Alert archive / Louisiana / Mesoscale Discussions in 2021
Mesoscale Discussion 14
The Storm Prediction Center issued this mesoscale discussion at Jan 6, 2021, 9:38 PM CST for 21 parishes in Louisiana; Amite County, Pike County, Wilkinson County, Mississippi. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jan 6, 2021, 9:38 PM CST (03:38 UTC)
- Expired
- Jan 6, 2021, 11:45 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
All 24 counties
Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Lafayette Parish, LA, Livingston Parish, LA, Pointe Coupee Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Vermilion Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Amite County, MS, Pike County, MS, Wilkinson County, MS
The nearest sounding before it
Lake Charles Mun, LA (KLCH), launched 00:00Z, 3.6 hours before the alert went out and 141 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
- 28 J/kg
- Mixed-layer CIN
- -22 J/kg
- Mixed-layer LCL
- 655 m above ground
- 0-6 km bulk shear
- 68 kt
- 0-1 km storm-relative helicity
- 336 m²/s²
- 0-3 km storm-relative helicity
- 366 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
759
ACUS11 KWNS 070338
SWOMCD
SPC MCD 070338
LAZ000-MSZ000-070545-
Mesoscale Discussion 0014
NWS Storm Prediction Center Norman OK
0938 PM CST Wed Jan 06 2021
Areas affected...Southern Louisiana
Concerning...Severe potential...Watch unlikely
Valid 070338Z - 070545Z
Probability of Watch Issuance...5 percent
SUMMARY...Thunderstorms overspreading the region through Midnight-1
AM are generally expected to remain sub-severe, but sporadic,
localized damaging wind gusts are possible, with an isolated tornado
not completely out of the question, particularly near coastal areas.
DISCUSSION...An organized mesoscale convective system has been
maintained beneath strongly difluent mid/upper flow, just ahead of
the vigorous short wave trough which continues to pivot toward the
Sabine River/Piney Woods vicinity. A number of lower/mid
tropospheric cyclonic circulations have developed within the line,
which has been advancing eastward around 30-35 kt, within sheared,
30-60+ kt in the 850-500 mb layer (veering from southerly to
west-southwesterly with height).
Despite the strong forcing and favorable kinematic environment,
thermodynamic profiles characterized by generally weak lapse rates
and rather modest to weak low-level moisture (even over the
northwestern Gulf of Mexico) remain limiting factors concerning
severe weather potential. Across and inland of Louisiana coastal
areas, at least a shallow near-surface stable layer lingers, with
little appreciable increase in surface dew points across southern
Louisiana as temperatures have begun to cool.
The recent gust to 37 kt at Lake Charles is probably indicative of
the general wind gust potential with the squall line as it
progresses eastward into the lower Mississippi Valley through
05-07Z. However, localized stronger, potentially damaging, wind
gusts and perhaps an isolated tornado might not be entirely out of
the question, mainly along a weak baroclinic zone near immediate
coastal areas.
..Kerr/Grams.. 01/07/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...JAN...LIX...LCH...
LAT...LON 30199219 31319199 31309023 29299044 28259229 28379309
30199219Nearby
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.