Alert archive / Texas / Mesoscale Discussions in 2012

Mesoscale Discussion 476

April 8, 20126 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 8, 2012, 1:27 PM CDT for 6 counties in Texas. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued
Apr 8, 2012, 1:27 PM CDT (18:27 UTC)
Expired
Apr 8, 2012, 3:00 PM CDT
In force
93 min
Issued by
the Storm Prediction Center

Counties Dallas County, TX, Ellis County, TX, Henderson County, TX, Kaufman County, TX, Navarro County, TX, Rockwall County, TX

The radar

The Dallas/Ft Worth radar (KFWS), 59 km from the middle of the area, began a volume at 18:29 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

Fort Worth, TX (KFWD), launched 12:00Z, 6.5 hours before the alert went out and 70 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, Fort Worth, TX at 12:00Z on 2012-04-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 432 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, Fort Worth, TX at 12:00Z on 2012-04-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 134 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
432 J/kg
Mixed-layer CIN
-104 J/kg
Mixed-layer LCL
723 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
134 m²/s²
0-3 km storm-relative helicity
67 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.8

Open this sounding in Storm Lab

The text

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

564 
ACUS11 KWNS 081827
SWOMCD
SPC MCD 081827 
TXZ000-082000-

MESOSCALE DISCUSSION 0476
NWS STORM PREDICTION CENTER NORMAN OK
0127 PM CDT SUN APR 08 2012

AREAS AFFECTED...PARTS OF N CNTRL TX...INCLUDING THE DALLAS/FORTH
WORTH METROPLEX

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 081827Z - 082000Z

IT STILL APPEARS UNLIKELY THAT A WW WILL BE NEEDED THIS AFTERNOON
...BUT TRENDS WILL BE MONITORED FOR THE POSSIBILITY OF AN INCREASING
SEVERE THREAT.

TO THE SOUTH OF A WEAKENING STORM CLUSTER NEAR THE RED RIVER...NEW
CONVECTIVE DEVELOPMENT IS UNDERWAY NEAR AND NORTH THROUGH WEST OF
THE DALLAS/FORT WORTH METROPLEX.  THIS APPEARS BASED WITHIN A ZONE
OF STRONGER LOWER/MID TROPOSPHERIC WARM ADVECTION...IN THE PRESENCE
OF MOST UNSTABLE CAPE OF 1000-2000 J/KG...BUT GENERALLY WEAK SHEAR
AND ONLY MODEST WESTERLY DEEP LAYER MEAN FLOW ON THE ORDER OF 20 KT.
 
HOWEVER...LATEST RUC GUIDANCE SUGGESTS THAT INHIBITION IS BECOMING
INCREASINGLY NEGLIGIBLE FOR BOUNDARY LAYER PARCELS NEAR A WEAK
SURFACE LOW AND FRONT ACROSS AND TO THE SOUTH AND EAST OF THE
METROPLEX...WHERE DEEPENING CONVECTIVE DEVELOPMENT IS ALSO EVIDENT. 
PERSISTENT LOW-LEVEL CONVERGENCE NEAR THIS LOW MAY HELP FOCUS
INTENSIFYING BOUNDARY LAYER BASED STORM DEVELOPMENT BETWEEN NOW AND
20-21Z.  FORCING MAY BECOME ENHANCED BY THE SOUTHEASTWARD
PROGRESSION OF A HIGH LEVEL IMPULSE ACCOMPANIED BY AT LEAST WEAK
MID-LEVEL COOLING AND HEIGHT FALLS.  

ALTHOUGH NEAR SURFACE FLOW FIELDS ARE ALSO LIGHT...A SUBSTANTIAL
EASTERLY COMPONENT ALONG THE BOUNDARY...VEERING TO WESTERLY AND
NORTHWESTERLY ALOFT...MAY PROVIDE MARGINALLY SUFFICIENT SHEAR FOR
UPDRAFT ROTATION...PERHAPS...EVENTUALLY...AN ORGANIZING STORM
CLUSTER.  SOME HAIL IS POSSIBLE...ALONG WITH AT LEAST LOW
PROBABILITIES FOR POTENTIALLY DAMAGING WIND GUSTS.  A SHORT-LIVED
TORNADO MAY NOT BE COMPLETELY OUT OF THE QUESTION...BUT STILL SEEMS
ONLY A REMOTE POSSIBILITY.

..KERR.. 04/08/2012

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

ATTN...WFO...FWD...

LAT...LON   32549739 32869694 32969651 32889605 32359570 31939614
            31959680 32139727 32549739

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 7, 9:53 PM CDTMesoscale DiscussionSPCCrockett, Schleicher, Sutton, Terrell97 min
Apr 8, 5:48 PM CDTMesoscale DiscussionSPCAnderson, Cherokee, Freestone, Henderson, Houston, Leon and 3 more117 min

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.