NY NJ PA Weather Forecasts

Active afternoon expected, Bermuda high to develop next week

7:38 AM

Summer like conditions will return to the forecast area with some of the warmest, dare I say hot, conditions for the forecast area for not only this afternoon, but also for next week!

This morning, despite the passage of the “cold front” yesterday, the forecast area is in a warm and humid air mass.  This air mass is supported by the southwesterly and westerly upper and mid level winds ahead of an intensify upper low, which can be seen to the left.

This upper low is entering a period of peak strength over the Great Lakes and is sending a series of disturbances through the Ohio Valley and eventually through the Mid Atlantic.

There are several factors this morning that strongly hint at the potential for some strong to severe thunderstorms this afternoon.  For one, dew points this morning are already in the mid to upper 60’s which indicates that the lower levels of the atmosphere are saturated with moisture.  The latest analysis from the SPC shows that the most unstable conditions can be found over the forecast area and over the coastal waters.  As the sun continues to warm the atmosphere this morning and early after, I expect the atmosphere to become increasingly unstable as temperatures soar through the 80’s and breaking into the lower 90’s, especially over the Delaware River Valley.  Meanwhile, the upper level features already would support strong to severe thunderstorms this morning.  Mid level wind shear is increasing throughout eastern Pennsylvania through Connecticut and are likely to increase in strength as a strong jet max at 500 MB increases speed shear.  There is some directional horizontal shear, but not as impressive as the growing speed shear.  This means that while there is a slight tornado threat for all of the Mid Atlantic today, the more pressing threat from the shear will be strong downdraft wind gusts.  Also of note is the cold air aloft is producing lapse rates over 6°C between 700 MB and 500 MB.  This means that the air is significantly colder aloft and supports a rising motion in the atmosphere.  The stronger the rising motion, the more thunderstorms can build and intensify.  As the lower levels destabilize in the coming hours, the combination of the low level lapse rate and mid level lapse rate will make a strong case for rising motion, which will support the development of thunderstorms.  Of course, the addition of strong disturbances will also aid in the development of the thunderstorms as well.

So this afternoon, expect thunderstorms to develop throughout the forecast area.  The severe thunderstorms will be capable of large hail, wind gusts over 55 mph, frequent lightning, heavy downpours, and an isolated tornado.  The thunderstorms will move through the region between 2 PM and 8 PM this afternoon and evening.  The rush hour will likely be impacted by the potential of damaging winds, urban flash flooding, and significantly reduced visibility.

A final disturbance will swing around the base of the trough, which will be lifting into eastern Canada, tonight.  This disturbance will spawn an additional low pressure over Virginia, which will move quickly through the Delmarva Peninsula and east of New Jersey over night tonight.  Model guidance originally had this low pressure system moving slower as the trough remained over the eastern Great Lakes.  However, with the upper low and trough moving slightly faster than earlier forecasted, the exit of the low pressure system will be much faster.  I expect an area of steady light to moderate showers to race through much of southeastern Pennsylvania, southern and central New Jersey, and Long Island overnight as the low pressure system passes.  Showers will linger into Saturday morning, however strong subsidence due to the lifting trough an exiting disturbance will bring clearing skies and much drier air into the forecast area by late Saturday morning.

High pressure will dominate the forecast area for the rest of the weekend with dry conditions and seasonably mild conditions through the period.  In fact, this weekend aside from Saturday morning, will be a rather pleasant weekend to go down to the shore and enjoy the Long Island and New Jersey beaches!

The upcoming week though does not look as enticing.  For the first time in this summer season, the Bermuda high will build and establish itself over the forecast area.  However, the theme of this summer will remain, wet.

As you can see with the map to the left, the Bermuda high will bring warm and humid air into the forecast area.  Moisture will move into the forecast area from the Gulf of Mexico and the Tropical Atlantic, which will support a warm and humid air mass throughout the forecast area and all of the Mid Atlantic.  This type of air mass will support temperatures in the 80’s and 90’s with dew points in the 60’s and possibly breaking into the 70’s if the ridge was the only player.  However, the pesky trough that has plagued the eastern two thirds of the nation will continue to have a strong influence on the forecast.  While I don’t expect any well defined cold fronts, disturbances (some of them potentially strong) as seen in the yellow lines, will rotate through the Tennessee Valley and towards the Mid Atlantic each afternoon.  This disturbances combined with the warm, humid, and unstable air mass will support the potential for strong to severe thunderstorms each afternoon and evening.  This will naturally blunt the potential for high temperatures to reach their maximum levels in the afternoon and continue to produce a threat for rainfall each day through next week.  So while the forecast area does get warmer and more summer-like, the threat for rain will remain.

Tags: air mass, Albany, Allentown, Atlantic City, atlantic ocean, Belmar, Bridgeport, Citi Field, coastal waters, Connecticut, delaware river valley, dew points, eastern Pennsylvania, forecast area, Freehold, hail, Hartford, heavy rain, horizontal shear, humid air, Islip, lapse rates, level features, levels of the atmosphere, lightning, Long Island, Long Island Sound, Mets, mid level, New Jersey, New Jersey coast, New York, New York City, Newark, peak strength, Pennsylvania, Philadelphia, Phillies, Poughkeepsie, Reading, Scranton, several factors, severe thunderstorms, spc, Sussex, thunderstorms, tides, tornado, tornado threat, unstable conditions, White Plains, Wild Wood, wind gusts, wind shear, Yankee Stadium, Yankees