supercells. Various model output
suggests that at least widely scattered thunderstorms may begin to
form across and inland of coastal areas by around 17-18Z, before
gradually intensifying and increasing further within northwestward
and northward spreading large-scale ascent aided by low-level warm
advection.
While it is possible that it may take a couple of hours for a more
substantive increase in severe weather potential to develop, as
storms acquire better inflow of more unstable near-surface air,
initial storms may pose at least some risk for severe hail. The
risk for a brief tornado may also not be completely negligible,
though clockwise curved low-level hodographs will initially be weak.
..Kerr/Gleason.. 04/08/2024
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LCH...SHV...HGX...CRP...EWX...
LAT...LON 29189796 30279668 31559496 32079393 31989315 31709266
30679286 30279415 29849513 29319588 28649711 28589781
29189796