Alert archive / Louisiana / Mesoscale Discussions in 2015

Mesoscale Discussion 1827

September 27, 2015Jefferson Parish, Plaquemines Parish, Saint Bernard Parish, Louisiana

The Storm Prediction Center issued this mesoscale discussion at Sep 27, 2015, 10:23 AM CDT for Jefferson Parish, Plaquemines Parish, Saint Bernard Parish, Louisiana. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Sep 27, 2015, 10:23 AM CDT (15:23 UTC)
Expired
Sep 27, 2015, 12:30 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
20%

Counties Jefferson Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 3.4 hours before the alert went out and 93 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 2015-09-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 69 joules per kilogram.LCLLFCEL10008507005003002001001 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 12:00Z on 2015-09-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 32 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
69 J/kg
Mixed-layer CIN
-86 J/kg
Mixed-layer LCL
985 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
32 m²/s²
0-3 km storm-relative helicity
99 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.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 27, 5:58 PM CDTMesoscale DiscussionSPCOrleans, Saint Bernard3 hr

Nearby

Mesoscale Discussions in Louisiana, 2015Every mesoscale discussion in 2015

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.