Alert archive / Texas / Mesoscale Discussions in 2011

Mesoscale Discussion 577

April 25, 201113 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 25, 2011, 5:21 PM CDT for 13 counties in Texas. It was in force for 54 min.

The area

The outline as issued.

The facts

Issued
Apr 25, 2011, 5:21 PM CDT (22:21 UTC)
Expired
Apr 25, 2011, 6:15 PM CDT
In force
54 min
Issued by
the Storm Prediction Center

Counties Bosque County, TX, Delta County, TX, Ellis County, TX, Henderson County, TX, Hill County, TX, Hopkins County, TX, Hunt County, TX, Kaufman County, TX, Lamar County, TX, Navarro County, TX, Rains County, TX, Rockwall County, TX, Van Zandt County, TX

The radar

The Dallas/Ft Worth radar (KFWS), 90 km from the middle of the area, began a volume at 22:22 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, 10.4 hours before the alert went out and 86 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 2011-04-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2645 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 2011-04-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 346 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
2645 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
564 m above ground
0-6 km bulk shear
50 kt
0-1 km storm-relative helicity
346 m²/s²
0-3 km storm-relative helicity
373 m²/s²
Significant tornado parameter
6.1
Supercell composite
21.8

Open this sounding in Storm Lab

The text

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

032 
ACUS11 KWNS 252221
SWOMCD
SPC MCD 252221 
TXZ000-OKZ000-252315-

MESOSCALE DISCUSSION 0577
NWS STORM PREDICTION CENTER NORMAN OK
0521 PM CDT MON APR 25 2011

AREAS AFFECTED...PORTIONS N-CENTRAL/NE TX THROUGH SERN OK.

CONCERNING...TORNADO WATCH 201...

VALID 252221Z - 252315Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 201 CONTINUES.

ORIGINAL WW IS SCHEDULED TO EXPIRE AT 23Z...AND MAY BE ALLOWED TO DO
SO OVER MOST AREAS EXCEPT FAR SRN PORTIONS.  WW SHOULD BE EXTENDED
IN TIME AT LEAST FOR REMAINING COUNTIES BENEATH/AHEAD OF N-CENTRAL
TX CONVECTION.

SFC MESOANALYSIS SHOWS THERMAL GRADIENT/OUTFLOW BOUNDARY FROM
EARLIER CONVECTION EXTENDING FROM NEAR PSN WNWWD TOWARD TSTM COMPLEX
S OF DAL.  THIS CONVECTION...INCLUDING PREVIOUSLY TORNADIC
SUPERCELL...WILL MOVE ESEWD ACROSS PORTIONS NAVARRO/HENDERSON
COUNTIES DURING NEXT 2 HOURS...NEAR THAT BOUNDARY WHERE LOW-LEVEL
SHEAR/VORTICITY AND STORM-RELATIVE INFLOW SHOULD BE MAXIMIZED. 
MODIFIED RAOBS AND RUC SOUNDINGS SUGGEST 2000-2500 J/KG MLCAPE IN
IMMEDIATE INFLOW REGION OF THIS CONVECTION...SUPPORTED BY SFC TEMPS
80S F AND DEW POINTS UPPER 60S TO 70 F ALONG/S OF BOUNDARY.  AMBIENT
STORM ENVIRONMENT WILL REMAIN FAVORABLE KINEMATICALLY AS WELL...WITH
EFFECTIVE SHEAR MAGNITUDES 50-60 KT.  ONCE THIS ACTIVITY EXITS WW
AREA...DRYLINE AND COLD FRONTAL PASSAGE WILL RESULT IN THREAT FOR
TORNADIC TSTMS SHIFTING EWD INTO WW 205 AND SWD OVER WW 204. 
QUASI-LINEAR ACTIVITY FARTHER NE ACROSS NE TX AND SE OK WILL BE
COVERED BY WW 205.

..EDWARDS.. 04/25/2011

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

ATTN...WFO...SHV...TSA...FWD...

LAT...LON   31789811 32499696 33409614 34189520 33679534 32839556
            32019556 31789811

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 24, 7:35 PM CDTMesoscale DiscussionSPCCarson, Gray, Hansford, Hemphill, Hutchinson, Lipscomb and 5 more2 hr
Apr 24, 8:48 PM CDTMesoscale DiscussionSPCBosque, Brown, Callahan, Coleman, Collin, Comanche and 36 more117 min
Apr 24, 11:25 PM CDTMesoscale DiscussionSPCBosque, Brown, Callahan, Camp, Coke, Coleman and 39 more65 min
Apr 24, 11:43 PM CDTSevere Thunderstorm WatchSPCBosque, Bowie, Camp, Cass, Collin, Comanche and 40 more5 hr
Apr 24, 11:58 PM CDTMesoscale DiscussionSPCHemphill, Lipscomb, Ochiltree92 min
Apr 25, 3:29 AM CDTMesoscale DiscussionSPCBosque, Camp, Collin, Dallas, Delta, Denton and 24 more61 min
Apr 25, 4:41 AM CDTSevere Thunderstorm WatchSPCBowie, Camp, Cass, Collin, Dallas, Delta and 21 more7 hr
Apr 25, 7:23 AM CDTMesoscale DiscussionSPCBowie, Camp, Cass, Gregg, Harrison, Marion and 3 more97 min
Apr 25, 10:46 AM CDTMesoscale DiscussionSPCAnderson, Bosque, Bowie, Brazos, Camp, Cass and 42 more59 min
Apr 25, 11:00 AM CDTTornado WatchSPCBosque, Bowie, Camp, Cass, Collin, Cooke and 34 more7 hr
Apr 25, 1:28 PM CDTMesoscale DiscussionSPCBowie, Camp, Cass, Collin, Cooke, Dallas and 30 more92 min
Apr 25, 2:16 PM CDTMesoscale DiscussionSPCAngelina, Bastrop, Bell, Blanco, Brazos, Burleson and 27 more59 min
Apr 25, 2:41 PM CDTTornado WatchSPCAnderson, Angelina, Bastrop, Bell, Blanco, Bosque and 49 more9 hr
Apr 25, 3:22 PM CDTTornado Watch PDSSPCBowie, Camp, Cass, Franklin, Gregg, Harrison and 7 more8 hr
Apr 25, 5:24 PM CDTMesoscale DiscussionSPCArmstrong, Carson, Childress, Collingsworth, Donley, Gray and 3 more66 min
Apr 25, 6:57 PM CDTMesoscale DiscussionSPCAnderson, Angelina, Bell, Blanco, Brazos, Burleson and 22 more2 hr

Nearby

Mesoscale Discussions in Texas, 2011Every mesoscale discussion in 2011

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.