John Homenuk

AM Update: Heavy rain with localized flooding possible tonight

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Good morning and Happy Thursday! As we move forward towards the end of the week, which seems to be approaching rapidly after Tuesday’s holiday, the weather has been continually pleasant throughout the majority of the Northeast States. Aside for a few local exceptions, seasonable weather has been the beat of the drum over the past 48 hours, with just a few isolated showers and storms in the Mid Atlantic up until Wednesday Night.

Things have already begun to change, as you may have noticed by a newly southeast wind direction along the shores which is pushing inland. This is known more affectionately as an “onshore flow” and it often signals changing weather in the Northeast, when high pressure systems are beginning to lose their grip or control on the area’s weather. Today is no different: Clouds will increase and the onshore flow will begin to aid in moisture advecting towards the region.

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Miguel Pierre

Storms may return late Thursday into Friday

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Enjoy the pleasant, warm weather over the next 24 hours: Unsettled weather is likely to return over the days that follow as  disturbances begin moving into the Northeast and Mid-Atlantic from the west on Thursday. There’s now an increasing likelihood of a period of heavy rainfall with some thunderstorms in the parts of the region later Thursday night into Friday morning.

Some mid-level warm air advection and sheared vorticity will cause cloud cover to increase throughout the Northeast tomorrow. A few showers are possible over the interior during the afternoon or evening, though high pressure offshore will likely provide enough subsidence (sinking air) to keep most of the region dry. Temperatures tomorrow will reach the mid to upper 70s near the coast and lower 80s inland, with more cloud cover along the coast and an onshore flow.

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John Homenuk

Western US Ridge will serve as pattern’s focal point

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Much has been made over the past few weeks regarding the potential development of a large ridge, which forecast models once suggested would build into the Ohio Valley and Northeast States, providing widespread heat and humidity. As you may have figured out yourself, this ridge has yet to develop — and it doesn’t look it will at all, succumbing to the overall hemispheric pattern which has kept the ridge angled towards the Western United States.

Medium range forecast models were much too aggressive with the development of the ridge, once suggesting that the core of it would build into the Ohio Valley. In fact, for a few model cycles both the GEFS and ECMWF suggested that heat would build into the Eastern US, but have since backed off. The development of these large ridges is quite common in the summer (in other words, this isn’t all that anomalous), but the positioning of the ridge is often modulated by the surrounding environment. This year is no different.

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John Homenuk

Transitional weather expected to continue through the week

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Happy Independence Day to all of you! While today is a day to spend enjoying with family, friends and loved ones, we’re taking a moment to look ahead at what the weather will have to offer over the coming days. The pattern over the last several days (and even the past few weeks, really) has been markedly transitional — there has been no true established pattern in terms of temperature of precipitation. As forecasters, we are often looking for changes in how the atmosphere will behave — but this pattern doesn’t show any sign of changing.

Forecast models, especially in the medium range, are in very good agreement that the weather pattern will remain progressive and transitional. Multiple frontal systems and low pressure areas are expected to impact the Northeast states, with a few days of warm temperatures followed by chances for showers and storms, and a few days of temperatures slightly below average for this time of year.

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