MD 0272 CONCERNING SEVERE POTENTIAL…TORNADO WATCH LIKELY FOR SOUTHERN LA
Mesoscale Discussion 0272
NWS Storm Prediction Center Norman OK
1047 PM CDT Thu Mar 17 2022
Areas affected...Southern LA
Concerning...Severe potential...Tornado Watch likely
Valid 180347Z - 180645Z
Probability of Watch Issuance...80 percent
SUMMARY...Conditions are expected to become more favorable for
supercells capable of all severe hazards, including tornadoes, over
the next few hours. A Tornado Watch will likely be needed to cover
this threat.
DISCUSSION...The air mass across southern LA continues to recover
ahead of a shortwave trough moving across the southern Plains.
Current surface observations show dewpoints ranging from the mid 60s
across southwest LA into the upper 50s across south-central LA, amid
surface temperatures in the upper 60s. As shown by the 00Z LCH
sounding, these surface conditions do not yet result in
surface-based buoyancy and all of the storms thus far appear to be
rooted between 925 and 850 mb. The more buoyant air currently
remains to the southwest of the region. However, it is expected to
advect northward/northeastward over the next few hours, bringing mid
to upper 60s dewpoints into the area. Surface-based buoyancy is
anticipated as a result of this moisture increase.
In addition to the improving thermodynamics, the kinematic
environment is already quite impressive. Recent KLCH VAD profile
sampled over 400 m2/s2 of 0-1 km storm-relative helicity. Some
convective influence may be ongoing currently due to a nearby
thunderstorm, but low-level curvature has been gradually increasing
over the last few hours.
Given these trends, the potential for supercells capable of all
severe hazards, including tornadoes, is expected to increase over
the next several hours. A Tornado Watch will likely be needed to
address this increasing threat.
..Mosier/Hart.. 03/18/2022
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...JAN...LIX...LCH...
LAT...LON 29799346 30369373 31139310 31099048 29979054 29529173
29799346
