Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS11 KWNS 250709
SPC MCD 250708
Mesoscale Discussion 0327
NWS Storm Prediction Center Norman OK
0208 AM CDT Sat Mar 25 2017
Areas affected...Parts of far southeast TX and southern/central LA
Concerning...Tornado Watch 82...83...
Valid 250708Z - 250815Z
The severe weather threat for Tornado Watch 82, 83 continues.
SUMMARY...Although an isolated strong to damaging wind and brief
tornado threat continues, overall a slowly diminishing severe threat
is expected over the next several hours across Tornado Watch 82 and
83. Downstream watch issuance into additional portions of southern
LA appears unlikely.
DISCUSSION...Radar trends over the past hour or so indicate a slow
deceleration of an ongoing line of thunderstorms across
central/southern LA into far southeast TX. A moist low-level airmass
(with mid to upper 60s surface dewpoints and resultant MLCAPE of
250-1000 J/kg) downstream should support maintenance of this line as
it moves eastward across LA, with a continued isolated strong to
damaging wind/brief tornado risk given sufficient low and mid-level
shear. However, low-level winds are expected to veer more to
southwesterly and weaken some over the next several hours across
this region as the mid/upper-level cyclone over OK/KS fills. These
slowly weakening winds will probably limit greater organization of
the line with eastward extent, and suggest that the overall severe
threat should slowly diminish through the overnight hours. Although
the possibility of downstream watch issuance will be dependent on
later radar trends, at the moment it appears unlikely.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 29819343 29679436 29699463 29909458 30159405 30549359
31059311 32019251 32029208 31149207 30459154 30139168