Alert archive / Texas / Mesoscale Discussions in 2009

Mesoscale Discussion 615

April 28, 200913 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2009, 1:19 AM CDT for 13 counties in Texas. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued: Apr 28, 2009, 1:19 AM CDT (06:19 UTC)
Expired: Apr 28, 2009, 2:45 AM CDT
In force: 86 min
Issued by: the Storm Prediction Center

Counties Austin County, TX, Bastrop County, TX, Colorado County, TX, Fayette County, TX, Fort Bend County, TX, Grimes County, TX, Harris County, TX, Lee County, TX, Liberty County, TX, Montgomery County, TX, San Jacinto County, TX, Waller County, TX, Washington County, TX

The radar

The Houston radar (KHGX), 123 km from the middle of the area, began a volume at 06:20 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

Lake Charles Mun, LA (KLCH), launched 00:00Z, 6.3 hours before the alert went out and 291 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1808 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 657 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 107 m²/s²
0-3 km storm-relative helicity: 130 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 4.1

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.

Issued	Product	Office	Counties	Lasted
Apr 27, 7:08 PM CDT	Mesoscale Discussion	SPC	Panola, Shelby	67 min
Apr 28, 4:50 PM CDT	Severe Thunderstorm Watch	SPC	Culberson, Jeff Davis, Loving, Pecos, Reeves, Ward and 1 more	6 hr
Apr 28, 5:03 PM CDT	Mesoscale Discussion	SPC	Bell, Brazos, Burleson, Coryell, Falls, Grimes and 11 more	57 min

Nearby

Mesoscale Discussions in Texas, 2009 Every 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; radar from the NEXRAD Level II archive.