Alert archive / Texas / Mesoscale Discussions in 2017

Mesoscale Discussion 807

May 21, 2017Jim Hogg County, Webb County, Zapata County, Texas

The Storm Prediction Center issued this mesoscale discussion at May 21, 2017, 3:54 PM CDT for Jim Hogg County, Webb County, Zapata County, Texas. It was in force for 96 min.

The area

The outline as issued.

The facts

Issued: May 21, 2017, 3:54 PM CDT (20:54 UTC)
Expired: May 21, 2017, 5:30 PM CDT
In force: 96 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

Counties Jim Hogg County, TX, Webb County, TX, Zapata County, TX

The radar

The Corpus Christi radar (KCRP), 174 km from the middle of the area, began a volume at 20:56 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

Corpus Christi, TX (KCRP), launched 12:00Z, 8.9 hours before the alert went out and 190 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: 3780 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 573 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 2 m²/s²
0-3 km storm-relative helicity: 74 m²/s²
Significant tornado parameter: 1.6
Supercell composite: 8.7

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 21, 12:44 PM CDT	Mesoscale Discussion	SPC	Dimmit, Kinney, Maverick, Val Verde, Webb, Zavala	91 min
May 21, 2:22 PM CDT	Mesoscale Discussion	SPC	Hardin, Newton	113 min
May 21, 4:35 PM CDT	Mesoscale Discussion	SPC	Dallam, Hansford, Hartley, Moore, Oldham, Sherman	2 hr

Nearby

Mesoscale Discussions in Texas, 2017 Every mesoscale discussion in 2017

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.