Monday, November 5, 2012

Impulse responsible for today's showers to morph into another Nor'Easter

Today's showery weather in the Mid-South is the result of an impulse in the mid-levels of the atmosphere that is dropping southeast into the region from Missouri.  Over the next 72 hours, this impulse will move off the Mid-Atlantic coastline, strengthen, phase with a trailing impulse of energy, and explode into a Nor'Easter that will hit areas just affected by Hurricane Sandy last week with more strong wind, rain, and high surf.

The Nor'Easter is expected to exacerbate the damage in coastal areas with additional high water and certainly will frustrate those in the Northeast that are still without power, fuel, and other essentials.  More snow is expected inland from Vermont to western Massachusetts into southeastern (inland) New York and Pennsylvania. Strong wind could further damage fragile infrastructure and set back efforts to restore power and communications to coastal areas from Virginia to Long Island.  Below are snapshots from the GFS computer model showing the  progression of the energy creating this system.

Locally, behind this system, we'll be under the influence of a  trough of low pressure for another day before high pressure ridging takes hold, allowing temperatures to moderate heading towards the weekend.  Our next chance of rain and thunderstorms arrives early next week and it's cause can be seen in the last panel below as another trough moves into the Pacific Northwest. For the complete MWN forecast, click here.

500mb mid-level impulse over the Mid-South at 6pm Monday.
Huge ridge of high pressure over the western U.S.

500mb mid-level impulse moves to the SE Atlantic coast by 6pm Tuesday.
Trailing energy diving into Mid-South from Canada.

Lead impulse strengthens off the Mid-Atlantic coast by Wednesday late evening while
trailing energy catches up.  Nor'Easter in full swing for the Mid-Atlantic. Ridging building
into the Mid-South, starting a warming trend for late week.

Maturation of Nor'Easter as energy phases off the Northeast coast on Thursday evening.
Ridge centered over Mississippi River Valley - very pleasant weather locally.

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