Alert archive / Arkansas / Mesoscale Discussions in 2012
Mesoscale Discussion 305
The Storm Prediction Center issued this mesoscale discussion at Mar 20, 2012, 1:48 PM CDT for 28 counties in Arkansas. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- Mar 20, 2012, 1:48 PM CDT (18:48 UTC)
- Expired
- Mar 20, 2012, 3:45 PM CDT
- In force
- 117 min
- Issued by
- the Storm Prediction Center
All 28 counties
Arkansas County, AR, Ashley County, AR, Bradley County, AR, Calhoun County, AR, Cleburne County, AR, Cleveland County, AR, Conway County, AR, Dallas County, AR, Desha County, AR, Drew County, AR, Faulkner County, AR, Grant County, AR, Independence County, AR, Izard County, AR, Jackson County, AR, Jefferson County, AR, Lincoln County, AR, Lonoke County, AR, Monroe County, AR, Ouachita County, AR, Prairie County, AR, Pulaski County, AR, Saline County, AR, Searcy County, AR, Stone County, AR, Van Buren County, AR, White County, AR, Woodruff County, AR
The radar
The Little Rock radar (KLZK), 47 km from the middle of the area, began a volume at 18:49 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
Little Rock, AR (KLZK), launched 12:00Z, 6.8 hours before the alert went out and 209 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
- 223 J/kg
- Mixed-layer CIN
- -72 J/kg
- Mixed-layer LCL
- 474 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 175 m²/s²
- 0-3 km storm-relative helicity
- 222 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 1.3
The text
As transmitted, in the capitals the NWS used until 2016.
730
ACUS11 KWNS 201849
SWOMCD
SPC MCD 201848
ARZ000-MSZ000-202045-
MESOSCALE DISCUSSION 0305
NWS STORM PREDICTION CENTER NORMAN OK
0148 PM CDT TUE MAR 20 2012
AREAS AFFECTED...CENTRAL/EASTERN AR
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 201848Z - 202045Z
AT LEAST AN ISOLATED SEVERE THREAT...IN THE FORM OF DAMAGING WINDS
AND/OR A TORNADO IN ADDITION TO LOCALLY HEAVY/REPETITIVE
RAINFALL...MAY DEVELOP/INCREASE THROUGH MID/LATE AFTERNOON ACROSS
CENTRAL/EASTERN AR. ESPECIALLY PORTIONS OF SOUTH-CENTRAL/SOUTHEAST
AR ARE BEING MONITORED FOR A POSSIBLE WATCH.
WITHIN A MERIDIONAL LONGWAVE REGIME WITH NEARLY UNIDIRECTIONAL DEEP
SOUTHERLY FLOW...SHOWERS/TSTMS CONTINUE TO BE FOCUSED ALONG
COMPOSITE OUTFLOW WITHIN A GENERAL NORTH-SOUTH CORRIDOR ACROSS
NORTHERN LA INTO SOUTH-CENTRAL AR THIS AFTERNOON...INCLUDING ONGOING
SEVERE TSTMS IN NORTH-CENTRAL LA. DIURNAL HEATING/MODEST CLOUD
BREAKS HAS ALLOWED TEMPERATURES TO REACH THE MIDDLE/UPPER 70S F AS
OF 18Z...WITH LITTLE OR NO LOW-LEVEL INHIBITION LIKELY REMAINING
WITH MLCAPE TO 500-1000 J/KG.
GIVEN LIMITED FORCING ATOP THE WARM SECTOR AND THE MERIDIONAL
SCENARIO...THE CONVECTIVE MODE SHOULD REMAIN QUASI-LINEAR AND
CONTINUE TO DECIDEDLY FAVOR THE GENERAL NORTH-SOUTH COMPOSITE
BOUNDARY IN TERMS OF THE MOST SUSTAINED/VIGOROUS CONVECTION. THAT
SAID...IT IS POSSIBLE THAT SOME SHOWERS/TSTMS IN THE NEARBY WARM
SECTOR COULD SUFFICIENTLY DEEPEN/ACQUIRE ROTATION GIVEN A RELATIVELY
HIGH DEGREE OF LOW LEVEL SHEAR/SRH...ESPECIALLY IF BOUNDARY LAYER
MIXING REMAINS LIMITED /SURFACE DEWPOINTS DO NOT DIMINISH/. WSR-88D
VWP DATA FROM LITTLE ROCK IS SUGGESTIVE OF 0-1 KM SRH ON THE ORDER
OF 150-200 M2/S2 AMID STRONG DEEP LAYER SOUTHERLY FLOW...WHICH WOULD
SUPPORT LINE-EMBEDDED BOWS/MESOVORTICES ALONG WITH THE CONDITIONAL
POSSIBILITY OF SOME SUPERCELLS IMMEDIATELY AHEAD OF THE CONVECTIVE
LINE. WILL CONTINUE TO MONITOR CONVECTIVE TRENDS FOR A POSSIBLE
UPSWING IN CONVECTION ACROSS SOUTHERN AR THIS AFTERNOON AND/OR THE
POSSIBILITY THAT STRONG/SUSTAINED CONVECTION ONGOING IN NORTHERN LA
COULD NORTHWARD-BREACH TORNADO WW 92.
..GUYER.. 03/20/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MEG...JAN...LZK...SHV...
LAT...LON 33189258 33589296 34869280 36039281 36319218 35919104
33609118 33099147 33189258SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 19, 7:28 PM CDT | Tornado Watch | SPC | Howard, Little River, Miller, Sevier | 9 hr |
| Mar 19, 8:48 PM CDT | Mesoscale Discussion | SPC | Benton, Carroll, Crawford, Madison, Sebastian, Washington | 57 min |
| Mar 19, 10:17 PM CDT | Mesoscale Discussion | SPC | Baxter, Boone, Marion, Newton, Pope, Searcy | 58 min |
| Mar 19, 10:35 PM CDT | Severe Thunderstorm Watch | SPC | Baxter, Boone, Marion, Newton, Searcy | 3 hr |
| Mar 20, 2:55 PM CDT | Tornado Watch | SPC | Arkansas, Baxter, Bradley, Calhoun, Cleburne, Cleveland and 25 more | 7 hr |
| Mar 20, 5:57 PM CDT | Mesoscale Discussion | SPC | Arkansas, Fulton, Independence, Izard, Jackson, Monroe and 4 more | 93 min |
Nearby
Mesoscale Discussions in Arkansas, 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.