Alert archive / Texas / Mesoscale Discussions in 2016

Mesoscale Discussion 424

April 20, 201612 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 20, 2016, 2:41 PM CDT for 12 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 20, 2016, 2:41 PM CDT (19:41 UTC)
Expired: Apr 20, 2016, 4:45 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 5%

Counties Concho County, TX, Crockett County, TX, Irion County, TX, Kimble County, TX, Mason County, TX, McCulloch County, TX, Menard County, TX, Schleicher County, TX, Sutton County, TX, Terrell County, TX, Tom Green County, TX, Val Verde County, TX

The radar

The San Angelo radar (KSJT), 90 km from the middle of the area, began a volume at 19:44 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 nearest sounding before it

Del Rio, TX (KDLF), launched 12:00Z, 7.7 hours before the alert went out and 145 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: 892 J/kg
Mixed-layer CIN: -86 J/kg
Mixed-layer LCL: 629 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 95 m²/s²
0-3 km storm-relative helicity: 108 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 0.9

Open this sounding in Storm Lab

The text

As transmitted.

126 
ACUS11 KWNS 201942
SWOMCD
SPC MCD 201941 
TXZ000-202145-

MESOSCALE DISCUSSION 0424
NWS STORM PREDICTION CENTER NORMAN OK
0241 PM CDT WED APR 20 2016

AREAS AFFECTED...PORTIONS OF SWRN/CNTRL TX

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 201941Z - 202145Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...A FEW TSTMS MAY REACH SVR LEVELS FROM PARTS OF THE
STOCKTON PLATEAU ACROSS PORTIONS OF THE EDWARDS PLATEAU THROUGH THE
AFTERNOON. HOWEVER...SVR COVERAGE IS EXPECTED TO BE TOO LIMITED FOR
WW ISSUANCE.

DISCUSSION...WEAK CONVERGENCE ALONG DIFFUSE OUTFLOW BOUNDARIES AND
DIFFERENTIAL HEATING ZONES AMIDST CONVECTIVELY RECYCLED MOISTURE AND
INSOLATION IS SUPPORTING INCIPIENT CONVECTIVE DEVELOPMENT OVER THE
CONCHO VALLEY. ADDITIONAL CUMULUS CONGESTUS OVER THE DAVIS/GLASS
MOUNTAINS HAS GIVEN WAY TO ISOLATED TSTM DEVELOPMENT. STEEPENING
LOW-LEVEL LAPSE RATES ARE CONTRIBUTING TO 1000-2000 J/KG OF MLCAPE
THAT WILL COMBINE WITH 30-40 KT OF EFFECTIVE BULK SHEAR TO SUPPORT
ISOLATED ORGANIZED CONVECTIVE STRUCTURES DEVELOPING FROM THE
AFOREMENTIONED ACTIVITY...AND SPREADING EWD/SEWD. SPORADIC SVR
WIND/HAIL MAY OCCUR...THOUGH THE DEARTH OF LARGE-SCALE ASCENT AND
PRESENCE OF ONLY WEAK SFC BOUNDARIES SUGGEST THAT ANY SVR RISK
SHOULD REMAIN VERY ISOLATED.

..COHEN/HART.. 04/20/2016

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

ATTN...WFO...EWX...SJT...MAF...

LAT...LON   30670235 31220163 31510008 31179891 30529903 29780099
            29840244 30670235

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 19, 8:45 PM CDT	Mesoscale Discussion	SPC	Archer, Baylor, Bell, Blanco, Borden, Bosque and 67 more	3 hr
Apr 19, 9:59 PM CDT	Severe Thunderstorm Watch	SPC	Brown, Callahan, Coleman, Comanche, Cooke, Eastland and 16 more	5 hr
Apr 19, 11:39 PM CDT	Mesoscale Discussion	SPC	Brown, Callahan, Coke, Coleman, Collin, Comanche and 25 more	2 hr
Apr 20, 1:37 AM CDT	Mesoscale Discussion	SPC	Brown, Callahan, Coleman, Collin, Comanche, Dallas and 14 more	53 min
Apr 20, 4:54 PM CDT	Mesoscale Discussion	SPC	Armstrong, Borden, Briscoe, Carson, Childress, Collingsworth and 27 more	2 hr

Nearby

Mesoscale Discussions in Texas, 2016 Every mesoscale discussion in 2016

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.