Weather Journal: Monday’s snow pales compared to March 25 years ago | Weather Journal


Monday’s snow beat the 1993 Superstorm in the record books. Incredible, but true.

Here’s how: Roanoke officially measured 3.7 inches of snow on Monday. It may have been somewhat more or less at your house, but that’s what was measured with the National Weather Service-approved official measuring stick at the WDBJ (Channel 7) studio on Hershberger Road. Within a 50-mile radius of Roanoke, most snow accumulation reports were 3 to 7 inches, a few spots slightly less and a few spots slightly more.

For Roanoke, that was the heaviest March 12 snow on record, dating to the start of official Roanoke weather data in 1912. It beat out March 12 snowfalls of 3.5 inches in 1914, 2.6 inches in 2005, and 1.9 inches in 1993.

So Roanoke got more snow on this March 12 than it did on the same date from the “Blizzard of 1993.” But, of course, there were 14 more inches on March 13, 1993.

This March 12 snow was, of course, no comparison to the blizzard churned by the Superstorm of 1993. But the recent snow’s eclipsing of the 1993 storm’s March 12 snow total is symbolic of my dilemma today for this Weather Journal column.

I had planned to do a full 25-year retrospective on the Superstorm in this space today, but got figuratively buried by tracking the snow event we just had.

The “Blizzard of ’93,” as it is often called locally, is one of those weather events that resonates through the decades even for people who have little overall interest in weather. Snowfall depths of 1 to 3 feet were stacked into drifts of 6 to 10 feet in some areas by 40 mph winds gusting much higher — a true blizzard, very rare for our region.

Scientists have calculated that the 1993 storm dumped more total volume of snow on the U.S. than any other storm in known history. It brought more than a foot of snow in a stripe all the way from Alabama to Maine, with the western edge of accumulating snow reaching deep into the Tennessee and Ohio Valleys. Typical nor’easters don’t do that.

The Superstorm is known for its blizzard effects in the regions that experienced snow, but it also spawned a hurricane-like storm surge on the Florida Gulf Coast, a tornado outbreak on the Florida peninsula, a derecho in Cuba, and high seas all along the Eastern Seaboard.

The 1993 Superstorm erupted from an unprecedented convergence of three branches of the jet stream over the central Gulf of Mexico, quickly bombing a massively deep cyclone (yes, a “bomb cyclone”) that tracked northeast, just inland over the Southeast U.S. and then along the coast into New England.

While unprecedented in the U.S. history of observed weather, the Superstorm’s formation was forecast many days in advance, even though computer forecast modeling was far less advanced than today.

Monday’s snowfall, by comparison, was really not extraordinary in any way.

As was discussed in this space a week ago, it was a textbook pattern for a medium to large wet late-season snowfall in our region, one much like the patterns resulting in similar winter storms in our past. We had a vigorous upper-level low digging southeast, a developing coastal low off the Carolinas, blocking high pressure over Greenland, a southerly suppressed jet stream and a guiding low-pressure system spinning near Newfoundland.

That’s one reason I stuck to a 3- to 6-inch call on the weather blog, which turned out to be pretty close, rather than bounce up and down and around with forecast model gymnastics in the final hours.

Very few weather events we experience are truly unique; the vast majority are reasonable facsimiles of something that happened 10 or 20 or 50 years ago. Pattern recognition and historical analogs are an important piece of meteorology that I hope rising generations of weather forecasters don’t overlook with myriad computer forecast models at their fingertips.

Much of meteorology is recognizing what has happened before and will again, but sometimes, as the 1993 Superstorm shows, forecasters must try to predict what hasn’t happened before.

Weather Journal runs on Wednesday.

2018-03-13 23:02:54

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