Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1127 AM CDT Sun Apr 02 2017
Valid 021630Z - 031200Z
...THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
FAR EAST TEXAS AND NORTHERN LOUISIANA...
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
HIGH ACROSS PORTIONS OF EAST TEXAS...NORTHERN AND CENTRAL
LOUISIANA...CENTRAL AND SOUTHERN MISSISSIPPI...AND EXTREME SOUTHERN
ARKANSAS... ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
MODERATE FROM PORTIONS OF EAST TEXAS TO MISSISSIPPI...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
ENHANCED FROM PORTIONS OF EAST AND SOUTH TEXAS TO FAR WESTERN
ALABAMA...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLIGHT FROM EASTERN PORTIONS OF THE SOUTHERN PLAINS TO WESTERN
ALABAMA...
...SUMMARY...
Widespread severe thunderstorms capable of significant tornadoes,
severe wind, and severe hail will spread across portions of east
Texas to the lower Mississippi Valley through tonight. The greatest
risk for tornadoes will exist from portions of far east Texas
eastward across northern Louisiana this afternoon and evening.
...Portions of east Texas to the lower Mississippi Valley through
tonight...
A long-lived thunderstorm cluster that crossed central Texas through
the overnight/morning hours is losing organization as it is
advancing into east Texas. Convection continues to form ahead of the
remnant outflow boundary related to the cluster -- from parts of the
Upper TX Coast through the lower Sabine Valley region within a
warm-advection plume. This plume of warm advection is associated
with an amplifying midlevel shortwave trough, whose accompanying
midlevel speed maximum is emerging over south Texas. As the
shortwave trough continues to advance eastward, the low-level mass
response will facilitate poleward return of rich boundary-layer
moisture -- e.g., 15 g/kg mean mixing ratio per Lake Charles 12Z
observed sounding. As such, an expansive warm sector associated with
MLCAPE around 1500-3000 J/kg will become established through the
afternoon from the western/central Gulf Coast northward to a
precipitation-reinforced warm frontal zone forecast to extend from
part of east-central TX eastward across northern Louisiana.
With open-warm-sector convective development now becoming apparent
ahead of the remnants of the convective cluster, it is expected that
this activity will mature as it interacts with the
northward-advancing warm frontal zone. This is where effective SRH
around 300-400 m2/s2 amid strong deep shear and increasing buoyancy
will exist. Given increasing confidence in semi-discrete
supercells/supercell clusters interacting with this warm frontal
zone around peak heating, confidence has increased in greater
tornado potential -- including significant tornadoes -- across the
now-upgraded High Risk area. The significant-tornado potential will
spread toward the lower Mississippi Valley into the evening hours.
Into the evening and overnight hours tonight, a band of warm
advection/confluence will facilitate the development of a
pre-frontal squall line that will advance eastward across parts of
LA/MS and far southern AR. In addition to the potential for
extensive wind damage, meso-vortices and embedded supercells capable
of producing tornadoes are expected to spread eastward through the
lower Mississippi Valley into the overnight hours. Increased
confidence in this scenario warrants eastward extension of the
Moderate Risk area.
..Cohen.. 04/02/2017
prayers be with those in the path.
