New England's weather has been dominated by an unseasonably strong Greenland Block since late June. This has led to very unsettled weather that has really begun taking its toll with rounds of flooding and severe thunderstorms moving through the region multiple days a week. That Greenland Block is now starting to break down, which is going to lead to some changes for New England's overall weather.
On June 29, we published an article detailing a weather pattern change that was coming for the 4th of July. In that article, we wrote:
"The blocking high over the North Atlantic Ocean is not budging. As long as that big ridge of high pressure is sitting in the north Atlantic, it will be very difficult for New England to get out of the trough, even as the Omega Block breaks down."
Now that the Greenland Block is starting to weaken, it will lead to a gradual shift in the overall pattern. This shift is gradual as the weakening of the block will be slow. Blocking patterns are always stubborn and take a while to break down. During the early part of next week through the middle of next week, the trough over the northeast will likely begin to flatten.
This flattening of the ridge will allow consistent hotter, summer-like temperatures to stick around in New England next week as well as speed up the progression of low pressure systems. With the jet stream flatter, these systems will be able to shoot through New England much faster rather than get hung up for days on end.
This faster speed of low pressure can be seen in the upcoming week. A system will come through the region Tuesday (July 25), bringing the chance for thunderstorms and downpours that afternoon. However, unlike previous weeks, this system will exit by Wednesday morning (July 26). In previous weeks, this system would hang around all week, bringing the potential for showers and storms for days instead of just one day. Temperatures will start to increase early in the week as well.
This pattern shift continues to evolve heading into the latter part of next week as the breakdown of the block continues. While there's still a degree of uncertainty a week out, confidence is growing for a ridge to build into New England, allowing hot, humid and mainly sunny weather. As of now, it looks like southern New England will have the best chance of seeing truly hot weather.
Just how hot it gets at the end of next week remains an uncertainty, but a heat wave for southern New England (three consecutive days at 90+°) is in the cards for Wednesday through Friday (July 26-28). There are more questions about northern New England heat as some energy from low pressure systems to New England's north may work into the ridge, allowing for storms and more clouds.
While the overall pattern is looking drier for the end of next week, thunderstorms can't be ruled out. These storms, especially for southern New England, would be more likely to be the result of daytime heating, typical of summer, rather than connected to a broad area of low pressure.
In our July weather outlook published on July 2, we wrote that there were signals of a warmer end to the month. This pattern shift are those signals coming to life.
Whether this will be a full-fledged pattern change or a temporary shift remains to be seen. New England could revert back to more of a trough by the end of July. Right now, longer term guidance is pointing toward this return to the trough for the start of August. Of course, this far ahead, we'll just need to keep watching.
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