Alert archive / Iowa / Tornado Watches in 2018

Tornado Watch 404

October 9, 201842 counties in Iowa; 11 counties in Kansas; 37 counties in Missouri

The Storm Prediction Center issued this tornado watch at Oct 9, 2018, 1:46 PM CDT for 42 counties in Iowa; 11 counties in Kansas; 37 counties in Missouri. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Oct 9, 2018, 1:46 PM CDT (18:46 UTC)
Expired
Oct 9, 2018, 9:00 PM CDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
1 in
Strongest gust expected
55 kt
All 90 counties

Adair County, IA, Adams County, IA, Appanoose County, IA, Benton County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Clarke County, IA, Dallas County, IA, Davis County, IA, Decatur County, IA, Delaware County, IA, Franklin County, IA, Grundy County, IA, Hamilton County, IA, Hardin County, IA, Iowa County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Keokuk County, IA, Linn County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Monroe County, IA, Polk County, IA, Poweshiek County, IA, Ringgold County, IA, Story County, IA, Tama County, IA, Taylor County, IA, Union County, IA, Van Buren County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Wayne County, IA, Anderson County, KS, Atchison County, KS, Doniphan County, KS, Douglas County, KS, Franklin County, KS, Jefferson County, KS, Johnson County, KS, Leavenworth County, KS, Linn County, KS, Miami County, KS, Wyandotte County, KS, Adair County, MO, Andrew County, MO, Bates County, MO, Buchanan County, MO, Caldwell County, MO, Carroll County, MO, Cass County, MO, Chariton County, MO, Clay County, MO, Clinton County, MO, Cooper County, MO, Daviess County, MO, DeKalb County, MO, Gentry County, MO, Grundy County, MO, Harrison County, MO, Henry County, MO, Holt County, MO, Howard County, MO, Jackson County, MO, Johnson County, MO, Lafayette County, MO, Linn County, MO, Livingston County, MO, Macon County, MO, Mercer County, MO, Nodaway County, MO, Pettis County, MO, Platte County, MO, Putnam County, MO, Randolph County, MO, Ray County, MO, Saline County, MO, Schuyler County, MO, Scotland County, MO, Sullivan County, MO, Worth County, MO

The radar

The Pleasant Hill radar (KEAX), 130 km from the middle of the area, began a volume at 18:50 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
60%
One or more EF2 to EF5 tornadoes
30%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
10%
Ten or more severe hail reports
5%
One or more hailstones of 2 inches or more
5%
Six or more combined severe hail and wind reports
40%

Warnings issued inside it

20 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Oct 9, 2:16 PM CDTTornado WarningDMXMahaska, Marion, Monroe29 min
Oct 9, 2:54 PM CDTTornado WarningEAXCaldwell, Ray36 min
Oct 9, 3:06 PM CDTTornado WarningDVNBenton, Iowa39 min
Oct 9, 3:09 PM CDTTornado WarningDVNDelaware51 min
Oct 9, 3:32 PM CDTTornado WarningDMXAppanoose, Monroe43 min
Oct 9, 3:38 PM CDTTornado WarningDVNBenton, Iowa52 min
Oct 9, 3:42 PM CDTTornado WarningDMXMahaska, Marion, Monroe22 min
Oct 9, 4:03 PM CDTTornado WarningDVNIowa, Keokuk, Washington27 min
Oct 9, 4:21 PM CDTTornado Warning Tornado observedDMXPoweshiek, Tama24 min
Oct 9, 4:28 PM CDTTornado WarningDMXRinggold, Taylor47 min
Oct 9, 4:29 PM CDTTornado WarningEAXMercer31 min
Oct 9, 4:31 PM CDTTornado WarningDVNIowa, Johnson44 min
Oct 9, 4:58 PM CDTTornado Warning Tornado observedDMXTama32 min
Oct 9, 4:59 PM CDTTornado WarningDMXJasper, Poweshiek31 min
Oct 9, 5:13 PM CDTTornado WarningDMXAdair, Adams, Union32 min
Oct 9, 5:14 PM CDTTornado WarningDVNBenton, Iowa, Johnson, Linn46 min
Oct 9, 5:44 PM CDTTornado Warning Tornado observedDMXAdair46 min
Oct 9, 5:51 PM CDTTornado WarningDVNLinn24 min
Oct 9, 6:11 PM CDTTornado Warning Tornado observedDMXAdair, Dallas, Guthrie49 min
Oct 9, 6:30 PM CDTTornado WarningDMXPolk, Warren30 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 6.8 hours before the alert went out and 260 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, Omaha, NE at 12:00Z on 2018-10-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Omaha, NE at 12:00Z on 2018-10-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 57 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
592 m above ground
0-6 km bulk shear
54 kt
0-1 km storm-relative helicity
57 m²/s²
0-3 km storm-relative helicity
28 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

104 
WWUS20 KWNS 091844
SEL4  
SPC WW 091844
IAZ000-KSZ000-MOZ000-100200-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 404
NWS Storm Prediction Center Norman OK
145 PM CDT Tue Oct 9 2018

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Central and eastern Iowa
  Northeast Kansas
  Western and northern Missouri

* Effective this Tuesday afternoon and evening from 145 PM until
  900 PM CDT.

* Primary threats include...
  A few tornadoes likely with a couple intense tornadoes possible
  Isolated damaging wind gusts to 65 mph possible

SUMMARY...Scattered showers and embedded thunderstorms should
increase in coverage and intensity during the late afternoon and
early evening. Low-level wind profiles are conducive for a few
rotating storms capable of tornadoes and damaging winds.

The tornado watch area is approximately along and 70 statute miles
east and west of a line from 40 miles south southeast of Olathe KS
to 50 miles northwest of Cedar Rapids IA. For a complete depiction
of the watch see the associated watch outline update (WOUS64 KWNS
WOU4).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 402...WW 403...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 1 inch. Extreme turbulence and surface wind
gusts to 55 knots. A few cumulonimbi with maximum tops to 450. Mean
storm motion vector 21030.

...Grams

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Oct 8, 7:03 PM CDTMesoscale DiscussionSPCAppanoose, Clarke, Dallas, Decatur, Jasper, Lucas and 9 more57 min
Oct 9, 12:59 PM CDTMesoscale DiscussionSPCAppanoose, Benton, Buchanan, Clarke, Davis, Decatur and 19 more3 hr
Oct 9, 2:45 PM CDTMesoscale DiscussionSPCCedar, Clinton, Dubuque, Jackson, Jones, Muscatine and 1 more2 hr
Oct 9, 3:53 PM CDTMesoscale DiscussionSPCAppanoose, Benton, Black Hawk, Boone, Buchanan, Clarke and 29 more2 hr
Oct 9, 5:09 PM CDTTornado WatchSPCAllamakee, Clayton, Fayette4 hr
Oct 9, 6:37 PM CDTMesoscale DiscussionSPCAllamakee, Appanoose, Benton, Black Hawk, Bremer, Buchanan and 21 more83 min
Oct 9, 9:09 AM CDTMesoscale DiscussionSPCChautauqua, Cherokee, Cowley, Elk, Labette, Montgomery2 hr
Oct 9, 11:31 AM CDTMesoscale DiscussionSPCAllen, Anderson, Bourbon, Cherokee, Coffey, Crawford and 18 more89 min
Oct 9, 12:17 PM CDTTornado WatchSPCAllen, Bourbon, Cherokee, Crawford, Labette, Montgomery and 3 more8 hr
Oct 9, 3:06 PM CDTMesoscale DiscussionSPCDouglas, Franklin, Jefferson, Johnson, Leavenworth, Linn and 2 more84 min
Oct 9, 6:22 PM CDTMesoscale DiscussionSPCOzark, Taney83 min

Nearby

Tornado Watches in Iowa, 2018Tornado Watches in Missouri, 2018Tornado Watches in Kansas, 2018Every tornado watch in 2018

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.