Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS03 KWNS 270723
SPC AC 270722
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0222 AM CDT Thu Apr 27 2017
Valid 291200Z - 301200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER CENTRAL
THROUGH NORTHEAST TEXAS INTO NORTHWEST LOUISIANA AND SOUTHWEST AR...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM A PORTION OF
THE SOUTHERN PLAINS TO THE MIDDLE MS VALLEY REGION...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM A PORTION
OF THE SOUTHERN PLAINS TO THE OHIO VALLEY...
More numerous severe storms are expected from central through east
Texas into the lower Mississippi Valley Saturday. Other strong to
severe storms might also occur over a portion of the Ohio Valley
Dominant feature of interest will be a shortwave trough that will
amplify over the southern Rockies before continuing east through the
southern Plains on Saturday. Downstream from this feature an upper
ridge will build over the eastern states. At the surface a
quasi-stationary front will extend from the Ohio Valley into OK.
However, a cold front will merge with this boundary and continue
southeast through OK and TX, reaching the lower MS Valley by the end
of the period.
...Southern Plains through the lower Mississippi Valley region...
Storms will likely be ongoing along baroclinic zone from OK into
AR/MO, and some of this activity will pose an ongoing threat for
hail and strong wind gusts. A moist and strongly unstable warm
sector will reside across central and eastern TX into the lower MS
Valley. A capping inversion associated with the EML will probably
limit thunderstorm development across most of TX until the arrival
of deeper forcing for ascent accompanying the shortwave trough and
attendant cold front later in the afternoon. Strong vertical shear
and large hodographs will exist in warm sector, but initiation
should remain confined to cold frontal zone where storms may a
tendency to be undercut as they evolve into linear modes.
Nevertheless, embedded supercell and bowing segments appear likely.
Large hail and damaging wind will be the primary threats, but a few
tornadoes will also be possible as activity develops through east TX
and the lower MS Valley during the period.
...Ohio Valley area...
Storms should be ongoing early Saturday within zone of isentropic
ascent just north of the stationary front, and this activity will
pose some ongoing risk for hail and a few strong wind gusts. The
tendency will be for the upper ridge to build along with some
weakening of the eastern extension of the low-level jet, and these
may provide limiting factors to overall severe threat. Nevertheless,
storms will be embedded within strong unidirectional wind/shear
profiles, and there will be some opportunity for activity to
intensify in frontal zone as inflow originates from an increasingly
unstable warm sector. A further eastward expansion of the slight
risk area might be warranted in later outlooks.