Alert archive / Texas / Mesoscale Discussions in 2012

Mesoscale Discussion 818

May 15, 201219 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 15, 2012, 3:07 PM CDT for 19 counties in Texas. It was in force for 113 min.

The area

The outline as issued.

The facts

Issued
May 15, 2012, 3:07 PM CDT (20:07 UTC)
Expired
May 15, 2012, 5:00 PM CDT
In force
113 min
Issued by
the Storm Prediction Center
Chance of a watch
20%

Counties Aransas County, TX, Brooks County, TX, Cameron County, TX, Duval County, TX, Hidalgo County, TX, Jim Hogg County, TX, Jim Wells County, TX, Kenedy County, TX, Kleberg County, TX, La Salle County, TX, Live Oak County, TX, McMullen County, TX, Nueces County, TX, Refugio County, TX, San Patricio County, TX, Starr County, TX, Webb County, TX, Willacy County, TX, Zapata County, TX

The radar

The Corpus Christi radar (KCRP), 99 km from the middle of the area, began a volume at 20:09 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, 8.1 hours before the alert went out and 110 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, Corpus Christi, TX at 12:00Z on 2012-05-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 886 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, Corpus Christi, TX at 12:00Z on 2012-05-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 68 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
886 J/kg
Mixed-layer CIN
-10 J/kg
Mixed-layer LCL
520 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
68 m²/s²
0-3 km storm-relative helicity
316 m²/s²
Significant tornado parameter
0.3
Supercell composite
1.8

Open this sounding in Storm Lab

The text

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

503 
ACUS11 KWNS 152007
SWOMCD
SPC MCD 152007 
TXZ000-152200-

MESOSCALE DISCUSSION 0818
NWS STORM PREDICTION CENTER NORMAN OK
0307 PM CDT TUE MAY 15 2012

AREAS AFFECTED...DEEP S TX

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 152007Z - 152200Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...SCATTERED STORMS...SOME WITH LARGE HAIL...WILL PERSIST FOR
SEVERAL MORE HOURS. LOCALLY GUSTY WINDS MAY OCCUR BUT A LARGE SCALE
SEVERE EVENT IS NOT ANTICIPATED.

DISCUSSION...SURFACE ANALYSIS SHOWS WEAK LOW PRESSURE OVER DEEP S TX
WITH WEAK SURFACE CONVERGENCE. RELATIVELY COOL AIR EXISTS ALOFT WITH
THE UPPER LOW...AND HEATING HAS RESULTED IN MARGINAL INSTABILITY.
FAVORABLY LONG HODOGRAPHS EXIST WITH SPEED SHEAR ALOFT FOR A FEW
SMALL SUPERCELLS. LOW LEVEL SHEAR IS VERY WEAK...THUS THE MAIN
THREAT SHOULD BE HAIL WITH THE STRONGEST CORES UNTIL SUNSET.

..JEWELL/HART.. 05/15/2012

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

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

LAT...LON   27569970 28079976 28489908 28479850 28289675 28059679
            27269731 26119707 25869705 25789750 26029829 26379911
            27409959 27569970

Nearby

Mesoscale Discussions in Texas, 2012Every mesoscale discussion in 2012

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.