The upper-level low that's been hanging around New England for much of this week will remain in place for one more day before beginning to slide to the northeast of New England, well into Canada. High pressure will begin to build to New England's west today, which will help keep showers from forming amid the cyclonic flow from the upper low. Some showers will still be possible at elevation across the higher terrain.
A cold pool aloft will remain centered over New England for Thursday. This will bring the coolest high temperatures of the fall season thus far. Highs will top out no higher than the 50s anywhere in New England with 40s across the typical cold spots in northern New England. The pressure gradient between the departing low and building high will create a chilly breeze with gusts of 15-30mph across the region.
Heading into tonight, the building high pressure will remain well to New England's west. This will allow the breeze to continue through tonight. While another chilly night is expected, it won't get as cold as it could if the high pressure was overhead. The breezy conditions will limit the amount of cooling that can occur. This will help limit frost development tonight. Frost advisories are in effect for southern Vermont, western Massachusetts and northwest Connecticut.
Heading into Friday and Saturday, the stalled upper-level low will push well away from New England. A transition to more zonal flow is expected, which will help push the upper low away. It will also allow for a couple quick hitting, low-impact systems to move through the region. The first of these will come Saturday morning, as an area of low pressure skirts to the north. This will pull a cold front across northern New England in the morning. This may ignite a couple showers across the northern tier of New England as it passes.
Southern and central New England will likely see sunnier, dry and mild conditions on Saturday as the cooler air will lag behind the front. The northern third of New England will see generally more clouds, breezy and much cooler weather as the front crosses in the morning. Highs will likely get well into the 60s with some near 70° in southern New England with more 50s across the north with a chilly breeze.
On Sunday, all of New England will be cooler as the front clears the region. Another system will zip through New England Sunday afternoon and Monday. There are timing differences with this system with some guidance pointing toward potential showers beginning Sunday morning while others hold it off until later in the afternoon. These differences likely have to do with dry air and surface high pressure over New England on Sunday. This will eat away at showers initially.
While the timing remains a bit uncertain, general trends point toward clouds and showers moving west to east Sunday afternoon and continue into Monday. Sunday is very unlikely to be a washout. Generally speaking, more rainfall from the system is expected across northern New England with much more limited precipitation in southern New England. The system is expected to deepen Sunday night as it passes through New England, which will help precipitation become more widespread.
After this system, next week may end up pretty similar to this past week with a ridge over the west and a trough remaining over the northeast. This will keep temperatures cool with more frost and freeze potential. An expansive area of high pressure will likely preclude any more organized shower activity, but some pop-up showers will be possible in the trough, similar to this past week. This setup will likely last through at least midweek.
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