Severe Storm Outlook Narrative (AC)
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
000
ACUS02 KWNS 240547
SWODY2
SPC AC 240547

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1247 AM CDT Fri Mar 24 2017

Valid 251200Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE LOWER MISSISSIPPI VALLEY AND CENTRAL GULF COAST STATES...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE LOWER TO MID MISSISSIPPI VALLEY AND CENTRAL GULF COAST STATES
OUTSIDE OF THE SLIGHT RISK AREA...

...SUMMARY...
Wind damage and isolated large hail will be possible across parts of
the lower Mississippi Valley into the central Gulf Coast States on
Saturday. An isolated risk for hail and strong wind gusts will also
be possible in the mid Mississippi Valley.

...Lower Mississippi Valley/Central Gulf Coast States...
An upper-level low will move east northeastward into the mid
Mississippi Valley on Saturday as a cold front advances eastward
from the southern Plains into the lower Mississippi Valley.
Thunderstorms may be ongoing along and just ahead of the front in
eastern Arkansas and western Louisiana at the start of the period.
This convection is forecast to move eastward into a moist airmass
across much of Louisiana and Mississippi where surface dewpoints are
forecast to be in the lower to mid 60s F. Additional convection may
develop well ahead of the front as surface temperatures warm across
the moist sector during the day.

Due to the moist airmass, moderate instability is expected to
develop by midday across parts of the lower Mississippi Valley and
central Gulf Coast States. NAM and GFS forecast soundings confine
the strongest instability across southeast Louisiana and south
central Mississippi where MLCAPE is forecast to be in 1000 to 1500
J/kg range. In addition, forecast soundings in the lower Mississippi
Valley show gradually veering winds with height and some speed shear
in the mid-levels. This should result in 0-6 km shear values in the
30 to 40 kt range which would be favorable for rotating storms and
multicell line segments. Discrete cells out across the moist sector
could become supercelluar and be associated with large hail and
isolated damaging wind gusts. Thunderstorms that develop along the
front should be linear and may be accompanied by wind damage and
hail.

...Mid Mississippi Valley...
An upper-level low will move east northeastward into the mid
Mississippi Valley on Saturday as a cold front advances eastward
across the region. Thunderstorms may be ongoing along the front at
the start of the period with this convection moving eastward into
the lower Ohio and western Tennessee Valleys. The convection may
gradually intensify as surface heating takes place ahead of the
front. NAM forecast soundings along the moist corridor in western
Tennessee and western Kentucky at 21Z show weak instability with
MLCAPE values of 500 to 750 J/kg. This combined with 0-6 km shear
values of 30 to 40 kt may be enough for a marginal severe threat.
Strong wind gusts and hail could occur with the stronger storms
mainly during the mid afternoon near peak heating.

..Broyles.. 03/24/2017

$$


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.