Plain-language summary:
After a modestly hot day today, a cold
front will pass late tonight into tomorrow morning, bringing cooler
temperatures. This cold front will only bring clouds and a few showers, unlike other
cold fronts over the past few weeks. Tuesday through Thursday look to be mostly
sunny with low humidity and cool nights. It could turn warmer, especially in
western areas, but more likely more humid and rainier on Friday before turning
cooler and drier again next weekend. There is no strong signal for anomalous
temperatures or precipitation afterward, but persistence and wet ground favors
slightly below average temperatures, but perhaps with less rain and more sunshine.
Meteorological discussion:
A very strong ridge in the central
U.S. will nose just a bit into our area today, promoting above average
temperatures and decent sunshine, a rarity for the past few weeks. However, a
cold front will quickly move through from north to south tonight into tomorrow,
bringing a rather narrow band of clouds and scattered showers, with rain lasting
no more than an hour or two at any one location. Unlike with previous cold
fronts, upper-level ridging will prevent widespread showers and thunderstorms. It
will be cooler tomorrow, with showers lingering in the morning south of the
U.S./Canada border but being mostly sunny to the north. Tuesday through
Thursday look to be mostly sunny with low humidity and cool nights as Canadian
high pressure moves directly overhead, although it may turn cloudier in western areas later Thursday. Once again though, long-range model predictions of a significant warmup and/or heat wave in our region around this time are going to bust, with the real heat staying well to the southwest. It is truly incredible
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| Source: TropicalTidbits |
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| Source: TropicalTidbits |
As the ridge remains strong in the
central U.S., northwesterly flow in our area will prevent the heat from
extending into our area. However, a subtle trough moving across Ontario and Quebec by
Friday could turn the flow to more westerly or west-southwesterly, allowing for
warm and moisture advection. Given the pattern over the past few weeks, that is
more likely to just lead to clouds and rain rather than actual heat, especially
from Vermont eastward, but it is a bit early to tell for sure. A cold front
will likely dry and cool things out again for next weekend, with another
Canadian high pressure moving in. This air mass will likely be even cooler than
the one coming tomorrow, with the cool Canadian air masses becoming stronger as
the higher-latitudes lose daylight and cool down quickly as fall approaches. However,
the cold front could stall not far to the south of our region, and ridging
could develop overtop the front. Any system developing along the front would
become a slow-moving cut-off low, bringing a day or two of clouds and rain, and
it is too early to say if that stays weak and to the southeast or strengthens more,
comes north, and affects our region. The cold front and associated trough will
also likely steer any tropical cyclone in the Atlantic away from the Northeast
U.S. coast, even as the Atlantic hurricane season quickly ramps up now.
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| Source: TropicalTidbits |
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| Source: TropicalTidbits |
There is a lack of strong signals beyond next weekend. The NAO and PNA are both expected to be near neutral. Persistence and wet ground would favor slightly below average temperatures, though it may be sunnier and less humid and rainy if broad southern Canadian high pressure systems move into our region and become more dominant. This would lead to cooler nights but perhaps near average daytime highs, a flip from the past few weeks. There is the aforementioned caveat of possibly having a slow-moving cut-off low bring clouds and rain for a day or two at a time if surface high pressure and upper-level ridging take hold overtop in Canada, though without a really negative NAO, truly blocked patterns are unlikely.
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| Source: Climate Prediction Center |
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| Source: TropicalTidbits |
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