Rare thundersnow buries a large swath of the northeastern US | DW News

Key Concepts

• Bombogenesis: Rapid intensification of a low-pressure system.
• Blizzard Warning: Issued when sustained winds of 35 mph or greater and considerable falling and/or blowing snow reduce visibility to ¼ mile or less for at least three hours.
• Thundersnow: Thunder and lightning occurring during a snowstorm.
• Slantwise Convection: A type of atmospheric convection where air rises diagonally, contributing to thundersnow formation.
• Tripolar Electric Field: The electric charge distribution within winter snow clouds.
• Coastal Flooding: Flooding of coastal areas due to storm surge and high waves.

Northeastern US Blizzard – Detailed Report

The northeastern United States is currently experiencing a severe winter storm, with blizzard warnings in effect for over 40 million people. The storm is impacting areas from Maine to the Delmarva Peninsula, a stretch of approximately 600 km. Authorities in multiple states have issued stay-at-home orders for Monday due to hazardous conditions. New York City is already significantly impacted, with substantial snowfall accumulation. Forecasters indicate this could be the largest blizzard in the region in nearly a decade. Public transportation and airport operations have been disrupted.

Storm Development and Intensity – Bombogenesis Explained

Meteorologist Matthew Kapuji explained the storm’s rapid intensification as a process called “bombogenesis.” This refers to the explosive development of a weather system, driven by a quickly deepening low-pressure area. This intensification results in hurricane-force winds as the low-pressure system draws in cold air and significant moisture. The overlap of these two elements is producing heavy snowfall, thunder, lightning, and coastal flooding, alongside plummeting temperatures.

Thundersnow – A Rare and Dangerous Phenomenon

The storm is also generating “thundersnow,” a relatively rare meteorological event. Kapuji detailed that thundersnow occurs when thunder and lightning accompany heavy snowfall. This is facilitated by “slantwise convection,” a unique form of atmospheric convection where air rises diagonally instead of vertically, as in typical summertime thunderstorms.

Research by Kagawa and Mishimoto in 1994 identified that winter snow clouds contain a “tripolar electric field” – a specific charge distribution. Typically, the positive charge on the underside of these clouds is too diffuse to spark lightning. However, tall structures like wind turbines and skyscrapers can concentrate this positive charge, increasing the likelihood of lightning strikes. Reports indicate dozens of lightning strikes to wind turbines south of New England and a strike within New York City itself. Kapuji further explained that stronger winds actually increase the potential for lightning in winter storms by removing an ionizing layer that normally dissipates the charge.

Regional Impacts and Forecast

As of the broadcast, Boston was experiencing heavy snowfall at a rate of 5 to 6 cm per hour. Conditions are expected to improve over the next 12 hours. New York City is nearing the end of the storm, and Washington D.C. has already been impacted. Kapuji characterized the storm as a “high-end” event, occurring approximately once every 5 to 10 years in the affected region.

Personal Anecdote & Storm Severity

Kapuji shared a personal anecdote about experiencing thundersnow as a child in Plymouth, Massachusetts, emphasizing his fascination with the phenomenon. This personal connection underscored the rarity and intensity of the current storm.

Data and Statistics

• 40 million+ people: Under blizzard warnings.
• 600 km: Length of the area under blizzard warnings (Maine to Delmarva Peninsula).
• 5-6 cm/hour: Snowfall rate in Boston at the time of the broadcast.
• 5-10 years: Approximate recurrence interval for a storm of this magnitude.

Logical Connections

The report logically progresses from a broad overview of the storm’s impact to a detailed explanation of its meteorological drivers. The discussion of bombogenesis provides the foundation for understanding the storm’s intensity, while the explanation of thundersnow adds a layer of complexity and highlights the unusual nature of the event. The regional forecast provides a timeline for the storm’s progression and potential recovery.

Conclusion

The northeastern United States is facing a significant winter storm characterized by blizzard conditions, heavy snowfall, and the rare phenomenon of thundersnow. The storm’s rapid intensification, driven by bombogenesis, has created hazardous conditions and disrupted daily life. While the worst of the storm is expected to subside within 12-24 hours, recovery efforts will take days. The event underscores the power of winter storms and the importance of understanding the complex meteorological processes that drive them.