Alert archive / Mississippi / Mesoscale Discussions in 2007

Mesoscale Discussion 9

January 4, 20076 parishes in Louisiana; 25 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Jan 4, 2007, 10:56 PM CST for 6 parishes in Louisiana; 25 counties in Mississippi. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued: Jan 4, 2007, 10:56 PM CST (04:56 UTC)
Expired: Jan 5, 2007, 12:30 AM CST
In force: 94 min
Issued by: the Storm Prediction Center

All 31 counties

Jefferson Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, Saint Tammany Parish, LA, Washington Parish, LA, Clarke County, MS, Covington County, MS, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Jasper County, MS, Jefferson Davis County, MS, Jones County, MS, Lamar County, MS, Lauderdale County, MS, Lawrence County, MS, Marion County, MS, Newton County, MS, Pearl River County, MS, Perry County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS

The radar

The Mobile radar (KMOB), 100 km from the middle of the area, began a volume at 04:58 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

Slidell Radar S, LA (KSIL), launched 00:00Z, 4.9 hours before the alert went out and 58 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: 478 J/kg
Mixed-layer CIN: -17 J/kg
Mixed-layer LCL: 547 m above ground
0-6 km bulk shear: 58 kt
0-1 km storm-relative helicity: 221 m²/s²
0-3 km storm-relative helicity: 236 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 4.9

Open this sounding in Storm Lab

The text

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

000 
ACUS11 KWNS 050456
SWOMCD
SPC MCD 050456 
ALZ000-MSZ000-LAZ000-050630-

MESOSCALE DISCUSSION 0009
NWS STORM PREDICTION CENTER NORMAN OK
1056 PM CST THU JAN 04 2007

AREAS AFFECTED...SRN AND CNTRL MS...SE LA

CONCERNING...TORNADO WATCH 2...

VALID 050456Z - 050630Z

THE TORNADO THREAT WILL CONTINUE ACROSS TORNADO WATCH 2 OVER THE
NEXT SEVERAL HOURS. ALSO...THE TORNADO THREAT SHOULD EXPAND ENEWD
CNTRL MS.

A LINE OF THUNDERSTORMS IS INCREASING IN INTENSITY AND IS LOCATED
ALONG THE INTERSTATE 55 CORRIDOR FROM NEAR LAKE PONTCHARTRAIN IN SE
LA NWD INTO SWRN MS. LATEST SFC ANALYSIS SHOWS THAT DEWPOINTS AHEAD
OF THE LINE HAVE RISEN OVER THE LAST HOUR WITH JACKSON MS AND
MERIDIAN MS BOTH AT 66 F.  THIS IS A RESULT OF SSELY FLOW NEAR THE
SFC WHICH IS TRANSPORTING LOW-LEVEL MOISTURE NWD ACROSS SCNTRL MS.
IN ADDITION...A 45 KT LOW-LEVEL JET IS LOCATED ACROSS SCNTRL MS
WHICH IS CREATING VERY STRONG LOW-LEVEL SHEAR PROFILES. ALTHOUGH
INSTABILITY IS RELATIVELY WEAK...THE SHEAR PROFILES COMBINED WITH
LCL HEIGHTS BELOW 500 METERS WILL BE FAVORABLE FOR ROTATING STORMS
AND TORNADOES AS THE CONVECTIVE LINE MOVES EWD TONIGHT. WIND DAMAGE
WILL ALSO BE POSSIBLE WITH THE BETTER ORGANIZED STORMS EMBEDDED IN
THE LINE.

..BROYLES.. 01/05/2007

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...BMX...MOB...JAN...LIX...

28968894 29018994 29359021 30639032 32049026 32718992
32718857 32238833 30958825 29358838

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 4, 6:34 PM CST	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, Jefferson, Lafourche, Livingston and 7 more	86 min
Jan 4, 8:33 PM CST	Mesoscale Discussion	SPC	Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles, Saint Tammany and 1 more	87 min
Jan 4, 8:47 PM CST	Tornado Watch	SPC	Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 6 more	7 hr
Jan 5, 2:26 AM CST	Mesoscale Discussion	SPC	Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard	64 min
Jan 5, 12:47 AM CST	Mesoscale Discussion	SPC	Alcorn, Itawamba, Lowndes, Monroe, Prentiss, Tishomingo	28 min
Jan 5, 1:15 AM CST	Tornado Watch	SPC	Choctaw, Clay, Lowndes, Noxubee, Oktibbeha, Webster and 1 more	6 hr

Nearby

Mesoscale Discussions in Mississippi, 2007 Mesoscale Discussions in Louisiana, 2007 Every mesoscale discussion in 2007

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.