Alert archive / Louisiana / Mesoscale Discussions in 2012

Mesoscale Discussion 89

February 1, 20128 parishes in Louisiana; Hancock County, Pearl River County, Mississippi

The Storm Prediction Center issued this mesoscale discussion at Feb 1, 2012, 5:18 PM CST for 8 parishes in Louisiana; Hancock County, Pearl River County, Mississippi. It was in force for 87 min.

The area

The outline as issued.

The facts

Issued: Feb 1, 2012, 5:18 PM CST (23:18 UTC)
Expired: Feb 1, 2012, 6:45 PM CST
In force: 87 min
Issued by: the Storm Prediction Center

Counties Ascension Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Saint Charles Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Hancock County, MS, Pearl River County, MS

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 11.3 hours before the alert went out and 62 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: 781 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 457 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 168 m²/s²
0-3 km storm-relative helicity: 235 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 3.4

Open this sounding in Storm Lab

The text

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

523 
ACUS11 KWNS 012319
SWOMCD
SPC MCD 012318
LAZ000-MSZ000-020045-

MESOSCALE DISCUSSION 0089
NWS STORM PREDICTION CENTER NORMAN OK
0518 PM CST WED FEB 01 2012

AREAS AFFECTED...SERN LA...EXTREME SERN MS

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 012318Z - 020045Z

TSTMS MAY PRODUCE STRONG WIND GUSTS ACROSS PORTIONS OF SERN LA AND
EXTREME SERN MS THROUGH 01Z. A WW WILL NOT BE NEEDED.

A SMALL...AND OCCASIONALLY BOWING...CONVECTIVE LINE SEGMENT
CONTINUES MOVING EWD ACROSS LIVINGSTON AND ASCENSION PARISHES INVOF
A REMNANT OUTFLOW BOUNDARY EMANATING FROM EARLIER CONVECTION.
SLIDELL WSR-88D DATA INDICATED A WELL-DEFINED REAR-INFLOW JET IN
ASSOCIATION WITH THIS ACTIVITY AS IT PASSED NEAR BATON
ROUGE...THOUGH THIS JET CURRENTLY APPEARS ILL-DEFINED BELOW 5.5 KFT.
HOWEVER...WITH 0-6-KM BULK SHEAR MAGNITUDES OF 45-50 KT PER SLIDELL
VWP DATA...AND AROUND 500 J/KG OF MLCAPE NEAR AND SOUTH OF THE
BOUNDARY...THE LINE SEGMENT MAY CONTINUE BE MAINTAINED TOWARD LAKE
PONTCHARTRAIN WITH ADDITIONAL DEVELOPMENT ALREADY NOTED OVER ITS SRN
FLANK. WEAK DCVA IN ASSOCIATION WITH THE GLANCING INFLUENCE OF A
MID-LEVEL SHORTWAVE TROUGH MAY ALSO SUPPORT CONVECTIVE INITIATION
DURING THE NEXT COUPLE OF HOURS PRIOR TO NOCTURNAL STABILIZATION.
STRONG WIND GUSTS...AND AN ISOLATED DMGG WIND GUST OR TWO...CANNOT
BE RULED OUT WITH THE STRONGEST STORMS. THE MARGINAL/BRIEF DURATION
OF ANY SVR THREAT PRECLUDES THE NEED FOR A WW.

..COHEN.. 02/01/2012

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

ATTN...WFO...LIX...

LAT...LON   29539056 29769102 30239114 30539087 30849016 30818953
            30038930 29658974 29539056

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 1, 1:06 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Calcasieu, Cameron, East Feliciana and 5 more	114 min
Feb 1, 10:18 AM CST	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 6 more	117 min
Feb 1, 12:37 PM CST	Severe Thunderstorm Watch	SPC	Bienville, Bossier, Caddo, Claiborne, Lincoln, Union and 1 more	5 hr
Feb 1, 1:22 PM CST	Mesoscale Discussion	SPC	Bossier, Caddo, Claiborne, Union, Webster	113 min
Feb 1, 1:36 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 12 more	84 min
Feb 1, 2:58 PM CST	Mesoscale Discussion	SPC	Bienville, Bossier, Claiborne, Lincoln, Morehouse, Union and 2 more	2 hr
Feb 1, 3:45 PM CST	Severe Thunderstorm Watch	SPC	East Carroll, Morehouse, West Carroll	3 hr
Feb 1, 4:49 PM CST	Mesoscale Discussion	SPC	Attala, Benton, Calhoun, Carroll, Chickasaw, Choctaw and 17 more	56 min
Feb 1, 4:59 PM CST	Severe Thunderstorm Watch	SPC	Alcorn, Attala, Benton, Calhoun, Carroll, Chickasaw and 21 more	4 hr

Nearby

Mesoscale Discussions in Louisiana, 2012 Mesoscale Discussions in Mississippi, 2012 Every mesoscale discussion 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.