Intense Lake-Effect Snowstorm Unleashes Mesovortexes in Northeast Illinois and Northwest Indiana

On January 19, 2024, a highly localized and intense band of lake-effect snow impacted northeast Illinois and northwest Indiana, leaving behind a trail of fascination and wonder.

Mesovortexes: A Spinning Spectacle

The snowfall, which reached nearly three feet in a narrow swath only a few miles wide, was accompanied by an extraordinary display of more than a dozen wintry whirlwinds known as mesovortexes. These mesmerizing phenomena, often separated by small moats or cutoffs, intensified snowfall locally and created a captivating spectacle.

Mesovortexes are small eddies approximately 10 to 20 miles wide that act like miniature low-pressure systems. They trace their paths on radar and satellite imagery, creating captivating loop-de-loops that mesmerize viewers.

Awe-Inspiring Display

The presence of mesovortexes during this lake-effect snowstorm drew widespread attention from meteorologists and weather enthusiasts alike. Social media platforms were flooded with comments expressing amazement at the remarkable display.

Many noted the rarity and beauty of the phenomenon, with some claiming it was one of the most impressive sequences of mesovortexes they had ever witnessed.

Significant Snow Accumulation

The mesovortexes played a significant role in the extreme snowfall, leading to significant accumulations in affected areas. Michigan City, Indiana, recorded an impressive 35 inches of snow, while South Bend, Indiana, just 34 miles to the east, received only 6 inches, highlighting the localized nature of the snowfall.

Snowfall rates of 2 inches or more per hour were observed in some areas, leading to repeated snowfall accumulations.

Radar Animation Captures the Evolution

A radar animation shared on social media showcased the evolution of the curled snow squalls and their serpentine shape, mesmerizing viewers with its intricate patterns. The animation spanned over 30 hours, capturing the dynamic nature of the mesovortexes and their impact on the snowfall.

Understanding Mesovortex Formation

The formation of mesovortexes is primarily attributed to convergence, the gathering of winds near the ground. When winds converge, they are forced to rise faster, creating favorable conditions for the development of these whirlwinds.

In this particular case, the convergence of winds resulted in a single, elongated north-south oriented snow band, characterized by intense snowfall. The converging winds, acting like two hands rubbing a rope of dough, sculpted the snow band and contributed to the formation of mesovortexes.

Similar Phenomena Elsewhere

Mesovortexes are not unique to this particular lake-effect snowstorm. Similar phenomena have been observed in other locations under specific atmospheric conditions.

• Von Karmen Vortex Shedding: Similar configurations have been observed in other locations where von Karmen vortex shedding occurs. This process produces alternating mesovortexes due to wind curling back on itself downwind of an obstacle or high terrain.
• Rotating Snow Squalls and Waterspouts: Localized convergence processes have led to rotating snow squalls over Lake Tahoe and waterspouts in significant lake-effect snow bands over Lake Erie. These phenomena share similarities with mesovortexes in their formation mechanisms and localized impact.
• Landspouts: In the springtime, convergence bands can give rise to “landspouts,” which are tornado-like whirlwinds that form due to invisible eddies of surface wind beneath towering clouds. Landspouts are another example of convergence-induced atmospheric phenomena that exhibit rotating characteristics.

Conclusion: A Convergence of Wonder

The localized lake-effect snowstorm in northeast Illinois and northwest Indiana featured a remarkable display of mesovortexes, which intensified snowfall and created a visually stunning spectacle.

The convergence of winds, acting like hands rubbing a rope of dough, played a crucial role in the formation of these mesovortexes. Similar phenomena have been observed in other locations, highlighting the diverse and dynamic nature of atmospheric processes that can lead to localized and intense weather events.