High pressure slides east, making way for approaching systems

After nearly a week dominated by expansive high pressure, low pressure will temporarily take over heading for the weekend. The area of high pressure will continue to drift eastward away from New England today and Friday, though dry weather will continue to dominate during this time. Clouds will begin to increase on Friday, however.

On Saturday, two systems will be around New England. The first is a cutoff low pressure to the west and the second is a coastal storm that will pass offshore to the east. Some ridging will likely develop between these two systems, leading to a mainly dry Saturday for most of New England. The exception will be far western New England, who will be closer to the incoming cold front during the afternoon. Here, scattered showers could break out in the afternoon. Far eastern Maine could also see activity from the passing storm.

Photo byNew England Storm Center

Heading into Saturday afternoon and night, the coastal storm will impact Nova Scotia as it moves away from New England. This storm is now being monitored by the National Hurricane Center as it may try to take on some tropical characteristics. The NHC currently gives the storm a 20% chance of development. This doesn't change anything or heighten concerns, it's just an interesting development. The system will likely cause rough surf in the Gulf of Maine.

The center of the system to the west will make its closest pass at New England later Saturday before lifting northward. The system will send its cold front through New England from Saturday afternoon through Sunday morning. This will spread a period of rain from west to east during this time frame. Much of New England won't see showers arrive until Saturday evening. This band of rain will push eastward through the evening and into Maine by Sunday morning.

CMC showing potential weather Saturday evening:

Photo byCMC/Tropical Tidbits

When all is said and done, western New England will likely have seen up to a half inch of rain with some areas seeing up to an inch, mainly across northern Vermont. Lesser amounts will generally be seen farther east in New England as the line of rain weakens. Far eastern Maine may also see higher amounts depending on the exact track of the coastal system. The more impactful rain totals are looking to stay to the east and west of New England.

Weather Prediction Center rainfall forecast through Sunday morning:

Photo byWeather Prediction Center

The shield of rain from the cold front will have cleared New England by Sunday morning, but the region will remain under broad cyclonic flow, so a couple showers could spring up in the afternoon, mainly in the higher terrain. Overall, conditions will be drying heading into the afternoon on the flip side of the front. Temperatures will also be cooler on Sunday and brief humidity that began to build on Friday and Saturday will be erased.

Photo byNew England Storm Center

One interesting development for Sunday is the fact that the freezing levels may drop to around 5,000 feet across the Green and White Mountains. With the potential for lingering showers in the mountains on Sunday, some of the higher peaks could see some showers turn to a wintry mix.

ICON showing projected freezing altitude on Sunday. This shows at what height above sea level the temperature drops to 32°:

Photo byWindy.com

After this weekend, high pressure looks to build back into New England for the start of next week, leading to another period of mainly tranquil weather. The cutoff low pressure system will remain to the north early in the week, so showers chances will still be around for the mountains.

Weather map for next Tuesday (September 10):

Photo byWeather Prediction Center