Alert archive / Texas / Mesoscale Discussions in 2012

Mesoscale Discussion 116

February 12, 201215 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Feb 12, 2012, 10:30 AM CST for 15 counties in Texas. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Feb 12, 2012, 10:30 AM CST (16:30 UTC)
Expired
Feb 12, 2012, 2:30 PM CST
In force
4 hr
Issued by
the Storm Prediction Center

Counties Concho County, TX, Crockett County, TX, Edwards County, TX, Gillespie County, TX, Irion County, TX, Kerr County, TX, Kimble County, TX, Llano County, TX, Mason County, TX, McCulloch County, TX, Menard County, TX, San Saba County, TX, Schleicher County, TX, Sutton County, TX, Tom Green County, TX

The radar

The San Angelo radar (KSJT), 69 km from the middle of the area, began a volume at 16:32 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 (KDRT), launched 12:00Z, 4.5 hours before the alert went out and 156 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 2012-02-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2012-02-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 131 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1596 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
131 m²/s²
0-3 km storm-relative helicity
238 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.

195 
ACUS11 KWNS 121630
SWOMCD
SPC MCD 121630 
TXZ000-122030-

MESOSCALE DISCUSSION 0116
NWS STORM PREDICTION CENTER NORMAN OK
1030 AM CST SUN FEB 12 2012

AREAS AFFECTED...SWRN TX

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 121630Z - 122030Z

A BAND OF SNOW WILL SPREAD FROM SOUTH TO NORTH ACROSS THE EDWARDS
PLATEAU LATE THIS MORNING INTO THE EARLY AFTERNOON.  SNOW RATES MAY
EXCEED ONE HALF INCH PER HOUR BEFORE CHANGING TO SLEET.

LLJ IS BEGINNING TO INCREASE ACROSS THE RIO GRANDE VALLEY INTO SWRN
TX AHEAD OF TRANSITORY SHORTWAVE TROUGH.  BY EARLY EVENING IT
APPEARS A STRONG LLJ...IN EXCESS OF 50KT...WILL BE POSITIONED ACROSS
THE EDWARDS PLATEAU INTO WRN OK.  LATEST RADAR DATA EXHIBITS AN E-W
BAND OF MOSTLY SNOW FROM TERRELL COUNTY...EWD TO GILLESPIE COUNTY IN
THE HILL COUNTRY.  THIS BAND IS EVOLVING ALONG THE NOSE OF STRONGEST
WARM ADVECTION AND IS SPREADING/DEVELOPING NWD AT ROUGHLY 20KT. 
GIVEN THE LOW WBZ LEVELS JUST NORTH OF THIS SNOW BAND IT APPEARS THE
ONSET OF PRECIPITATION WILL BE MOSTLY SNOW.  HOWEVER...WITH TIME
WARM ADVECTION WILL CERTAINLY WARM THE PROFILES SUCH THAT A CHANGE
OVER TO SLEET SHOULD BE NOTED.  OVERALL...TRANSITORY NATURE OF
CONVECTIVE BAND SHOULD LIMIT SNOW TOTALS.

..DARROW.. 02/12/2012

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

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

LAT...LON   30900194 31680089 31659914 30789842 30039915 29930105
            30140192 30900194

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.