Alert archive / Texas / Mesoscale Discussions in 2011

Mesoscale Discussion 2321

November 15, 201114 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Nov 15, 2011, 12:02 AM CST for 14 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Nov 15, 2011, 12:02 AM CST (06:02 UTC)
Expired: Nov 15, 2011, 2:30 AM CST
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Bandera County, TX, Bexar County, TX, Dimmit County, TX, Edwards County, TX, Frio County, TX, Kerr County, TX, Kinney County, TX, La Salle County, TX, Maverick County, TX, Medina County, TX, Real County, TX, Uvalde County, TX, Val Verde County, TX, Zavala County, TX

The radar

The Laughlin AFB radar (KDFX), 12 km from the middle of the area, began a volume at 06:01 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 883Nov 15, 2:05 AM CST

The nearest sounding before it

Del Rio, TX (KDRT), launched 00:00Z, 6.0 hours before the alert went out and 47 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: 460 J/kg
Mixed-layer CIN: -105 J/kg
Mixed-layer LCL: 948 m above ground
0-6 km bulk shear: 58 kt
0-1 km storm-relative helicity: 99 m²/s²
0-3 km storm-relative helicity: 192 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.2

Open this sounding in Storm Lab

The text

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

060 
ACUS11 KWNS 150602
SWOMCD
SPC MCD 150602 
TXZ000-150830-

MESOSCALE DISCUSSION 2321
NWS STORM PREDICTION CENTER NORMAN OK
1202 AM CST TUE NOV 15 2011

AREAS AFFECTED...PORTIONS SW/S-CENTRAL TX.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 150602Z - 150830Z

SVR POTENTIAL MAY INCREASE ACROSS THIS AREA DURING 06Z-09Z TIME
FRAME AS TSTMS CONTINUE TO INCREASE IN COVERAGE OVER ADJOINING AREAS
OF MEX...AND MOVE NEWD TO EWD ACROSS RIO GRANDE.  OCNL STG/DAMAGING
GUSTS AND LARGE HAIL ARE POSSIBLE.

MOISTURE CHANNEL IMAGERY INDICATES PROGRESSIVE MID-UPPER TROUGH
MOVING EWD ACROSS NRN CHIHUAHUA...SW OF BIG BEND REGION.  PRECURSORY
PLUME OF ENHANCED LARGE-SCALE ASCENT IS MANIFEST ON IR IMAGERY AS
BAROCLINIC-LEAF SIGNATURE WITH COOLING CLOUD TOPS TRANSLATING EWD
ACROSS ERN CHIHUAHUA...COAHUILA AND RIO GRANDE AREA BETWEEN BIG BEND
AND DRT.  AS THIS LIFT/COOLING ALOFT AND RELATED STEEPENING OF
MIDLEVEL LAPSE RATES HAS BEGUN TO SPREAD OVER INCREASING LOW-LEVEL
MOISTURE ALONG ERN FLANKS OF SERRANIAS DEL BURRO RANGE...WIDELY
SCATTERED TO SCATTERED TSTMS HAVE DEVELOPED SW DRT.  CONVECTION
SHOULD INCREASE IN COVERAGE/INTENSITY DURING NEXT FEW
HOURS...INDIVIDUAL CELLS MOVING NEWD AS AREA OF TSTMS
TRANSLATES/DEVELOPS EWD ACROSS BORDER.  MODIFIED RAOB AND RUC
SOUNDINGS SUGGEST MLCINH WEAK OVER MEX...BUT INCREASING MARKEDLY
NEAR RIO GRANDE AND WITH EWD EXTENT INTO TX.  HOWEVER...FAVORABLE
LOW-LEVEL WAA/MOISTURE TRANSPORT AND STORM-RELATIVE INFLOW JUST
ABOVE SFC SHOULD HELP TO MAINTAIN/INCREASE CONVECTION...IN
ENVIRONMENT OF STRENGTHENING GRADIENT WINDS ALOFT AND INCREASING
DEEP-LAYER SHEAR.  50-60 KT EFFECTIVE SHEAR SHOULD SPREAD EWD FROM
MEX ACROSS AREA BETWEEN DRT-LRD-HDO IN SUPPORT OF ORGANIZED
CONVECTION.  FCST WIND PROFILES...HOWEVER...SHOW SOME BACKING WITH
HEIGHT ALOFT THAT MAY RESULT IN MESSY STORM MODES...WITH POTENTIAL
FOR EMBEDDED SUPERCELLS/BOWS.  GUST POTENTIAL WILL BE LIMITED
SOMEWHAT BY CINH...ASSOCIATED BOTH WITH WARM NOSE IN SOUNDING NEAR
800-MB LEVEL AND WITH DIABATICALLY COOLED NEAR-SFC LAYER. 
HOWEVER...SVR WIND CANNOT BE RULED OUT...ESPECIALLY IF COLLECTIVE
COLD POOL CAN ORGANIZE.  COOLING ALOFT AND FAVORABLE DEEP-LAYER
SHEAR ALSO MAY SUPPORT HAIL THREAT.

INFORMATIONAL PER COORD W/WFO EWX...REFLECTIVITIES FROM KDFX WSR-88D
-- E OF DRT -- ARE RUNNING TOO HIGH.

..EDWARDS.. 11/15/2011

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

ATTN...WFO...CRP...EWX...SJT...

LAT...LON   28070004 28260029 28900061 29040061 29120073 29210073
            29270087 29400100 29470120 29600120 29550130 29740138
            30220124 30330071 30489976 30219890 29429848 28439896
            27659970 28070004

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Nov 15, 2:14 AM CST	Severe Thunderstorm Watch	SPC	Bandera, Dimmit, Edwards, Frio, Gillespie, Kendall and 10 more	7 hr
Nov 15, 5:35 AM CST	Mesoscale Discussion	SPC	Atascosa, Bexar, Blanco, Comal, Duval, Frio and 10 more	85 min
Nov 15, 6:38 AM CST	Severe Thunderstorm Watch	SPC	Atascosa, Bastrop, Bexar, Blanco, Caldwell, Comal and 10 more	6 hr
Nov 15, 8:57 AM CST	Severe Thunderstorm Watch	SPC	Anderson, Angelina, Austin, Brazoria, Brazos, Burleson and 38 more	9 hr
Nov 15, 10:35 AM CST	Mesoscale Discussion	SPC	Atascosa, Bexar, Blanco, Comal, Duval, Frio and 10 more	115 min
Nov 15, 2:30 PM CST	Mesoscale Discussion	SPC	Angelina, Chambers, Galveston, Hardin, Houston, Jasper and 15 more	2 hr
Nov 15, 3:49 PM CST	Mesoscale Discussion	SPC	Bowie, Camp, Cass, Delta, Fannin, Franklin and 6 more	116 min
Nov 15, 5:44 PM CST	Mesoscale Discussion	SPC	Newton, Orange, Sabine	61 min
Nov 15, 5:56 PM CST	Tornado Watch	SPC	Newton, Orange, Sabine	7 hr

Nearby

Mesoscale Discussions in Texas, 2011 Every mesoscale discussion in 2011

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.