Alert archive / Arkansas / Mesoscale Discussions in 2012
Mesoscale Discussion 2135
The Storm Prediction Center issued this mesoscale discussion at Dec 8, 2012, 3:40 PM CST for 16 counties in Arkansas; 10 parishes in Louisiana; 13 counties in Texas. It was in force for 65 min.
The area
The outline as issued.
The facts
- Issued
- Dec 8, 2012, 3:40 PM CST (21:40 UTC)
- Expired
- Dec 8, 2012, 4:45 PM CST
- In force
- 65 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
All 39 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, Lafayette County, AR, Lincoln County, AR, Little River County, AR, Miller County, AR, Nevada County, AR, Ouachita County, AR, Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Red River Parish, LA, Union Parish, LA, Webster Parish, LA, Bowie County, TX, Cass County, TX, Cherokee County, TX, Gregg County, TX, Harrison County, TX, Marion County, TX, Morris County, TX, Nacogdoches County, TX, Panola County, TX, Rusk County, TX, Shelby County, TX, Smith County, TX, Upshur County, TX
The radar
The Shreveport radar (KSHV), 69 km from the middle of the area, began a volume at 21:40 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, 9.7 hours before the alert went out and 63 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
- 480 J/kg
- Mixed-layer CIN
- -20 J/kg
- Mixed-layer LCL
- 569 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km storm-relative helicity
- 91 m²/s²
- 0-3 km storm-relative helicity
- 120 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 1.7
The text
As transmitted, in the capitals the NWS used until 2016.
630
ACUS11 KWNS 082141
SWOMCD
SPC MCD 082140
ARZ000-LAZ000-TXZ000-OKZ000-082245-
MESOSCALE DISCUSSION 2135
NWS STORM PREDICTION CENTER NORMAN OK
0340 PM CST SAT DEC 08 2012
AREAS AFFECTED...ARKLATEX
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 082140Z - 082245Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...A FEW ROBUST THUNDERSTORMS SHOULD EVOLVE ALONG A CORRIDOR
FROM SRN AR INTO NERN TX OVER THE NEXT FEW HOURS. MARGINALLY SEVERE
HAIL/GUSTY WINDS ARE THE PRIMARY THREATS.
DISCUSSION...MEAGER LARGE SCALE FORCING ALONG A WEAK DIABATICALLY
ENHANCED SFC BOUNDARY IS EXPECTED TO BE THE FOCUS FOR CONVECTION
OVER THE NEXT FEW HOURS. PARTIAL SUNSHINE HAS CONTRIBUTED TO MODEST
LOW LEVEL LAPSE RATES ACROSS THE ARKLATEX REGION WHERE SFC-3KM
VALUES ARE APPROACHING 6.5-7 C/KM. OVER THE LAST HOUR OR SO A LONE
THUNDERSTORM...DISPLAYING WEAK SUPERCELL CHARACTERISTICS AT
TIMES...EARLIER DEVELOPED OVER COLUMBIA COUNTY AR AND IS MOVING
ENEWD ACROSS SRN AR TOWARD AN AIRMASS THAT IS LESS CONDUCIVE FOR
ROBUST UPDRAFTS. DIABATIC HEATING ALONG THE WIND SHIFT WILL PROVE
INSTRUMENTAL IN ADDITIONAL DEVELOPMENT OVER THE NEXT FEW HOURS WITH
INCREASING LOW LEVEL WARM ADVECTION OVER NERN TX/SERN OK/SWRN AR
POSSIBLY AIDING DEVELOPMENT ACROSS THIS REGION AFTER DARK. EITHER
SCENARIO IS NOT EXPECTED TO RESULT IN ORGANIZED SEVERE THUNDERSTORMS
DUE TO WEAK LOW LEVEL STORM INFLOW WITHIN MODESTLY SHEARED
ENVIRONMENT. ASIDE FROM MARGINALLY SEVERE HAIL/WIND GUSTS THIS
ACTIVITY SHOULD REMAIN MOSTLY SUB-SEVERE.
..DARROW/HART.. 12/08/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...JAN...LZK...SHV...FWD...
LAT...LON 33789444 34239304 33999149 32889149 32159299 31319479
31989556 33789444Nearby
Mesoscale Discussions in Arkansas, 2012Mesoscale Discussions in Texas, 2012Mesoscale Discussions in Louisiana, 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.