Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 13
The Storm Prediction Center issued this mesoscale discussion at Jan 6, 2021, 5:09 PM CST for Brazoria County, Chambers County, Galveston County, Texas. It was in force for 96 min.
The area
The outline as issued.
The facts
- Issued
- Jan 6, 2021, 5:09 PM CST (23:09 UTC)
- Expired
- Jan 6, 2021, 6:45 PM CST
- In force
- 96 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 2
Counties Brazoria County, TX, Chambers County, TX, Galveston County, TX
The radar
The Houston radar (KHGX), 22 km from the middle of the area, began a volume at 23:11 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 12:00Z, 11.2 hours before the alert went out and 188 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
- 2326 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 119 m²/s²
- 0-3 km storm-relative helicity
- 157 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
836
ACUS11 KWNS 062310
SWOMCD
SPC MCD 062309
LAZ000-TXZ000-070045-
Mesoscale Discussion 0013
NWS Storm Prediction Center Norman OK
0509 PM CST Wed Jan 06 2021
Areas affected...Parts of upper Texas and southwest Louisiana
coastal areas
Concerning...Severe Thunderstorm Watch 2...
Valid 062309Z - 070045Z
The severe weather threat for Severe Thunderstorm Watch 2 continues.
SUMMARY...A risk for damaging wind gusts and/or an isolated tornado
remain possible, mainly across far southern and southeastern
portions of the Houston area, near/northwest through north of
Galveston through 6-7 PM CST.
DISCUSSION...Ongoing squall line with embedded supercell structures
appears largely supported by mid-level forcing for ascent, ahead of
the vigorous short wave trough now pivoting east of the central
Texas Interstate 35 corridor toward the Sabine River/Piney Woods.
This is contributing to lift through warm capping layers, but, north
of middle Texas coastal areas, boundary-layer moisture return has
only been sufficient for very weak mixed-layer CAPE across and
northeast of the Greater Houston Metropolitan area.
Based on latest observational data, potential for substantive
further intensification of the evolving convective system appears
minimal as activity progresses across the coast into coastal waters
between now and 00-01Z. The primary severe weather potential
probably will remain focused with the supercell/bowing segment in
radar reflectivities now spreading south of Houston toward coastal
areas near/north of Galveston. Low-level hodographs across this
region have been moderately large and clockwise curved, and could
still contribute to a risk for locally damaging wind gusts and/or an
isolated tornado or two.
..Kerr.. 01/06/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LCH...HGX...
LAT...LON 29219550 29449516 29889464 29849421 29759369 29119452
28769517 28799591 29219550SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jan 6, 11:56 AM CST | Mesoscale Discussion | SPC | Bastrop, Brazos, Burleson, Falls, Fayette, Grimes and 8 more | 2 hr |
| Jan 6, 12:59 PM CST | Severe Thunderstorm Watch | SPC | Austin, Bastrop, Brazoria, Brazos, Burleson, Chambers and 24 more | 7 hr |
Nearby
Mesoscale 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.