Plain-language summary:
An incredibly dry, sunny, and calm weather pattern will mostly continue for another week, though increased clouds with a few showers are possible or likely for the middle to later part of next week. It will also remain moderately hot and humid, more typical for July, through early week before increased clouds lead to cooler daytime temperatures but warmer nights. Cooler and drier air will likely move in for next weekend before turning warmer and more humid again through the middle of the following week. However, by then, the persistent weather pattern will likely slowly break down, with a change to more fall-like weather with at least occasional rain, more frequent and bigger temperature fluctuations, and more wind afterward. However, weather systems could still move somewhat more slowly than usual.
Meteorological discussion:
It has remained rain-free for a week, and it appears that it will remain mostly rain-free for another week! Strong upper-level ridging persists over eastern Canada, and the upper-level ridge overtop an upper-level low over the southern U.S. is making for a very slow-moving pattern in which the surface high pressure and clear skies stay over our region for day after day. Repeated upper-level troughs and storminess in the western U.S. is also helping to enhance the downstream eastern Canadian ridge. This is despite the surprisingly slightly positive PNA, but that could be more of a reflection of the central and eastern Canadian upper-level ridge extending west into Alberta somewhat overtop the upper-level trough in the western U.S. It has also and will continue to get gradually hotter and more humid as the sunny and rather calm weather continues, helping to slowly dry out the ground, albeit with the shorter daylight hours and lower sun angle making the warming and drying less effective than they would be in the peak of summer. Some lower elevations will reach near 85F (29C) early this week, with moderate humidity, making it feel more like a typical moderately hot and humid July day. The ridge has also pushed the remnants of Francine well to our southwest, blocking them from reaching our region.
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| Source: TropicalTidbits |
However, there are subtle signs that this blocking ridge pattern will eventually break down. On Monday, a surface low-pressure will strengthen and develop some tropical characteristics in the warm waters just off the North Carolina before being pulled inland by the strong ridging to the north and quickly weakening and losing tropical characteristics. Remnants of the system will slowly push north and may eventually bring at least cloudier weather to our region, at least south of the U.S./Canada border, if not also a few showers. The clouds will decrease daytime temperatures but will keep nights warmer. The strong ridge still looks to mostly suppress rainfall, with most of the remnants dying out after a backdoor cold front (more commonly found in spring) comes from the north or north-northeast likely on Friday, bringing a surge of cooler, drier air that pushes any moisture and clouds back to the south, and with the front itself likely only bringing clouds and a few showers.
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| Source: TropicalTidbits |
The repeated troughs in the western U.S. appear to end late next week, getting replaced by an upper-level ridge as the PNA becomes even more positive, with both the NAO and AO turning negative. This allows one of the troughs and associated surface low-pressure systems to finally push slowly eastward into the Great Lakes and slowly attack the blocking ridge, though this might take a few days. By the middle of the following week, the increased southerly flow of moisture ahead of the storm will likely lead to increased clouds and eventually some rain as the low-pressure system moves into our region, though the timing is uncertain as always when slow-moving blocking ridges are involved, of which models often struggle to accurately forecast their demise or movement out of a region. There is still no indication of a major storm for now though. Ahead of the storm, it will likely turn warm and humid again. Whenever the blocking ridge breaks down, more fall-like weather is expected afterward, with somewhat faster-moving weather systems (though perhaps still not as fast as usual with the negative NAO), more wind, and more changeable temperatures between warm and cool air masses, though the overall weather pattern still supports above average temperatures more often than below average temperatures in our region.
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