Alert archive / Louisiana / Mesoscale Discussions in 2011
Mesoscale Discussion 306
The Storm Prediction Center issued this mesoscale discussion at Mar 29, 2011, 5:26 PM CDT for 4 states. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Mar 29, 2011, 5:26 PM CDT (22:26 UTC)
- Expired
- Mar 29, 2011, 7:30 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
All 51 counties
Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Columbia County, AR, Desha County, AR, Drew County, AR, Lafayette County, AR, Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Jackson Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Richland Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Attala County, MS, Bolivar County, MS, Carroll County, MS, Grenada County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Leake County, MS, Leflore County, MS, Madison County, MS, Montgomery County, MS, Sharkey County, MS, Sunflower County, MS, Warren County, MS, Washington County, MS, Yazoo County, MS, Gregg County, TX, Harrison County, TX, Marion County, TX, Panola County, TX, Rusk County, TX, Shelby County, TX
The radar
The Shreveport radar (KSHV), 124 km from the middle of the area, began a volume at 22:27 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 12:00Z, 10.4 hours before the alert went out and 115 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 503 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 96 m²/s²
- 0-3 km storm-relative helicity
- 164 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.5
The text
As transmitted, in the capitals the NWS used until 2016.
269
ACUS11 KWNS 292226
SWOMCD
SPC MCD 292226
MSZ000-ARZ000-LAZ000-TXZ000-300030-
MESOSCALE DISCUSSION 0306
NWS STORM PREDICTION CENTER NORMAN OK
0526 PM CDT TUE MAR 29 2011
AREAS AFFECTED...NERN/E-CNTRL TX...NRN LA...SRN AR...W-CNTRL/CNTRL
MS
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 292226Z - 300030Z
THE THREAT FOR ELEVATED THUNDERSTORMS PRODUCING LARGE HAIL WILL
OCCUR ACROSS NERN/E-CNTRL TX...SRN AR...NRN LA...AND W-CNTRL/CNTRL
MS THROUGH THIS EVENING. A SEVERE TSTM WATCH MAY BE NEEDED.
ELEVATED CONVECTION CONTINUES TO INITIATE AND DEEPEN ACROSS PORTIONS
OF NERN/E-CNTRL TX INTO NRN LA IN RESPONSE TO A BROAD AREA OF
LOW-LEVEL ISENTROPIC ASCENT TO THE NORTH OF THE SFC FRONT DRAPED
ACROSS THE LOWER MS VALLEY REGION. THE MOST ROBUST CONVECTIVE
INITIATION IS NOTED WITHIN A 30-MILE-WIDE ZONE CENTERED ALONG A LINE
FROM 40 MILES NNE OF LFK TO 35 MILES SW OF MLU...WHICH COINCIDES
WITH A LOW-LEVEL CONFLUENCE AXIS EVIDENT IN KINEMATIC FIELDS BASED
ON REGIONAL PROFILER DATA. THIS ACTIVITY IS FORECAST TO CONTINUE TO
INCREASE IN COVERAGE AND INTENSITY OVER THE NEXT FEW
HOURS...ESPECIALLY AS ASCENT INCREASES WITH THE APPROACH OF A
MID-LEVEL WAVE CURRENTLY CROSSING KS/OK EVIDENT IN WV IMAGERY. AS
WARM ADVECTION ATOP THE NEAR-SURFACE COLD LAYER CONTINUES AND
MID-LEVEL LAPSE RATES STEEPEN...ELEVATED INSTABILITY WILL INCREASE
WITH MUCAPE VALUES AOA 500 J PER KG OVERSPREADING THE DISCUSSION
AREA THROUGH THE EVENING...ALLOWING FOR CONVECTION TO INTENSIFY WITH
TIME. MODERATE MID-LEVEL FLOW WILL ALLOW FOR CLOUD-BEARING SHEAR
MAGNITUDES OF 40 TO 50 KT...POTENTIALLY YIELDING ELEVATED SUPERCELL
STRUCTURES WITH A THREAT FOR LARGE HAIL. A SEVERE THUNDERSTORM WATCH
MAY BE NEEDED TO THE NORTH OF TORNADO WATCH NUMBER 72.
..COHEN.. 03/29/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MEG...JAN...LZK...SHV...
LAT...LON 33249393 33539280 33939116 33878953 32828926 32379003
32199122 32029191 31709304 31489419 31669469 32189508
32919475 33249393SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 29, 6:26 PM CDT | Severe Thunderstorm Watch | SPC | Ashley, Chicot | 8 hr |
| Mar 29, 2:48 PM CDT | Mesoscale Discussion | SPC | Acadia, Allen, Ascension, Assumption, Beauregard, Calcasieu and 29 more | 87 min |
| Mar 29, 3:17 PM CDT | Tornado Watch | SPC | Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 34 more | 7 hr |
| Mar 29, 6:47 PM CDT | Mesoscale Discussion | SPC | Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 33 more | 118 min |
| Mar 29, 2:18 PM CDT | Mesoscale Discussion | SPC | Atascosa, Bandera, Bee, Bexar, DeWitt, Dimmit and 22 more | 117 min |
| Mar 29, 3:57 PM CDT | Severe Thunderstorm Watch | SPC | Aransas, Atascosa, Bandera, Bastrop, Bee, Bexar and 39 more | 7 hr |
| Mar 29, 5:59 PM CDT | Mesoscale Discussion | SPC | Aransas, Atascosa, Bandera, Bastrop, Bee, Bexar and 33 more | 2 hr |
Nearby
Mesoscale Discussions in Louisiana, 2011Mesoscale Discussions in Mississippi, 2011Mesoscale Discussions in Arkansas, 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.