Alert archive / Louisiana / Mesoscale Discussions in 2021
Mesoscale Discussion 381
The Storm Prediction Center issued this mesoscale discussion at Apr 14, 2021, 5:17 AM CDT for 18 parishes in Louisiana; 15 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 14, 2021, 5:17 AM CDT (10:17 UTC)
- Expired
- Apr 14, 2021, 7:45 AM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 33 counties
Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, De Soto Parish, LA, Evangeline Parish, LA, Grant Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, LaSalle Parish, LA, Natchitoches Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Sabine Parish, LA, Saint Landry Parish, LA, Vernon Parish, LA, Winn Parish, LA, Angelina County, TX, Hardin County, TX, Jasper County, TX, Liberty County, TX, Montgomery County, TX, Nacogdoches County, TX, Newton County, TX, Orange County, TX, Polk County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Trinity County, TX, Tyler County, TX
The radar
The Ft Polk radar (KPOE), 77 km from the middle of the area, began a volume at 10:15 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Lake Charles Mun, LA (KLCH), launched 00:00Z, 10.3 hours before the alert went out and 101 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
- 7 J/kg
- Mixed-layer CIN
- -558 J/kg
- Mixed-layer LCL
- 548 m above ground
- 0-6 km bulk shear
- 59 kt
- 0-1 km storm-relative helicity
- 3 m²/s²
- 0-3 km storm-relative helicity
- 116 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 7.7
The text
As transmitted.
819
ACUS11 KWNS 141017
SWOMCD
SPC MCD 141017
LAZ000-MSZ000-TXZ000-141245-
Mesoscale Discussion 0381
NWS Storm Prediction Center Norman OK
0517 AM CDT Wed Apr 14 2021
Areas affected...East Texas/WEstern and Central Louisiana
Concerning...Severe potential...Watch unlikely
Valid 141017Z - 141245Z
Probability of Watch Issuance...20 percent
SUMMARY...An isolated large-hail threat will continue across parts
of east Texas and Louisiana early this morning. Weather watch
issuance will not be issued at this time but convective trends will
continue to be monitored.
DISCUSSION...The latest mosaic radar imagery shows scattered
thunderstorms ongoing from parts of southeast Texas northeastward
into western and central Louisiana. Convective coverage has recently
increased in the Sabine River Valley in a regime of warm advection.
The storms are developing along the northeastward edge of a moist
and unstable airmass. The RAP is analyzing MUCAPE in the 1000 to
2000 J/kg across southeast Texas and western Louisiana. In addition,
RAP forecast soundings in this area early this morning have
effective shear near 40 kt and 700-500 mb lapse rates near 7.0 C/km.
This should be enough for an isolated large-hail threat with
supercells that develop. The greatest potential for hail may be
across southeast Texas where mid-level lapse rates are steeper and
instability is greater than in areas further northeast.
..Broyles/Edwards.. 04/14/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...JAN...LIX...LCH...SHV...HGX...
LAT...LON 32099292 32079422 31889482 31559515 31089541 30519562
30079556 29809529 29779468 30049365 30029239 30049190
30539155 31129158 31829209 32099292SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 14, 1:40 PM CDT | Severe Thunderstorm Watch | SPC | Calcasieu, Cameron | 6 hr |
| Apr 14, 12:43 PM CDT | Mesoscale Discussion | SPC | Bee, Colorado, DeWitt, Fort Bend, Goliad, Gonzales and 8 more | 2 hr |
| Apr 14, 4:49 PM CDT | Mesoscale Discussion | SPC | Archer, Baylor, Callahan, Clay, Eastland, Jack and 8 more | 116 min |
| Apr 14, 5:27 PM CDT | Mesoscale Discussion | SPC | Aransas, Bee, Brazoria, Calhoun, Chambers, DeWitt and 12 more | 2 hr |
Nearby
Mesoscale Discussions in Louisiana, 2021Mesoscale Discussions in Texas, 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; radar from the NEXRAD Level II archive.