Alert archive / Mississippi / Mesoscale Discussions in 2011

Mesoscale Discussion 445

April 15, 201110 parishes in Louisiana; 21 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Apr 15, 2011, 7:51 PM CDT for 10 parishes in Louisiana; 21 counties in Mississippi. It was in force for 54 min.

The area

The outline as issued.

The facts

Issued: Apr 15, 2011, 7:51 PM CDT (00:51 UTC)
Expired: Apr 15, 2011, 8:45 PM CDT
In force: 54 min
Issued by: the Storm Prediction Center

All 31 counties

Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, Livingston Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA, Clarke County, MS, Covington County, MS, Forrest County, MS, Hancock County, MS, Jasper County, MS, Jefferson Davis County, MS, Jones County, MS, Kemper County, MS, Lamar County, MS, Lauderdale County, MS, Lawrence County, MS, Marion County, MS, Newton County, MS, Noxubee County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Smith County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 89 km from the middle of the area, began a volume at 00:54 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

Jackson, MS (KJAN), launched 00:00Z, 0.9 hours before the alert went out and 96 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: 173 J/kg
Mixed-layer CIN: -18 J/kg
Mixed-layer LCL: 1488 m above ground
0-6 km bulk shear: 74 kt
0-1 km storm-relative helicity: 34 m²/s²
0-3 km storm-relative helicity: 165 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.3

Open this sounding in Storm Lab

The text

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

966 
ACUS11 KWNS 160051
SWOMCD
SPC MCD 160051 
MSZ000-LAZ000-160145-

MESOSCALE DISCUSSION 0445
NWS STORM PREDICTION CENTER NORMAN OK
0751 PM CDT FRI APR 15 2011

AREAS AFFECTED...ERN MS/SERN LA

CONCERNING...TORNADO WATCH 144...

VALID 160051Z - 160145Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 144 CONTINUES.

DESPITE THE 00Z KJAN SOUNDING /JUST EAST OF THE REMNANT DRYLINE/
INDICATING AN SBCAPE VALUE OF 2820 J PER KG...THE MOIST LAYER IS
VERY SHALLOW BENEATH A VERY DEEP LAYER OF DRY AIR /YIELDING AN
MLCAPE VALUE OF 222 J PER KG/. THIS DRY AIR IS ASSOCIATED WITH A
STRONG DRY INTRUSION WRAPPING AROUND THE SRN SEMICIRCLE OF THE PV
ANOMALY CENTERED OVER THE MID-MS VALLEY REGION. CONVECTION AHEAD OF
THE DRYLINE IN FAR ERN MS AND SERN LA APPEARS TO BE STRUGGLING TO
DEEPEN DUE TO DRY AIR ENTRAINMENT INTO UPDRAFTS. NO OTHER CONVECTIVE
INITIATION HAS BEEN NOTED ALONG THE DRYLINE PARALLELING THE NATCHEZ
TRACE PARKWAY. WITH THE CONTINUED DRY AIR ADVECTION ALOFT...AN
UPWARD TREND IN CONVECTION IS NOT ANTICIPATED. IF THIS VERIFIES
DURING THE NEXT HALF HOUR...THEN WW 144 WILL BE ALLOWED TO BE
CANCELLED EARLY /AFTER 01Z/.

..COHEN.. 04/16/2011

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

ATTN...WFO...MOB...JAN...LIX...LCH...

LAT...LON   29819120 30199135 30779112 31409025 32168957 32758906
            33358871 33488837 32868836 32468844 30568879 29899064
            29819120

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 15, 7:16 PM CDT	Mesoscale Discussion	SPC	George, Greene, Jackson, Stone	59 min
Apr 15, 7:48 PM CDT	Tornado Watch	SPC	George, Greene, Perry, Stone, Wayne	6 hr
Apr 15, 10:41 PM CDT	Mesoscale Discussion	SPC	George, Greene	94 min

Nearby

Mesoscale Discussions in Mississippi, 2011 Mesoscale Discussions in Louisiana, 2011 Every mesoscale discussion in 2011

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.