Date: Tue, 15.05.18 18:21
DAY2SVR: Nws Storm Prediction Center Norman Ok
ACUS02 KWNS 151720
SPC AC 151720
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1220 PM CDT Tue May 15 2018
Valid 161200Z - 171200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE CENTRAL/SOUTHERN HIGH PLAINS TO THE ARKLATEX...
A few strong to severe thunderstorms, accompanied by a risk for
damaging winds and large hail, are possible from the
central/southern High Plains to the Arklatex on Wednesday.
Through Wednesday afternoon, mid-level heights will rise across
parts of the southern/central Rockies, placing much of the
southern/central Plains under approximately 25-35 kt of
northwesterly 500mb flow. Meanwhile, one or more decaying convective
complexes will potentially be propagating east/southeast across
portions of Oklahoma and far northern Texas (generally near the Red
River). The evolution of this convection will have considerable
implications with regards to the placement of outflow boundaries and
mesoscale-convective vortices (MCVs) during the morning and
afternoon hours. Regardless, diurnal heating and modification of
post-outflow air, combined with a residual elevated mixed layer,
should yield around 1500-2500 J/kg of MLCAPE across much of the
region by afternoon.
The most likely area for robust convective initiation will be across
west Texas and the Panhandle, where upslope flow and surface dew
points in the upper 50s/low 60s will encourage development during
the afternoon and evening. While not particularly strong, veering
flow with height is expected to support some updraft organization as
cells move east/southeast into higher moisture. Given sufficient
effective shear and instability, the strongest cells will be capable
of large hail, damaging winds, and perhaps a tornado. Rising heights
are forecast to limit cell coverage versus previous days; however,
confidence in higher coverage would warrant an upgrade to slight
risk in later outlooks.
Farther east across north Texas/southern Oklahoma and into Arkansas,
convective placement/evolution is more uncertain, due to the
aforementioned complexities associated with early-day storms.
Additionally, 500mb flow will decrease with eastward extent. Despite
these questions/drawbacks, steep mid-level lapse rates and diurnal
heating will offer a conditional threat for a few stronger cells,
primarily capable of damaging winds and severe hail. Some of this
threat may persist into the overnight hours, driven/focused by any
MCVs and related outflow progressing east from High Plains
...MAXIMUM RISK BY HAZARD...
Tornado: 2% - Marginal
Wind: 5% - Marginal
Hail: 5% - Marginal
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