A very powerful storm system moved through the southern Rockies during the night of the 10th and early morning of the 11th.  Intense surface low pressure formed over western Kansas with a central pressure by sunrise on the 11th of 977 Mb.  The weather situation was very dynamic with 500 Mb winds over 100 kts and a very sharp dry punch clearly visible on the satellite pictures.  During the day the warm front that extended east from the low reached into southern Iowa, then extended eastward.  There were two things that occurred during the day.  The first was a very strong supercell that formed over northern Missouri during the morning.  This storm lifted north-northeast at about 50 kts into Iowa, producing a long track tornado with a path extending nearly all the way to Des Moines.  During the afternoon the warm front surged north with the northeast progression of the surface dry line.  Dew points rose into the mid 60s to the south of the warm front across much of the southeast half to two thirds of Iowa.  Surface temperatures in these areas reached the 60s north, with 70s south.  With the atmosphere primed, the dry line began to move into Iowa.  Dew point temperatures behind the dry line were in the 30s with southwest winds of 30 to 50 MPH.  A broken squall line formed on the nose of the dry punch and became severe quickly.  The storm cells themselves were not all that large, but nearly every cell along the line did carry a mesoscale circulation.  There were several tornado touchdowns as the line lifted north as well.  The primary severe weather during this even was the tornadic nature of it.  There were reports of wind and hail, but everything considered these reports were pretty scattered.  There were very few reports of wind and hail with the first supercell as it lifted north out of Missouri.  One inch diameter hail was reported in Ringgold County east of Redding.  Reports of winds and hail were more frequent with the second line of thunderstorms.  There were numerous reports of hail up to marble size with this line, however there were not all that many reports of hail larger than that.  A few reports of three quarter to one inch diameter hail were received from Marion and Polk Counties.  The most significant hail occurred in northeast Iowa in Butler County.  Golf ball size hail fell in the town of Parkersburg as the line passed over the city.  There were more reports of wind with the second round.  Nearly all locations reported winds of at least 50 MPH as the line passed overhead.  Scattered reports of winds of 70 to 85 MPH were received.  Wind damage occurred in Boone County as high winds downed power lines and downed outbuildings north of Ogden.  The greatest wind damage occurred over northeast Iowa in Black Hawk and Franklin Counties.  A building was blown off of its foundation and onto an adjacent road southwest of Hampton in Franklin County.  A roof of a barn was damaged and a grain wagon was tipped over northwest of Hampton.  Roof and house damage was reported over parts of Black Hawk County as well.  Five injuries occurred in Warren County at Carlisle when winds of around 65 MPH toppled a school bus.  Twenty one children were on board the bus when it overturned with 5 treated for minor injuries.  Spotty damage was reported around the greater Des Moines metropolitan area.   Several tornadoes occurred with this system.  The most significant tornado entered southern Iowa around mid day.  This  tornado reached minimal F3 intensity just east of Mt. Ayr (Ringgold County).  Property damage is estimated at over $500,000 in Ringgold county alone. Across the Des Moines area of responsibility, at least 15 homes were destroyed, and 60 residences were damaged as around a dozen tornadoes touched down.  A supercell thunderstorm moved north from Missouri into southern Iowa late in the morning of April 11.  The storm produced a tornado in northern Missouri and crossed into Iowa in Ringgold County. The storm, and tornado, moved north through Ringgold County with a continuous damage path half way through the county.   The damage path continued north through northern Ringgold County, southeast Union County and into northwest Clarke County.  In this area, the path was not continuous.  Based on damage reports, the tornado continued to produce occasional damage in Madison County.  Chaser reports indicate the tornado had a multi-vortex structure as it moved through Ringgold and Union Counties.  The last reported sighting was in northern Polk County where a brief touchdown was reported with no damage.  The storm likely produced one tornado from the Missouri border to Madison County with an intermittent damage track.   Damage in Ringgold County was severe with initial estimates around $1 million.  The county was later declared a federal disaster area by President Bush.  A second tornado briefly touched down in northern Polk County.  The touchdown in Polk County was indeed a separate tornado.  Even though the tornado was from the same parent cell, the system had occluded and was in the process of forming a new tornado as it passed over the western part of the Des Moines area.  Reports from this tornado indicate that at least 9 homes were damaged or destroyed, one business destroyed, and a school building damaged.  In addition to losses to homes, one farmstead was hit with considerable damage and some livestock damage.  A series of tornadoes formed on the heels of the supercell tornado as the dry line pushed into the state.  Most of these were brief touchdowns, however the storms were moving around 60 MPH.  Three tornadoes touched down in Boone County.  The most significant tornado touched down north of Ogden.  It produced a 3 mile long track up to 1/8 mile wide.  Farm site hit along highway P70.  Barn and grain bins destroyed, knocking out windows in house. Otherwise only minor damage to house. Debris scattered 1 mile to next farm site where there was minor damage to many buildings. Track continued north-northeast across highway E26 into the campground at Don Williams Lake. A storage building was destroyed, several trees downed, plus outhouses, picnic tables and signs were damaged. The damage track dissipated on the northeast side of the Don Williams Recreation Area.  There were several brief touchdowns with relatively minor damage in Guthrie, Greene, and Hamilton Counties.  A stronger tornado touched down in southeast Black Hawk County, causing significant damage to two homes in the La Porte City area.  The most serious tornado in terms of loss of life occurred in Wapello County.  A tornado developed in rural southern Wapello County, a mile southwest of Agency, Iowa, around 1600 CDT, on Wednesday, April 11.  The tornado path was 50 to 100 yards wide with sporadic touchdowns toward the north-northeast for the next 6 miles.    Survey responses indicated that the duration of impact at any one location was only 15 to 30 seconds as the tornado quickly moved through Agency and over farms at a 60 mph horizontal movement.   The Odd Fellows Lodge in Agency was destroyed, and over 50 residences were damaged.  Two women inside were killed, three people injured and three people had no injuries.  As the storm moved through Agency, a garage was lifted and carried about 100 meters off of its foundation.  The car inside was twisted and covered with debris.  In another incident, one house was hit by the tornado causing damage to the house.  The family dog was in the dog pen at the time.  The tornado lifted the pen and twirled it through the air.  The dog pen was deposited some distance downstream and what was truly amazing was the fact that the dog was uninjured.  Following the tornado, U.S. Highway 34 was closed for 2 hours in order to removed debris from the highway. Governor Tom Vilsack visited the area during a storm survey.  The governor spoke with Brenda Brock of the  National Weather Service, Ellen Gordon, Administrator, Iowa Emergency Management Division, emergency management personnel (fire department, law enforcement, mayor) and the public.  A proclamation for emergency disaster assistance was signed.

Hail in RINGGOLD, IOWA
From 11-APR-01 10:45:00 to 11-APR-01 10:45:00 (CST)
Location: REDDING
Magnitude: 1.00 
Property damage: 3K
Reported by: LAW ENFORCEMENT

Tornado in HAMILTON, IOWA
From 11-APR-01 14:38:00 to 11-APR-01 14:41:00 (CST)
Location: WEBSTER CITY
Tornado F-scale: F1
Property damage: 70K
Reported by: LAW ENFORCEMENT

Two farm buildings blown down in rural area south of Webster City.

Tornado in WAPELLO, IOWA
From 11-APR-01 15:00:00 to 11-APR-01 15:08:00 (CST)
Location: AGENCY
Tornado F-scale: F2
Property damage: 400K
Reported by: LAW ENFORCEMENT

Quick moving tornado, touchdown with strongest part in Agency.  Nine buildings with major damage, 43 with minor.  Two buildings destroyed.  Two dead, three injured.

Tornado in WEBSTER, IOWA
From 11-APR-01 14:37:00 to 11-APR-01 14:37:00 (CST)
Location: DAYTON
Tornado F-scale: F0
Property damage: 30K
Reported by: LAW ENFORCEMENT

Brief touchdown with damage reported to trailers and a building.

Tornado in BLACK HAWK, IOWA
From 11-APR-01 16:07:00 to 11-APR-01 16:17:00 (CST)
Location: LA PORTE CITY
Tornado F-scale: F1
Property damage: 125K
Reported by: LAW ENFORCEMENT

Tornado with intermittent track over open country.

Tornado in JASPER, IOWA
From 11-APR-01 14:40:00 to 11-APR-01 14:51:00 (CST)
Location: COLFAX
Tornado F-scale: F1
Property damage: 10K
Reported by: LAW ENFORCEMENT

Intermittent track through open country.  Tornado moved into Marshall County northwest of Baxter.

Tornado in MARSHALL, IOWA
From 11-APR-01 14:51:00 to 11-APR-01 14:51:00 (CST)
Location: RHODES
Tornado F-scale: F0
Property damage: 1K
Reported by: LAW ENFORCEMENT

Intermittent track as tornado moved in from Jasper County and roped out.

Hail in POLK, IOWA
From 11-APR-01 13:51:00 to 11-APR-01 13:51:00 (CST)
Location: WEST DES MOINES
Magnitude: 0.75 
Reported by: AMATEUR RADIO

Thunderstorm Wind in LUCAS, IOWA
From 11-APR-01 14:00:00 to 11-APR-01 14:00:00 (CST)
Location: CHARITON
Magnitude: 61 E
Property damage: 7K
Reported by: NEWSPAPER

Thunderstorm Wind in BLACK HAWK, IOWA
From 11-APR-01 15:58:00 to 11-APR-01 15:58:00 (CST)
Location: CEDAR FALLS
Magnitude: 75 E
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in BLACK HAWK, IOWA
From 11-APR-01 16:18:00 to 11-APR-01 16:18:00 (CST)
Location: JUBILEE
Magnitude: 70 E
Property damage: 15K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in BLACK HAWK, IOWA
From 11-APR-01 16:22:00 to 11-APR-01 16:22:00 (CST)
Location: LA PORTE CITY
Magnitude: 70 E
Property damage: 25K
Reported by: EMERGENCY MANAGER

Tornado in RINGGOLD, IOWA
From 11-APR-01 10:40:00 to 11-APR-01 11:10:00 (CST)
Location: MT AYR
Tornado F-scale: F3
Property damage: 1.5M
Reported by: STORM CHASER

Tornado moved our of Missouri into Ringgold County, across the county into Union County.

Tornado in UNION, IOWA
From 11-APR-01 11:10:00 to 11-APR-01 11:27:00 (CST)
Location: AFTON
Tornado F-scale: F2
Property damage: 150K
Reported by: STORM CHASER

Tornado moved from Ringgold County, across Union County, into Clarke County.

Tornado in CLARKE, IOWA
From 11-APR-01 11:27:00 to 11-APR-01 11:45:00 (CST)
Location: MURRAY
Tornado F-scale: F2
Property damage: 125K
Reported by: STORM CHASER

Tornado moved from Union County into Clarke County, then moved into Madison County.

Thunderstorm Wind in MARSHALL, IOWA
From 11-APR-01 14:53:00 to 11-APR-01 14:53:00 (CST)
Location: STATE CENTER
Magnitude: 53 E
Property damage: 5K
Reported by: AMATEUR RADIO

Thunderstorm Wind in WARREN, IOWA
From 11-APR-01 14:05:00 to 11-APR-01 14:05:00 (CST)
Location: CARLISLE
Magnitude: 56 E
Property damage: 20K
Reported by: BROADCAST MEDIA

School bus overturned by wind gust.

Thunderstorm Wind in BLACK HAWK, IOWA
From 11-APR-01 16:19:00 to 11-APR-01 16:19:00 (CST)
Location: LA PORTE CITY
Magnitude: 70 E
Property damage: 100K
Reported by: NEWSPAPER

Thunderstorm Wind in FRANKLIN, IOWA
From 11-APR-01 15:25:00 to 11-APR-01 15:25:00 (CST)
Location: SHEFFIELD
Magnitude: 70 E
Property damage: 50K
Reported by: NEWSPAPER

Hail in MARION, IOWA
From 11-APR-01 14:20:00 to 11-APR-01 14:20:00 (CST)
Location: KNOXVILLE
Magnitude: 0.88 
Property damage: 2K
Reported by: AMATEUR RADIO

Thunderstorm Wind in BOONE, IOWA
From 11-APR-01 14:20:00 to 11-APR-01 14:20:00 (CST)
Location: OGDEN
Magnitude: 75 E
Property damage: 40K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in MARSHALL, IOWA
From 11-APR-01 14:53:00 to 11-APR-01 14:53:00 (CST)
Location: STATE CENTER
Magnitude: 53 M
Property damage: 2K
Reported by: AMATEUR RADIO

Thunderstorm Wind in HAMILTON, IOWA
From 11-APR-01 14:40:00 to 11-APR-01 14:40:00 (CST)
Location: WEBSTER CITY
Magnitude: 61 E
Property damage: 10K
Reported by: UNKNOWN

Thunderstorm Wind in MADISON, IOWA
From 11-APR-01 13:21:00 to 11-APR-01 13:21:00 (CST)
Location: WINTERSET
Magnitude: 52 E
Property damage: 2K
Reported by: LAW ENFORCEMENT

Hail in MARION, IOWA
From 11-APR-01 13:30:00 to 11-APR-01 13:30:00 (CST)
Location: KNOXVILLE
Magnitude: 1.00 
Property damage: 3K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in DALLAS, IOWA
From 11-APR-01 13:33:00 to 11-APR-01 13:33:00 (CST)
Location: REDFIELD
Magnitude: 61 E
Property damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in DALLAS, IOWA
From 11-APR-01 13:35:00 to 11-APR-01 13:35:00 (CST)
Location: DE SOTO
Magnitude: 61 E
Property damage: 3K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in DALLAS, IOWA
From 11-APR-01 13:41:00 to 11-APR-01 13:41:00 (CST)
Location: DALLAS CENTER
Magnitude: 56 E
Property damage: 2K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in DALLAS, IOWA
From 11-APR-01 13:49:00 to 11-APR-01 13:49:00 (CST)
Location: PERRY
Magnitude: 61 E
Property damage: 5K
Reported by: LAW ENFORCEMENT

Hail in POLK, IOWA
From 11-APR-01 13:53:00 to 11-APR-01 13:53:00 (CST)
Location: GRIMES
Magnitude: 0.75 
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in BOONE, IOWA
From 11-APR-01 14:15:00 to 11-APR-01 14:15:00 (CST)
Location: PILOT MOUND
Magnitude: 75 E
Property damage: 10K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in BOONE, IOWA
From 11-APR-01 14:23:00 to 11-APR-01 14:23:00 (CST)
Location: BOONE
Magnitude: 50 M
Reported by: BROADCAST MEDIA

Hail in MARION, IOWA
From 11-APR-01 14:25:00 to 11-APR-01 14:25:00 (CST)
Location: KNOXVILLE
Magnitude: 0.88 
Property damage: 1K
Reported by: EMERGENCY MANAGER

Hail in BUTLER, IOWA
From 11-APR-01 15:37:00 to 11-APR-01 15:37:00 (CST)
Location: PARKERSBURG
Magnitude: 1.75 
Property damage: 15K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in POLK, IOWA
From 11-APR-01 14:08:00 to 11-APR-01 14:08:00 (CST)
Location: JOHNSTON
Magnitude: 50 E
Property damage: 2K
Reported by: NWS EMPLOYEE(OFF DUTY)

Hail in POLK, IOWA
From 11-APR-01 13:51:00 to 11-APR-01 13:51:00 (CST)
Location: WEST DES MOINES
Magnitude: 0.75 
Reported by: AMATEUR RADIO

Thunderstorm Wind in HARDIN, IOWA
From 11-APR-01 15:00:00 to 11-APR-01 15:00:00 (CST)
Location: HUBBARD
Magnitude: 70 E
Property damage: 15K
Reported by: UNKNOWN

Thunderstorm Wind in HARDIN, IOWA
From 11-APR-01 15:20:00 to 11-APR-01 15:20:00 (CST)
Location: ELDORA
Magnitude: 70 E
Property damage: 20K
Reported by: UNKNOWN

Thunderstorm Wind in FRANKLIN, IOWA
From 11-APR-01 15:10:00 to 11-APR-01 15:10:00 (CST)
Location: COULTER
Magnitude: 65 E
Property damage: 10K
Reported by: AMATEUR RADIO

Thunderstorm Wind in FRANKLIN, IOWA
From 11-APR-01 15:20:00 to 11-APR-01 15:20:00 (CST)
Location: HAMPTON
Magnitude: 75 E
Property damage: 30K
Reported by: AMATEUR RADIO

Thunderstorm Wind in FRANKLIN, IOWA
From 11-APR-01 15:20:00 to 11-APR-01 15:20:00 (CST)
Location: HAMPTON
Magnitude: 65 E
Property damage: 10K
Reported by: AMATEUR RADIO

Thunderstorm Wind in FRANKLIN, IOWA
From 11-APR-01 15:23:00 to 11-APR-01 15:23:00 (CST)
Location: HAMPTON
Magnitude: 52 E
Property damage: 10K
Reported by: AMATEUR RADIO

Thunderstorm Wind in CERRO GORDO, IOWA
From 11-APR-01 15:26:00 to 11-APR-01 15:26:00 (CST)
Location: THORNTON
Magnitude: 52 M
Property damage: 1K
Reported by: AMATEUR RADIO

Thunderstorm Wind in CASS, IOWA
From 11-APR-01 12:26:00 to 11-APR-01 12:26:00 (CST)
Location: CUMBERLAND
Magnitude: 52 M
Property damage: 1K
Reported by: TRAINED SPOTTER

Hail in MARION, IOWA
From 11-APR-01 14:20:00 to 11-APR-01 14:20:00 (CST)
Location: KNOXVILLE
Magnitude: 0.88 
Property damage: 1K
Reported by: AMATEUR RADIO

Tornado in MADISON, IOWA
From 11-APR-01 11:45:00 to 11-APR-01 12:00:00 (CST)
Location: WINTERSET
Tornado F-scale: F1
Property damage: 75K
Reported by: STORM CHASER

Tornado moved from Clarke County into Madison County before lifting.

Tornado in POLK, IOWA
From 11-APR-01 12:37:00 to 11-APR-01 12:37:00 (CST)
Location: SAYLORVILLE
Tornado F-scale: F0
Reported by: BROADCAST MEDIA

Brief touchdown in open area north of Interstate 35/80.

Tornado in BOONE, IOWA
From 11-APR-01 14:04:00 to 11-APR-01 14:05:00 (CST)
Location: OGDEN
Tornado F-scale: F0
Property damage: 5K
Reported by: TRAINED SPOTTER

Short lived tornado in mostly open area.

Tornado in BOONE, IOWA
From 11-APR-01 14:06:00 to 11-APR-01 14:08:00 (CST)
Location: OGDEN
Tornado F-scale: F1
Property damage: 150K
Reported by: TRAINED SPOTTER

Relatively brief touchdown, destroyed a barn.

Tornado in BOONE, IOWA
From 11-APR-01 14:10:00 to 11-APR-01 14:16:00 (CST)
Location: PILOT MOUND
Tornado F-scale: F1
Property damage: 75K
Reported by: LAW ENFORCEMENT

Tracked over mainly open country.

Tornado in GUTHRIE, IOWA
From 11-APR-01 13:25:00 to 11-APR-01 13:28:00 (CST)
Location: BAYARD
Tornado F-scale: F1
Property damage: 60K
Reported by: LAW ENFORCEMENT

Tracked through mostly open area southeast of Bayard and destroyed a barn.

Tornado in GREENE, IOWA
From 11-APR-01 14:05:00 to 11-APR-01 14:07:00 (CST)
Location: PATON
Tornado F-scale: F0
Property damage: 10K
Reported by: TRAINED SPOTTER

Brief touchdown with some minor damage in Paton.

Tornado in GREENE, IOWA
From 11-APR-01 13:45:00 to 11-APR-01 13:45:00 (CST)
Location: JEFFERSON
Tornado F-scale: F0
Reported by: LAW ENFORCEMENT

Brief touchdown in open country.