Alert archive / Mississippi / Mesoscale Discussions in 2012

Mesoscale Discussion 113

February 4, 2012Baldwin County, Mobile County, Alabama; Plaquemines Parish, Saint Bernard Parish, Louisiana; 5 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Feb 4, 2012, 4:46 PM CST for Baldwin County, Mobile County, Alabama; Plaquemines Parish, Saint Bernard Parish, Louisiana; 5 counties in Mississippi. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued
Feb 4, 2012, 4:46 PM CST (22:46 UTC)
Expired
Feb 4, 2012, 6:15 PM CST
In force
89 min
Issued by
the Storm Prediction Center

Counties Baldwin County, AL, Mobile County, AL, Plaquemines Parish, LA, Saint Bernard Parish, LA, George County, MS, Greene County, MS, Harrison County, MS, Jackson County, MS, Stone County, MS

The radar

The Mobile radar (KMOB), 50 km from the middle of the area, began a volume at 22:48 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 12:00Z, 10.8 hours before the alert went out and 108 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-pSkew-T log-p diagram, Slidell Radar S, LA at 12:00Z on 2012-02-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 334 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Slidell Radar S, LA at 12:00Z on 2012-02-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 82 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
334 J/kg
Mixed-layer CIN
-3 J/kg
Mixed-layer LCL
441 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
82 m²/s²
0-3 km storm-relative helicity
115 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.6

Open this sounding in Storm Lab

The text

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

704 
ACUS11 KWNS 042246
SWOMCD
SPC MCD 042246 
ALZ000-MSZ000-LAZ000-050015-

MESOSCALE DISCUSSION 0113
NWS STORM PREDICTION CENTER NORMAN OK
0446 PM CST SAT FEB 04 2012

AREAS AFFECTED...FAR SERN LA...FAR SERN MS...FAR SWRN AL

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 042246Z - 050015Z

A FEW STORMS MAY PRODUCE STRONG WIND GUSTS INTO EARLY EVENING ACROSS
FAR SERN LA...FAR SERN MS...AND FAR SWRN AL...WITH A WEAKENING TREND
EXPECTED AFTER 01Z. A WW IS NOT NEEDED.

A PREFRONTAL SQUALL LINE CONTINUES MOVING EWD AROUND 20 KT...
CURRENTLY EXTENDING FROM EAST OF THE HATTIESBURG MS AREA SWD TOWARD
THE EAST END OF LAKE PONTCHARTRAIN TO NEAR GRAND ISLE LA. LOW-LEVEL
ASCENT AT THE LEADING EDGE OF CONVECTIVE OUTFLOW AMIDST A WEAKLY
BUOYANT -- MLCAPE OF 500 TO 1000 J PER KG -- AND ANOMALOUSLY MOIST
TROPOSPHERE -- PW VALUES OF 180 TO 190 PERCENT OF NORMAL PER BLENDED
AMSU/SSMI DATA -- SHOULD ALLOW STORMS TO CONTINUE MOVING EWD ALONG
THE CNTRL GULF COAST. ONLY MODEST AMOUNTS OF DEEP-LAYER SHEAR PER
AREA VWP DATA WILL CONTRIBUTE TO MAINTAINING SOME CONVECTIVE
ORGANIZATION...WITH LOCALLY GUSTY WINDS OWING TO WATER LOADING
PROCESSES AND WEAK/BROAD...LINE-EMBEDDED MESOSCALE CIRCULATIONS.
HOWEVER...WEAK LOW-LEVEL FLOW PER MOBILE VWP DATA...THE LACK OF
DEEP-LAYER FORCING FOR ASCENT...THE ABSENCE OF GREATER
BUOYANCY...AND THE ABSENCE OF A MORE ORGANIZED COLD POOL WILL
GREATLY MINIMIZE ANY THREAT FOR SVR WIND GUSTS. AFTER
01Z...NOCTURNAL STABILIZATION WILL BE ASSOCIATED WITH A REDUCTION IN
THE THREAT FOR STRONG STORMS.

..COHEN.. 02/04/2012

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

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

LAT...LON   30418780 30158816 29668875 29068918 29298980 30028962
            30708926 31208880 31318826 31148779 30758771 30418780

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Feb 3, 7:14 PM CSTMesoscale DiscussionSPCBeauregard, De Soto, Sabine91 min

Nearby

Mesoscale Discussions in Mississippi, 2012Mesoscale Discussions in Alabama, 2012Mesoscale Discussions in Louisiana, 2012Every 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; radar from the NEXRAD Level II archive.