Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 241849
SWOMCD
SPC MCD 241848
LAZ000-TXZ000-242115-

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
early/mid evening.

..Picca/Guyer.. 03/24/2017

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

ATTN...WFO...LCH...SHV...HGX...FWD...CRP...EWX...

LAT...LON   32209366 32209366 31199379 30149438 29749524 29209620
            29059695 29239728 29739755 30619740 31149725 32089651
            32649605 32839562 32919490 32499413 32209366




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