Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 1909
The Storm Prediction Center issued this mesoscale discussion at Oct 27, 2021, 1:59 AM CDT for 14 counties in Texas. It was in force for 91 min.
The area
The outline as issued.
The facts
- Issued
- Oct 27, 2021, 1:59 AM CDT (06:59 UTC)
- Expired
- Oct 27, 2021, 3:30 AM CDT
- In force
- 91 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 537...539
Counties Collin County, TX, Cooke County, TX, Dallas County, TX, Denton County, TX, Ellis County, TX, Grayson County, TX, Hood County, TX, Hunt County, TX, Johnson County, TX, Kaufman County, TX, Rockwall County, TX, Somervell County, TX, Tarrant County, TX, Wise County, TX
The radar
The Dallas/Ft Worth radar (KFWS), 44 km from the middle of the area, began a volume at 07:03 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
Fort Worth, TX (KFWD), launched 00:00Z, 7.0 hours before the alert went out and 19 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
- 1353 J/kg
- Mixed-layer CIN
- -69 J/kg
- Mixed-layer LCL
- 1163 m above ground
- 0-6 km bulk shear
- 24 kt
- 0-1 km storm-relative helicity
- 147 m²/s²
- 0-3 km storm-relative helicity
- 323 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 4.2
The text
As transmitted.
986
ACUS11 KWNS 270700
SWOMCD
SPC MCD 270659
TXZ000-OKZ000-270830-
Mesoscale Discussion 1909
NWS Storm Prediction Center Norman OK
0159 AM CDT Wed Oct 27 2021
Areas affected...Much of north central Texas
Concerning...Severe Thunderstorm Watch 537...539...
Valid 270659Z - 270830Z
The severe weather threat for Severe Thunderstorm Watch 537, 539
continues.
SUMMARY...Increasingly widespread severe gusts appear possible
across and northeast of the Dallas-Fort Worth metroplex through 3-4
AM CDT.
DISCUSSION...To the south of a developing MCV, 50+ kt rear inflow
has developed with an increasingly organized segment of the squall
line, to the southwest of the Dallas-Fort Worth Metroplex. Surface
gusts in excess of 50 kt have already been recorded at Graham and
Abilene within the past hour or so, and the potential for
increasingly widespread severe gusts seems likely to increase as
this activity overspread the Metroplex through 07-09Z. The boundary
layer across much of north central Texas is seasonably moist and
characterized by moderately large CAPE in excess of 1000 J/kg, in
the presence of strengthening deep-layer shear and mid/upper forcing
for ascent ahead of the approaching negatively-tilted trough, which
should aid removal of remaining mid-level inhibition.
..Kerr.. 10/27/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FWD...OUN...
LAT...LON 31839753 32309798 32909775 33339779 33569768 33769695
33729627 33469596 32709589 31839753SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 26, 7:23 PM CDT | Severe Thunderstorm Watch | SPC | Archer, Baylor, Brown, Callahan, Clay, Coke and 45 more | 8 hr |
| Oct 26, 9:37 PM CDT | Mesoscale Discussion | SPC | Archer, Baylor, Callahan, Clay, Coke, Coleman and 26 more | 83 min |
| Oct 27, 1:32 AM CDT | Severe Thunderstorm Watch | SPC | Anderson, Bastrop, Bell, Bexar, Blanco, Bosque and 48 more | 6 hr |
| Oct 27, 5:13 AM CDT | Mesoscale Discussion | SPC | Atascosa, Austin, Bastrop, Bexar, Brazos, Burleson and 22 more | 2 hr |
| Oct 27, 7:36 AM CDT | Mesoscale Discussion | SPC | Chambers, Hardin, Jasper, Jefferson, Newton, Orange and 1 more | 84 min |
| Oct 27, 7:55 AM CDT | Tornado Watch | SPC | Angelina, Brazoria, Chambers, Fort Bend, Galveston, Hardin and 16 more | 9 hr |
| Oct 27, 9:08 AM CDT | Mesoscale Discussion | SPC | Hardin, Jasper, Jefferson, Newton, Orange, Tyler | 97 min |
| Oct 27, 9:44 AM CDT | Mesoscale Discussion | SPC | Bowie, Cass, Harrison, Marion, Panola, Shelby | 2 hr |
| Oct 27, 10:08 AM CDT | Tornado Watch | SPC | Harrison, Marion, Panola, Shelby | 5 hr |
| Oct 27, 10:59 AM CDT | Mesoscale Discussion | SPC | Newton | 91 min |
| Oct 27, 12:52 PM CDT | Mesoscale Discussion | SPC | Bowie, Cass, Harrison, Marion, Panola, Shelby | 83 min |
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.