Last Friday, New England Storm published an article detailing the United States' stuck weather. The weather across the country has been stuck in place for much of June thanks to an Omega Blocking pattern. This block has been creating cooler and unsettled conditions in the east and west and hot and dry conditions in the middle of the country. This block has been unusually persistent, especially given the time of year. These kinds of blocks are much more typical of spring than summer.
Pattern that has been stuck in place for most of June:
This persistent Omega Block is showing signs of weakening as the weekend approaches. The pattern is finally changing. The large ridge in the center of the country is flattening out and will likely disappear into the weekend. Texas and Louisiana will "cool off" (there's really no such thing as cool in Texas and Louisiana this time of year) from the 100s with heat indices around 115-120. The heat dome in the south is looking to continue to slide eastward.
At this same time, a ridge (a bump in the jet stream) will begin to build into the west. This will allow heat to build across the west coast. In last week's article, it was stated that a trough (a dip in the jet stream) was needed to dig into the west to help push the ridge eastward. Instead, the country's midsection ridge is flattening as the western ridge builds.
New pattern developing across the country, with one piece remaining the same:
This leads us to the "piece" of the pattern that is remaining in place for New England. While the ridge builds in the west, the trough will remain over the northeast. On the map above, four pieces of the pattern are highlighted. Three of them are different while one remains the same: 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. On top of this, the NAO Index is forecast to remain negative while the PNA Index is forecast to remain positive. Without going too deep into details, this promotes blocking to continue into July for New England. This would lead to an overall continued unsettled pattern for the region with continued high humidity.
This doesn't mean the weather won't change for New England at all. The breakdown of the Omega Block will allow temperatures to warm to seasonable levels (upper 70s to low 80s), although intense summer heat may continue to be elusive as long as the trough is in place (whether this is a positive or a negative is up for you to decide). Vermont will have the best shot at hitting the highest temperatures next week.
NOAA temperature outlook showing warmer weather sliding east. This outlook also shows the ridge building in the west:
New England is also looking at generally drier times this weekend into the middle of next week. It will be unsettled with a cutoff low moving through the region Sunday through Tuesday, but overall coverage of showers and storms may be less than this past week.
New England's weather pattern can be summed up in one sentence: slow moving cutoff lows bringing showers and storms for days on end with brief ridging in between allowing drier weather.
This can be seen by looking back at the weather this past week and looking forward to next week. Widespread showers and storms fired on Sunday, Monday, Tuesday and Wednesday (June 25-28). More isolated storms fired on Thursday (June 29), followed by a brief ridge bring mainly dry conditions to most of New England on Friday and Saturday (June 30-July 1). Then, another low will move through the region, bringing a return to more widespread showers and storms from Sunday through at least Tuesday (July 2-4). No days are looking to be washed out at this time.
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