Alert archive / Arkansas / Mesoscale Discussions in 2012

Mesoscale Discussion 1916

September 7, 201234 counties in Arkansas

The Storm Prediction Center issued this mesoscale discussion at Sep 7, 2012, 3:09 PM CDT for 34 counties in Arkansas. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued
Sep 7, 2012, 3:09 PM CDT (20:09 UTC)
Expired
Sep 7, 2012, 4:15 PM CDT
In force
66 min
Issued by
the Storm Prediction Center
Chance of a watch
20%
All 34 counties

Baxter County, AR, Cleburne County, AR, Conway County, AR, Craighead County, AR, Cross County, AR, Faulkner County, AR, Franklin County, AR, Fulton County, AR, Garland County, AR, Independence County, AR, Izard County, AR, Jackson County, AR, Johnson County, AR, Lawrence County, AR, Logan County, AR, Lonoke County, AR, Marion County, AR, Montgomery County, AR, Newton County, AR, Perry County, AR, Poinsett County, AR, Pope County, AR, Prairie County, AR, Pulaski County, AR, Randolph County, AR, Saline County, AR, Scott County, AR, Searcy County, AR, Sharp County, AR, Stone County, AR, Van Buren County, AR, White County, AR, Woodruff County, AR, Yell County, AR

The radar

The Little Rock radar (KLZK), 79 km from the middle of the area, began a volume at 20:11 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

Springfield, MO (KSGF), launched 12:00Z, 8.2 hours before the alert went out and 201 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.

Skew-T log-pSkew-T log-p diagram, Springfield, MO at 12:00Z on 2012-09-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1095 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Springfield, MO at 12:00Z on 2012-09-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 256 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
1095 J/kg
Mixed-layer CIN
-182 J/kg
Mixed-layer LCL
1368 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
256 m²/s²
0-3 km storm-relative helicity
257 m²/s²
Significant tornado parameter
0.0
Supercell composite
5.9

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 7, 2:35 PM CDTSevere Thunderstorm WatchSPCBenton, Carroll, Crawford, Franklin, Madison, Sebastian and 1 more6 hr
Sep 7, 3:44 PM CDTMesoscale DiscussionSPCClay, Greene, Mississippi2 hr
Sep 7, 5:15 PM CDTSevere Thunderstorm WatchSPCArkansas, Baxter, Boone, Clay, Cleburne, Conway and 40 more7 hr
Sep 7, 6:06 PM CDTMesoscale DiscussionSPCBaxter, Boone, Carroll, Crawford, Franklin, Fulton and 9 more84 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.