Alert archive / Texas / Mesoscale Discussions in 2012

Mesoscale Discussion 494

April 11, 201214 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 11, 2012, 8:54 PM CDT for 14 counties in Texas. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued: Apr 11, 2012, 8:54 PM CDT (01:54 UTC)
Expired: Apr 11, 2012, 10:00 PM CDT
In force: 66 min
Issued by: the Storm Prediction Center

Counties Armstrong County, TX, Carson County, TX, Donley County, TX, Gray County, TX, Hansford County, TX, Hartley County, TX, Hemphill County, TX, Hutchinson County, TX, Lipscomb County, TX, Moore County, TX, Ochiltree County, TX, Potter County, TX, Roberts County, TX, Sherman County, TX

The radar

The Amarillo radar (KAMA), 68 km from the middle of the area, began a volume at 01:54 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

Amarillo Airport, TX (KAMA), launched 00:00Z, 1.9 hours before the alert went out and 68 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: 706 J/kg
Mixed-layer CIN: -12 J/kg
Mixed-layer LCL: 1480 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 73 m²/s²
0-3 km storm-relative helicity: 172 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 1.9

Open this sounding in Storm Lab

The text

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

921 
ACUS11 KWNS 120154
SWOMCD
SPC MCD 120154 
OKZ000-TXZ000-120300-

MESOSCALE DISCUSSION 0494
NWS STORM PREDICTION CENTER NORMAN OK
0854 PM CDT WED APR 11 2012

AREAS AFFECTED...OK/TX PANHANDLES

CONCERNING...TORNADO WATCH 155...

VALID 120154Z - 120300Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 155 CONTINUES.

TORNADO WATCH 155 CONTINUES UNTIL 03Z...BUT THE SEVERE THREAT IS
EXPECTED TO BE INCREASINGLY ISOLATED/MARGINAL THE REMAINDER OF THE
EVENING. PERIODIC SEVERE HAIL ALONG WITH LOCALLY HEAVY RAINFALL
REMAIN POSSIBLE. CURRENT THINKING IS THAT TORNADO WATCH 155 WILL BE
ALLOWED TO EXPIRE AT/BY 03Z.

OVERALL STORM INTENSITY HAS SLOWLY WANED OVER THE PAST HOUR WITH
ONGOING ACTIVITY ACROSS THE TX PANHANDLE...AND THIS SAME TREND
SHOULD CONTINUE AS THE BOUNDARY LAYER CONTINUES TO COOL AND/OR IS
CONVECTIVELY OVERTURNED. NONETHELESS...A SOUTH-SOUTHEASTERLY LOW
LEVEL JET HAS ALREADY SHOWN SOME SIGNS OF INCREASE ACROSS THE REGION
THIS EVENING /PER REGIONAL PROFILERS AND WSR-88D VWPS/...AND AN
ASSOCIATED WARM ADVECTION REGIME WILL CONTINUE TO SUPPORT A
LOOSE/GENERALLY EASTWARD MOVING CLUSTER OF TSTMS TONIGHT. SOME OF
THE STRONGEST UPDRAFTS WILL REMAIN CAPABLE OF SEVERE
HAIL...ESPECIALLY IN AREAS 50 MILES EITHER SIDE OF I-40 WHERE THE
AIRMASS REMAINS RELATIVELY UNSTABLE. LOCALLY HEAVY RAINFALL WILL
OTHERWISE BE POSSIBLE AS STORMS CONGEAL/EXHIBIT A MODEST FORWARD
MOTION.

..GUYER.. 04/12/2012

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

ATTN...WFO...OUN...LUB...AMA...

LAT...LON   35710277 36720234 36549993 34550072 35710277

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 11, 9:12 PM CDT	Mesoscale Discussion	SPC	Andrews, Cochran, Crane, Dawson, Ector, Gaines and 16 more	93 min
Apr 12, 2:28 PM CDT	Mesoscale Discussion	SPC	Carson, Gray, Hansford, Hemphill, Hutchinson, Lipscomb and 2 more	2 hr
Apr 12, 3:34 PM CDT	Mesoscale Discussion	SPC	Childress, Collingsworth, Foard, Hardeman, Wilbarger	86 min
Apr 12, 6:06 PM CDT	Mesoscale Discussion	SPC	Baylor, Childress, Collingsworth, Cottle, Foard, Hall and 5 more	114 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.