Alert archive / Texas / Mesoscale Discussions in 2012

Mesoscale Discussion 425

April 2, 201223 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 2, 2012, 11:45 PM CDT for 23 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Apr 2, 2012, 11:45 PM CDT (04:45 UTC)
Expired
Apr 3, 2012, 1:45 AM CDT
In force
2 hr
Issued by
the Storm Prediction Center
All 23 counties

Brown County, TX, Callahan County, TX, Coleman County, TX, Comanche County, TX, Concho County, TX, Eastland County, TX, Edwards County, TX, Gillespie County, TX, Kerr County, TX, Kimble County, TX, Kinney County, TX, Lampasas County, TX, Llano County, TX, Mason County, TX, McCulloch County, TX, Menard County, TX, Mills County, TX, Real County, TX, Runnels County, TX, San Saba County, TX, Schleicher County, TX, Sutton County, TX, Val Verde County, TX

The radar

The San Angelo radar (KSJT), 89 km from the middle of the area, began a volume at 04:47 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

Del Rio, TX (KDRT), launched 00:00Z, 4.8 hours before the alert went out and 164 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, Del Rio, TX at 00:00Z on 2012-04-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2072 joules per kilogram.LCLLFCEL10008507005003002001001 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, Del Rio, TX at 00:00Z on 2012-04-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 129 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
2072 J/kg
Mixed-layer CIN
-123 J/kg
Mixed-layer LCL
2285 m above ground
0-6 km bulk shear
54 kt
0-1 km storm-relative helicity
129 m²/s²
0-3 km storm-relative helicity
242 m²/s²
Significant tornado parameter
0.0
Supercell composite
4.5

Open this sounding in Storm Lab

The text

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

305 
ACUS11 KWNS 030446
SWOMCD
SPC MCD 030445
TXZ000-030645-

MESOSCALE DISCUSSION 0425
NWS STORM PREDICTION CENTER NORMAN OK
1145 PM CDT MON APR 02 2012

AREAS AFFECTED...EDWARDS PLATEAU...CONCHO VALLEY...BIG COUNTRY OF TX

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 030445Z - 030645Z

TSTM INITIATION SHOULD OCCUR BETWEEN 06-08Z ALONG AND JUST BEHIND A
COLD FRONT PROGRESSING ACROSS THE REGION. LARGE HAIL SHOULD BE THE
PRIMARY INITIAL THREAT WITH POTENTIAL FOR SUPERCELL STRUCTURES
EMBEDDED WITHIN A GROWING CONVECTIVE CLUSTER. THE PROBABILITY OF A
WW ISSUANCE IS 80 PERCENT.

04Z SURFACE ANALYSIS PLACED A COLD FRONT FROM NEAR KABI TO 30 SE
K6R6. THIS FRONT HAS SLOWED IN EWD PROGRESSION IN RESPONSE TO THE
NEXT LOBE OF LARGE-SCALE ASCENT EMANATING INTO WRN TX /PER WATER
VAPOR IMAGERY/. IN THE IMMEDIATE FRONTAL ZONE...SURFACE DEW POINTS
HAVE STEADILY INCREASED THROUGH THE 50S. HOWEVER...RICHER LOW-LEVEL
MOISTURE CHARACTERIZED BY 60S SURFACE DEW POINTS HAS SURGED ACROSS
THE HILL COUNTRY AND SHOULD CONTINUE TO ADVECT NWWD ON 30-40 KT
LOW-LEVEL SELYS PER THE DFX VAD WIND PROFILE. AS THIS SURGE
ENCOUNTERS THE SURFACE FRONT...TSTMS WILL LIKELY DEVELOP...HIGHLY
SUPPORTED BY OPERATIONAL AND CONVECTION-ALLOWING MODEL GUIDANCE.

VERY STEEP MID-LEVEL LAPSE RATES AND 50-60 KT EFFECTIVE SHEAR WILL
LIKELY RESULT IN SUPERCELL STRUCTURES CAPABLE OF PRODUCING VERY
LARGE HAIL INITIALLY. CONVECTION MAY EXPAND ALONG/JUST BEHIND THE
FRONT...WITH INCREASING HAIL COVERAGE/DECREASING HAIL INTENSITY.
WITH THE AMBIENT WARM SECTOR LIKELY TO REMAIN CAPPED EXCEPT WITHIN
THE IMMEDIATE FRONTAL ZONE...THE TORNADO RISK MAY REMAIN LOW. BUT IF
A SUPERCELL CAN MATURE AND REMAIN SUSTAINED WITHOUT BEING UNDERCUT
BY THE FRONT/OUTFLOWS...A TORNADO OR TWO WOULD BE POSSIBLE.

..GRAMS.. 04/03/2012

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

ATTN...WFO...FWD...EWX...SJT...

LAT...LON   29810165 30590093 31600011 32199984 32569943 32499885
            32069823 31339812 30169903 29220002 28970052 29060075
            29550127 29810165

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 2, 7:17 PM CDTMesoscale DiscussionSPCHansford, Hemphill, Hutchinson, Lipscomb, Ochiltree, Roberts58 min
Apr 2, 9:12 PM CDTMesoscale DiscussionSPCArcher, Baylor, Clay, Hardeman, Haskell, Hemphill and 12 more63 min
Apr 2, 10:51 PM CDTSevere Thunderstorm WatchSPCArcher, Baylor, Clay, Jack, Montague, Wichita and 2 more5 hr
Apr 3, 1:14 AM CDTMesoscale DiscussionSPCArcher, Baylor, Callahan, Clay, Jack, Montague and 7 more2 hr
Apr 3, 3:32 AM CDTMesoscale DiscussionSPCArcher, Baylor, Borden, Brown, Callahan, Clay and 24 more88 min
Apr 3, 8:36 AM CDTMesoscale DiscussionSPCArcher, Bell, Blanco, Bosque, Brown, Burnet and 40 more84 min
Apr 3, 9:18 AM CDTSevere Thunderstorm WatchSPCBosque, Clay, Collin, Comanche, Cooke, Coryell and 33 more8 hr
Apr 3, 11:47 AM CDTMesoscale DiscussionSPCBosque, Collin, Cooke, Coryell, Dallas, Delta and 32 more118 min
Apr 3, 12:08 PM CDTTornado WatchSPCAnderson, Bell, Bosque, Collin, Coryell, Dallas and 30 more9 hr
Apr 3, 1:12 PM CDTMesoscale DiscussionSPCBosque, Collin, Dallas, Denton, Ellis, Erath and 16 more93 min
Apr 3, 1:46 PM CDTMesoscale DiscussionSPCCamp, Cass, Cherokee, Franklin, Gregg, Harrison and 9 more89 min
Apr 3, 2:21 PM CDTMesoscale DiscussionSPCLamar, Montague84 min
Apr 3, 2:36 PM CDTTornado WatchSPCAngelina, Bowie, Brazos, Camp, Cass, Cherokee and 23 more7 hr
Apr 3, 3:05 PM CDTMesoscale DiscussionSPCGrayson, Lamar, Red River85 min
Apr 3, 4:38 PM CDTMesoscale DiscussionSPCAustin, Bastrop, Brazos, Burleson, Caldwell, Fayette and 10 more67 min
Apr 3, 5:00 PM CDTMesoscale DiscussionSPCAnderson, Bowie, Camp, Cass, Delta, Falls and 18 more60 min
Apr 3, 6:53 PM CDTMesoscale DiscussionSPCAnderson, Angelina, Bastrop, Bowie, Brazos, Burleson and 24 more67 min

Nearby

Mesoscale Discussions in Texas, 2012Every mesoscale discussion in 2012

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.