The northern tier of the United States has generally been under zonal flow for the latter part of this week. Zonal flow occurs when the jet stream is in a more stable state, lying "flat" across the United States. This allows for a strong west-to-east motion when it comes to weather events moving across the country. A strong west-to-east motion allows for weather systems to move across the country fairly quickly, both high and low pressure systems.
This will continue with high pressure sliding offshore today as a weak low pressure system pushes to the north of New England this evening into Saturday morning. This system will drag its cold front across the region, resulting in scattered showers. These showers will push northwest to southeast this evening through Saturday. Showers will be most numerous across northern New England, closer to the center of the low, with more scattered activity in southern New England.
Showers will end by Saturday morning for most in New England, with clouds from the front clearing out by the afternoon. The exception will be eastern Maine, who may see showers last for much of the day. Showers won't have much to work with, so they will be light. Total rainfall should be no more than a quarter inch across northern New England with many in southern New England not seeing measurable precipitation.
Continuing the theme of high and low pressure trading places over New England, ridging will begin to build back in for Saturday afternoon. This will last through Sunday, bringing mainly seasonable (if not a bit warm) temperatures and overall comfortable early October weather for the weekend.
New England's next area of low pressure will dig into the center of the country and push eastward into early next week. This system will bring New England its next chance for widespread showers Sunday night into Monday. Overall rainfall does look rather light once again with this system. Showers will likely be numerous Monday morning for most.
Over this weekend, the large-scale pattern will begin to change. The setup will transition from a rather flat, zonal flow to a more amplified pattern. This occurs when the jet stream takes on a more wavy pattern, leading to more distinct troughs and ridges. An expansive ridge will begin to build across the west and into the center of the country with a trough digging across the east.
This will allow for much cooler, though mainly seasonable air to enter New England after the cold front from Monday's system clears the region.Temperatures for much of next week are looking quite cool with widespread highs in the 50s to low 60s for all of New England. Overnight lows will also be dropping, with the first chance for a more widespread frost by the middle of the week. So far, Essex County in Vermont is the only county to have seen a frost advisory this season. That should be changing next week.
As we mentioned in our monthly outlook, this may be a persistent pattern as the western ridge looks to hold in place for the next couple weeks. This would keep general troughing over New England during this time. This can be seen in the Climate Prediction Center's temperature outlooks. Both the 6-10 day and 8-14 day outlooks look very similar and showcase a classic ridge-in-the-west-trough-in-the-east pattern.
This does appear to be a mainly dry stretch, at least for next week as the cold front will usher in a rather dry northwest flow. With that said, New England will be under troughing and energy from upper level systems may cycle some spot showers into the region at times. Most of the country is favored to see drier than average conditions persist next week, after the Monday system.
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