Mesoscale Discussion 246

Issued

Mar 12, 2012, 1:23 AM CDT (06:23 UTC)

Expired

Mar 12, 2012, 3:30 AM CDT

In force

2 hr

Issued by

the Storm Prediction Center

Counties Ascension Parish, LA, Assumption Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Livingston Parish, LA, Saint Charles Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Vermilion Parish, LA

The Lake Charles radar (KLCH), 144 km from the middle of the area, began a volume at 06:23 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.

183 
ACUS11 KWNS 120623
SWOMCD
SPC MCD 120623 
LAZ000-120830-

MESOSCALE DISCUSSION 0246
NWS STORM PREDICTION CENTER NORMAN OK
0123 AM CDT MON MAR 12 2012

AREAS AFFECTED...SOUTHERN LA

CONCERNING...TORNADO WATCH 72...

VALID 120623Z - 120830Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 72 CONTINUES.

TORNADO WATCH 72 CONTINUES UNTIL 08Z /LOCALLY EXTENDED/ ACROSS
SOUTH-CENTRAL LA. AN ISOLATED TORNADO/DAMAGING WIND THREAT...ALONG
WITH LOCALLY HEAVY RAINFALL...WILL CONTINUE TO SPREAD EASTWARD
ACROSS SOUTH-CENTRAL/SOUTHEAST LA OVER THE NEXT FEW HOURS. CURRENT
THINKING IS THAT THIS POTENTIAL WILL REMAIN SUFFICIENTLY
LIMITED/ISOLATED SUCH THAT AN ADDITIONAL WATCH IS NOT ANTICIPATED TO
THE EAST OF TORNADO WATCH 72 ACROSS SOUTHEAST LA.

A NORTHEAST-SOUTHWEST ARCING BAND/CLUSTER OF TSTMS CONTINUES TO
PERSIST/SPREAD EASTWARD ACROSS SOUTH-CENTRAL LA EARLY IN THE
OVERNIGHT. THIS COINCIDES WITH THE ENTRANCE BRANCH OF A MODERATELY
STRONG /BUT PERHAPS WANING/ SOUTHERLY LOW LEVEL JET...ALONG WITH AN
ASSOCIATED SLOW NORTHWARD INFLUX OF AN INCREASINGLY MOIST MARITIME
GULF AIRMASS /UPPER 60S F SURFACE DEWPOINTS/. EMBEDDED
SUPERCELLS/VORTICES HAVE BEEN NOTED OVER THE PAST FEW HOURS WITHIN
THIS CONVECTIVE LINE...AND A SIMILAR POTENTIAL MAY CONTINUE IN AN
ISOLATED/LIMITED SENSE IN LA COASTAL AREAS GIVEN THE MOIST NATURE OF
THE BOUNDARY LAYER/SUFFICIENT LOW-LEVEL SHEAR. THAT SAID...
EXPECTATIONS ARE FOR THE OVERALL SEVERE THREAT TO SLOWLY WANE
THROUGH THE EARLY MORNING HOURS OWING TO A WEAKENING LLJ/INCREASING
SURFACE RIDGING ETC. OTHERWISE...HEAVY/ POTENTIALLY REPETITIVE
RAINFALL WILL LIKELY LINGER ACROSS FAR SOUTH-CENTRAL/SOUTHEAST LA
OVER THE NEXT FEW HOURS...AS MOIST/CONFLUENT TRAJECTORIES /WITH PW
VALUES AROUND 1.5 IN/ PERSIST IN PROXIMITY TO THE SLOW
EASTWARD-MOVING COMPLEX.

..GUYER.. 03/12/2012

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

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

LAT...LON   29289311 29699272 30059183 30409141 30649070 30369011
            29379060 29169231 29289311

Mesoscale Discussions in Louisiana, 2012Every mesoscale discussion in 2012

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.