Thursday, October 28, 2010

A storm to remember

Finally, after two solid days of severe weather, calmer conditions are returning to the Charlotte region today.

Autumn weather is returning, too (see below), but the storm system responsible for the damage across our area will not be forgotten. It's become a part of weather history.

The center of the trouble was a low pressure system that deepened rapidly Monday over the Dakotas and Minnesota, then eventually pushed northeast into Canada. It was storm of epic proportions, and its impact was felt all the way into the Southeast.

Shortly after 6:30 p.m. Tuesday, the barometric pressure in Bigfork, Minn., dropped to 28.20 inches. That's the equivalent of 955 millibars of pressure -- the same as you'd get in a Category 3 hurricane with winds of 110 to 120 mph.

Nearby International Falls, Minn., had a pressure of 28.24 inches at 4 p.m. Tuesday.

Bigfork's low pressure broke the record for the deepest storm system in Great Lakes history. The previous record was 28.27, set in the Ohio blizzard on Jan. 28, 1978. I lived through that event, and maybe one day I'll write about it.

The storm had a tragic impact. On Wednesday afternoon, a Notre Dame University student was killed while video-taping the football team's practice session. Declan Sullivan, 20, was standing on the 50-foot tower when a wind gust blew it over. The South Bend Regional Airport, 5 miles away, reported a 51 mph wind gust about the same time.

On Lake Superior, a reporting station recorded sustained winds of 68 mph and gusts of 78 mph early Wednesday morning. Waves were 20 feet on the lake -- the kind of waves you see in storms on the open ocean.

With the pressure so low, winds whipped around the system in a counter-clockwise motion. Those winds helped create tremendous shear in the atmosphere, so the thunderstorms that formed along a cold front being dragged eastward by the low pressure system turned into tornadic storms.

On Tuesday, there were 373 reports of tornadoes, damaging wind and hail. Among those were 46 tornado reports, including those from Lincoln, Catawba and Stokes counties near Charlotte.

On Wednesday, there were 32 more reports, including 14 tornadoes.

First Frost coming?: You might want to start planning ahead for the possibility of our first frost of the season, on Saturday morning.

It appears as if temperatures will fall into the mid 30s to the north and west of Charlotte, and the mid to upper 30s near Charlotte. Winds are forecast to be light, so frost is a possibility.

Halloween Outlook: It looks great. Temperatures will rebound from the chilly conditions expected Friday and Saturday morning, with highs Sunday around 70 degrees. Conditions should be clear to partly cloudy Sunday evening, with temperatures in the 60s.


Anonymous said...

Steve, you really ought to do a post explaining the convoluted process by which the NWS uses to "confirm" a tornado caused damage instead of high wind. They're usually reported as "apparent" until days later. So what's the the magical process and why does it take so long?