Power Outage in Mason City, IA

Emergency Manager reports a few tree limbs down around town with some damage to power lines. Time estimated via radar.

Local 911 call center reported a power line down on a tree and an associated fire along Birch Dr. Time estimated from radar.

Law enforcement reported 6 inch diameter tree limbs and multiple power lines down throughout the town of Clear Lake. Several boats on Clear Lake were either capsized or lost power. Time was estimated by radar.

Trained spotter reported wind gusts to around 60 mph in the downtown area. Power out as well.

Emergency manager reported multiple tree limbs down throughout the town of Mason City. Some have fallen on power lines or are blocking roads. A few power poles snapped as well. Power out in multiple locations. Time estimated by radar.

Wind damage to farm outbuildings. Roof damage to homes and power lines down along 320th St north of Mason City.

Large trees toppled power lines along State Street in downtown Mason City.

Power line was down on the 300 block of Kentucky Ave.

High winds partially blew down a barn. The Emergency manager also reported power lines blown down.

An MCS moved into the state in the early morning hours from Minnesota, producing heavy rainfall across large portions of north-central Iowa. Highest amounts reported were generally in the 4-4.50 range with a 4.60 report in Winnebago county. The MCS progressed generally S and SSE across central Iowa through the morning hours and was able to strengthen enough by the early afternoon to produce wind damage reports in far south central Iowa, including a few large trees, overturned campers, and downed power lines.

A very dynamic weather pattern was set up over Iowa during the afternoon of the 4th into the evening hours. A closed upper low was located to west of Iowa with a negatively tilted trough lifting northeast through the state. A strong area of low pressure developed at the surface over south central Nebraska. The surface low moved north into southeast South Dakota during the evening and overnight hours. A cold front from the low advanced across the state as the low lifted. In addition, several boundaries were present during the mid afternoon hours. An outflow boundary extended east to west along the Iowa-Missouri border, with the synoptic warm front extending east to west across northern Iowa. The atmosphere was very unstable with most unstable CAPE values of 2000 to 3000 J/kg pushing into Iowa from the south. Downdraft CAPE was between 600 and 1000 J/kg. Lifted indices along and south of the southern boundary were between -5 and -10 C. The atmosphere was strongly sheared with 50 kts of effective shear available. With the boundary remaining over southern Iowa through the afternoon, the LCL level was quite low, between 500 and 1000 meters. Very high precipitable water values of 1.5 inches were present. The freezing level was quite high for early October at 13,000 to 13,500 feet. CAPE available in the -10 to -30 C layer of the atmosphere was between 400 and 800 J/kg. An initial round of thunderstorms developed north of the warm front during the mid afternoon hours. They produced heavy rain and some small hail. The largest hail was penny size in Dallas County. Storms produced heavy rainfall as well with 1.2 inches falling northeast of Grinnell in a short period of time. The next wave of thunderstorms developed over north central Iowa. The storms produced hail and reports of one to one and one half inch diameter hail occurred with them. As the dry line moved toward the state, a line of strong thunderstorms developed over west central into north central Iowa. Severe weather was quite limited however. Golf ball size hail was reported in Calhoun County south of Pomeroy, and high winds caused considerable damage in the Lone Rock area of Kossuth County. In addition, winds near 85 MPH downed high tension power poles along Highway 15 south of Fenton.

A strong cold front passed through the state and had become stationary over southeast Iowa during the day on the first. A band of precipitation developed behind the front and set up over northwest Iowa. During the morning, an area of thunderstorms developed over Nebraska and lifted northeast along the line. As the colder air moved in and the thunderstorms approached, a mixture of rain and snow changed to snow with quick accumulation of 5 to 7 inches over the far northwest part of the CWA. Ringsted in Emmet County reported 6.5 inches before 1700 CST. Much of the snow accumulated on grassy areas, though an accumulation of 2 to 3 inches of slush was reported. Another round of thunderstorms developed during the evening and continued through much of the night. A band of snow fall across southwest into north central Iowa. North central Iowa was hit the hardest with 6 to 11 inches of snow. The snow caused numerous power outages as the heavy wet snow stuck to trees and power lines. Mason City was hardest hit with several thousand outages. Sporadic outages were reported over the northwest half of the state due to the combination of wet snow and north winds of 20 to 35 MPH. There were also numerous traffic accidents reported as roads became slick with slushy snow and ice pellet accumulations. There were several school delays and some cancellations, however not as numerous as would have been the case during mid winter. The main problem with roads was the slush. Though much of the snow melted, what was left was of a wet cement consistency. The combination of the dense snow and some road coverage lead to the high number of accidents. A state record for heavy snowfall so late in the season was set as both Britt and the the Northwood area received 11 inches of snow. Algona was was close behind with 10.5 inches of snow. The previous record May snowfall in Iowa was 10 inches at LeMars on 28 May 1947. Some of the other higher totals included 9.7 inches at Northwood in Worth County, 7.3 inches in Palo Alto County north of Whittenmore, 7 inches in Butler County at Dumont, Calhoun County at Rockwell City, Worth County at Manly, and Ringsted in Emmet County. Mason City in Cerro Gordo County received 6.5 inches, with a little over 6 inches reported in Webster County northwest of Badger.

A strong low pressure system passed to the northeast of Iowa on the 29th, with a strong cold front sweeping south across the state. The airmass was quite warm ahead of the front, with the atmosphere able to destabilize as the cooler air moved into the state. Deep mixing took place to near 700 mb, allowing the higher momentum air to mix down toward the surface. Flow in the layer around 850 mb was in the 45 to 55 kt range. A band of strong winds developed over north central Iowa during the late morning to early afternoon hours. Sustained winds were in the 30 to 40 MPH range, with wind gusting to 50 to 60 MPH. A wind gust of 59 MPH was recorded at the Mason City Airport. Damage was minor and limited to tree limb damage and spotty power outages for the most part. The winds resulted in some lodging of the corn crop as well. The fall harvest was underway. Sparks from combine activities resulted in scattered crop fires through the area. For the most part damage was limited or restricted to crop lands, though the small fires spread rapidly in the high winds. Reports of fires spreading with the wind for as long as 2 miles were received. Several homes had to be evacuated due to smoke and the threat of fire. Fires also swept into an auto junk yard in Cerro Gordo County causing some damage there.

Very warm and humid air was in place over Iowa during the 30th and the 1st with high temperatures in the 90s and dew points in the mid 70s to low 80s. The airmass was capped on the 30th, and remained fairly capped on the evening of the 1st as a cold front moves southeast into the state. The cap weakened first over northern Iowa and then gradually farther to the south as the night progressed. The freezing level was quite high, in the 14,500 to 15,000 foot range. In spite of CAPE values in the -10 to -30 C layer of the atmosphere in the 400 to 700 J/kg range, hail production was limited with only spot reports of golf ball to ping pong ball size hail. Precipitable water increased to around 1.5 inches during the evening. CAPE was around 4000 J/kg, with the lifted index around -10 C. A narrow line of thunderstorms formed along the cold front with the main mode of severe weather being high winds. Downdraft CAPE was high, around 1500 J/kg. This resulted in wind of 60 to 70 MPH at several locations. The factor against the stronger storm development was the lack of shear, with only 20 kts available. There were numerous reports of trees and power lines being downed by the high winds. A boat was blown from a dock into a house in the Clear Lake area. Windows were also blown out of a house there as well. Power was knocked out to about 1000 customers in the Mason City, Clear Lake Area.

A strong low pressure area developed over Kansas during the afternoon of the 25th. The low lifted north-northeast and intensified very rapidly to a record deep low pressure over southern Minnesota by the afternoon of the 26th. Central pressure dropped to around 955 mb as it reached northern Minnesota. Strong winds developed around the low on the 26th with sustained winds across the state of Iowa in the 30 to 35 MPH range, with gusts to around 50 MPH. The highest wind gusts recorded were in the Boone area, with a gust to 58 MPH during the early morning, and at the Estherville Airport with a gust of 58 MPH during the mid afternoon. The winds continued relatively strong into the night. Pressure gradients tightened overnight with another round of high winds working south toward Iowa. The stronger winds briefly moved into north central Iowa shortly before midnight, producing a 58 MPH wind gust at the Mason City Airport. Scattered reports of power outages were received, with about 200 customers out of power across the state. Damage was only very minor.

A strong low pressure system moved across Kansas through northern Missouri. Thunderstorms lifted northeast across Iowa during the evening of the 10th. The was no severe weather from the thunderstorms, however a gravity wave formed in the wake of the area of thunderstorms. This produced high winds of 60 to 75 MPH over parts of north central Iowa. Large trees were uprooted by the winds with scattered power outages reported. A secondary burst occurred during the early morning hours in Audubon County with high winds breaking 10 inch diameter branches east of Gray.

Part 1 of 2: A major winter storm system affected the central U.S. during Christmas week. There were two upper level systems involved with this storm. The southern stream low dove into the southern U.S. and then turned northeast. The turn was sharper than is typical as the northern stream upper low pushed southeast. The southern stream and polar low interacted with each other, resulting in a Fuji Wara effect. The southern low turned north, then eventually northwest and moved from northern Louisiana into Iowa. This resulted in a considerable amount of warm air being drawn north over Iowa. Cold air remained in place at the surface due to an existing deep snow cover over most of the state and a polar high pressure over western Ontario. Freezing rain broke out on the morning of the 23rd over west central Iowa, and spread into the north central counties by the afternoon of the 23rd. Freezing rain continued through the rest of the day, tapering off during the early morning hours of the 24th. To the north of the freezing rain area, 3 to 5 inches of snowfall occurred. Much of the area received one quarter to one half inch of ice. The hardest hit areas were from Audubon and Guthrie Counties, north into Carroll, Calhoun, and parts of Crawford Counties. At one point, reports indicated that power was out in 65% of the homes in Audubon, Crawford, and Carroll Counties. These areas received in excess of 1 inch of freezing rain. Tree and power line damage was widespread in these areas. Over 10,000 customers lost power in these counties, some for several days. Farther to the north and east there was damage with patchy power outages, but the damage was not as severe as to the southwest. Driving conditions were treacherous through the entire area with accidents and spin-outs too numerous to mention.

A strong low pressure system lifted northeast across the state during the afternoon of the 2nd. At the same time, the upper level system lifted northeast and captured the surface feature by the afternoon hours. Several rounds of thunderstorms rotated in spiral bands across the state. The atmosphere became unstable during the afternoon with MUCAPE in the 2000 J/kg range and the effective shear around 30 kts. A band of thunderstorms rotated north into northern Iowa. The storms produced winds around 60 MPH in parts of northern Iowa. The highs winds caused some damage to a bar and business in Manly. Earlier, as the storms moved through central Iowa, lightning struck several power poles in Dallas County, setting them on fire.

A frontal boundary extended southwest to northeast across Iowa during the early morning hours of the 15th. At the same time, a large MCS developed over northern Nebraska and tracked east into southern Minnesota into northern Iowa. The airmass was quite unstable over Iowa and favorable for elevated convection as the system moved in. CAPE values remained in the 2000 to 3500 J/kg range along and south of the boundary with lifted indices in the -8 range. The environment was quite strongly sheared with 50 to 60 kts of shear. The downdraft CAPE was in the 500 to 700 J/kg range. Thunderstorms intensified as they moved across Iowa with a small bow echo element developing as the MCS began to interact with the frontal boundary. The event took shape as it moved into north central Iowa and produced 60 to 70 MPH winds as it moved from Kossuth County, east-southeast toward Tama County. Hail was limited with the event as the freezing level had not changed much from the previous day and was still in the 15,500 foot range. One report of three-quarter inch diameter hail was received from Franklin County. There were numerous reports of tree and power line damage. Two semitrailer trucks were blown off of Interstate 35 in southwest Cerro Gordo County between mile post 185 and 186. The two drivers received minor injuries. Reported wind damage included several out buildings and at least two barns flattened by high winds. Some of the harder hit areas were in Bremer County in the Plainfield area. Barns were blown down, along with numerous trees and power poles. The roof of a convenience store was peeled back in Plainfield. Damage extended along U.S. Highway 218 from Plainfield north to at least the Chickasaw County line.

An extremely unstable and hot airmass was in place over Iowa during the day on the 19th. The weather situation was complicated with a warm front extending from northwest into central, into southeast Iowa during the mid afternoon. Earlier in the day, and MCS moved across north central into east central and southeast Iowa. This MCS laid down an outflow boundary that pushed southwest into the state, and eventually met up with the warm front. Along and southwest of the boundary, considerable dew point pooling took place. Afternoon temperatures reached the upper 90s to near 105 with dew points in the upper 70s to mid 80s. CAPE values soared to the 8000 to 10,000 J/kg range by early evening as the lifted index fell to the -10 to -15 C. range. A very strong cap was in place with 700 mb temperatures warming to between +14 and +17 C. The freezing level was unusually high, in the 16,500 to 17,000 foot range. Thunderstorms tried to develop by the early evening, but as additional warmer and drier air pushed into the area the dissipated. After sunset a cluster of thunderstorms developed over southern Minnesota and northern Iowa along the north edge of the cap as a cold front pushed into the state from the northwest. The shear environment was quite favorable with shear in the 55 to 70 kt range in the zero to 6 km layer. The storms eventually developed into an MCC and skirted the northern edge of Iowa. They produced strong winds and some hail. The hail was limited by the very warm airmass with reports of hail in the penny to nickle size range. High winds caused damage to trees and power lines with wind speeds in the 60 to 70 MPH range with the stronger storms in the Winnebago, Worth, and Bremer County areas of north central and northeast Iowa.

An unseasonably warm and moist airmass moved into the central U.S. during the night of the 16th into the day of the 17th. Southwest winds of 35 to 55 kts at 850 mb drew in +10 degree C. dew points. Surface dew points were in the middle 50s to low 60s in southwest Iowa. Thunderstorms erupted as a result of the instability it produced. The freezing level was just over 9000 feet, making it easy for hail to develop. Most of the severe weather from this event was in the form of hail. One storm produced 65 MPH winds in Winnebago County the downed power lines and blew vehicles off the road. It appears this was enhanced by a gravity wave. Thunderstorms continued off and on through the day, though most were not severe. By the mid afternoon hours thunderstorms began producing small hail. Some hail of penny to nickle size developed from Hamilton to Cerro Gordo Counties. A second line of storms moved into southwest Iowa as the cold front from this weather system approached. One thunderstorm produced one inch diameter hail for several minutes southwest of Jefferson in Greene County. A look at records indicates that this is the first time severe criteria hail has occurred in the Des Moines CWA in nearly 20 years. The last time was back on the 9th of November of 1984. This event set a record for the latest occurrence of severe hail in the Des Moines CWA.

An area of thunderstorms was located to the south of the area during the mid evening hours. The thunderstorms weakened, setting off an apparent gravity wave. Strong winds developed over northwest and north central Iowa. Most of the winds were in the 40 to 55 MPH range, however winds near 70 MPH buffeted parts of Palo Alto, Kossuth, Cerro Gordo, and Winnebago Counties. Large tree limbs were down through the area and power was knocked out as a result.

A spring storm system developed during the afternoon of the 8th. A strong frontal boundary extended from low pressure in southwest Kansas, northeast across southeast Iowa, into southern Wisconsin. Late in the afternoon, a strong upper level system moved out of the Rockies and begin to lift northeast into the central U.S. Warm and moist air was drawn north ahead of the low pressure system. Dew point temperatures reached the mid to upper 50s over northern Missouri into southeast Iowa. The warm air was lifted over a cold dome of air located over northwest Iowa, where surface temperatures were in the 20s. Freezing rain was widespread over northwest, north central, and west central Iowa. Thunderstorms with freezing rain were also reported with the system. Many places received one quarter inch or more of ice accretion. Areas toward Storm Lake and Estherville reported widespread one quarter to one half inch of ice acretion. The ice did cause scattered power outages in these areas. Spotty power outages were reported as well, however about the time it became critical the colder air moved into northwest Iowa. This changed the precipitation over to ice pellets and light snow.

Very unstable conditions were in place across Iowa. Surface dew point temperatures were in the mid 70s across the northern part of the state with a warm front approaching from the south. At the same time, an old outflow boundary moved into the northern part of the state from convection that had taken place during the previous night in Minnesota. Thunderstorms erupted along the boundary. As they moved through the Mason City area, winds gusted to 52 MPH in the city, causing some minor damage. One small tree was blown over and a few power lines were taken down by branches.

A powerful late winter storm moved through the central u.s. on the 24th and 25. Low pressure formed over eastern Colorado and tracked into southwest Iowa by the evening of the 24th. The low "bombed" out as it tracked northeast across Iowa and into northeast Wisconsin by the morning of the 25th. Temperatures warmed well above freezing over all of the Des Moines CWA during the late afternoon and evening of the 24th. As the low tracked northeast, a line of showers and thunderstorms marked the passage of a cold front. Temperatures fell below freezing within a few hours of the fronts passage. Winds increased rapidly from the west to northwest. During the early morning hours, winds across the entire state were sustained at 30 to 40 MPH with frequent gusts to around 50 MPH. The winds continued into the mid afternoon hours. Blizzard conditions developed across the north central counties of the state before dawn on the 25th. Very little in the way of snowfall occurred. In fact, most of the snow on the ground was packed ice and not able to blow. An area of light snow moved through northern Iowa between midnight and 6 AM CST. Visibility decreased as wind driven snow in suspension swept southeast into Iowa out of Minnesota. Just north of the Iowa border, significant snow had fallen and was able to blow. Low level winds in excess of 70 MPH were able to transport the blowing snow south. Visibility decreased to under one quarter of a mile very rapidly over the north central sections of the state. Numerous roads, in fact nearly all, were closed due to poor visibility and drifting snow. A serious accident occurred in Interstate 35 south of Clear Lake involving three tractor semi-trailers and several cars. Reports from emergency personnel indicated ambulance rescue was nearly impossible, and in fact delayed for a period, as it was not possible to determine whether they were traveling in the northbound or southbound lane of the interstate. The Interstate was closed at that point. The Iowa State Highway Patrol closed Interstate 35 from U.S. Highway 20 north to the Minnesota border. As the surface low continued to exit the region at a very fast pace, winds decreased during the mid and late afternoon hours. Visibility increased over the enter blizzard to greater than three miles by the late afternoon.

A powerful storm system moved through the central U.S. during the day on the 16th. Low pressure tracked southeast into northern Missouri, then tracked northeast into the Great Lakes. Behind the low was a strong Arctic high pressure area. The pressure gradient was very tight between the two systems. As a result, very strong winds ushered in the Arctic air into the state. Although very little in the way of new snow fell in Iowa, snow covered the ground to a depth of 6 to 14 inches statewide. Most of the snow was loose snow, however freezing drizzle fell over the southeast half of the state during the previous night and limited the lifting of the snow to a point. As the Arctic air spilled into Iowa, temperatures fell from the mid to upper 20s into the single digits above and below zero within a few hours. Northwest winds of 25 to 40 MPH were common over the northwest half of the state, with occasional gusts to 50 MPH. The highest official wind gust in the Des Moines CWA was in Carroll with a gust to 52 MPH. Visibility dropped to zero very quickly as the cold air moved in with blizzard conditions reported. Travel was not recommended across the northwest half of Iowa. Interstate 35 was closed at the 142 mile marker, or at U.S. Highway 20, by early afternoon. By the late afternoon the interstate was closed from the 113 mile marker, just north of U.S. Highway 30. Reports indicated a 37 car pile up north of U.S. Highway 20 began the closure. Most businesses closed for the day and activities were postponed or cancelled. Wind chill indices dropped into the dangerously low category with wind chill values across the state between 40 and 65 degrees below zero. Spotty power outages were also reported, however no widespread outages occurred. To the southeast of the blizzard area conditions were not a whole lot better. Winds of 25 to 35 MPH were common with gusts to between 40 and 45 MPH. Visibilities were not as limited due to the layer of freezing drizzle on the snow. Occasional whiteout conditions were reported, but extended durations did not occur. Wind chill values in these areas were generally between 40 and 50 degrees below zero.