Posts

John Homenuk

Wintry weather likely in the Northeast Sunday into Monday

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A much discussed storm system will finally make its trek east through the United States this weekend, arriving in the Ohio Valley and Northeast United States from Sunday into Monday. An initial disturbance pushes eastwards on Sunday, shearing out and weakening but still providing the impetus for some preliminary wintry weather. The more significant disturbance waits until Sunday Night and Monday to impact the Northeast US, bringing with it a significant amount of moisture and lift for precipitation. Snow is expected to shift northeastwards from the Ohio Valley gradually as Sunday evening goes on.

That’s where the complications begin: A surge of warm air associated with the system will be battling a departing high pressure, which will be on borrowed time as it moves away into the Atlantic Ocean. This spells the likelihood of mixed precipitation and transitioning precipitation types after a start as snow, especially near the coast where wintry precipitation amounts will be extremely limited. But inland, where cold air is expected to be more stout, a few inches of snow are possible before the changeover.

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John Homenuk

First in a series of wintry events likely late this weekend

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A changing hemispheric pattern will lead to the development of an active, colder regime across the Northern 1/3 of the United States. Changes are already afoot, and are expected to continue developing through this weekend. A large ridge building near Alaska will begin forcing arctic air southwards into Canada, suppressing the jet stream in the United States and allowing colder air to seep into the Northern 1/3 of the country.

An active jet stream pattern is expected to continue to bring disturbances into the United States with relative frequency. The first arrives late this weekend into early next week, and forecast models have come into relative agreement on the storm system’s evolution. There are still considerable uncertainties regarding track and intensity, all of which will have major impacts on sensible weather.

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John Homenuk

Aleutian ridge, cross polar flow will lead to more wintry pattern

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A pattern change discussed for several weeks is already underway, and will kick into high gear over the next several days. A much discussed ridge over Alaska will build northward later this week towards the North Pole. We call this a “poleward reaching” ridge — effectively named — as it develops towards the Arctic and polar regions from the North Pacific and Alaska. This is important for several reasons; but mainly because it helps to dislodge cold air which is typically bottled up in the arctic regions.

The ridge north of Alaska will continue to build this weekend into early next week — a very anomalous feature, even globally — and cold air will surge southward on its east end into the West and Central United States. This very same cold will eventually seep eastwards towards the Ohio Valley and East Coast. It won’t come all at once, in fact it likely will be in multiple rounds, but the cold will be anomalous.

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John Homenuk

Snow returns tonight to the interior, higher elevations

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The second snow event in the Interior Northeast in as many days will unfold later this afternoon and evening, likely lingering through Wednesday morning, as a storm system develops into the Ohio Valley and eventually off the Mid Atlantic Coast. The primary surface low will drive northward into the Ohio Valley, helping moisture surge northward into the Northeast United States with a southwesterly flow.

Meanwhile, the secondary surface low will develop off the Mid-Atlantic coast which at least in some small scale will aid in cold air filtration into the system from a cold high pressure to the north. The main process allowing snow to fall in Northeast Pennsylvania, Northwest New Jersey, and Southeast New York, however, will be dynamic cooling, which occurs when precipitation falls heavily enough to cool the air around it.

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