Alert archive / Alabama / Mesoscale Discussions in 2011

Mesoscale Discussion 191

March 5, 20114 states

The Storm Prediction Center issued this mesoscale discussion at Mar 5, 2011, 1:31 PM CST for 4 states. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued: Mar 5, 2011, 1:31 PM CST (19:31 UTC)
Expired: Mar 5, 2011, 3:00 PM CST
In force: 89 min
Issued by: the Storm Prediction Center

All 23 counties

Baldwin County, AL, Butler County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Escambia County, AL, Geneva County, AL, Mobile County, AL, Pike County, AL, Bay County, FL, Escambia County, FL, Holmes County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL, Washington County, FL, Plaquemines Parish, LA, Saint Bernard Parish, LA, George County, MS, Harrison County, MS, Jackson County, MS

The radar

The Mobile radar (KMOB), 86 km from the middle of the area, began a volume at 19:30 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.

Tornado Watch 40Mar 5, 3:15 PM CST

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 7.5 hours before the alert went out and 180 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: 960 J/kg
Mixed-layer CIN: -5 J/kg
Mixed-layer LCL: 451 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 194 m²/s²
0-3 km storm-relative helicity: 264 m²/s²
Significant tornado parameter: 1.0
Supercell composite: 5.8

Open this sounding in Storm Lab

The text

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

549 
ACUS11 KWNS 051932
SWOMCD
SPC MCD 051931
FLZ000-ALZ000-MSZ000-LAZ000-052100-

MESOSCALE DISCUSSION 0191
NWS STORM PREDICTION CENTER NORMAN OK
0131 PM CST SAT MAR 05 2011

AREAS AFFECTED...PARTS OF SE LA...SRN MS...SRN AL AND WRN FL

CONCERNING...TORNADO WATCH 39...

VALID 051931Z - 052100Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 39 CONTINUES.

A NEW WW WILL LIKELY BE ISSUED BY 22Z EXPIRATION OF WW 39.

CENTRAL GULF COAST MESOSCALE CONVECTIVE SYSTEM CONTINUES TO EXPAND
SOUTHWARD INTO THE NORTH CENTRAL GULF OF MEXICO...WHILE MAINTAINING
INTENSITY INLAND OF COASTAL AREAS.  SIGNIFICANT WIND DAMAGE/TORNADO
POTENTIAL HAS BEEN MOST PROMINENT WITH MULTIPLE MESOCYCLONES
EMBEDDED WITHIN THE EVOLVING SQUALL LINE.  WHILE THIS MAY REMAIN THE
CASE AS IT ADVANCES TOWARD THE EASTERN GULF COAST LATE THIS
AFTERNOON...THE FORWARD PROGRESSION OF THE LINE HAS ACCELERATED IN
EXCESS OF 40 KTS...AND A BROADER WIND DAMAGE THREAT COULD STILL
DEVELOP ALONG THE GUST FRONT.

UNCERTAINTY REMAINS CONCERNING HOW FAR INLAND THIS THREAT WILL
DEVELOP LATE THIS AFTERNOON.  THE STRONGEST PORTION OF THE LINE
APPEARS LIKELY TO REMAIN FOCUSED NEAR THE COAST OR JUST
OFFSHORE...AND SURFACE TRAJECTORIES EMANATING FROM THE SOUTHEASTERN
RIDGE MAY SLOW MOISTENING NORTH AND EAST OF MOBILE BAY.
HOWEVER...AS THE DIGGING UPSTREAM IMPULSE BEGINS TO TAKE A MORE
EASTWARD TURN INTO THE LOWER MISSISSIPPI VALLEY...STRONG FORCING MAY
SUPPORT NORTHWARD DEVELOPMENT OF THE CONVECTIVE LINE THROUGH MUCH OF
SOUTH CENTRAL/SOUTHEASTERN ALABAMA AFTER 22-23Z.

..KERR.. 03/05/2011

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

ATTN...WFO...TAE...BMX...MOB...LIX...

LAT...LON   30668940 31308798 31718710 31928626 31868568 31428531
            30548528 29598570 28618696 27718798 27518956 27949112
            28759038 29508968 30668940

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 5, 8:40 AM CST	Mesoscale Discussion	SPC	Mobile	65 min
Mar 5, 8:54 AM CST	Tornado Watch	SPC	Baldwin, Choctaw, Clarke, Mobile, Washington	7 hr
Mar 5, 3:13 PM CST	Tornado Watch	SPC	Baldwin, Choctaw, Clarke, Coffee, Conecuh, Covington and 8 more	7 hr
Mar 4, 9:33 PM CST	Mesoscale Discussion	SPC	Saint Tammany, Tangipahoa, Washington	57 min
Mar 5, 11:12 AM CST	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Jefferson, Lafourche and 12 more	93 min

Nearby

Mesoscale Discussions in Alabama, 2011 Mesoscale Discussions in Florida, 2011 Mesoscale Discussions in Mississippi, 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.