Alert archive / Missouri / Tornado Watches in 2009

Tornado Watch 258

May 7, 20094 states

The Storm Prediction Center issued this tornado watch at May 7, 2009, 1:44 PM CDT for 4 states. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
May 7, 2009, 1:44 PM CDT (18:44 UTC)
Expired
May 7, 2009, 7:37 PM CDT
In force
6 hr
Issued by
the Storm Prediction Center
Largest hail expected
3 in
Strongest gust expected
60 kt
All 65 counties

Adams County, IA, Appanoose County, IA, Clarke County, IA, Decatur County, IA, Fremont County, IA, Mills County, IA, Montgomery County, IA, Page County, IA, Pottawattamie County, IA, Ringgold County, IA, Taylor County, IA, Union County, IA, Wayne County, IA, Atchison County, KS, Brown County, KS, Doniphan County, KS, Douglas County, KS, Jackson County, KS, Jefferson County, KS, Johnson County, KS, Leavenworth County, KS, Nemaha County, KS, Wyandotte County, KS, Adair County, MO, Andrew County, MO, Atchison County, MO, Buchanan County, MO, Caldwell County, MO, Carroll 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, 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, Sullivan County, MO, Worth County, MO, Cass County, NE, Douglas County, NE, Johnson County, NE, Nemaha County, NE, Otoe County, NE, Pawnee County, NE, Richardson County, NE, Sarpy County, NE

The radar

The Pleasant Hill radar (KEAX), 153 km from the middle of the area, began a volume at 18:45 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
40%
One or more EF2 to EF5 tornadoes
20%
Ten or more severe wind reports
40%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
60%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
May 7, 4:10 PM CDTSevere Thunderstorm WarningDMXDecatur, Wayne50 min
May 7, 6:47 PM CDTSevere Thunderstorm WarningEAXGentry28 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, 6.7 hours before the alert went out and 196 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 2009-05-07Temperature 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 2009-05-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 33 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
2057 m above ground
0-6 km bulk shear
72 kt
0-1 km storm-relative helicity
33 m²/s²
0-3 km storm-relative helicity
200 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 7, 1:12 PM CDTMesoscale DiscussionSPCDecatur, Fremont, Mills, Montgomery, Page, Ringgold and 1 more93 min
May 7, 3:55 PM CDTMesoscale DiscussionSPCAppanoose, Decatur, Fremont, Montgomery, Page, Ringgold and 2 more65 min
May 7, 5:42 PM CDTMesoscale DiscussionSPCAdams, Appanoose, Clarke, Davis, Decatur, Fremont and 8 more2 hr
May 7, 5:56 PM CDTMesoscale DiscussionSPCLee64 min
May 7, 6:14 PM CDTSevere Thunderstorm WatchSPCAudrain, Boone, Callaway, Knox, Lewis, Lincoln and 10 more8 hr

Nearby

Tornado Watches in Missouri, 2009Tornado Watches in Iowa, 2009Tornado Watches in Kansas, 2009Every tornado watch in 2009

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.