US: East Coast Nor’easter, Large High Builds To Bring Tranquil End To Sept

Written by Mark Vogan on September 20, 2015 in Autumn 2015, Summer 2015, United States of America with 0 Comments

While a trough digs into the Eastern US now we have heights building once again over the Plains and this forces a trough split into the new work week with a piece lifting up into the Maritimes and Atlantic while the other drops into the Southeast and it’s the piece left behind that bares watching.

The remnants of Grace is opening up but models show this feature regrouping as it gets lifted north just off the EC. If this feature bundles with the help of warm ocean then we may be talking an early fall Nor’easter from Virginia to Maine with coastal gales and heavy rain.

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This is a classic warm late Sept/early Oct pattern settling in with ridging building NNE from California through Plains to Ontario. You need to watch the tropics when the core of ridging lifts up into eastern Canada and the negative holds over the Gulf and off South Atlantic coast.

Beautiful Saturday evening sky at Walt Disney World, FL.

Credit: weatherbug.com

Philadelphia sky this evening.

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Meanwhile we’re talking another trough dropping down the West Coast through next week but a plume of rich tropical moisture looks set to greatly enhance shower and thunderstorm activity over the Four Corners and Southwest while later in the week we have a trough and system pushing into the Pacific Northwest.

The below GFS surface shows the evolution of this week’s pattern with large, sprawling Canadian high dropping into the East then as it drops down off the EC and winds turn SW, heat and humidity returns but this pattern looks to grow increasingly benign as we approach the end of the month and begin Oct.