Gloomy weather will settle over the Northeast Friday evening, the first night of meteorological summer, which spans June 1 to September 30. The gloom will persist through the weekend into at least early next week for most of the region. Friday will actually start off feeling like summer, with temperatures soaring well into the 80s for most of the Mid-Atlantic and Southern New England away from southern facing shore lines. A cold front will trigger showers and thunderstorms Friday afternoon through Friday evening though, the first in a series of cold fronts that will contribute to a cool and damp weekend.
Tropical moisture will flow into the Northeast in conjunction with the warmth Friday, resulting in the potential for moderate flash flooding associated with thunderstorms over inland areas of Pennsylvania, New York and Maryland ahead of the first cold front. Thunderstorms will weaken as they approach the coast due to loss of day time heating and slowing of the front, but scattered showers and thunderstorms that survive will reach New York City and areas further south and east by midnight. Heavier storms may persist over Washington, D.C. throughout the night due to upward motion just northeast of the upper-level low delivering this weekend’s unsettled weather. The severe weather threat is minimal, although some strong wind gusts and pea sized hail are possible with afternoon thunderstorms over Pennsylvania, Maryland and Upstate New York.
Saturday, clouds will envelop most of the Northeast as the upper-level low settles over the Washington, D.C. metro area. Friday’s cold front will stall on an axis between Portland, ME and the New York Bight, just south of Long Island. The front’s presence will keep low clouds and showers around throughout the day. North of the front temperatures will be slightly cooler than normal, in the upper 60s and low 70s. Along and south of the front temperatures will be about seasonal, in the mid 70s to low 80s. Shower chances will increase throughout the afternoon in places like Philadelphia, Atlantic City, New York City and Bridgeport as the upper-level low intensifies and drifts further east-northeast. The heaviest of the showers will most likely be confined to an area between northern Virginia and southern New Jersey, where the upward motion will be greatest. Elsewhere, showers will generally be lighter. North of the stalled front in cities like Buffalo and Burlington, sun may peak through clouds by late afternoon.
Saturday night, high pressure will expand off the coast of Maine, sending a backdoor cold front with cool, oceanic air towards the coast. Temperatures Sunday will be stuck in the 60s as far south as Baltimore and as far west as Harrisburg. Eastern Long Island and Southeastern New England may only just barely reach 60 degrees as meteorological summer advances into its third day. Despite the cool temperatures, partly sunny skies will ensue north and east of the upper-level low, namely in southern New England. Closer to the upper-level low in the Mid-Atlantic, clouds will remain. North, south, and west of the maritime air mass, the sun will break through the clouds and temperatures will return to the mid 70s.
Conditions marginally improve Monday for the afflicted coastal areas as the upper-level low weakens and a surface low drags a third cold front across the region. Temperatures will warm slightly compared to Sunday ahead of the front, but it will still remain mostly cloudy. Conversely, it will be slightly cooler for areas that experience pleasant weather Sunday.
The forecast becomes more uncertain as the first week of June begins. Temperatures near the coast warm up Tuesday in the warm sector of another upper-level low. How far south this low passes will determine whether parts of the northeast experience summer-like temperatures from the Bermuda high, or continue to experience cooler temperatures more reminiscent of spring. Most models including the ECMWF ensemble keep the Northeast cool into next week. However, recent runs of the GFS have kept the Northeast in the warm sector, indicating the possibility of the gloom ending earlier than anticipated. As we know more, we will be sure to update you about the extent of this dreary weather.