THE BLIZZARD THAT CHANGED THE NWS...
November 11th, 1940, one of the worst winter storms ever seen whiplashed the upper Midwest. Occurring on Armistice Day, the freak storm killed 154 and became legendary as "the Armistice Day Blizzard". It's fury and lack of warning caused a public uproar that changed the face and operation of the what was then known as the U.S. Weather Bureau.
While I'm too young to remember the storm, it wouldn't matter anyway as its impacts where I grew up in eastern Iowa were confined to wind, a dramatic drop in temperatures, and a few flurries. Not far away though, the blizzard threatened life, livestock, and wildlife, bringing the world to a standstill for up to a week in parts of rural Minnesota. Today is the 83 year anniversary of this incredible event, a storm that I believe for November 11th is unmatched in intensity and impact. It arguably is the G.O.A.T. (the greatest blizzard of all-time) to strike the Midwest.
Barricades of snow in Madison, Minnesota November 1940
Jeff Boyne of the NWS in La Crosse, Wisconsin put together a fantastic summary of the factors and conditions that drove the event and how it ultimately changed the function of what today is called the National Weather Service. Some excerpts of Boyne's are included below. To get Jeff's full report you can follow this link. https://www.weather.gov/arx/nov111940 Otherwise, to find out more about the explosive power of the storm, read on.
THE COLD HARD FACTS
On November 11, 1940, a rapidly deepening low pressure system moved northeast from Kansas City, MO northeast through the Upper Mississippi River Valley and into the Upper Great Lakes. This low pressure area produced the lowest pressure reading ever recorded up to this time at Charles City, IA (28.92 inches), La Crosse, WI (28.72 inches), and Duluth, MN (28.66 inches). Armistice Day (now known as Veteran's Day) began for many with patches of sunshine and temperatures in the 40s and 50s. The weather forecast for that morning was for colder temperatures and a few flurries. The day was so nice that duck hunters dressed in short-sleeved shirts rushed to the marshes along the Mississippi River early that morning.
During the late morning and early afternoon, a strong cold front moved through the region. Behind this front, the weather became rather blustery and the temperature plunged to the single digits by the next morning. Rain turned to sleet and eventually to driving snow. Twelve duck hunters were trapped on the Mississippi River between St. Paul and Prairie du Chien by gale-force winds and threatening waves. These hunters sought shelter on small islands and eventually froze to death. Rescue work the next day was hindered by ice which had developed during the preceding night.
Minneapolis Star Tribune November 1940
Minneapolis Star Tribune November 1940
Elsewhere heavy snow fell across the Dakotas, much of Minnesota and western Iowa, and northwest Wisconsin. The greatest snow total was 26.6 inches in Collegeville, MN. In addition, 30 to 50 mph+ winds caused considerable blowing and drifting of snow which trapped unsuspecting motorists.
Watkins, Minnesota November 11, 1940 John McNab
Twenty foot drifts were reported near Willmar, MN. The blizzard left 49 dead in Minnesota, and gales on Lake Michigan caused ship wrecks resulting in another 59 deaths. In total, the storm claimed a total of 154 lives, and killed thousands of cattle in Iowa. More than a million turkeys were killed by the storm in Wisconsin, Minnesota, and other states. The blizzard became know as the “Armistice Day Storm”.
Watkins, Minnesota following the Armistice Day Blizzard 11/11/1940
This storm, along with a slow moving blizzard which would move across northern Minnesota in mid March 1941, caused the Weather Bureau to rethink its forecasting procedures. Forecasting for the entire region had been directed by the Chicago office, but in the wake of this storm, responsibilities were distributed to regional centers to provide more timely and accurate predictions. More on the aftermath and repercussions later.
THE METEOROLOGICAL SET-UP
Preceding Armistice Day, a strong weather system moving into the Pacific Northwest had taken down the Tacoma Narrows Bridge. Until the collapse on November 7, 1940 the bridge had been the 3rd longest suspension span in the world. The Tacoma Narrows Bridge, an engineering wonder, had already acquired the name Galloping Gertie due to its motion in the wind. A four mile an hour breeze could start oscillations in the bridge while stronger breezes often had no effect. On November 7, 1940 winds of 35 to 45 mph caused the center span to undulate 3-5 feet and the bridge failed before the center of the storm system reached shore. On November 8, 1940 the storm center remained off the Washington coast producing gale force winds. Meanwhile pressure was falling over the Pacific Northwest.
The path of the Armistice Day storm
By November 10th the storm system had moved across the Rocky Mountains to redevelop over Trinidad Colorado (Knarr, 1941). Initially the system pushed east then it curved northward into the central United States where it would leave a path of icy destruction. During the next 6 hours the storm center moved to the vicinity of Iowa Falls, Iowa. West of the center blizzards raged across South Dakota and a widespread ice storm across Nebraska left hundreds of people impacted by the storm. East of the center a broad swath of warm air streamed up the Mississippi Valley.
Weather map 6:30am November 11, 1940
During the day and into the night severe weather erupted across much of the Midwest. A tornado was reported one mile west of Davenport Iowa, 2-3 inches of heavy rain fell in spots over the Mississippi Valley, and heavy snow began to fall across Minnesota and Western Iowa. Gale velocities were measured at 80 mph at Grand Rapids, Michigan, and were estimated to be even higher over the lakes. By the time the storm was centered over Lake Superior, the barometer reading had plummeted to 28.57 inches of mercury.
Weather Map 12:30pm November 11, 1940
SNOW REPORTS
On November 10, 1940, a weak low pressure system (ahead of the Armistice Day low pressure system) began to produce light snow across northern and western Minnesota, and northern Wisconsin. The snow rates then rapidly increased on the morning of November 11th as a much stronger low pressure system moved from Kansas City, MO to just north of La Crosse, WI. The heavy snow then continued to fall into the afternoon into the morning of November 12th as the low pressure system continued to strengthen and move slowly northeast into northern Ontario. In addition to the snow, sustained 30 to 50 mph winds caused considerable blowing and drifting of snow which trapped unsuspecting motorists. Below you can see where snow accumulated.
In Iowa, the snow was mainly confined to the western and northern parts of the state. The highest snow total was 13 inches in Cushing.