A persistent mid-level pattern is tied into cooler than average temperatures in the Midwest and a relentless string of nor'easters in New England. A stubborn high-pressure block will keep the Stateline cool for at least the next week
Many weather patterns this month can be attributed to a blocking high pressure near or over Greenland, known as the Greenland block. Air pressure rises in the upper latitudes of the North Atlantic, creating a large area of high pressure. The jet stream diverts around the high, causing it to squeeze and dip farther south in eastern North America. This forces colder air into the Midwest and the East.
This pattern has also contributed to the numerous nor'easters this month. Storms typically form in the zone between cold air over land and milder air over the ocean. The current jet stream pattern then steers these storms into New England. The third nor'easter in only two weeks is slamming the Northeast with heavy snow and strong winds once again.
We may briefly see 50s this weekend, but 40s, and even 30s quickly return next week. In order for the Midwest to warm up, the Greenland block will need to weaken, but that may take a while.