Alert archive / Missouri / Mesoscale Discussions in 2019

Mesoscale Discussion 488

April 30, 2019Monroe County, Randolph County, Saint Clair County, Illinois; 14 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Apr 30, 2019, 7:29 PM CDT for Monroe County, Randolph County, Saint Clair County, Illinois; 14 counties in Missouri. It was in force for 61 min.

The area

The outline as issued.

The facts

Issued: Apr 30, 2019, 7:29 PM CDT (00:29 UTC)
Expired: Apr 30, 2019, 8:30 PM CDT
In force: 61 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

Counties Monroe County, IL, Randolph County, IL, Saint Clair County, IL, Bollinger County, MO, Cape Girardeau County, MO, Carter County, MO, City of Saint Louis, MO, Crawford County, MO, Iron County, MO, Jefferson County, MO, Madison County, MO, Perry County, MO, Reynolds County, MO, Saint Francois County, MO, Sainte Genevieve County, MO, Washington County, MO, Wayne County, MO

The radar

The St Louis radar (KLSX), 116 km from the middle of the area, began a volume at 00:33 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Tornado Watch 115Apr 30, 8:05 PM CDT

The nearest sounding before it

Springfield, MO (KSGF), launched 00:00Z, 0.5 hours before the alert went out and 308 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: 390 J/kg
Mixed-layer CIN: -76 J/kg
Mixed-layer LCL: 893 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 158 m²/s²
0-3 km storm-relative helicity: 312 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 4.0

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
Apr 30, 8:03 PM CDT	Tornado Watch	SPC	Bond, Clinton, Fayette, Jackson, Jefferson, Madison and 6 more	5 hr
Apr 30, 10:13 PM CDT	Mesoscale Discussion	SPC	Bond, Clinton, Fayette, Jackson, Madison, Marion and 5 more	92 min

Nearby

Mesoscale Discussions in Missouri, 2019 Mesoscale Discussions in Illinois, 2019 Every mesoscale discussion in 2019

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.