Alert archive / Texas / Mesoscale Discussions in 2016

Mesoscale Discussion 447

April 25, 201619 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 25, 2016, 6:48 PM CDT for 19 counties in Texas. It was in force for 57 min.

The area

The outline as issued.

The facts

Issued: Apr 25, 2016, 6:48 PM CDT (23:48 UTC)
Expired: Apr 25, 2016, 7:45 PM CDT
In force: 57 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Atascosa County, TX, Bee County, TX, Bexar County, TX, Blanco County, TX, Caldwell County, TX, Comal County, TX, DeWitt County, TX, Goliad County, TX, Gonzales County, TX, Guadalupe County, TX, Hays County, TX, Jim Wells County, TX, Karnes County, TX, Kendall County, TX, Live Oak County, TX, McMullen County, TX, San Patricio County, TX, Travis County, TX, Wilson County, TX

The radar

The Austin/San Antonio radar (KEWX), 64 km from the middle of the area, began a volume at 23:49 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

Corpus Christi, TX (KCRP), launched 12:00Z, 11.8 hours before the alert went out and 172 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: 1837 J/kg
Mixed-layer CIN: -80 J/kg
Mixed-layer LCL: 521 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 24 m²/s²
0-3 km storm-relative helicity: 145 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.8

Open this sounding in Storm Lab

The text

As transmitted.

205 
ACUS11 KWNS 252349
SWOMCD
SPC MCD 252348 
TXZ000-260045-

MESOSCALE DISCUSSION 0447
NWS STORM PREDICTION CENTER NORMAN OK
0648 PM CDT MON APR 25 2016

AREAS AFFECTED...S TX

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 252348Z - 260045Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...A FEW STRONG/SEVERE STORMS WILL CONTINUE ACROSS PARTS OF S
TX FOR THE NEXT COUPLE OF HOURS.  LARGE HAIL WILL BE THE MAIN
THREAT.

DISCUSSION...LATEST RADAR IMAGERY SHOWS A SMALL CLUSTER OF ISOLATED
STORMS ONGOING OVER S TX.  THE STORMS HAVE INITIATED NEAR A N-S
TROUGH/DRYLINE...SEPARATING AN UPPER 50S/LOW 60S DEWPOINT BOUNDARY
LAYER NEAR AND E OF THE RIO GRANDE FROM MOIST/TROPICAL MID 70S
DEWPOINT AIR ADVECTING INLAND ACROSS THE TX COASTAL PLAIN.  THE
ENVIRONMENT SUPPORTING THE CONVECTION IS CHARACTERIZED BY A VERY
UNSTABLE AIRMASS /3000 TO 4000 J/KG MIXED-LAYER CAPE/ ALONG AND E OF
THE DRYLINE...ALONG WITH MODERATE FLOW ALOFT WHICH VEERS WITH HEIGHT
YIELDING A WIND PROFILE SUPPORTIVE OF MID-LEVEL ROTATION.

THE TWO STRONGEST STORMS ATTM -- ONE MOVING NWD ACROSS BEXAR COUNTY
AND THE OTHER DRIFTING SLOWLY EWD ACROSS MCMULLEN COUNTY -- MAY
PRODUCE HAIL TO AROUND 2" IN DIAMETER...AND SHOULD PERSIST FOR THE
NEXT 1-2 HOURS.  ATTM HOWEVER...IT APPEARS THAT THE ONSET OF
BOUNDARY-LAYER COOLING A BIT LATER THIS EVENING WILL SUPPORT A
GRADUAL DECREASE IN STORM INTENSITY/SEVERE RISK.

FINALLY...A FEW ATTEMPTS AT CONVECTION HAVE BEEN EVIDENT OVER THE
HIGHER TERRAIN OF NRN MEXICO W OF MFE /MCALLEN TX/...BUT SUSTAINED
STORMS HAVE NOT DEVELOPED TO THIS POINT.  THOUGH SOME GUIDANCE HAS
SUGGESTED POTENTIAL FOR A STORM OR TWO MOVING ACROSS THE RIO GRANDE
INTO DEEP S TX THIS EVENING...ATTM SUCH A SCENARIO APPEARS UNLIKELY.

..GOSS/DARROW.. 04/25/2016

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

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

LAT...LON   30329846 30329737 29259720 28249721 27609773 27529823
            28229868 29469885 30029874 30329846

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 25, 3:47 PM CDT	Mesoscale Discussion	SPC	Atascosa, Bandera, Bexar, Blanco, Frio, Gillespie and 9 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.