Plain-language summary:
Today will be a mostly sunny and seasonably warm day for most of the region, with some afternoon high clouds in western areas, as post-tropical cyclone
Lee moves away. A sneaky and strengthening storm will bring heavy rain to
eastern New England Monday night, with still some uncertainty in how far west
the rain extends. After that, an extended period of dry, mostly sunny, and calm
weather ensues, likely through next weekend, with temperatures gradually
warming up, though nights could still be a bit cool especially outside urban
areas. Even beyond that, no major storms or temperature extremes are expected,
though it will generally be on the warm side.
Meteorological discussion:
After bringing heavy rain and strong
winds to Maine for the past day, post-tropical cyclone Lee is weakening and
pulling off to the northeast, with clear skies and much lighter winds today. Some high clouds are entering in western areas, but there will still be some sunshine, and temperatures will be seasonably warm across the area.
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| Source: Penn State Meteorology |
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| Source: TropicalTidbits |
However, a subtle trough is already
approaching from the west, with the main disturbance being on its southern edge
in the Ohio Valley right now. This disturbance will move to the East Coast by
tomorrow evening, interacting with the warm Gulf Stream, causing it to intensify.
However, the intensification and northward movement will be limited by the positive
tilt of the trough, and it will also be west of a northern disturbance over
northeastern Ontario, which is not a good spot for the two disturbances to
phase into a stronger storm. Still, given the intensifying storm pulling in
abundant Atlantic moisture, eastern New England is on track to receive a short
period of heavy rain Monday night into early Tuesday morning. Exactly how far
west the heavy rain extends is still a bit uncertain despite the rain starting in 24
hours, as the details of these coastal storms are notoriously difficult to
predict. Still, the Champlain Valley on northwest looks to get light rain at most, with a few
showers from the northern disturbance.
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| Source: TropicalTidbits |
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| Source: TropicalTidbits |
After both disturbances move off to the east, a broad high pressure moves in by Tuesday night and will persist for the rest of the week, with dry weather, light winds, and temperatures gradually warming up, unlike last week. This pattern is promoted by an upper-level trough entering the western North America mid-week with the associated downstream upper-level ridge in the central and eastern U.S. However, given the clear skies, drier air, light winds, and longer nights, nighttime lows will actually be cooler, reaching below 50F (10C) outside urban areas most nights, though no frost is expected given the warming air mass aloft. Afternoon temperatures could approach 80F (27C) by the end of the week, especially in western areas. By next weekend, it is possible that a weak backdoor cold front could slide from the north or northeast, cooling temperatures down, but this is uncertain and appears relatively unlikely for now. Beyond that, a weak closed upper-level low trapped near the Bahamas underneath the ridge could move northward, steered by the strengthening Bermuda high, and bring clouds and rain by the following Monday, although it would likely be weaker by this time. This would only occur if the ridge over the eastern U.S. expands into eastern Canada and remains strong. A trough entering in from central Canada would push such an upper-level low to the east out to sea.
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| Source: TropicalTidbits |
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| Source: TropicalTidbits |
While there is obviously considerable
uncertainty in the weather pattern beyond this, it still looks unlikely that we
will see any particularly hot or cold air masses with a fairly flat jet stream
across North America, leading to still unusually little day-to-day temperature variation.
The weather pattern looks to be mostly on the warm side, with no frost expected
for the foreseeable future. With the flat jet stream, major storms look
unlikely as well, especially with all of the tropical cyclone activity
remaining well offshore in the Atlantic.
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| Source: TropicalTidbits |
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