Alert archive / Iowa / Mesoscale Discussions in 2017
Mesoscale Discussion 749
The Storm Prediction Center issued this mesoscale discussion at May 17, 2017, 2:25 PM CDT for 4 states. It was in force for 65 min.
The area
The outline as issued.
The facts
- Issued
- May 17, 2017, 2:25 PM CDT (19:25 UTC)
- Expired
- May 17, 2017, 3:30 PM CDT
- In force
- 65 min
- Issued by
- the Storm Prediction Center
All 85 counties
Adair County, IA, Adams County, IA, Audubon County, IA, Boone County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Clarke County, IA, Crawford County, IA, Dallas County, IA, Decatur County, IA, Franklin County, IA, Fremont County, IA, Greene County, IA, Guthrie County, IA, Hamilton County, IA, Hardin County, IA, Harrison County, IA, Jasper County, IA, Lucas County, IA, Madison County, IA, Marion County, IA, Mills County, IA, Monona County, IA, Montgomery County, IA, Page County, IA, Polk County, IA, Pottawattamie County, IA, Ringgold County, IA, Sac County, IA, Shelby County, IA, Story County, IA, Taylor County, IA, Union County, IA, Warren County, IA, Wayne County, IA, Webster County, IA, Wright County, IA, Atchison County, KS, Brown County, KS, Doniphan County, KS, Geary County, KS, Jackson County, KS, Jefferson County, KS, Leavenworth County, KS, Marshall County, KS, Nemaha County, KS, Pottawatomie County, KS, Riley County, KS, Shawnee County, KS, Wabaunsee County, KS, Andrew County, MO, Atchison County, MO, Buchanan County, MO, Caldwell County, MO, Clay County, MO, Clinton County, MO, Daviess County, MO, DeKalb County, MO, Gentry County, MO, Grundy County, MO, Harrison County, MO, Holt County, MO, Linn County, MO, Livingston County, MO, Mercer County, MO, Nodaway County, MO, Platte County, MO, Sullivan County, MO, Worth County, MO, Burt County, NE, Cass County, NE, Cuming County, NE, Dodge County, NE, Douglas County, NE, Gage County, NE, Johnson County, NE, Lancaster County, NE, Nemaha County, NE, Otoe County, NE, Pawnee County, NE, Richardson County, NE, Sarpy County, NE, Saunders County, NE, Washington County, NE
The radar
The Omaha radar (KOAX), 93 km from the middle of the area, began a volume at 19:28 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
Omaha, NE (KOAX), launched 12:00Z, 7.4 hours before the alert went out and 94 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
- 121 J/kg
- Mixed-layer CIN
- -156 J/kg
- Mixed-layer LCL
- 1106 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 119 m²/s²
- 0-3 km storm-relative helicity
- 132 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
196 ACUS11 KWNS 171925 SWOMCD SPC MCD 171925 IAZ000-MOZ000-KSZ000-NEZ000-172030- Mesoscale Discussion 0749 NWS Storm Prediction Center Norman OK 0225 PM CDT Wed May 17 2017 Areas affected...Northeast KS...Northern MO...Eastern NE...IA Concerning...Tornado Watch 231... Valid 171925Z - 172030Z The severe weather threat for Tornado Watch 231 continues. SUMMARY...Greatest tornado threat appears to be shifting to the northern half of WW231. DISCUSSION...Surface low has moved quickly into east-central NE, just northwest of OMA. Substantial boundary-layer drying has advected northeast across KS into western MO where surface dew points have lowered into the low-mid 50s. This drying should continue as south-southwesterly winds are gusting well in excess of 40kt across southeast KS/southwest MO. In response to large-scale forcing shifting into the mid MS Valley, boundary-layer moisture will likely hold across the northern half of IA into southern WI. It appears the most robust convection will focus along a corridor from southeast NE...northeast toward southwest WI. Numerous showers/thunderstorms are evolving within this zone and discrete supercells should mature over the next few hours. Tornado threat should increase across this region, along and south of synoptic front draped from northwest IA into southeast MN. ..Darrow.. 05/17/2017 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DMX...EAX...FSD...OAX...TOP... LAT...LON 41979684 42989303 39649303 38649684 41979684
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| 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, 2:38 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, 3:24 PM CDT | Mesoscale Discussion | SPC | Benton, Buchanan, Cedar, Clinton, Davis, Delaware and 17 more | 66 min |
| May 17, 3:44 PM CDT | Tornado Watch | SPC | Benton, Buchanan, Cedar, Clinton, Delaware, Des Moines and 15 more | 9 hr |
| May 17, 6:05 PM CDT | Mesoscale Discussion | SPC | Allamakee, Benton, Black Hawk, Bremer, Buchanan, Cedar and 18 more | 55 min |
| May 16, 7:03 PM CDT | Severe Thunderstorm Watch | SPC | Cheyenne, Decatur, Rawlins | 5 hr |
| May 16, 9:53 PM CDT | Mesoscale Discussion | SPC | Cowley, Harper, Sumner | 37 min |
| May 16, 10:07 PM CDT | Severe Thunderstorm Watch | SPC | Barber, Cowley, Harper, Sumner | 6 hr |
| May 16, 10:45 PM CDT | Severe Thunderstorm Watch | SPC | Barton, Butler, Chase, Comanche, Dickinson, Edwards and 17 more | 5 hr |
| May 17, 1:49 AM CDT | Mesoscale Discussion | SPC | Butler, Chase, Chautauqua, Cowley, Elk, Geary and 4 more | 56 min |
Nearby
Mesoscale Discussions in Iowa, 2017Mesoscale Discussions in Missouri, 2017Mesoscale Discussions in Nebraska, 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.