October 4, 2013

On the afternoon of Oct 4 a strong system moving through the northern plains brought a cold front to the region. An unstable air mass was able to move into the area ahead of the system setting the stage for thunderstorms. As the main trough moved through the plains in continued to deepen allowing for strong winds. The combination of wind shear and instability lead to an outbreak of severe thunderstorms in northeast KS as the cold front progressed eastward. Damaging winds were the primary outcome from this event.

The same powerful storm system that produced severe weather across eastern Nebraska on October 3rd remain in the area on the 4th. A strong area of low pressure moved from eastern Colorado into southern South Dakota during the day. As this occurred, a dry line was sweeping across central and into eastern Nebraska. A warm front continued to lift north into northeast Nebraska and western Iowa by late afternoon. With unseasonably warm and moist air in the region the atmosphere became strongly unstable. This instability coupled with a strong wind field associated with the powerful storm system and created and environment favorable for significant severe weather. Supercells developed near the intersection of the dry line and warm front over northeast Nebraska during the afternoon and tracked northeast. The supercells were responsible for large hail, damaging winds, and significant tornadoes. Other isolated thunderstorms developed south along the dry line into western Iowa producing very large hail and damaging winds during the evening of the 4th.

A strong cold front and dryline moved across Central Kansas into South Central Kansas during the afternoon and evening hours of October 4th, 2013. Showers and thunderstorms developed along this front with damaging winds and some quarter sized hail reports.

Thunderstorms produced three tornadoes which tracked over Dixon and Dakota Counties in extreme northeast Nebraska on the late afternoon of October 4th. One damaging tornado crossed into Dixon County from Wayne County Nebraska, a brief tornado formed and dissipated in Dixon County, and another tornado developed in northern Dakota County before crossing the Missouri River into Union County South Dakota.

The same powerful storm system that produced severe weather across eastern Nebraska on October 3rd remain in the area on the 4th. A strong area of low pressure moved from eastern Colorado into southern South Dakota during the day. As this occurred, a dry line was sweeping across central and into eastern Nebraska. A warm front continued to lift north into northeast Nebraska and western Iowa by late afternoon. With unseasonably warm and moist air in the region the atmosphere became strongly unstable. This instability coupled with a strong wind field associated with the powerful storm system and created and environment favorable for significant severe weather. Supercells developed near the intersection of the dry line and warm front over northeast Nebraska during the afternoon and tracked northeast. The supercells were responsible for large hail, damaging winds, and significant tornadoes. Other isolated thunderstorms developed south along the dry line into western Iowa producing very large hail and damaging winds during the evening of the 4th.

Thunderstorms produced eleven tornadoes, several of them causing damage, which tracked wholly or partly in northwest Iowa during the afternoon and early evening of October 4th. There were also two reports of large hail and one report of non tornadic damaging thunderstorm winds.

Thunderstorms produced two tornadoes which tracked over extreme southeast Union County in southeast South Dakota on the late afternoon on October 4th. One tornado crossed over the Missouri River into Union County from Dakota County Nebraska. The other tornado formed in Union County and crossed the Big Sioux River into Plymouth County Iowa. Both tornadoes caused damage.

Thunderstorms developed during the evening of October 4th ahead of an approaching warm front. These storms produced locally heavy rains that caused flash flooding to occur across portions of Floyd and Winneshiek Counties. A vehicle became stranded in flood waters near Floyd (Floyd County) with the occupants having to be rescued by emergency personnel. Dime to quarter sized hail also fell near Marble Rock and Charles City (Floyd County).

A cold front generated scattered thunderstorms, when it passed through extreme eastern Kansas, during the evening hours of October 4, 2013. Tree damage was reported in Leavenworth County.

A cold front generated scattered thunderstorms, when it passed through northwest Missouri, during the evening hours of October 4, 2013. A gust to 61 mph was reported at the St. Joseph Rosecrans Airport.

Thunderstorms developed along a cold front over central Oklahoma during the late afternoon hours of the 4th. These storms moved slowly eastward and affected northeastern Oklahoma during the evening. One of these storms became severe, producing hail up to golfball size and some wind damage across portions of Osage County.