The Alberta Clipper, a fast-moving and powerfully windy storm system, is bringing back a few days of winter. Spring warmth has already shown itself in the US Midwest and in New England, with temperatures well into the teens so this will be a shock.
A clipper originates when a warm, moist wind from the Pacific Ocean travels down the lee side of the western Canadian mountains, into Alberta. It then engages with the cold air that sits in the Canadian Prairies and develops into a storm.
This developing area of low pressure gets whipped along in the overhead jet stream, sending the storm rushing across the Great Lakes, towards the Atlantic Ocean, often travelling the US part of the journey, roughly 3,000km, in around two days.
This Clipper has grazed northeast North Dakota, deepening as it entered Minnesota. Minneapolis felt the temperature drop to zero Celsius and a northwest wind gusting up to 70km per hour.
Parts of Wisconsin, Michigan, and Minnesota accumulated over 13cm of snow on Saturday. Snow fell during Saturday in Chicago, Illinois, but here it was the winds that did the most damage. Northwesterlies of over 80 km/h brought trees down on to houses and cars.
Buffalo, having started April at 19C, had 3cm of snow on the ground on the third day. The forecast track of this Alberta clipper is likely to leave snow on the ground throughout New England.
Although not unprecedented for a New England Spring, this will be an unwelcome return to a brief winter. After all, Providence, Rhode Island started April at 21C.
Source: Al Jazeera and agencies