Alert archive / Louisiana / Mesoscale Discussions in 2012

Mesoscale Discussion 117

February 13, 2012Iberia Parish, St. Mary Parish, Terrebonne Parish, Louisiana

The Storm Prediction Center issued this mesoscale discussion at Feb 13, 2012, 8:25 PM CST for Iberia Parish, St. Mary Parish, Terrebonne Parish, Louisiana. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Feb 13, 2012, 8:25 PM CST (02:25 UTC)
Expired
Feb 13, 2012, 10:30 PM CST
In force
2 hr
Issued by
the Storm Prediction Center

Counties Iberia Parish, LA, St. Mary Parish, LA, Terrebonne Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 2.4 hours before the alert went out and 160 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 00:00Z on 2012-02-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Slidell Radar S, LA at 00:00Z on 2012-02-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 387 square meters per square second.1939587897117136Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
942 m above ground
0-6 km bulk shear
59 kt
0-1 km storm-relative helicity
387 m²/s²
0-3 km storm-relative helicity
589 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

592 
ACUS11 KWNS 140226
SWOMCD
SPC MCD 140225
LAZ000-140430-

MESOSCALE DISCUSSION 0117
NWS STORM PREDICTION CENTER NORMAN OK
0825 PM CST MON FEB 13 2012

AREAS AFFECTED...COASTAL LA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 140225Z - 140430Z

MARGINAL THREAT FOR A BRIEF ISOLATED TORNADO AND AN ISOLATED STRONG
WIND GUST OR TWO WILL EXIST ALONG THE CNTRL AND ERN LA COAST THIS
EVENING. THREAT APPEARS TOO LIMITED FOR A WW ISSUANCE...BUT TRENDS
WILL CONTINUE TO BE MONITORED.

LOW TOPPED LINE OF CONVECTION WILL CONTINUE EWD THROUGH SCNTRL AND
COASTAL LA WITHIN ZONE OF LOW LEVEL WARM ADVECTION IN VICINITY OF
40-50 KT LLJ AXIS. INSTABILITY IS VERY MARGINAL WITH MUCAPE AROUND
200-300 J/KG WHICH IS CONFIRMED BY LACK OF LIGHTNING ACTIVITY.
STORMS APPEAR ROOTED JUST ABOVE THE SURFACE LAYER AND THOUGH THE 0-1
KM HODOGRAPHS ARE LARGE /IN EXCESS OF 400 M2/S2/ EFFECTIVE STORM
RELATIVE HELICITY IS LIKELY MUCH LOWER. NEVERTHELESS...STORMS ARE
EMBEDDED WITHIN SUFFICIENT SHEAR FOR UPDRAFT ROTATION WHICH
CONTINUES TO BE OBSERVED MAINLY WITH STORMS OFFSHORE AND NEAR THE
COAST WHERE DEWPOINTS ARE NEAR 60 AND STORMS ARE ROOTED CLOSER TO
THE SURFACE.

..DIAL.. 02/14/2012

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

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

LAT...LON   29079044 29379121 29469173 29599215 30009179 29789073
            29309022 29079044

Nearby

Mesoscale 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.