The start of meteorological summer has arrived. While the very beginning of the month certainly feels like summer, there is a big time cool down coming. This cool down currently looks like it will be more of the rule than the exception this month. Here's a breakdown of weather trends heading into the month.
TEMPERATURES
After a scorching start to the month, temperatures will be cooling down as the jet stream "flips". The set up for late May into the first two days of June featured a massive jet stream ridge in the east and a trough in the west. Heading further into the month, a ridge will build back into the west, which will lead to troughing in the east. This means heat for the northwest and cooler weather for the east. This will lead to below average temperatures for New England for the first week of the month.
Aiding the cool temperatures for next week will be a stalled frontal boundary. The strong cold front that will drop through New England will stall to the south. An area of low pressure will form on this boundary and funnel a lot of clouds and showers into the region through next Thursday (June 8). This area of low pressure does look to finally begin pulling away by the end of next week. Early indications are showing temperatures returning to average by next weekend.
An overall cooler trend does look to stay in place through much of the month. This is primarily due to El Nino conditions continuing to develop. El Nino tends to cause persistent jet stream ridging in the west. As already discussed, a western ridge will develop next week. Initially, El Nino was favored to form by the end of summer into the fall, however, the transition to El Nino is happening more rapidly than anticipated. This means persistent ridges in the west will likely occur during June, keeping New England cooler.
On top of this, North Atlantic Oscillation (NAO) is set to enter into a negative phase. Negative phases of NAO tend to lead to cooler temperatures while positive phases lead to warmer temperatures. This is more pronounced in the winter, but effects can still be felt in the summer. You can see the NAO index forecast through June 15th. The index remains below zero, but does show signs of rebounding back toward zero in the second half of the month.
While cooler temperatures overall are expected, it currently does not look like it will be cold (cold being relative to summer). Temperatures look more to be slightly below average than well below average. Average highs reach the low 80s in southern and central New England and the upper 70s for northern New England by the end of the month.
Remember these are overall trends, there are many factors that go into determining daily high temperatures. Despite overall cool weather, there will likely still be short term warm ups, like what we're in right now, with temperatures rocketing into the upper 80s and 90s...but for two days only.
DROUGHT DEVELOPMENT?
The most recent drought monitor shows much of Vermont, the Great North Woods, northern and downeast Maine and Cape Cod in abnormally dry conditions. These areas did not see nearly as much rain as the rest of New England during recent spring rain storms. Above average precipitation is favored in northeastern New England, with an average amount elsewhere in the region.
Vermont missed much of the rain from our latest two larger rain storms and is currently the driest place in the region. This is where drought development is likely to occur at some point later in June. With potentially above average precipitation in northern Maine expected, drought conditions are looking to hold off this month.
LOOKING BACK
Looking back at my May weather outlook, it did pan out just about as expected. There was a cool start with a (very) warm end. There was more persistent cool temperatures in the middle and latter part of the month than expected.
Comments