Alert archive / Louisiana / Mesoscale Discussions in 2009

Mesoscale Discussion 2139

October 27, 2009Plaquemines Parish, Louisiana

The Storm Prediction Center issued this mesoscale discussion at Oct 27, 2009, 5:04 AM CDT for Plaquemines Parish, Louisiana. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued
Oct 27, 2009, 5:04 AM CDT (10:04 UTC)
Expired
Oct 27, 2009, 6:30 AM CDT
In force
86 min
Issued by
the Storm Prediction Center

County Plaquemines Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 10.1 hours before the alert went out and 117 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 2009-10-27Temperature 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 2009-10-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 97 square meters per square second.19395878Sfc1 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
1650 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
97 m²/s²
0-3 km storm-relative helicity
189 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.

000 
ACUS11 KWNS 271005
SWOMCD
SPC MCD 271004 
LAZ000-271130-

MESOSCALE DISCUSSION 2139
NWS STORM PREDICTION CENTER NORMAN OK
0504 AM CDT TUE OCT 27 2009

AREAS AFFECTED...FAR SERN LA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 271004Z - 271130Z

A SLIM CHANCE FOR A STRONG WIND GUST OR BRIEF TORNADO WILL EXIST
WITH STRONGER STORMS APPROACHING THE COAST.  A WW IS NOT
ANTICIPATED.

VOLUMETRIC RADAR DATA INDICATE A NE-SW ORIENTED BAND OF SUPERCELLS
TO THE S OF PLAQUEMINES PARISH MOVING 195/15-20 KT.  EXTRAPOLATION
OF CURRENT MOTION WOULD BRING THESE STORMS ACROSS THE FAR SERN PART
OF THE PARISH BETWEEN 1000-1130Z.  HOWEVER...BASED ON LATEST
MESOANALYSIS...THIS ACTIVITY APPEARS TO BE SLIGHTLY ELEVATED TO THE
N OF A DEEPENING SURFACE WAVE AND WARM FRONT SITUATED TO THE S OF
THE LA COAST.  ISOLATED SEVERE WEATHER IS POSSIBLE WITH THESE STORMS
AS THEY CLIP THE COAST...BUT THE PRESENCE OF THE STABLE SURFACE
CONDITIONS N OF WARM FRONT SHOULD LIMIT A GREATER THREAT FOR
DAMAGING WINDS OR TORNADOES.

..MEAD.. 10/27/2009

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

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

LAT...LON   29038985 29568974 29868915 29798861 29098881 28818912
            28828947 29038985

Nearby

Mesoscale Discussions in Louisiana, 2009Every mesoscale discussion in 2009

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.