NY NJ PA Weather Forecasts

Another perfect beach day on the way

7:50 AM

Surface high pressure from the Great Lakes remains in control over the forecast area, providing the region with perfect outdoor and beach conditions through today.  However, the upper levels will be shifting and changing over the next 24 hours to provide a much more active pattern than what has been seen over the past 24 hours.

The water vapor satellite image once again spells out what is going on in the atmosphere this morning.  The trough that has dominated the weather pattern for weeks on end is now shifting to the west towards the Mississippi Valley.  This process is producing strong subsidence or sinking air over the Mid Atlantic and Northeast, thus the high pressure system at the surface.  However, take a look over the Atlantic.  A different type of ridge is developing and building over the western Atlantic this morning.  This ridge has an air mass full of moisture and is tropical in nature.  This ridge is called a Bermuda High as the center of the surface high pressure is usually around the small tropical island.  This ridge will continue to build to the west as the trough repositions itself towards the Mississippi Valley.  As a result, the forecast area will be under the influence of southwesterly winds from 850 MB to 200 MB, which will pull a warm, moist, and tropical air mass from the Gulf of Mexico and tropical Atlantic into the Mid Atlantic and Northeast.  Of course, if this was just the end of the story, then we can expect near to above normal temperatures and humid afternoon.  However, this summer has been anything but a dull story, but an active parade of convective events after another.

Note the disturbance over the Great Lakes this morning.  This disturbance will dive into the Ohio Valley tonight and continue toweaken.  As the disturbance turns in the new upper level wind pattern towards the Mid Atlantic, the threat of showers and thunderstorms will increase for the region by Monday afternoon.  Expect this story to continue to play out through all of next week with a threat of showers and thunderstorms each afternoon.  I think, based on the overall storm track with this disturbances, that at least initially the focus for the thunderstorms will be over eastern Pennsylvania, the Delaware River Valley, and the Hudson Valley.  Coastal locations may dodge a bullet here and there due to stabilizing marine influences as well.  Each day will have to be monitored for thunderstorm potential based on the position and strength of each approaching disturbance.

Temperatures through the period will range from the upper 70’s to upper 80’s for afternoon highs along with dew points in the mid 60’s to lower 70’s, making for some rather warm and humid afternoons.  There is a potential for a few isolated locations to break into the lower 90’s under the right conditions, being clear skies in the afternoon and a lack of rain.

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