Alert archive / Iowa / Mesoscale Discussions in 2017
Mesoscale Discussion 751
The Storm Prediction Center issued this mesoscale discussion at May 17, 2017, 3:24 PM CDT for 13 counties in Illinois; 23 counties in Iowa; Clark County, Missouri. It was in force for 66 min.
The area
The outline as issued.
The facts
- Issued
- May 17, 2017, 3:24 PM CDT (20:24 UTC)
- Expired
- May 17, 2017, 4:30 PM CDT
- In force
- 66 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 95%
All 37 counties
Benton County, IA, Buchanan County, IA, Cedar County, IA, Clinton County, IA, Davis County, IA, Delaware County, IA, Des Moines County, IA, Dubuque County, IA, Henry County, IA, Iowa County, IA, Jackson County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Lee County, IA, Linn County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Van Buren County, IA, Wapello County, IA, Washington County, IA, Carroll County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Jo Daviess County, IL, Knox County, IL, McDonough County, IL, Mercer County, IL, Rock Island County, IL, Stark County, IL, Stephenson County, IL, Warren County, IL, Whiteside County, IL, Clark County, MO
The radar
The Quad Cities radar (KDVN), 60 km from the middle of the area, began a volume at 20:25 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
Davenport, (KDVN), launched 12:00Z, 8.4 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.
- Mixed-layer CAPE
- 103 J/kg
- Mixed-layer CIN
- -348 J/kg
- Mixed-layer LCL
- 1223 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 84 m²/s²
- 0-3 km storm-relative helicity
- 79 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
246 ACUS11 KWNS 172024 SWOMCD SPC MCD 172024 WIZ000-ILZ000-IAZ000-MOZ000-172130- Mesoscale Discussion 0751 NWS Storm Prediction Center Norman OK 0324 PM CDT Wed May 17 2017 Areas affected...Eastern IA...Northwest IL Concerning...Severe potential...Watch likely Valid 172024Z - 172130Z Probability of Watch Issuance...95 percent SUMMARY...Tornado watch will likely be issued by 21z for portions of eastern IA and northwest IL. DISCUSSION...Buoyancy has gradually increased across eastern IA and northwest IL this afternoon where MLCAPE values are now on the order of 1000 J/kg. CINH has decreased and thunderstorms are gradually maturing well ahead of strong negative-tilt short-wave trough. While substantial low-level drying has surged across MO it appears near-60F surface dew points should hold across this region. Severe threat is increasing across this region and a new tornado watch is warranted to account for expected supercell development. ..Darrow/Goss.. 05/17/2017 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LOT...ILX...MKX...DVN...ARX...DMX...EAX... LAT...LON 40549259 42679197 42558916 41068968 40239082 40549259
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 17, 3:44 PM CDT | Tornado Watch | SPC | Boone, Bureau, Carroll, DeKalb, Henderson, Henry and 18 more | 9 hr |
| May 16, 7:31 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Benton, Black Hawk, Boone and 59 more | 59 min |
| May 16, 8:46 PM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Black Hawk, Boone, Bremer, Butler, Cerro Gordo and 29 more | 5 hr |
| May 16, 9:43 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Calhoun, Carroll, Cass and 16 more | 62 min |
| May 16, 11:48 PM CDT | Mesoscale Discussion | SPC | Adair, Allamakee, Black Hawk, Boone, Bremer, Butler and 28 more | 117 min |
| May 17, 11:39 AM CDT | Mesoscale Discussion | SPC | Adair, Adams, Appanoose, Audubon, Boone, Carroll and 28 more | 66 min |
| May 17, 12:08 PM CDT | Tornado Watch | SPC | Adair, Adams, Appanoose, Audubon, Black Hawk, Boone and 64 more | 7 hr |
| May 17, 12:23 PM CDT | Mesoscale Discussion | SPC | Allamakee, Clayton | 97 min |
| May 17, 2:25 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Boone, Calhoun, Carroll and 32 more | 65 min |
| May 17, 2:38 PM CDT | Mesoscale Discussion | SPC | Allamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 15 more | 97 min |
| May 17, 3:13 PM CDT | Tornado Watch | SPC | Allamakee, Chickasaw, Clayton, Fayette, Floyd, Howard and 2 more | 9 hr |
| May 17, 6:05 PM CDT | Mesoscale Discussion | SPC | Allamakee, Benton, Black Hawk, Bremer, Buchanan, Cedar and 18 more | 55 min |
Nearby
Mesoscale Discussions in Iowa, 2017Mesoscale Discussions in Illinois, 2017Mesoscale Discussions in Missouri, 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.