Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS11 KWNS 241849
SPC MCD 241848
Mesoscale Discussion 0317
NWS Storm Prediction Center Norman OK
0148 PM CDT Fri Mar 24 2017
Areas affected...Portions of central and eastern Texas
Concerning...Severe potential...Watch possible
Valid 241848Z - 242115Z
Probability of Watch Issuance...60 percent
SUMMARY...Thunderstorms will gradually strengthen this afternoon
across central/eastern Texas, with an attendant threat for strong
wind gusts and a few instances of severe hail. Towards mid/late
evening, the tornado threat will likely increase as storms approach
the Sabine Valley. As such, a watch could be needed in the next 1-2
hours, with a tornado watch more likely this evening.
DISCUSSION...Recent radar mosaic data depict slowly organizing bands
of convection near/east of the I-35 corridor early this afternoon.
Convective intensity at present is quite marginal, as considerable
cloud cover has limited surface heating/destabilization. However,
stronger forcing for ascent will overspread richer moisture farther
east (evident in low-level cloud streets in visible imagery) over
the next several hours. As mid-level lapse rates steepen, this
thermodynamic profile should support around 1000-1500 J/kg of MLCAPE
across parts of the discussion area. In turn, convection is forecast
to intensify through the afternoon and into the evening hours.
Considerable large-scale ascent and more meridional flow aloft with
northward extent may maintain more of a linear structure, favoring
primarily damaging winds initially. In turn, convective trends are
being monitored for a possible watch this afternoon, with the
probability of issuance around 60%. By mid evening, low-level
storm-relative helicity should increase substantially, in response
to a strengthening low-level jet across east Texas. Moreover, richer
low-level moisture will continue to stream north, with surface dew
points reaching the mid/upper 60s. This low-level
thermodynamic/kinematic environment will favor an increasing tornado
threat with any line-embedded and/or semi-discrete cells.
Additionally, more discrete convection will be capable of severe
hail, considering favorable mid-level shear and sufficient buoyancy.
A Tornado Watch will likely be needed across this region by
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 32209366 32209366 31199379 30149438 29749524 29209620
29059695 29239728 29739755 30619740 31149725 32089651
32649605 32839562 32919490 32499413 32209366