What caused so much severe weather in upstate NY?

After a tumultuous week of weather, immediate conditions have settled down. Many are left picking up the pieces, though, after several tornadoes, damaging hail and drenching rains caused widespread damage throughout upstate New York.

The city of Rome was hit particularly hard by a tornado that tipped vehicles over, collapsed buildings and left more than 15,000 customers without power. The National Weather Service in Binghamton confirmed a tornado touched down at roughly 3:25 p.m. on July 16; more details will be released in a statement by 8 p.m.

The USA TODAY Network-New York has journalists on the scene and the Democrat and Chronicle will keep you updated on developments in Rome.

More: Tornado, storms ravage Rome and Canandaigua in upstate NY. The latest

What caused so much severe weather in a week?

On July 10, upstate New York experienced the remnants of tropical cyclone Beryl, which spawned the largest number of tornado warnings ever issued in a single day by the National Weather Service in Buffalo. For July 16 and 17, the severe weather was the result of a mesoscale convective complex , a large area of thunderstorms that forms its own low pressure system and spin, said Kirk Apffel, meteorologist with the Weather Service in Buffalo.

The remnants of that circulation passed to the north of Western New York, with the timing corresponding with the warmest parts of the day and favorable conditions to generate wind shear and the severe thunderstorms in the area, Apffel said. Strong enough wind shear can tilt a thunderstorm’s updraft enough to separate from the downdraft, allowing the storm to maintain longer.

How rare were the conditions that caused the severe weather?

The formation of a mesoscale convective complex can happen a few times in any given year, Apffel said. The weather brought by the tropical remnants was, in context, exceedingly rare due to the volume of tornado warnings and tornadoes. Reports of hail bigger than 2 inches in diameter like on July 15 are rare but not unprecedented. The estimated hail size for that diameter is a lime or hen egg; 2.5 inches in diameter is tennis-ball-sized.

More: NY declares state of emergency after tornado and storm damage. Here's what it means

Severe weather roundup

NOAA’s Storm Prediction Center logs reports of hail, tornadoes and thunderstorms, including the damage caused, in an archive of storm reports. Here are some of the reports for July 10, 15 and 16 in New York. More reports for Tuesday will come out throughout the day on Wednesday.

Tornado reports

July 10

• Arkwright, Chautauqua County: EF-1 tornado with 110 mph peak winds
• Eden, Erie County: EF-0 tornado with 85 mph peak winds
• Aurora, Erie County: EF-1 tornado with peak 110 mph winds
• Darien, Genesee County: EF-0 tornado with peak 75 mph winds
• Wolcott, Wayne County: EF-Unknown with unknown winds
• Redfield, Oswego County: EF-1 with peak 90 mph peak winds
• Forestport, Oneida County: EF-0 tornado with peak 60 mph winds

July 15

• Canandaigua, Ontario County: EF-0 tornado with peak 75 mph winds
• Virgil, Cortland County: EF-0 tornado

July 16

Rome, Oneida County: EF Unknown

Notable hail reports

July 10

• Glenfield, Lewis County: 1-inch hail
• Orchard Park, Erie County: 1-inch hail

July 15

• Buffalo, Erie County: 1.25-inch hail
• Canandaigua, Ontario County: 1.75-inch hail
• Victor, Ontario County: 2.5-inch hail

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Wind Reports

There were dozens of wind reports from around the state on all three severe weather days, most focused on the damage caused: downed trees and powerlines, utility poles snapped, barn roofs blown off and microbursts. All of the reports have unknown wind speeds.

How to see damage across the state

One NOAA tool that helps visualize where damage occurred and often corresponding photos, is the Damage Assessment Toolkit. This storm damage viewer allows users to look at storm damage over a set time frame, with symbols to indicate where the damage took place and any possible photos. The viewer is accessible online at apps.dat.noaa.gov/stormdamage/damageviewer .

— Steve Howe covers weather, climate and lake issues for the Democrat and Chronicle. An RIT graduate, he returned to Rochester after working around the state and in Utah. Share with him at showe@gannett.com .

This article originally appeared on Rochester Democrat and Chronicle: What caused so much severe weather in upstate NY?