NYC Weekend Weather – Return of the Polar Vortex? – Jul 11, 2014

You may have heard from media reports that the dreaded polar vortex is set to make a return to the Eastern US during the middle of the coming week. I’ll discuss that in detail below. First, for the weekend forecast:

Today & Saturday – a very pleasant couple of days in the wake of the cold front that finally pushed through our area yesterday. You can feel a marked drop in humidity, and temperatures are much more comfortable. Saturday, high temperatures should top out in the mid 80s in NYC.

Sunday – a chance for afternoon thunderstorms and a high in the mid 80s, chance of rain increasing through out the day into the overnight hours.

Polar Vortex?

Forecast models are in good agreement that beginning Tuesday into most of the rest of next week, an upper air vortex (see below, the trough with an inclosed region surrounded by the blue arrows) will drop into the Midwest and Northeast from the northern regions of Canada. This vortex can be technically referred to as a polar vortex, a term that instantly revives media hype about how cold it will be. But keep in mind, during the summer, polar regions heat up as well, so even the coldest polar airmass and vortexes are much milder than their winter counterparts. Furthermore, the influence of the sun is quite strong as we just passed the summer solstice, so the sun is sitting at a very high angle each day and is highly effective at heating the air quickly. Hence, temperatures are expected to be much below normal for some areas, but we’re not talking about snow or ice.

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Upper air forecast from GFS for Monday, 8PM EDT, 500mb absolute vorticity.

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Next Week

There will be a good deal of energy traveling with the polar vortex, so we’re expecting a somewhat disturbed pattern of weather for the beginning of next week. Tuesday & Wednesday will see the best chances for rain and thunderstorms with a cold front approaching us from the west. Before the cold front, we’ll still see temperatures in the mid to upper 80s with a chance for thunderstorms Monday. Once the cold front passes, we’ll be right in the mix with the “polar” air mass, so our high temperatures will drop into the low 80s, and overnight lows will drop into the upper 60s for the latter part of the week.
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