Alert archive / Texas / Mesoscale Discussions in 2016

Mesoscale Discussion 407

April 17, 20167 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 17, 2016, 5:25 PM CDT for 7 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 17, 2016, 5:25 PM CDT (22:25 UTC)
Expired: Apr 17, 2016, 7:30 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 40%

Counties Bandera County, TX, Bexar County, TX, Blanco County, TX, Frio County, TX, Gillespie County, TX, Kendall County, TX, Medina County, TX

The radar

The Austin/San Antonio radar (KEWX), 97 km from the middle of the area, began a volume at 22:27 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, 10.4 hours before the alert went out and 184 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: 595 J/kg
Mixed-layer CIN: -88 J/kg
Mixed-layer LCL: 625 m above ground
0-6 km bulk shear: 54 kt
0-1 km storm-relative helicity: 331 m²/s²
0-3 km storm-relative helicity: 477 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 11.7

Open this sounding in Storm Lab

The text

As transmitted.

825 
ACUS11 KWNS 172226
SWOMCD
SPC MCD 172225 
TXZ000-180030-

MESOSCALE DISCUSSION 0407
NWS STORM PREDICTION CENTER NORMAN OK
0525 PM CDT SUN APR 17 2016

AREAS AFFECTED...SOUTH-CENTRAL TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 172225Z - 180030Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...ADDITIONAL STRONG TO SEVERE STORMS WILL CONTINUE TO
DEVELOP LATE THIS AFTERNOON INTO THE EARLY EVENING ACROSS
SOUTH-CENTRAL TX...WITH TRANSIENT SUPERCELLS CAPABLE OF PRODUCING
LARGE HAIL AND STRONG WIND GUSTS...WHILE A BRIEF TORNADO CANNOT BE
RULED OUT.

DISCUSSION...AT 2145Z...MOSAIC AND SINGLE-SITE RADAR IMAGERY SHOWED
AN ONGOING BROKEN BAND OF STORMS/STORM CLUSTERS EXTENDING FROM
BLANCO/GILLESPIE COUNTIES SOUTHWARD TO LA SALLE COUNTY.  THESE
STORMS AND OTHER RECENT STORMS HAVE CONTINUED TO DEVELOP ALONG A
WESTWARD-MOVING BOUNDARY /LIKELY NOW CONVECTIVELY ENHANCED FROM
COMPOSITE OUTFLOW BOUNDARIES/ THROUGH A MODERATELY UNSTABLE
ENVIRONMENT /MLCAPE OF 1500-2500 J PER KG/.  MEANWHILE...GIVEN THE
SAME THERMODYNAMIC ENVIRONMENT...NEW STORMS ARE EXPECTED TO DEVELOP
WITH THE CONTINUED MERGER OF THE COMPOSITE WESTWARD-MOVING BOUNDARY
WITH ANOTHER BOUNDARY EXTENDING FROM NEAR FREDERICKSBURG TO
KERRVILLE AND WEST OF HONDO IN MEDINA COUNTY TO EASTERN DIMMIT
COUNTY.  THIS PROCESS HAS ALREADY OCCURRED NEAR FREDERICKSBURG TO
HONDO.  AFTER THE STORMS FORM WITH THE MERGER OF THE TWO
BOUNDARIES...NEW DEVELOPMENT THEREAFTER MAY BE LIMITED...AS THE AIR
MASS IS CONVECTIVELY OVERTURNED/STABILIZED FROM EAST TO WEST. 

18Z NAM SUGGESTED AN INCREASE IN EFFECTIVE BULK SHEAR INTO THIS
EVENING...SUPPORTING DEEP ROTATING UPDRAFTS.  THIS COMBINED WITH THE
AVAILABLE INSTABILITY SUGGESTS ADDITIONAL TRANSIENT STRONG TO SEVERE
WILL REMAIN A CONCERN INTO THE EARLY EVENING...WITH LARGE HAIL AND
STRONG WIND GUSTS THE PRIMARY THREATS.  A TORNADO THREAT CANNOT BE
RULED OUT AS SURFACE TO 850-MB WINDS VEER TO THE SOUTHEAST TO EAST
WITH THE PASSAGE OF THE WESTWARD-MOVING BOUNDARY.  THIS WILL
INCREASE THE LOW-LEVEL HODOGRAPH CURVATURE...ENHANCING LOW-LEVEL
SHEAR.  TRENDS IN RADAR IMAGERY CONTINUE TO SUGGEST STORMS REMAIN
TRANSIENT /PEAKING IN INTENSITY...THEN WEAKENING/.

..PETERS/EDWARDS.. 04/17/2016

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

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

LAT...LON   28319891 28589940 28969965 29739939 30419904 30479866
            30339836 29649846 28759863 28319891

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 16, 7:07 PM CDT	Severe Thunderstorm Watch	SPC	Archer, Baylor, Clay, Foard, Hardeman, Knox and 2 more	7 hr
Apr 16, 7:42 PM CDT	Mesoscale Discussion	SPC	Borden, Coke, Concho, Crockett, Fisher, Glasscock and 18 more	93 min
Apr 16, 8:27 PM CDT	Mesoscale Discussion	SPC	Armstrong, Briscoe, Carson, Childress, Collingsworth, Cottle and 16 more	63 min
Apr 16, 10:43 PM CDT	Mesoscale Discussion	SPC	Brown, Callahan, Coke, Coleman, Comanche, Concho and 20 more	92 min
Apr 16, 10:48 PM CDT	Mesoscale Discussion	SPC	Archer, Baylor, Clay, Foard, Hardeman, Knox and 2 more	117 min
Apr 16, 11:51 PM CDT	Severe Thunderstorm Watch	SPC	Brown, Callahan, Coke, Coleman, Comanche, Concho and 27 more	7 hr
Apr 17, 1:47 AM CDT	Mesoscale Discussion	SPC	Archer, Baylor, Clay, Foard, Hardeman, Knox and 2 more	58 min
Apr 17, 2:01 AM CDT	Mesoscale Discussion	SPC	Brown, Callahan, Coleman, Comanche, Concho, Eastland and 17 more	59 min
Apr 17, 7:48 AM CDT	Mesoscale Discussion	SPC	Bell, Bosque, Burnet, Coryell, Falls, Hamilton and 3 more	87 min
Apr 17, 2:47 PM CDT	Mesoscale Discussion	SPC	Atascosa, Bandera, Bexar, Blanco, Caldwell, Comal and 8 more	88 min

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.