Alert archive / Texas / Mesoscale Discussions in 2015

Mesoscale Discussion 366

April 18, 201554 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2015, 6:40 PM CDT for 54 counties in Texas. It was in force for 95 min.

The area

The outline as issued.

The facts

Issued
Apr 18, 2015, 6:40 PM CDT (23:40 UTC)
Expired
Apr 18, 2015, 8:15 PM CDT
In force
95 min
Issued by
the Storm Prediction Center
All 54 counties

Bandera County, TX, Bell County, TX, Blanco County, TX, Bosque County, TX, Brown County, TX, Burnet County, TX, Callahan County, TX, Coleman County, TX, Collin County, TX, Comanche County, TX, Concho County, TX, Coryell County, TX, Dallas County, TX, Denton County, TX, Eastland County, TX, Edwards County, TX, Ellis County, TX, Erath County, TX, Falls County, TX, Freestone County, TX, Gillespie County, TX, Hamilton County, TX, Hill County, TX, Hood County, TX, Johnson County, TX, Kaufman County, TX, Kendall County, TX, Kerr County, TX, Kimble County, TX, Lampasas County, TX, Limestone County, TX, Llano County, TX, Mason County, TX, McCulloch County, TX, McLennan County, TX, Menard County, TX, Mills County, TX, Navarro County, TX, Palo Pinto County, TX, Parker County, TX, Real County, TX, Rockwall County, TX, Runnels County, TX, San Saba County, TX, Schleicher County, TX, Somervell County, TX, Stephens County, TX, Sutton County, TX, Tarrant County, TX, Taylor County, TX, Tom Green County, TX, Uvalde County, TX, Val Verde County, TX, Williamson County, TX

The radar

The San Angelo radar (KSJT), 144 km from the middle of the area, began a volume at 23:39 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, 11.7 hours before the alert went out and 253 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 12:00Z on 2015-04-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 668 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 12:00Z on 2015-04-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -48 square meters per square second.19395878Sfc1 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
668 J/kg
Mixed-layer CIN
-134 J/kg
Mixed-layer LCL
705 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
-48 m²/s²
0-3 km storm-relative helicity
81 m²/s²
Significant tornado parameter
-0.0
Supercell composite
-0.4

Open this sounding in Storm Lab

The text

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

047 
ACUS11 KWNS 182340
SWOMCD
SPC MCD 182340 
TXZ000-190115-

MESOSCALE DISCUSSION 0366
NWS STORM PREDICTION CENTER NORMAN OK
0640 PM CDT SAT APR 18 2015

AREAS AFFECTED...PORTIONS OF TEXAS

CONCERNING...SEVERE THUNDERSTORM WATCH 72...76...

VALID 182340Z - 190115Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
72...76...CONTINUES.

SUMMARY...AN EVOLVING MESOSCALE CONVECTIVE SYSTEM WILL CONTINUE
SPREADING EWD ACROSS PORTIONS OF CNTRL TX...WITH DMGG WIND GUSTS AND
SVR HAIL EXPECTED.

DISCUSSION...CONVECTION HAS CONGEALED INTO A FORWARD-PROPAGATING MCS
ACROSS PARTS OF CNTRL TX AND WILL CONTINUE SPREADING EWD TOWARD THE
INTERSTATE 35 CORRIDOR INCLUDING THE DFW METROPLEX AND WACO. STEEP
TROPOSPHERIC LAPSE RATES SUPPORTING 1500-2000 J/KG OF MLCAPE COUPLED
WITH 30-45 KT OF DEEP SHEAR ORIENTED LARGELY ORTHOGONAL TO THE
LEADING CONVECTIVE LINE WILL CONTINUE TO SUPPORT SVR WIND/HAIL. THE
LARGE HAIL POTENTIAL MAY BE SOMEWHAT GREATER WITH TRAILING SUPERCELL
STRUCTURES ON THE SRN FLANK OF THE EVOLVING COLD POOL AND FARTHER S
WITH MORE DISCRETE CONVECTION ACROSS PARTS OF THE EDWARDS PLATEAU
AND TX HILL COUNTRY. IN THE WAKE OF CONVECTIVELY STABILIZED
AIR...PROSPECTS FOR ADDITIONAL SFC-BASED CONVECTIVE DEVELOPMENT MAY
BE RELATIVELY LOW OWING TO INCREASED MLCINH -- NOCTURNALLY ENHANCED.

..COHEN.. 04/18/2015

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

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

LAT...LON   29940144 32440015 33629633 31729605 30299787 29249995
            29940144

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 17, 7:26 PM CDTMesoscale DiscussionSPCCarson, Hansford, Hutchinson, Ochiltree, Roberts2 hr
Apr 17, 7:39 PM CDTMesoscale DiscussionSPCChambers, Galveston, Jefferson96 min
Apr 17, 9:10 PM CDTMesoscale DiscussionSPCAransas, Brooks, Calhoun, Duval, Hidalgo, Jim Hogg and 7 more95 min
Apr 17, 9:13 PM CDTSevere Thunderstorm WatchSPCBrazoria, Chambers, Fort Bend, Galveston, Hardin, Harris and 4 more5 hr
Apr 17, 10:59 PM CDTMesoscale DiscussionSPCAransas, Brooks, Hidalgo, Kenedy, Kleberg, Nueces91 min
Apr 17, 11:31 PM CDTMesoscale DiscussionSPCChambers, Galveston, Jefferson, Orange59 min
Apr 18, 1:52 PM CDTMesoscale DiscussionSPCArcher, Baylor, Brown, Callahan, Clay, Coleman and 23 more113 min
Apr 18, 2:13 PM CDTSevere Thunderstorm WatchSPCBandera, Bastrop, Bexar, Blanco, Bosque, Brown and 58 more8 hr
Apr 18, 2:27 PM CDTTornado WatchSPCArcher, Baylor, Childress, Clay, Collingsworth, Cottle and 9 more6 hr
Apr 18, 4:32 PM CDTMesoscale DiscussionSPCAtascosa, Bastrop, Bexar, Caldwell, Comal, Dimmit and 11 more2 hr
Apr 18, 4:48 PM CDTMesoscale DiscussionSPCHidalgo, Kenedy, Kleberg, Willacy2 hr
Apr 18, 5:23 PM CDTMesoscale DiscussionSPCCollin, Dallas, Ellis, Falls, Hill, Kaufman and 6 more3 hr
Apr 18, 5:46 PM CDTSevere Thunderstorm WatchSPCAnderson, Bell, Collin, Cooke, Dallas, Denton and 20 more5 hr
Apr 18, 6:03 PM CDTMesoscale DiscussionSPCBaylor, Childress, Collingsworth, Cottle, Foard, Hardeman and 3 more87 min

Nearby

Mesoscale Discussions in Texas, 2015Every 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.