Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 106
The Storm Prediction Center issued this mesoscale discussion at Feb 17, 2021, 1:55 AM CST for 5 parishes in Louisiana; 37 counties in Texas. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Feb 17, 2021, 1:55 AM CST (07:55 UTC)
- Expired
- Feb 17, 2021, 8:00 AM CST
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Freezing rain
All 42 counties
Allen Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Sabine Parish, LA, Vernon Parish, LA, Angelina County, TX, Austin County, TX, Bastrop County, TX, Brazos County, TX, Burleson County, TX, Colorado County, TX, DeWitt County, TX, Fayette County, TX, Fort Bend County, TX, Gonzales County, TX, Grimes County, TX, Hardin County, TX, Harris County, TX, Houston County, TX, Jackson County, TX, Jasper County, TX, Lavaca County, TX, Lee County, TX, Leon County, TX, Liberty County, TX, Madison County, TX, Milam County, TX, Montgomery County, TX, Nacogdoches County, TX, Newton County, TX, Polk County, TX, Robertson County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Trinity County, TX, Tyler County, TX, Victoria County, TX, Walker County, TX, Waller County, TX, Washington County, TX, Wharton County, TX
The radar
The Houston radar (KHGX), 104 km from the middle of the area, began a volume at 07:58 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, 7.9 hours before the alert went out and 184 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1598 m above ground
- 0-6 km bulk shear
- 75 kt
- 0-1 km storm-relative helicity
- -34 m²/s²
- 0-3 km storm-relative helicity
- 86 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
683
ACUS11 KWNS 170755
SWOMCD
SPC MCD 170755
LAZ000-TXZ000-171400-
Mesoscale Discussion 0106
NWS Storm Prediction Center Norman OK
0155 AM CST Wed Feb 17 2021
Areas affected...middle and upper coastal plains of TX...eastern
TX...southwest and west-central LA
Concerning...Freezing rain
Valid 170755Z - 171400Z
SUMMARY...Freezing rain will be the primary precipitation type from
the coastal plain on the middle and upper TX coast into western
parts of LA. Rates will range from 0.05 to 0.15 inch per 3 hours.
DISCUSSION...Water-vapor imagery shows a series of mid-level
shortwave troughs moving through the base of a large-scale trough
centered over the southern High Plains into northern Mexico. Strong
low-level warm air advection, implied by the strongly veering and
strengthening wind profile according to KHGX 88D VAD data, is
expected to intensify further through the overnight into the early
morning across the northwest Gulf Coast. Model guidance indicates
3-hourly liquid-equivalent rates approaching 0.05 inch near
Matagorda Bay, but a swath of heavier 3-hourly rates (0.05-0.15
inch) will extend from near College Station eastward into southwest
LA. Forecast soundings show the shallow sub-freezing airmass being
maintained roughly 1 county/parish tier inland from the coast during
the period. Atop this sub-freezing layer, a warm layer around 850
mb ranges from 6 to 9 degrees C---supporting freezing rain as the
primary precipitation type.
..Smith.. 02/17/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LCH...SHV...HGX...FWD...CRP...EWX...
LAT...LON 31799470 31669339 31269291 30649274 30009300 30139389
29909490 29249607 28409707 28579738 29759760 30959703
31599591 31799470SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 17, 7:38 AM CST | Mesoscale Discussion | SPC | Allen, Avoyelles, Beauregard, Caldwell, Catahoula, Concordia and 10 more | 4 hr |
| Feb 17, 10:53 AM CST | Mesoscale Discussion | SPC | Avoyelles, Bienville, Caldwell, Catahoula, Claiborne, Concordia and 20 more | 6 hr |
| Feb 17, 5:38 PM CST | Mesoscale Discussion | SPC | Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 1 more | 3 hr |
| Feb 16, 6:59 PM CST | Mesoscale Discussion | SPC | Armstrong, Briscoe, Carson, Castro, Childress, Collingsworth and 7 more | 4 hr |
| Feb 16, 8:14 PM CST | Mesoscale Discussion | SPC | Archer, Clay, Cooke, Grayson, Jack, Montague and 2 more | 4 hr |
| Feb 16, 9:41 PM CST | Mesoscale Discussion | SPC | Bell, Brazos, Burleson, Burnet, Falls, Lampasas and 5 more | 4 hr |
| Feb 17, 9:15 AM CST | Mesoscale Discussion | SPC | Bowie, Cass | 6 hr |
Nearby
Mesoscale Discussions in Texas, 2021Mesoscale Discussions in Louisiana, 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.