Alert archive / Louisiana / Mesoscale Discussions in 2011
Mesoscale Discussion 2007
The Storm Prediction Center issued this mesoscale discussion at Aug 18, 2011, 3:46 PM CDT for 16 parishes in Louisiana; 5 counties in Texas. It was in force for 89 min.
The area
The outline as issued.
The facts
- Issued
- Aug 18, 2011, 3:46 PM CDT (20:46 UTC)
- Expired
- Aug 18, 2011, 5:15 PM CDT
- In force
- 89 min
- Issued by
- the Storm Prediction Center
All 21 counties
Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, De Soto Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Natchitoches Parish, LA, Rapides Parish, LA, Red River Parish, LA, Sabine Parish, LA, Vernon Parish, LA, Webster Parish, LA, Winn Parish, LA, Harrison County, TX, Panola County, TX, Sabine County, TX, San Augustine County, TX, Shelby County, TX
The nearest sounding before it
Shreveport, LA (KSHV), launched 12:00Z, 8.8 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.
- Mixed-layer CAPE
- 174 J/kg
- Mixed-layer CIN
- -284 J/kg
- Mixed-layer LCL
- 2305 m above ground
- 0-6 km bulk shear
- 7 kt
- 0-1 km storm-relative helicity
- 91 m²/s²
- 0-3 km storm-relative helicity
- 152 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
141
ACUS11 KWNS 182046
SWOMCD
SPC MCD 182046
LAZ000-TXZ000-182215-
MESOSCALE DISCUSSION 2007
NWS STORM PREDICTION CENTER NORMAN OK
0346 PM CDT THU AUG 18 2011
AREAS AFFECTED...CNTRL/NWRN LA...FAR ERN TX
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 182046Z - 182215Z
A FEW STORMS COULD PRODUCE DMGG WIND GUSTS THIS AFTERNOON.
HOWEVER...THE ISOLATED NATURE OF THE SVR THREAT SHOULD PRECLUDE THE
NEED FOR A WW.
THE BOUNDARY LAYER BETWEEN AN OUTFLOW-REINFORCED REMNANT FRONT
DRAPED ACROSS NRN LA...AND THE SRN BRANCH OF THE FRONT EXTENDING
FROM NEAR NATCHEZ MS TOWARD SWRN LA...HAS BECOME HOT AND DEEPLY
MIXED OWING TO SFC TEMPERATURES HAVING CLIMBED TO 100-105F.
SCATTERED CONVECTION CONTINUES TO DEVELOP IN RESPONSE TO LOW-LEVEL
CONVERGENCE ALONG THE AFOREMENTIONED BOUNDARIES AND MODERATE
INSTABILITY. DCAPE VALUES OF 1200-1400 J/KG DUE IN PART TO LOW-LEVEL
LAPSE RATES NEARING DRY ADIABATIC...AND TEMPERATURE-DEWPOINT SPREADS
AROUND 40F...WILL SUPPORT MICROBURSTS CAPABLE OF PRODUCING GUSTY
WINDS. ISOLATED INSTANCES OF DMGG WIND GUSTS WILL BE POSSIBLE WITH
THE STRONGEST STORMS...THOUGH THE LACK OF VERTICAL WIND SHEAR /FLOW
BELOW 5 KM AGL AOB 10 KT PER SHREVEPORT VWP/ WILL MAINTAIN A
PULSE/DISORGANIZED CONVECTIVE EVOLUTION. AS SUCH...ANY SVR THREAT IS
ONLY EXPECTED TO OCCUR ON AN ISOLATED BASIS.
..COHEN.. 08/18/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...JAN...LCH...SHV...
LAT...LON 32639247 31939177 31019209 30719306 31349447 32359472
32879383 32639247SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 18, 1:04 PM CDT | Mesoscale Discussion | SPC | Ascension, Assumption, Concordia, East Baton Rouge, East Feliciana, Franklin and 20 more | 116 min |
Nearby
Mesoscale Discussions in Louisiana, 2011Mesoscale 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.