Alert archive / Texas / Mesoscale Discussions in 2013

Mesoscale Discussion 621

May 10, 201312 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 10, 2013, 8:43 AM CDT for 12 counties in Texas. It was in force for 32 min.

The area

The outline as issued.

The facts

Issued: May 10, 2013, 8:43 AM CDT (13:43 UTC)
Expired: May 10, 2013, 9:15 AM CDT
In force: 32 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

Counties Brazoria County, TX, Colorado County, TX, DeWitt County, TX, Fort Bend County, TX, Gonzales County, TX, Jackson County, TX, Karnes County, TX, Lavaca County, TX, Matagorda County, TX, Victoria County, TX, Wharton County, TX, Wilson County, TX

The radar

The Austin/San Antonio radar (KEWX), 135 km from the middle of the area, began a volume at 13:44 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 155May 10, 9:05 AM CDT

The nearest sounding before it

Corpus Christi, TX (KCRP), launched 12:00Z, 1.7 hours before the alert went out and 169 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: 2458 J/kg
Mixed-layer CIN: -177 J/kg
Mixed-layer LCL: 484 m above ground
0-6 km bulk shear: 54 kt
0-1 km storm-relative helicity: 115 m²/s²
0-3 km storm-relative helicity: 34 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 5.9

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

032 
ACUS11 KWNS 101343
SWOMCD
SPC MCD 101343 
TXZ000-101415-

MESOSCALE DISCUSSION 0621
NWS STORM PREDICTION CENTER NORMAN OK
0843 AM CDT FRI MAY 10 2013

AREAS AFFECTED...MIDDLE AND UPPER TX COASTAL PLAIN

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 101343Z - 101415Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...ISOLD LARGE HAIL POTENTIAL MAY AFFECT THE MIDDLE AND UPPER
TX COASTAL PLAIN.  A SEVERE WATCH DECISION WILL LIKELY NEED TO BE
MADE BY 14Z OR SO.

DISCUSSION...RADAR MOSAIC SHOWS A DIFFUSE CLUSTER OF EWD MOVING
STORMS FROM 20 MI E SAT TO 20 MI WSW UTS.  AN OUTFLOW BOUNDARY
EXTENDS FROM THE TRAILING EDGE OF THE LA MCS WWD TOWARDS THE STORM
OVER WILSON COUNTY.  THE STORMS ALONG AND N OF THE BOUNDARY ARE
LIKELY ROOTED AT THE TOP OF THE BOUNDARY-LAYER ON THE NERN PERIPHERY
OF AN UNCONVECTIVELY-MODIFIED EML PLUME OF VERY STEEP LAPSE RATES
SAMPLED BY THE 12Z CRP RAOB.  ADEQUATE MID LEVEL FLOW /40 KT AT KEWX
AND KHGX AT 6 KM AGL/ WILL ACT TO SUPPORT UPDRAFT ORGANIZATION.  AS
SUCH...A LARGE HAIL THREAT MAY DEVELOP/INCREASE AS THE STORMS MOVE
EWD AND IMPACT THE MIDDLE TO UPPER TX COASTAL PLAIN THROUGH THE
MORNING HOURS.

..SMITH/CARBIN.. 05/10/2013

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...HGX...CRP...EWX...

LAT...LON   29229820 29739733 29779633 29319484 28869541 28529622
            28709771 29229820

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 9, 7:48 PM CDT	Severe Thunderstorm Watch	SPC	Atascosa, Bandera, Bastrop, Bexar, Blanco, Caldwell and 22 more	6 hr
May 9, 9:41 PM CDT	Severe Thunderstorm Watch	SPC	Jasper, Newton, Sabine	8 hr
May 9, 10:29 PM CDT	Mesoscale Discussion	SPC	Atascosa, Bandera, Bexar, Comal, Dimmit, Frio and 8 more	2 hr
May 10, 1:29 AM CDT	Mesoscale Discussion	SPC	Atascosa, Bandera, Bexar, Dimmit, Edwards, Frio and 10 more	31 min
May 10, 9:02 AM CDT	Severe Thunderstorm Watch	SPC	Austin, Brazoria, Chambers, Colorado, Fort Bend, Galveston and 12 more	5 hr
May 10, 1:33 PM CDT	Mesoscale Discussion	SPC	Brewster, Edwards, Kinney, Maverick, Real, Terrell and 3 more	57 min
May 10, 2:37 PM CDT	Severe Thunderstorm Watch	SPC	Atascosa, Bandera, Bastrop, Bexar, Blanco, Brown and 41 more	7 hr
May 10, 5:04 PM CDT	Mesoscale Discussion	SPC	Bandera, Bastrop, Bell, Bexar, Blanco, Brazos and 43 more	116 min
May 10, 6:53 PM CDT	Mesoscale Discussion	SPC	Atascosa, Bandera, Bastrop, Bee, Bexar, Blanco and 31 more	2 hr

Nearby

Mesoscale Discussions in Texas, 2013 Every mesoscale discussion in 2013

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.