Summer-Like Weather Set to End as Cold Front Pushes Toward New England

Most of New England has one more day of well above average temperatures today. Far western and northern areas will be a notch cooler as clouds and some showers will arrive ahead of a rather strong cold front approaching the region. Widespread 80s are once again possible this afternoon.

Yesterday's high temperatures in the 80s weren't quite enough to break daily records in southern New England, but the widespread 80s in northern New England certainly were. Caribou's high of 83° beat their previous record by 9°. More daily records will be possible today across northern New England, but current records for October 7th are a bit warmer than October 6th's previous records, so it will be more difficult to achieve.

That cold front will push into New England later this evening and it will likely take until Wednesday afternoon to push all the way through the region. By tomorrow morning, the front will likely be draped near the New England coastline. A ribbon of enhanced moisture will flow into New England ahead of the front. Cold air advection will begin to occur rather quickly after this frontal passage, so Wednesday will be a much cooler day.

The main bulk of rain for a vast majority of New England will push through tonight through Wednesday morning. This will likely be a widespread moderate rainfall with a few embedded heavier downpours and possibly rumbles of thunder, but with the frontal passage occurring overnight and into the morning, it will limit convection activity for most.

Below: HRRR showing potential weather in the ore-dawn hours (1st image) and mid-morning Wednesday (2nd image):

The cold front has generally trended slower over the past 24 hours, so the rainfall may hold on into the afternoon in southern New England and northern New England's coastal plain. Showers will gradually taper off from west to east through the day. Should the bulk of rain be able to hold into the afternoon across the coastal plain, there may be an increased chance for thunderstorms to develop given the potential daytime heating.

Below: HRRR showing potential weather around mid-afternoon Wednesday:

A ribbon of enhanced moisture will flow into New England ahead of the front. Areas that see this ribbon line up with the cold front will see the most amount of rainfall. Exactly where this occurs across New England remains a bit of a point of contention. No matter what, a widespread half inch of rain is likely region-wide. This will be a much-needed rainfall, but, on its own, will only put a very small dent in a bad drought across northern New England.

The moisture ribbon may produce two areas of enhanced rainfall over New England: one over northwestern areas as the front will be strongest and one over southeastern New England as the merger with the moisture-plume will be complete. Overall, a lack of strong convergence and convection will likely limit rain totals, so amounts well over an inch are unlikely.

Below: Precipitable water values Wednesday morning, showing the plume of moisture surging into New England ahead of the front:

Cool, Canadian high pressure will build into New England behind the cold front, helping to lock in the cooler air through the rest of the work week. It may initially be breezy on Thursday as the pressure gradient between the center of the high pressure to our northwest and the departing trough to our east will be rather tight. The high pressure will sink southeastward through this time, gradually reducing winds as the center of the high moves directly over New England Thursday night into Friday.

Below: Current weather map for Friday:

Heading into this weekend, high pressure looks to remain in control initially, with a mainly dry and potentially warmer Saturday on tap. A developing coastal storm will be taking shape off the southeast coast. This system will work up the east coast, likely arriving in the Mid-Atlantic by Sunday morning. The high pressure over New England will likely be forced north as the system works up the coast.

Below: Current rainfall outlook for this upcoming Sunday (this is nowhere near locked in, these totals could easily trend higher or lower through the rest of this week):

This may set up a Rex block situation (when high pressure sits directly north of low pressure). The question will be how far north the system can push given the high pressure (will New England be on the dry and warm side of the block or the cooler and unsettled side?). As of now, showers may push into southern New England Sunday and early next week. How far north it gets will be the main thing to watch throughout this week.