Alert archive / Iowa / Mesoscale Discussions in 2017

Mesoscale Discussion 1390

July 21, 20174 states

The Storm Prediction Center issued this mesoscale discussion at Jul 21, 2017, 11:23 PM CDT for 4 states. It was in force for 67 min.

The area

The outline as issued.

The facts

Issued
Jul 21, 2017, 11:23 PM CDT (04:23 UTC)
Expired
Jul 22, 2017, 12:30 AM CDT
In force
67 min
Issued by
the Storm Prediction Center
All 76 counties

Benton County, IA, Black Hawk County, IA, Buchanan County, IA, Butler County, IA, Cedar County, IA, Clinton County, IA, Delaware County, IA, Dubuque County, IA, Franklin County, IA, Grundy County, IA, Hardin County, IA, Henry County, IA, Iowa County, IA, Jackson County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Linn County, IA, Louisa County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Muscatine County, IA, Polk County, IA, Poweshiek County, IA, Scott County, IA, Story County, IA, Tama County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Boone County, IL, Bureau County, IL, Carroll County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Grundy County, IL, Henry County, IL, Iroquois County, IL, Jo Daviess County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Knox County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Marshall County, IL, McHenry County, IL, Mercer County, IL, Ogle County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Stephenson County, IL, Whiteside County, IL, Will County, IL, Winnebago County, IL, Cass County, IN, Fulton County, IN, Jasper County, IN, Lake County, IN, LaPorte County, IN, Marshall County, IN, Newton County, IN, Porter County, IN, Pulaski County, IN, Saint Joseph County, IN, Starke County, IN, White County, IN, Berrien County, MI, Van Buren County, MI

The radar

The Quad Cities radar (KDVN), 38 km from the middle of the area, began a volume at 04:22 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.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 4.4 hours before the alert went out and 265 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, Lincoln, IL at 00:00Z on 2017-07-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2094 joules per kilogram.LCLEL10008507005003002001001 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, Lincoln, IL at 00:00Z on 2017-07-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 57 square meters per square second.1939Sfc1 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
2094 J/kg
Mixed-layer CIN
-2 J/kg
Mixed-layer LCL
1572 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
57 m²/s²
0-3 km storm-relative helicity
136 m²/s²
Significant tornado parameter
0.2
Supercell composite
6.5

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.

IssuedProductOfficeCountiesLasted
Jul 21, 8:35 PM CDTMesoscale DiscussionSPCBoone, Bureau, Carroll, Cook, DeKalb, DuPage and 23 more115 min
Jul 22, 12:53 AM CDTMesoscale DiscussionSPCBoone, Carroll, Cass, Clinton, Delaware, Fayette and 14 more67 min
Jul 22, 1:08 AM CDTSevere Thunderstorm WatchSPCAdams, Blackford, Boone, Carroll, Cass, Clinton and 31 more4 hr
Jul 22, 4:00 AM CDTMesoscale DiscussionSPCFayette, Franklin, Randolph, Rush, Union, Wayne90 min

Nearby

Mesoscale Discussions in Iowa, 2017Mesoscale Discussions in Illinois, 2017Mesoscale Discussions in Indiana, 2017Every 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.