Plain-language summary:
A very summerlike pattern with above average temperatures and a lack of any real cool air masses, but also a lack of extreme heat, will dominate for more than a week, and perhaps much more than that. It will be mostly sunny and dry and turning increasingly hot today through Tuesday, except scattered showers and thunderstorms north of the U.S./Canada border, especially on Tuesday. A cold front will bring scattered showers and thunderstorms Tuesday evening/night. The weather for the rest of the week heavily depends on the speed and track of Beryl, and it now appears likely that it will go far enough north to bring tropical warmth and humidity to southern areas as well as heavy rain in central and northern areas Thursday into Friday, though the details and timing are still a little uncertain. Southern areas especially will likely experience exceptionally warm nights, even if daytime temperatures are not particularly hot. Next weekend and beyond, it likely dries out and remains hot for a few days, perhaps very hot for a day or two ahead of a cold front. A cool down is likely around 9 or 10 days from now, but it is unlikely to be particularly strong or long-lasting, with hot temperatures likely returning soon afterward.
Meteorological discussion:
We have entered a very summerlike pattern with weak temperature gradients and rather hot and humid (though not extreme) air masses dominating. With a vertically stacked ridge in the western Atlantic, deep light westerly flow will lead to mostly sunny and dry conditions through Tuesday, except a few showers and thunderstorms north of the U.S./Canada border, especially on Tuesday. It will also turn progressively hotter through Tuesday, except it being cooler north of the U.S./Canada border on Tuesday due to increased clouds ahead of a cold front slowly pushing southward through Quebec. Southern low-elevation areas could exceed 90F (32C) on Monday and Tuesday. Humidity will be moderate to high, since there was no dry Canadian air mass to reach our region recently.
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| Source: TropicalTidbits |
A weak cold front will bring scattered showers and thunderstorms Tuesday evening/night, but the front is expected to become more diffuse and stall over our region or just to the south, with the cool air mass behind it not being very strong and unable to penetrate into the Bermuda/western Atlantic ridge. The forecast for the rest of next week heavily depends on the forward speed of tropical storm (soon to be hurricane) Beryl, currently in the northwestern Gulf of Mexico. Models are now showing Beryl moving faster to the north and getting picked up by a subtle trough in the central U.S., as opposed to a few days ago, when models showed Beryl being slower and farther southwest, stalling over Texas and missing the connection with the trough. This
is one of those very sensitive situations with a positive feedback
loop; the storm being bit farther north leads to more of a connection with the trough,
leading to an even faster movement north, etc. This has implications for our area, since now Beryl (and its remnants) are likely to continue trekking north around the strengthening Bermuda/western Atlantic ridge, eventually ending up over Ontario or Quebec by Friday, bringing its tropical cyclone environment and moisture north into our area, instead of being confined to the southern U.S. after the weak cold front pushes the tropical moisture south as earlier expected. If Beryl goes far enough north, areas south of the U.S./Canada border will end up being in the warm sector, being hot, very humid, and breezy, while areas north of the U.S./Canada border will get heavy rain. Even southern areas will initially get a round of possibly heavy rain Wednesday night into Thursday as the weak warm front lifts northward. However, the timing of this is highly sensitive to the forward speed of Beryl through tomorrow, and we won't know the details of impacts to our area until a few days from now. In northern areas that have more clouds and rain, it will not be particularly warm or hot, but nighttime temperatures in southern areas will be exceptionally high with the tropical air mass, in the 70s F (21-25C) for most lower elevation areas.
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| Source: TropicalTidbits |
After the remnants of Beryl move out, broad upper-level ridging will build across almost the entire contiguous U.S. and southern Canada, aided by a positive NAO and AO that doesn't allow arctic air to easily push southward, likely allowing hot temperatures and drier westerly flow to take over. However, there is a small chance that a weak upper-level low gets left behind and slowly meanders eastward in the Ohio Valley, which would continue to advect tropical moisture into our area. There will likely be a cool down around 9 or 10 days from now, as cooler Canadian high pressure attempts to come in, perhaps due to the positive PNA being more dominant briefly, though it is doubtful how much of the cooler air mass will penetrate into our region, especially in southern areas. Just ahead of the cold front is when it will be the hottest, when stronger westerly flow will advect warmer, drier air off the Rockies eastward into our area, and temperatures will also be boosted by compressional warming. Areas east of the Appalachians will have a further boost from downsloping off the Appalachians via westerly flow. After the cool down, general ridging looks to dominate afterward again, ensuring hot temperatures, though there is no indication of record heat anytime soon, which is quite rare in recent years in the middle of summer.
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| Source: TropicalTidbits |
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| Source: Climate Prediction Center |
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