Alert archive / Arkansas / Mesoscale Discussions in 2012
Mesoscale Discussion 309
The Storm Prediction Center issued this mesoscale discussion at Mar 20, 2012, 5:57 PM CDT for 10 counties in Arkansas; Howell County, Oregon County, Missouri. It was in force for 93 min.
The area
The outline as issued.
The facts
- Issued
- Mar 20, 2012, 5:57 PM CDT (22:57 UTC)
- Expired
- Mar 20, 2012, 7:30 PM CDT
- In force
- 93 min
- Issued by
- the Storm Prediction Center
Counties Arkansas County, AR, Fulton County, AR, Independence County, AR, Izard County, AR, Jackson County, AR, Monroe County, AR, Prairie County, AR, Sharp County, AR, White County, AR, Woodruff County, AR, Howell County, MO, Oregon County, MO
The radar
The Little Rock radar (KLZK), 73 km from the middle of the area, began a volume at 22:57 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
Little Rock, AR (KLZK), launched 12:00Z, 11.0 hours before the alert went out and 149 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.
234 ACUS11 KWNS 202257 SWOMCD SPC MCD 202257 ARZ000-MOZ000-210030- MESOSCALE DISCUSSION 0309 NWS STORM PREDICTION CENTER NORMAN OK 0557 PM CDT TUE MAR 20 2012 AREAS AFFECTED...ERN AR INTO SCNTRL MO CONCERNING...TORNADO WATCH 93... VALID 202257Z - 210030Z THE SEVERE WEATHER THREAT FOR TORNADO WATCH 93 CONTINUES. THREAT FOR ISOLATED TORNADOES AND DAMAGING WIND WILL PERSIST INTO THE MID EVENING OVER ERN AR. SOME THREAT FOR SEVERE STORMS COULD SPREAD NWD INTO SCNTRL MO THIS EVENING...AND THIS AREA IS BEING MONITORED. BROKEN LINE WITH OCCASIONAL SUPERCELL AND BOW STRUCTURES EXTENDS FROM NCNTRL SSEWD THROUGH SERN AR. STORMS ARE EMBEDDED WITHIN A MARGINAL THERMODYNAMIC ENVIRONMENT /MUCAPE AOB 500 J/KG/ BUT 40 KT VERTICAL SHEAR AND 0-1 KM STORM RELATIVE HELICITY FROM 200-300 M2/S2. ACTIVITY WILL CONTINUE TO POSE A SEVERE THREAT NEXT 2-3 HOURS AS IT LIFTS NNEWD. LATEST OBJECTIVE ANALYSIS INDICATES INSTABILITY DECREASES EVEN FURTHER WITH NWD EXTENT INTO SRN MO. TENDENCY HAS BEEN FOR STORMS TO WEAKEN AS THEY CROSS INTO MO...SO EXTENT OF SEVERE THREAT IN THIS REGION IS MORE UNCERTAIN. NEVERTHELESS...THE ENVIRONMENT MIGHT BECOME SUFFICIENT FOR AT LEAST A MODEST THREAT FOR DAMAGING WIND AND A COUPLE OF TORNADOES OVER A PORTION OF SRN MO...ESPECIALLY AS THE LLJ STRENGTHENS DURING THE EVENING. ..DIAL.. 03/20/2012 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...MEG...LZK...SGF... LAT...LON 33729145 35339182 36909229 36959130 34129095 33729145
SPC 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, 1:48 PM CDT | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Cleburne, Cleveland and 22 more | 117 min |
| Mar 20, 2:55 PM CDT | Tornado Watch | SPC | Arkansas, Baxter, Bradley, Calhoun, Cleburne, Cleveland and 25 more | 7 hr |
Nearby
Mesoscale Discussions in Arkansas, 2012Mesoscale Discussions in Missouri, 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.