Alert archive / Texas / Mesoscale Discussions in 2012

Mesoscale Discussion 411

April 2, 201219 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 2, 2012, 5:16 AM CDT for 19 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 2, 2012, 5:16 AM CDT (10:16 UTC)
Expired: Apr 2, 2012, 7:45 AM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Austin County, TX, Brazoria County, TX, Chambers County, TX, Colorado County, TX, Fayette County, TX, Fort Bend County, TX, Galveston County, TX, Grimes County, TX, Harris County, TX, Jackson County, TX, Liberty County, TX, Matagorda County, TX, Montgomery County, TX, Polk County, TX, San Jacinto County, TX, Walker County, TX, Waller County, TX, Washington County, TX, Wharton County, TX

The radar

The Houston radar (KHGX), 64 km from the middle of the area, began a volume at 10:15 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

Lake Charles Mun, LA (KLCH), launched 00:00Z, 10.3 hours before the alert went out and 248 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: 2527 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 714 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 13 m²/s²
0-3 km storm-relative helicity: 4 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

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

161 
ACUS11 KWNS 021017
SWOMCD
SPC MCD 021016
TXZ000-021245-

MESOSCALE DISCUSSION 0411
NWS STORM PREDICTION CENTER NORMAN OK
0516 AM CDT MON APR 02 2012

AREAS AFFECTED...PORTIONS MID-UPPER TX COASTAL PLAIN.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 021016Z - 021245Z

POTENTIAL MAY BE INCREASING FOR SPORADIC DAMAGING GUSTS OVER
DISCUSSION AREA AS LONG-LASTING MCS...STRENGTHENING AFTER NEARLY
DISSIPATING NEAR CRP...GETS BETTER ORGANIZED AGAIN.

10Z SFC THETAE AXIS WAS EVIDENT FROM NEAR BUOY 42002 AND OFFSHORE
STATION KVAF NWWD TO NEAR BYY...THEN BETWEEN CLL-AUS.
MCV...PRODUCED EARLIER WHEN TSTM COMPLEX WAS NEAR RIO GRANDE...WAS
EVIDENT IN REFLECTIVITY ANIMATIONS OVER MCMULLEN COUNTY...MOVING
ESEWD 10-15 KT.  MEANWHILE...ANTECEDENT/MID-UPPER LEVEL VORTICITY
MAX WAS EVIDENT IN MOISTURE CHANNEL IMAGERY OVER BURLESON COUNTY.
LATTER FEATURE WAS MOVING GENERALLY NWD...PERHAPS WITH SLGT NWWD
SHIFT RELATED TO NEARBY CONVECTIVE/MCV INFLUENCE.  PREVAILING
CYCLONIC MEAN WIND AROUND MID-UPPER PERTURBATION...COMBINED WITH
FORWARD-PROPAGATIONAL TENDENCY OF MCS INTO THETAE MAX...MAY LEAD TO
FURTHER NEWD CURVATURE OF MCS TRANSLATION THAN ALREADY INDICATED
OVER MATAGORDA BAY REGION.  CONVECTION WILL BE MOVING INTO VERY
MOIST AND FAVORABLY BUOYANT AIR MASS...BUT WITH WEAK DEEP-LAYER
SHEAR.  MODIFIED RUC SOUNDINGS REFLECT STEEP MIDLEVEL LAPSE RATES
PRESENT IN 00Z BRO/CRP RAOBS...WITH LOW-70S F SFC DEW POINTS
CONTRIBUTING TO EFFECTIVELY SFC-BASED INFLOW AND MLCAPE 1500-2500
J/KG.  ORGANIZED SVR THREAT WILL BE LIMITED BY LACK OF 1)
BOUNDARY-LAYER EVAPORATION/ACCELERATION POTENTIAL...AND 2) MORE
ROBUST MIDLEVEL WINDS.  HOWEVER...PRECIP LOADING...POSSIBLE
REAR-INFLOW JET FORMATION...AND SMALL-SCALE LEWP/BOW FEATURES MAY
ENHANCE WIND THREAT LOCALLY.

..EDWARDS.. 04/02/2012

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

ATTN...WFO...LCH...HGX...CRP...EWX...

LAT...LON   28299645 28859658 29379686 29619707 30019706 30349634
            30639603 30869585 31149564 31159531 30899488 30559462
            30189445 29649417 29429465 29309472 29089509 29019514
            28729565 28409632 28309639 28299645

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 2, 9:57 AM CDT	Mesoscale Discussion	SPC	Angelina, Hardin, Jasper, Nacogdoches, Newton, Orange and 5 more	63 min
Apr 2, 10:10 AM CDT	Severe Thunderstorm Watch	SPC	Angelina, Cherokee, Gregg, Harrison, Jasper, Nacogdoches and 8 more	7 hr
Apr 2, 12:15 PM CDT	Mesoscale Discussion	SPC	Bowie, Camp, Cass, Cherokee, Delta, Fannin and 18 more	90 min
Apr 2, 12:41 PM CDT	Severe Thunderstorm Watch	SPC	Anderson, Bowie, Camp, Cass, Delta, Fannin and 15 more	6 hr
Apr 2, 3:00 PM CDT	Mesoscale Discussion	SPC	Baylor, Childress, Collingsworth, Foard, Hardeman, Hemphill and 7 more	2 hr
Apr 2, 3:18 PM CDT	Mesoscale Discussion	SPC	Bowie, Delta, Fannin, Franklin, Hopkins, Hunt and 4 more	117 min
Apr 2, 3:37 PM CDT	Severe Thunderstorm Watch	SPC	Archer, Baylor, Brown, Callahan, Clay, Coleman and 28 more	7 hr
Apr 2, 6:51 PM CDT	Mesoscale Discussion	SPC	Archer, Baylor, Brown, Callahan, Clay, Coleman and 17 more	54 min

Nearby

Mesoscale Discussions in Texas, 2012 Every 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.