Alert archive / Texas / Mesoscale Discussions in 2021

Mesoscale Discussion 582

May 10, 20218 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 10, 2021, 2:07 PM CDT for 8 counties in Texas. It was in force for 113 min.

The area

The outline as issued.

The facts

Issued: May 10, 2021, 2:07 PM CDT (19:07 UTC)
Expired: May 10, 2021, 4:00 PM CDT
In force: 113 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 20%

Counties Grimes County, TX, Houston County, TX, Madison County, TX, Polk County, TX, San Jacinto County, TX, Trinity County, TX, Tyler County, TX, Walker County, TX

The radar

The Houston radar (KHGX), 165 km from the middle of the area, began a volume at 19:07 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, 7.1 hours before the alert went out and 216 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 1821 J/kg
Mixed-layer CIN: -14 J/kg
Mixed-layer LCL: 536 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 147 m²/s²
0-3 km storm-relative helicity: 243 m²/s²
Significant tornado parameter: 2.2
Supercell composite: 11.6

Open this sounding in Storm Lab

The text

As transmitted.

130 
ACUS11 KWNS 101908
SWOMCD
SPC MCD 101907 
TXZ000-102100-

Mesoscale Discussion 0582
NWS Storm Prediction Center Norman OK
0207 PM CDT Mon May 10 2021

Areas affected...Parts of southeastern Texas...northwest through
north of the Greater Houston area

Concerning...Severe potential...Watch unlikely 

Valid 101907Z - 102100Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated intense thunderstorm development is possible by
the 4-6 PM CDT time frame, if not before.  This could include a
supercell or two, posing a risk for large, damaging hail, strong
wind gusts and perhaps some potential for a tornado.  While
probabilities for a severe weather watch still appear low due to the
somewhat uncertain and isolated nature of the threat, trends will
continue to be monitored.

DISCUSSION...Attempts at deep convective development have been
ongoing near the intersection of a remnant convectively generated or
enhanced surface boundary and a stalling surface cold front, roughly
near the Huntsville vicinity.  This is occurring in the presence of
an environment conditionally supportive of considerable severe
weather potential, characterized by seasonably high boundary-layer
moisture content, relatively steep lower/mid tropospheric lapse
rates, and large CAPE.  Deep-layer shear is also strong near/beneath
a seasonably strong subtropical jet.

Forecast soundings suggest that at least weakly capping mid-level
layers are still present across the region, and mid/upper forcing
for ascent to contribute to further erosion of this capping remains
unclear.  However, various model output, including the NAM and Rapid
Refresh/High Resolution Rapid Refresh have been suggestive that the
initiation of at least an isolated storm or two is possible during
the 4-6 PM CDT, if not before.

If inhibition weakens sufficiently to support a sustained storm,
this may include a period of rapid intensification, with the
evolution of a supercell structure or two possible.  This could pose
a risk for large, damaging hail (in excess of 2 inches in diameter),
locally strong surface gusts, and perhaps some potential for a
tornado.

..Kerr/Thompson.. 05/10/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LCH...SHV...HGX...FWD...

LAT...LON   31539538 30999437 30619420 30529489 30469616 30999630
            31539538

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 9, 8:06 PM CDT	Mesoscale Discussion	SPC	Anderson, Bell, Blanco, Bosque, Burnet, Comal and 32 more	114 min
May 10, 10:28 AM CDT	Mesoscale Discussion	SPC	Delta, Fannin, Grayson, Lamar, Red River	92 min
May 10, 1:04 PM CDT	Mesoscale Discussion	SPC	Edwards, Kinney, Real, Terrell, Val Verde	116 min
May 10, 1:48 PM CDT	Severe Thunderstorm Watch	SPC	Atascosa, Bandera, Bexar, Crockett, Dimmit, Edwards and 14 more	10 hr
May 10, 5:47 PM CDT	Mesoscale Discussion	SPC	Brazos, Grimes, Jasper, Montgomery, Polk, San Jacinto and 2 more	88 min
May 10, 6:05 PM CDT	Mesoscale Discussion	SPC	Bee, Dimmit, Duval, Jim Wells, La Salle, Live Oak and 2 more	2 hr

Nearby

Mesoscale Discussions in Texas, 2021 Every 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.