GEORGETOWN (KXAN) – People in Georgetown, Texas, woke up Thursday morning and began to assess the damage from what will likely be one of the most costly hail storms in city history.

Hail from egg-sized to the size of tennis balls battered the city, especially the northwestern portions near Sun City and Serenada. The National Weather Service used the photo in the gallery below, which was taken in Georgetown just before 1 a.m., to confirm baseball-sized hail. That’s hail that reaches 2.75 inches in diameter.

Meteorologists say the storm system was a lone severe thunderstorm that erupted late Tuesday night, grew in intensity, unleashed its massive hail stones over Williamson County and then weakened and disappeared over northern Bastrop County.

Residents reported damage to their homes, trees, cars and windows and shared photos showing the impressive size of the hail stones:

National Weather Service chart showing hail size vs. updraft speed

Hail forms inside of a thunderstorm as super-cooled water droplets are lifted higher into the storm by the updraft until they freeze. The updraft, a wind blowing vertically upward inside of the thunderstorm, keeps the hail stone suspended, violently colliding into other droplets inside of the clouds and growing by collision and coalescence.

The hailstone will remain suspended in the upper levels of the cloud until its weight and gravity overcome the strength of the updraft, and the hailstone falls to the Earth. The stronger the updraft is, the longer the stone will stay suspended, and the larger it is able to grow.

Last night’s baseball size hail was produced by an 81 mph updraft wind, and fell into roofs and cars at estimated speeds of 50-60 miles per hour. To produce updraft winds inside of a thunderstorm that strong, you need tremendous instability in the atmosphere, and strong wind shear to keep the updraft and the downdraft in the thunderstorm separate and self-sustaining.