Alert archive / Mississippi / Tornado Watches in 2012

Tornado Watch 599

August 30, 201253 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Aug 30, 2012, 9:44 PM CDT for 53 counties in Mississippi. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Aug 30, 2012, 9:44 PM CDT (02:44 UTC)
Expired: Aug 31, 2012, 3:13 AM CDT
In force: 5 hr
Issued by: the Storm Prediction Center

All 53 counties

Attala County, MS, Bolivar County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Claiborne County, MS, Clarke County, MS, Clay County, MS, Coahoma County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Grenada County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Jasper County, MS, Jefferson Davis County, MS, Jones County, MS, Kemper County, MS, Lamar County, MS, Lauderdale County, MS, Lawrence County, MS, Leake County, MS, Leflore County, MS, Lincoln County, MS, Lowndes County, MS, Madison County, MS, Marion County, MS, Monroe County, MS, Montgomery County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Oktibbeha County, MS, Pike County, MS, Quitman County, MS, Rankin County, MS, Scott County, MS, Sharkey County, MS, Simpson County, MS, Smith County, MS, Sunflower County, MS, Tallahatchie County, MS, Walthall County, MS, Warren County, MS, Washington County, MS, Webster County, MS, Winston County, MS, Yalobusha County, MS, Yazoo County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 58 km from the middle of the area, began a volume at 02:45 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.

Warnings issued inside it

1 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Aug 30, 10:07 PM CDT	Tornado Warning	JAN	Attala, Choctaw, Winston	32 min

Discussions around it

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

The nearest sounding before it

Jackson, MS (KJAN), launched 00:00Z, 2.7 hours before the alert went out and 54 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 42 J/kg
Mixed-layer CIN: -83 J/kg
Mixed-layer LCL: 796 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 303 m²/s²
0-3 km storm-relative helicity: 319 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

932 
WWUS20 KWNS 310248
SEL9
SPC WW 310248
ARZ000-MSZ000-311000-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 599
NWS STORM PREDICTION CENTER NORMAN OK
945 PM CDT THU AUG 30 2012

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

       FAR EASTERN ARKANSAS
       MISSISSIPPI

EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 945 PM
UNTIL 500 AM CDT.

TORNADOES...THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS
LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 65 STATUTE
MILES EAST AND WEST OF A LINE FROM 50 MILES NORTHEAST OF
GREENWOOD MISSISSIPPI TO 20 MILES SOUTHEAST OF MC COMB
MISSISSIPPI.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...CONTINUE...WW 598...

DISCUSSION...SINCE AROUND 01Z...A RENEWAL IN DEEP CONVECTION HAS
OCCURRED FROM ALONG THE I-20 CORRIDOR BETWEEN JAN AND MEI SWD TO E
AND S OF MCB...PRESUMABLY OWING TO AN INCREASE IN LOW-LEVEL
CONFLUENCE PER AREA VAD DATA.  INSTABILITY IS WEAK BUT SUFFICIENT TO
SUPPORT CONVECTIVE ELEMENTS DEEP ENOUGH TO PRODUCE LIGHTNING.  GIVEN
THE PRESENCE OF LARGE...CLOCKWISE-CURVED HODOGRAPHS WITH 0-1 KM SRH
OF 200-350+ M2/S2...SETUP WILL REMAIN SUPPORTIVE OF EMBEDDED
SUPERCELL STRUCTURES CAPABLE OF BRIEF TORNADOES.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH EXTREME
TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI
WITH MAXIMUM TOPS TO 400. MEAN STORM MOTION VECTOR 18035.


...MEAD

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 30, 7:15 PM CDT	Mesoscale Discussion	SPC	Attala, Bolivar, Carroll, Choctaw, Claiborne, Clarke and 36 more	90 min
Aug 30, 9:05 PM CDT	Mesoscale Discussion	SPC	Adams, Attala, Bolivar, Carroll, Choctaw, Claiborne and 51 more	55 min

Nearby

Tornado Watches in Mississippi, 2012 Every tornado watch 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.