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Writer's pictureTim Dennis

High Pressure to Direct Systems Around New England This Week

A vigorous cold front will slice through New England on Tuesday. A deep northwest flow will develop behind the front, bringing a much cooler air mass into the region for the rest of the week. The low pressure system associated with this front will push just to the east of New England with high pressure building just to the west. This tight gradient will allow for gusty winds. Sustained winds of 15-25mph with gusts of 30-45mph are likely region-wide.



This will lead to very high fire risk once again. Southern New England is under their 3rd red flag warning in 4 days and 10th overall this fall for New England as a whole. Based on recent trends, more brush fires can be expected to ignite today. Last week, over 200 brush fires burned hundreds of acres in Massachusetts alone.



The high pressure building to the west of New England will shift to New England's north on Wednesday. This ridge will become rather strong, with the center of the high near 1,040 millibars. This will bring dry and mainly sunny skies for New England with chilly temperatures as a northerly flow around the high continues.



Despite the strong high pressure taking charge for New England, it will remain on the breezy side as the center of the high remains over Quebec. This will allow for a brisk northerly flow into New England. It won't be fully windy like Tuesday, but a stubborn breeze will be around during the daytime for the rest of the week.



Just a few days ago, there were signs that an approaching frontal system would bring New England a widespread soaking rain late this week, but this has officially been wiped off the board. This system will traverse the Great Lakes on Wednesday and Thursday. The system will weaken and dive well south of New England Thursday afternoon and evening, keeping any and all shower activity out of New England.



While this is going on, a storm system will be strengthening as it sits to New England's east (seen on the map above). Surface high pressure will shift out of New England on Friday. Strong ridging and high pressure will remain in place over eastern Canada and over the north Atlantic. This setup is blocking the storm system in and will allow the system to retrograde back westward, toward New England, on Friday.




The storm system will not push all the way back into New England, so precipitation will be limited for many. The farther east you are in New England, the better the chance of seeing some rain and/or snow showers from the system. On Friday, widespread showers are likely across eastern Maine. Shower activity will steadily diminish moving west of Maine with just isolated to spot shower chances.


There is still a split in guidance in just how far west the system (and its showers) can push, which is expected with these cutoff/retrograding storms. How close the system comes will drive shower chances. The Euro is more excited about showers for all of New England while the GFS and CMC are drier. Either way, this won't be much of a rainfall event (at all) for New England.


Below: Current Weather Prediction Center precipitation outlook for Friday morning to Saturday morning:


The exact track the system takes back toward New England is also important for eastern Maine and the higher terrain of New Hampshire. If the storm takes a more northerly route back (near Nova Scotia), it would support more by way of snow showers whereas a more southerly route back (well south of Nova Scotia), it would support mainly rain showers.


At this point, it looks like it will be a burst of snow showers at the onset Friday morning with a gradual changeover to rain showers as the day progresses for much of Maine and the rest of the higher terrain of northern New England. Both snow and rain accumulations are poised to be minimal for Maine and the White Mountains (and the Green Mountains if precipitation can push that far west). Only rain showers are expected across central and southern New England


Below: Euro showing potential weather Friday morning (1st image) and Friday evening (2nd image):


As one would expect with this kind of setup, there are questions regarding how long the system will stick around for New England. As of now, it does look like it will stick around for Saturday, keeping scattered showers in the picture, mainly for Maine.


Looking further ahead, a strong ridge is currently looking poised to set up near Greenland next week with a trough off the east coast. This would be consistent with the expected transition to a negative phase of NAO. Whether New England is dominated by the trough or ridge will help determine next week's weather. The one consistent is that no widespread soaking rain events are on the horizon.


Below: 500mb height anomaly next Tuesday showing the strong ridge to the north and a trough along the US east coast:


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