Alert archive / Texas / Mesoscale Discussions in 2015

Mesoscale Discussion 708

May 20, 201513 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 20, 2015, 5:07 PM CDT for 13 counties in Texas. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued: May 20, 2015, 5:07 PM CDT (22:07 UTC)
Expired: May 20, 2015, 6:00 PM CDT
In force: 53 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

Counties Brewster County, TX, Crockett County, TX, Edwards County, TX, Kerr County, TX, Kimble County, TX, Kinney County, TX, Menard County, TX, Pecos County, TX, Real County, TX, Schleicher County, TX, Sutton County, TX, Terrell County, TX, Val Verde County, TX

The radar

The Laughlin AFB radar (KDFX), 155 km from the middle of the area, began a volume at 22:08 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 192May 20, 5:25 PM CDT

The nearest sounding before it

Del Rio, TX (KDLF), launched 12:00Z, 10.1 hours before the alert went out and 111 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: 1266 J/kg
Mixed-layer CIN: -44 J/kg
Mixed-layer LCL: 618 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 75 m²/s²
0-3 km storm-relative helicity: 115 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

241 
ACUS11 KWNS 202208
SWOMCD
SPC MCD 202207 
TXZ000-202300-

MESOSCALE DISCUSSION 0708
NWS STORM PREDICTION CENTER NORMAN OK
0507 PM CDT WED MAY 20 2015

AREAS AFFECTED...EDWARDS PLATEAU AND ADJACENT RIO GRANDE VALLEY AREA

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

VALID 202207Z - 202300Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...CONVECTIVE DEVELOPMENT IS IN THE PROCESS OF INCREASING AND
INTENSIFYING...AND LIKELY WILL BE ACCOMPANIED BY THE RISK FOR SEVERE
WIND GUSTS AND HAIL INTO THE EVENING HOURS.  A WW PROBABLY WILL BE
ISSUED WITHIN THE HOUR.

DISCUSSION...ISOLATED...SUSTAINED AND INTENSE CONVECTIVE DEVELOPMENT
WEST OF SAN ANGELO APPEARS TO HAVE FORMED TO THE IMMEDIATE COOL SIDE
OF THE SOUTHWARD ADVANCING SURFACE FRONT.  HOWEVER...PROPAGATION OF
THIS ACTIVITY APPEARS INCREASINGLY TO THE RIGHT OF THE LIGHT WEST
SOUTHWESTERLY DEEP LAYER MEAN FLOW...AND INCREASINGLY PARALLEL TO A
SEGMENT OF THE FRONT ALONG WHICH ENHANCED LOW-LEVEL CONVERGENCE AND
LOW-LEVEL SHEAR MAY SUPPORT FURTHER UPSCALE CONVECTIVE GROWTH INTO
THE EVENING HOURS.

OTHER DISCRETE INTENSE STORMS CONTINUE TO FORM ALONG THE
SOUTHEASTERN SLOPES OF THE DAVIS MOUNTAINS...AND THE HIGHER TERRAIN
TO THE SOUTH AND WEST OF THE RIO GRANDE RIVER.  AS A WEAK UPPER
IMPULSE CONTINUES TO APPROACH THE REGION FROM THE WEST
SOUTHWEST...FAVORABLE MID/UPPER FORCING FOR ASCENT MAY CONTRIBUTE TO
STORM MAINTENANCE.  EVENTUALLY...IN THE PRESENCE OF SUFFICIENT DEEP
LAYER SHEAR...MODESTLY STEEP MID-LEVEL LAPSE RATES...AND SIZABLE
MIXED LAYER CAPE...ACTIVITY MAY BEGIN TO CONSOLIDATE WHILE SPREADING
ACROSS THE DEL RIO AREA.

..KERR/CORFIDI.. 05/20/2015

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

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

LAT...LON   29790334 31240262 31299965 29949916 29100080 29790334

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 19, 7:15 PM CDT	Mesoscale Discussion	SPC	Archer, Baylor, Callahan, Clay, Cooke, Eastland and 11 more	90 min
May 19, 8:58 PM CDT	Tornado Watch	SPC	Archer, Baylor, Clay, Foard, Hardeman, Knox and 2 more	5 hr
May 19, 9:18 PM CDT	Mesoscale Discussion	SPC	Comanche, Cooke, Denton, Eastland, Erath, Hood and 9 more	87 min
May 19, 11:15 PM CDT	Mesoscale Discussion	SPC	Archer, Baylor, Clay, Cooke, Cottle, Fannin and 8 more	90 min
May 20, 1:10 AM CDT	Mesoscale Discussion	SPC	Archer, Baylor, Clay, Cooke, Foard, Knox and 3 more	95 min
May 20, 1:35 PM CDT	Mesoscale Discussion	SPC	Crane, Pecos, Terrell, Upton	2 hr
May 20, 5:29 PM CDT	Severe Thunderstorm Watch	SPC	Brewster, Concho, Crane, Crockett, Edwards, Irion and 13 more	6 hr

Nearby

Mesoscale Discussions in Texas, 2015 Every mesoscale discussion in 2015

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.