Alert archive / Mississippi / Tornado Watches in 2013

Tornado Watch 128

April 18, 201312 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Apr 18, 2013, 5:52 PM CDT for 12 counties in Mississippi. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
Apr 18, 2013, 5:52 PM CDT (22:52 UTC)
Expired
Apr 18, 2013, 11:00 PM CDT
In force
5 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
60 kt

Counties Calhoun County, MS, Chickasaw County, MS, Itawamba County, MS, Lafayette County, MS, Lee County, MS, Monroe County, MS, Panola County, MS, Pontotoc County, MS, Quitman County, MS, Tallahatchie County, MS, Union County, MS, Yalobusha County, MS

The radar

The Columbus AFB radar (KGWX), 95 km from the middle of the area, began a volume at 22:52 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
30%
One or more EF2 to EF5 tornadoes
10%
Ten or more severe wind reports
20%
One or more gusts of 65 knots or more
10%
Ten or more severe hail reports
20%
One or more hailstones of 2 inches or more
10%
Six or more combined severe hail and wind reports
60%

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Little Rock, AR (KLZK), launched 12:00Z, 10.9 hours before the alert went out and 93 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, Little Rock, AR at 12:00Z on 2013-04-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1219 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, Little Rock, AR at 12:00Z on 2013-04-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 421 square meters per square second.19395878Sfc1 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
1219 J/kg
Mixed-layer CIN
-7 J/kg
Mixed-layer LCL
578 m above ground
0-6 km bulk shear
49 kt
0-1 km storm-relative helicity
421 m²/s²
0-3 km storm-relative helicity
522 m²/s²
Significant tornado parameter
3.3
Supercell composite
19.6

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 18, 12:48 PM CDTMesoscale DiscussionSPCBenton, Bolivar, Coahoma, DeSoto, Grenada, Humphreys and 13 more87 min
Apr 18, 1:43 PM CDTTornado WatchSPCAdams, Attala, Bolivar, Carroll, Choctaw, Claiborne and 28 more8 hr
Apr 18, 4:56 PM CDTMesoscale DiscussionSPCAttala, Bolivar, Calhoun, Carroll, Chickasaw, Choctaw and 27 more94 min
Apr 18, 6:52 PM CDTMesoscale DiscussionSPCAttala, Calhoun, Carroll, Chickasaw, Choctaw, Clay and 12 more83 min

Nearby

Tornado Watches in Mississippi, 2013Every tornado watch in 2013

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.