Alert archive / Iowa / Mesoscale Discussions in 2016

Mesoscale Discussion 1692

September 15, 201610 counties in Iowa; 9 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Sep 15, 2016, 3:51 PM CDT for 10 counties in Iowa; 9 counties in Nebraska. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued: Sep 15, 2016, 3:51 PM CDT (20:51 UTC)
Expired: Sep 15, 2016, 5:45 PM CDT
In force: 114 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Audubon County, IA, Carroll County, IA, Crawford County, IA, Harrison County, IA, Ida County, IA, Monona County, IA, Pottawattamie County, IA, Sac County, IA, Shelby County, IA, Woodbury County, IA, Burt County, NE, Cuming County, NE, Dakota County, NE, Dodge County, NE, Douglas County, NE, Sarpy County, NE, Saunders County, NE, Thurston County, NE, Washington County, NE

The radar

The Omaha radar (KOAX), 66 km from the middle of the area, began a volume at 20:54 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.

Severe Thunderstorm Watch 476Sep 15, 4:35 PM CDT

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 8.9 hours before the alert went out and 66 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: 696 J/kg
Mixed-layer CIN: -65 J/kg
Mixed-layer LCL: 648 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 118 m²/s²
0-3 km storm-relative helicity: 138 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.1

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
Sep 15, 1:58 PM CDT	Mesoscale Discussion	SPC	Buena Vista, Cherokee, Clay, Dickinson, Emmet, Ida and 7 more	3 hr
Sep 15, 4:38 PM CDT	Severe Thunderstorm Watch	SPC	Crawford, Harrison, Ida, Monona, Pottawattamie, Sac and 2 more	5 hr
Sep 15, 3:04 PM CDT	Mesoscale Discussion	SPC	Buffalo, Chase, Dawson, Deuel, Dundy, Frontier and 9 more	2 hr
Sep 15, 5:21 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Buffalo, Chase, Clay, Dawson, Dundy and 19 more	8 hr

Nearby

Mesoscale Discussions in Iowa, 2016 Mesoscale Discussions in Nebraska, 2016 Every mesoscale discussion in 2016

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.