Alert archive / Texas / Mesoscale Discussions in 2011
Mesoscale Discussion 613
The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2011, 3:29 AM CDT for 4 counties in Arkansas; Bossier Parish, Caddo Parish, Louisiana; 28 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 27, 2011, 3:29 AM CDT (08:29 UTC)
- Expired
- Apr 27, 2011, 5:30 AM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
All 34 counties
Hempstead County, AR, Lafayette County, AR, Little River County, AR, Miller County, AR, Bossier Parish, LA, Caddo Parish, LA, Anderson County, TX, Bowie County, TX, Camp County, TX, Cass County, TX, Cherokee County, TX, Delta County, TX, Franklin County, TX, Freestone County, TX, Gregg County, TX, Harrison County, TX, Henderson County, TX, Hopkins County, TX, Hunt County, TX, Kaufman County, TX, Lamar County, TX, Marion County, TX, Morris County, TX, Navarro County, TX, Panola County, TX, Rains County, TX, Red River County, TX, Rockwall County, TX, Rusk County, TX, Smith County, TX, Titus County, TX, Upshur County, TX, Van Zandt County, TX, Wood County, TX
The radar
The Shreveport radar (KSHV), 138 km from the middle of the area, began a volume at 08:29 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Shreveport, LA (KSHV), launched 00:00Z, 8.5 hours before the alert went out and 146 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.
- Mixed-layer CAPE
- 2270 J/kg
- Mixed-layer CIN
- -13 J/kg
- Mixed-layer LCL
- 961 m above ground
- 0-6 km bulk shear
- 55 kt
- 0-1 km storm-relative helicity
- 281 m²/s²
- 0-3 km storm-relative helicity
- 428 m²/s²
- Significant tornado parameter
- 5.6
- Supercell composite
- 23.5
The text
As transmitted, in the capitals the NWS used until 2016.
685
ACUS11 KWNS 270829
SWOMCD
SPC MCD 270829
LAZ000-ARZ000-TXZ000-OKZ000-271030-
MESOSCALE DISCUSSION 0613
NWS STORM PREDICTION CENTER NORMAN OK
0329 AM CDT WED APR 27 2011
AREAS AFFECTED...PORTIONS OF NERN TX...NWRN LA...SWRN AR...AND FAR
SERN OK
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 270829Z - 271030Z
THE THREAT FOR SVR TSTMS...MAINLY ELEVATED WITH A LARGE HAIL
THREAT...WILL INCREASE INTO THE EARLY MORNING HOURS ACROSS PORTIONS
OF NERN TX...NWRN LA...SWRN AR...AND FAR SERN OK. A WW IS POSSIBLE.
RECENT WATER VAPOR IMAGERY INDICATES A REGION OF ASCENT LEADING A
MID-LEVEL COLD CORE THAT IS CURRENTLY SWINGING THROUGH WRN OK. IN
RESPONSE...CONVECTION /LIKELY ELEVATED/ HAS RECENTLY DEVELOPED
ACROSS VAN ZANDT AND HENDERSON COUNTIES IN NERN TX. LATEST HIGH-RES
WRF GUIDANCE SUGGESTS THAT ADDITIONAL CONVECTION WILL INITIATE AS
THE ASCENT INTERCEPTS STEEP MID-LEVEL LAPSE RATES /AOA 8 C PER KM/
SUPPORTING MUCAPE VALUES OF 1500 TO 3000 J/KG. WITH EFFECTIVE BULK
SHEAR MAGNITUDES FROM 40 TO 60 KT...OCCASIONAL MID-LEVEL
MESOCYCLONES MAY DEVELOP IN ASSOCIATION WITH DEEPER UPDRAFTS...
ENHANCING THE THREAT FOR LARGE HAIL. WHILE CONVECTION WILL LIKELY BE
ROOTED ABOVE THE SFC...THE THREAT FOR DAMAGING WINDS CANNOT BE
ENTIRELY RULED OUT IF MERGING COLD POOLS RESULT IN UPSCALE GROWTH
SOUTHEAST OF A FRONT DRAPED NE TO SW ACROSS THE ARKLATEX REGION.
HOWEVER...OVERTURNING DUE TO EARLIER CONVECTION IN THIS REGION WILL
MITIGATE THIS POTENTIAL TO SOME DEGREE.
..COHEN.. 04/27/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...SHV...FWD...
LAT...LON 32209676 32859658 33589594 34019493 33809365 33039314
32109379 31619495 31669635 32209676SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 26, 7:59 PM CDT | Mesoscale Discussion | SPC | Chicot | 2 hr |
| Apr 26, 8:53 PM CDT | Mesoscale Discussion | SPC | Calhoun, Clark, Columbia, Dallas, Grant, Hempstead and 10 more | 97 min |
| Apr 26, 9:13 PM CDT | Mesoscale Discussion | SPC | Arkansas, Clay, Craighead, Crittenden, Cross, Desha and 21 more | 62 min |
| Apr 26, 9:33 PM CDT | Tornado Watch | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 11 more | 7 hr |
| Apr 26, 9:58 PM CDT | Tornado Watch | SPC | Craighead, Crittenden, Cross, Greene, Jackson, Lee and 8 more | 7 hr |
| Apr 26, 11:33 PM CDT | Mesoscale Discussion | SPC | Chicot, Desha, Phillips | 117 min |
| Apr 27, 4:53 AM CDT | Severe Thunderstorm Watch | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Clark and 19 more | 5 hr |
| Apr 27, 6:25 AM CDT | Mesoscale Discussion | SPC | Arkansas, Cleburne, Crittenden, Cross, Desha, Faulkner and 15 more | 65 min |
| Apr 27, 8:40 AM CDT | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Clay, Cleburne and 28 more | 65 min |
| Apr 27, 9:48 AM CDT | Mesoscale Discussion | SPC | Ashley, Bradley, Calhoun, Chicot, Clark, Cleveland and 10 more | 27 min |
| Apr 27, 11:02 AM CDT | Tornado Watch | SPC | Ashley, Chicot | 8 hr |
| Apr 27, 12:42 PM CDT | Severe Thunderstorm Watch | SPC | Baxter, Clay, Cleburne, Conway, Craighead, Crittenden and 19 more | 5 hr |
| Apr 27, 3:06 PM CDT | Mesoscale Discussion | SPC | Clay, Craighead, Greene, Mississippi, Poinsett | 54 min |
| Apr 27, 3:29 PM CDT | Tornado Watch | SPC | Mississippi | 5 hr |
| Apr 26, 9:42 PM CDT | Tornado Watch | SPC | Avoyelles, Beauregard, Rapides, Vernon | 7 hr |
| Apr 27, 2:26 AM CDT | Tornado Watch | SPC | Catahoula, Concordia, Franklin, Madison, Tensas | 6 hr |
| Apr 27, 10:45 AM CDT | Mesoscale Discussion | SPC | Concordia, East Carroll, Franklin, Madison, Richland, Tensas and 1 more | 90 min |
| Apr 26, 7:08 PM CDT | Mesoscale Discussion | SPC | Archer, Baylor, Childress, Clay, Collingsworth, Foard and 13 more | 97 min |
Nearby
Mesoscale Discussions in Texas, 2011Mesoscale Discussions in Arkansas, 2011Mesoscale Discussions in Louisiana, 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.