Alert archive / Louisiana / Mesoscale Discussions in 2012
Mesoscale Discussion 487
The Storm Prediction Center issued this mesoscale discussion at Apr 10, 2012, 1:56 PM CDT for 4 states. It was in force for 64 min.
The area
The outline as issued.
The facts
- Issued
- Apr 10, 2012, 1:56 PM CDT (18:56 UTC)
- Expired
- Apr 10, 2012, 3:00 PM CDT
- In force
- 64 min
- Issued by
- the Storm Prediction Center
All 56 counties
Ashley County, AR, Bradley County, AR, Calhoun County, AR, Clark County, AR, Cleveland County, AR, Columbia County, AR, Dallas County, AR, Drew County, AR, Hempstead County, AR, Howard County, AR, Lafayette County, AR, Lincoln County, AR, Little River County, AR, Miller County, AR, Nevada County, AR, Ouachita County, AR, Pike County, AR, Sevier County, AR, Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln 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, Choctaw County, OK, McCurtain County, OK, Bowie County, TX, Camp County, TX, Cass County, TX, Delta County, TX, Gregg County, TX, Harrison County, TX, Lamar County, TX, Marion County, TX, Morris County, TX, Panola County, TX, Red River County, TX, Shelby County, TX, Titus County, TX, Upshur County, TX
The radar
The Shreveport radar (KSHV), 69 km from the middle of the area, began a volume at 18:59 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
Shreveport, LA (KSHV), launched 12:00Z, 6.9 hours before the alert went out and 66 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
- 357 J/kg
- Mixed-layer CIN
- -85 J/kg
- Mixed-layer LCL
- 1193 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 103 m²/s²
- 0-3 km storm-relative helicity
- 96 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.9
The text
As transmitted, in the capitals the NWS used until 2016.
800
ACUS11 KWNS 101857
SWOMCD
SPC MCD 101856
ARZ000-LAZ000-TXZ000-OKZ000-102000-
MESOSCALE DISCUSSION 0487
NWS STORM PREDICTION CENTER NORMAN OK
0156 PM CDT TUE APR 10 2012
AREAS AFFECTED...SERN OK INTO ARKLATEX
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 101856Z - 102000Z
STRONG TO SEVERE STORMS WILL BECOME INCREASINGLY POSSIBLE THIS
AFTERNOON...BUT DUE TO ISOLATED NATURE...A WW IS NOT ANTICIPATED.
1830Z VISIBLE IMAGERY SHOWS CU FIELDS GRADUALLY INCREASING IN THE
VICINITY OF TWO SEPARATE SURFACE FEATURES...A STATIONARY FRONT
EXTENDING INTO A REMNANT CONVECTIVELY INDUCED SURFACE BOUNDARY FROM
NRN AL/MS WWD INTO CNTRL OK...AND AN AREA OF SURFACE CONFLUENCE
NOTED FROM E CNTRL TX INTO CNTRL MS. AMPLE SURFACE HEATING AND A
MOIST AIR MASS CHARACTERIZED BY DEW POINTS IN THE 60S HAS
CONTRIBUTED TO MODERATE INSTABILITY. HOWEVER...A SUBTLE WARM LAYER
LIKELY STILL EXISTS AROUND 750 MB...EVIDENCED BY THE PREDOMINANTLY
STABLE APPEARANCE OF THE CLOUD FIELDS ON VISIBLE IMAGERY /WITH THE
EXCEPTION OF NRN LA WHERE MORE VERTICAL DEVELOPMENT IS NOTED/. MODEL
FORECAST SOUNDINGS INDICATE THE STABLE LAYER SHOULD GRADUALLY ERODE
WITHIN THE NEXT FEW HOURS...SUPPORTING MORE ROBUST UPDRAFTS WITH
TIME. MORE PROBLEMATIC IS SOMEWHAT NEBULOUS UPPER FORCING...ALTHOUGH
THE LA CONVECTION IS LIKELY RESPONDING TO A DECAYING UPPER
WAVE...NOTED ON WV IMAGERY FROM CNTRL TX INTO SRN MS/LA. FARTHER N
WHERE THE GREATEST INSTABILITY EXISTS OVER SERN OK INTO SRN AR HAS
NO NOTABLE UPPER FEATURE TO INSTIGATE DEEP MOIST CONVECTION...AND
MAY POSSIBLY BE SUPPRESSED IN SUBSIDENCE FOLLOWING THE
AFOREMENTIONED WAVE. AS SUCH...ALTHOUGH THUNDERSTORMS ARE
EXPECTED...THE DEVELOPMENT OF STRONG TO SEVERE STORMS IS EXPECTED TO
REMAIN ISOLATED.
..HURLBUT.. 04/10/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...JAN...LZK...LCH...SHV...TSA...FWD...OUN...
LAT...LON 33209516 33359585 34039589 34499511 34229336 34099178
33719136 32459135 31509164 31439281 31809427 32449489
33209516SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 9, 8:07 PM CDT | Mesoscale Discussion | SPC | Craig, Nowata, Osage, Rogers, Washington | 83 min |
| Apr 9, 8:54 PM CDT | Mesoscale Discussion | SPC | Alfalfa, Beckham, Blaine, Caddo, Comanche, Cotton and 14 more | 66 min |
| Apr 10, 12:52 AM CDT | Mesoscale Discussion | SPC | Greer, Harmon, Jackson, Tillman | 23 min |
| Apr 10, 3:35 PM CDT | Mesoscale Discussion | SPC | Beaver, Cimarron, Ellis, Roger Mills, Texas | 115 min |
| Apr 9, 7:33 PM CDT | Mesoscale Discussion | SPC | Andrews, Borden, Cochran, Crane, Crosby, Dawson and 25 more | 57 min |
| Apr 10, 12:25 AM CDT | Mesoscale Discussion | SPC | Brewster, Pecos, Presidio, Terrell | 35 min |
Nearby
Mesoscale Discussions in Louisiana, 2012Mesoscale Discussions in Arkansas, 2012Mesoscale Discussions in Texas, 2012Every 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.