Alert archive / Texas / Mesoscale Discussions in 2021

Mesoscale Discussion 686

May 19, 20215 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 19, 2021, 8:46 AM CDT for 5 counties in Texas. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued
May 19, 2021, 8:46 AM CDT (13:46 UTC)
Expired
May 19, 2021, 10:15 AM CDT
In force
89 min
Issued by
the Storm Prediction Center
Concerning
Severe thunderstorm watch 191

Counties Brooks County, TX, Cameron County, TX, Hidalgo County, TX, Kenedy County, TX, Willacy County, TX

The radar

The Brownsville radar (KBRO), 79 km from the middle of the area, began a volume at 13:48 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

Brownsville Intl, TX (KBRO), launched 12:00Z, 1.8 hours before the alert went out and 81 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-pSkew-T log-p diagram, Brownsville Intl, TX at 12:00Z on 2021-05-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3667 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Brownsville Intl, TX at 12:00Z on 2021-05-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 57 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
3667 J/kg
Mixed-layer CIN
0 J/kg
Mixed-layer LCL
504 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
57 m²/s²
0-3 km storm-relative helicity
122 m²/s²
Significant tornado parameter
0.0
Supercell composite
6.3

Open this sounding in Storm Lab

The text

As transmitted.

728 
ACUS11 KWNS 191347
SWOMCD
SPC MCD 191346 
TXZ000-191515-

Mesoscale Discussion 0686
NWS Storm Prediction Center Norman OK
0846 AM CDT Wed May 19 2021

Areas affected...Portions of deep south TX

Concerning...Severe Thunderstorm Watch 191...

Valid 191346Z - 191515Z

The severe weather threat for Severe Thunderstorm Watch 191
continues.

SUMMARY...Damaging winds should remain the primary threat with a
line of storms moving eastward this morning.

DISCUSSION...A small, organized bow is present across parts of deep
south TX this morning, moving eastward around 35-40 kt. Based on its
current speed, this line of storms should approach the coast within
the next 1 to 1.5 hours (by 15Z/10 AM CDT). A very deep, moist
low-level airmass was observed on the 12Z BRO sounding, with a mean
mixing ratio of 19.1 g/kg. The presence of modestly steepened
mid-level lapse rates across this region is also contributing to
MLCAPE of 2500-3000 J/kg downstream of the ongoing convection. The
mid-level flow downstream from an upper low centered over the
southern/central High Plains is not overly strong this morning, but
around 30-35 kt of effective bulk shear should be enough to support
continued storm organization. Given the linear nature of the ongoing
convection and rather favorable thermodynamic environment, damaging
wind gusts will likely be the primary severe threat. Around 100
m2/s2 of 0-1 km SRH also suggests that a brief QLCS tornado embedded
within the line remains a possibility.

..Gleason.. 05/19/2021

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

ATTN...WFO...CRP...BRO...

LAT...LON   26219855 26799825 27369855 27399773 27239728 26879730
            26469717 25999710 25889753 26029782 25999803 26089840
            26219855

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 18, 7:34 PM CDTTornado WatchSPCAustin, Bee, Brazoria, Chambers, Colorado, Fort Bend and 17 more6 hr
May 18, 8:00 PM CDTMesoscale DiscussionSPCCherokee, Gregg, Harrison, Marion, Nacogdoches, Panola and 4 more60 min
May 18, 8:54 PM CDTMesoscale DiscussionSPCAustin, Fort Bend, Harris, Jackson, Montgomery, Waller and 1 more96 min
May 18, 10:39 PM CDTMesoscale DiscussionSPCHardin, Jasper, Jefferson, Newton, Orange, Tyler96 min
May 18, 11:00 PM CDTMesoscale DiscussionSPCDimmit, Duval, Jim Hogg, La Salle, Webb, Zapata90 min
May 19, 3:32 AM CDTMesoscale DiscussionSPCBrooks, Dimmit, Duval, Hidalgo, Jim Hogg, Jim Wells and 5 more118 min
May 19, 5:24 AM CDTSevere Thunderstorm WatchSPCBrooks, Cameron, Duval, Hidalgo, Jim Hogg, Jim Wells and 8 more8 hr
May 19, 7:09 AM CDTMesoscale DiscussionSPCHidalgo, Jim Hogg, Starr96 min
May 19, 2:10 PM CDTMesoscale DiscussionSPCCallahan, Coke, Coleman, Concho, Crane, Crockett and 24 more3 hr
May 19, 6:06 PM CDTMesoscale DiscussionSPCCrane, Crockett, Ector, Glasscock, Irion, Midland and 6 more84 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.