Nor’easter by the numbers
That was quite a storm. I certainly enjoyed the challenge of watching it mature. I started tracking it as an area of upper-level vorticity (energy) on Monday, Jan. 25, off the coast of California. It spun there for a few days before becoming a surface low and racing across the continent. By the time it reached the lower Great Lakes, it had intensified into a powerful winter storm.
Last Sunday afternoon, more than 100 million people from Michigan to Maine, and south to the Carolinas were under winter weather advisories. Before the storm reached the eastern seaboard, it was a full-blown Nor’easter.
Just a note about the infamous Nor’easters: many are under the impression that they come from the northeast, but that is not the case. The storm is named for the northeast wind that develops on the leading edge of the storm as it approaches from the southwest.
Not many winter storms can claim such a variety of weather, but a true Nor’easter is capped to the north by a blocking arctic airmass, while a south wind pulls warm, moist air into the bottom of the developing storm.
This week’s text-book Nor’easter didn’t leave much out. The leading edge of the storm served up heavy wet snow that changed to rain, as the system tipped and the wind backed to the south. Away from the coasts, that transition came with a few hours of freezing rain and ice pellets.
The contrast between the deep central pressure of the system and the cold air to the north created a tight pressure gradient which resulted in powerful wind gusts. Once offshore, the lowpressure area produced a rise in the water levels; high-water warnings were issued.
Here are a few statistics from the recent storm:
Rain: 76 mm for Western Head, N.S. That’s more than a month’s worth of rain in less than 18 hours.
Snow: Northeastern New Brunswick won the snowfall lottery with 35 cm in Mir-amichi. However, the rate of snowfall at Foxley River in Prince County, P.E.I., was impressive with 3 to 4 cm of snow per hour at the peak of the storm.
Wind gusts: Wind warnings were issued up and down south and east-facing coastlines. At 5 pm on Tuesday, there was a gust to 93 km/h at the Halifax air-port. While that seems high, at 4:30 pm, our friends in Grand Etang, N.S., expe-rienced hurricaneforce winds with sustained winds of 119 km/h and gusts to 180 km/h. Early Wednesday morning, the Wreckhouse winds were rocking with gusts of 160 km/h.
While I was crunching storm data numbers for this column, Mother Nature wasn’t through with Newfoundland and Labrador. Wind, rain and winter storm warnings were still in effect Wednesday afternoon.
Now, we’re all done with this one, but I should mention that an active storm track is setting up across our region. The next couple of systems will pull down on the jet stream; the new, more winter-like position of the controlling upper-air stream could have us shivering and shovelling to the end of the month.