Alert archive / Louisiana / Mesoscale Discussions in 2021
Mesoscale Discussion 214
The Storm Prediction Center issued this mesoscale discussion at Mar 17, 2021, 7:26 PM CDT for 6 parishes in Louisiana; Hancock County, Mississippi. It was in force for 94 min.
The area
The outline as issued.
The facts
- Issued
- Mar 17, 2021, 7:26 PM CDT (00:26 UTC)
- Expired
- Mar 17, 2021, 9:00 PM CDT
- In force
- 94 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 35
Counties Jefferson Parish, LA, Lafourche Parish, LA, Orleans Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Terrebonne Parish, LA, Hancock County, MS
The nearest sounding before it
Slidell Radar S, LA (KSIL), launched 00:00Z, 0.4 hours before the alert went out and 60 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 1681 J/kg
- Mixed-layer CIN
- -1 J/kg
- Mixed-layer LCL
- 710 m above ground
- 0-6 km bulk shear
- 63 kt
- 0-1 km storm-relative helicity
- 171 m²/s²
- 0-3 km storm-relative helicity
- 168 m²/s²
- Significant tornado parameter
- 2.4
- Supercell composite
- 9.7
The text
As transmitted.
382
ACUS11 KWNS 180027
SWOMCD
SPC MCD 180026
MSZ000-LAZ000-180200-
Mesoscale Discussion 0214
NWS Storm Prediction Center Norman OK
0726 PM CDT Wed Mar 17 2021
Areas affected...Parts of southeastern Louisiana
Concerning...Tornado Watch 35...
Valid 180026Z - 180200Z
The severe weather threat for Tornado Watch 35 continues.
SUMMARY...Thunderstorms may organize further and pose a risk for
damaging wind gusts and perhaps a tornado or two while overspreading
the Lake Pontchartrain and Greater New Orleans Metropolitan area by
9-10 PM CDT.
DISCUSSION...Near the southern periphery of the stronger mid-level
forcing for ascent, associated with the vigorous short wave trough
turning east-northeastward toward the lower Mississippi Valley, the
southern flank of an evolving squall line has been maintaining
strength the past few hours. As evident in the 18/00Z sounding
from LIX, the inflow environment ahead of it is characterized by
moderately large mixed-layer CAPE (1500+ J/KG), in the presence of
strongly sheared, 40-50 kt southwesterly deep-layer ambient mean
flow. The low-level hodograph is somewhat modest in size, but
perhaps sufficient (given the moist boundary-layer) to still support
some risk for a tornado within the evolving squall line. Otherwise,
the primary severe hazard may be potentially damaging outflow wind
gusts as it overspreads Lake Pontchartrain and the Greater New
Orleans area by 02-03Z.
..Kerr.. 03/18/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LIX...
LAT...LON 29529102 30199013 30518938 30358891 29698906 29029109
29529102SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 17, 7:07 PM CDT | Tornado Watch | SPC | Alcorn, Benton, Calhoun, Chickasaw, Itawamba, Lafayette and 8 more | 3 hr |
Nearby
Mesoscale Discussions in Louisiana, 2021Mesoscale Discussions in Mississippi, 2021Every mesoscale discussion in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.