New England weather this week: Back and forth

This week will see a generally progressive pattern, meaning high pressure and low pressure will likely continue to trade places over New England through the week, with neither dominating for an extended period of time. This will lead to multiple periods of quiet weather and unsettled weather throughout the week.

MONDAY

Thunderstorms return to New England today. This will come as another closed upper low will drop down into New England from Quebec. This will provide plenty of instability to fire up scattered to numerous thunderstorms after a partly cloudy start to the day. Storms will likely begin to fire up across the northern third of New England in the late morning to midday before dropping south and east into central and southern New England as the afternoon goes on. Storms will increase in numbers as the afternoon wears on as well.

Photo byNew England Storm Center

There will be a chance for storms to become strong to severe, especially across southern New England. The environment is favorable for potentially large hail development in some of the storms. This is due to steep lapse rates (the rapid rate of temperature decline with altitude) along with lower freezing levels. The altitude where the temperature drops below freezing will be down to around, or just below, 11,000 feet.

Photo byNew England Storm Center

Other storm threats will be strong to damaging winds gusts and torrential rainfall. Large hail may be the initial threat in storms with that threat shifting to strong winds as the storms decay. As far as the torrential rainfall threat goes, there will be weak flow, which will likely cause the storms to move slowly initially. Some parts of New England have seen an inch or two of rain overnight; should storms sit over these areas this afternoon, it could lead to some flooding issues. Isolated flooding issues will be possible in southern New England.

Photo byNew England Storm Center

As far as the main ingredients for severe weather go, there will be sufficient lift generated by the low. Moderate instability and moisture will be available for storms as well. The big factor that may limit activity will be weak shear. With the low nearly overhead, this will lead to a low amount of wind shear, which may make it difficult for strong storms to maintain intensity. If severe activity ends up limited today, it was because of the weak shear.

TUESDAY

This week will be characterized by quick moving systems with high and low pressure systems trading places. On Tuesday, the low from Monday will be replaced with building high pressure. This will bring a quiet, albeit warm, day for the region. Flow will come out of the southwest, which will allow for a summery day with highs in the 80s for most and dew points in the 60s.

WEDNESDAY

On Wednesday, the high pressure will push away with another low pressure system pushing in from the north. This low will be accompanied by a cold front. This front will push through New England during the day, entering northern areas in the morning and pushing south in the afternoon. This will allow for another round of showers and thunderstorms.

Photo byNew England Storm Center

The greatest chance for afternoon storms, and for stronger storms, will be across southern New England, where the front is more likely to cross during peak daytime heating. With the cold front pushing through, the highest storm threat will likely be strong winds. Areas across northern New England will see less storm activity and more general rainfall.

Outside of the storms and rainfall, the day will be warmer and humid, at least for central and southern New England. These areas will likely see highs well into the 80s with dew points well into the 60s. The northern third of New England will be cooler thanks to the passage of the cold front occurring earlier in the day, precluding a warm up in the afternoon.

THURSDAY & FRIDAY

High pressure from the north takes back over for Thursday and Friday. This high to the north, combined with the passage of a sharp cold front, will bring much cooler and less humid weather back to New England. Highs will likely be 10-15° cooler for central and southern New England compared to Wednesday. Both days should be dry with partly cloudy skies, though the second half of Friday will need to be watched as the next disturbance approaches.

Euro showing temperature departure from average on Thursday afternoon, showing much cooler conditions expected post-cold front:

Photo byECMWF/Tropical Tidbits

WEEKEND

A frontal system will likely approach New England late this week into the weekend, bringing a period of unsettled weather. As usual at this stage in the forecast, it's hard to say when exactly the greatest chance for showers will be, but periods of unsettled weather are likely across New England at some point this weekend. These showers will enter western New England first before pushing east. As of now, Saturday afternoon is looking wetter than Sunday afternoon for most, but trends in timing will be watched all week long.

Weather map for Saturday:

Photo byWeather Prediction Center