DAYS 1-5 (JUNE 26-30)
This “work-week” through Friday is also the final 5 days of June, and the theme of the weather will be generally the same throughout as upper level low pressure will gradually drift eastward across the Northeast and New England, all the while undergoing a very slow weakening process while disturbances rotate around it, providing opportunities for showers and thunderstorms at various times. Getting a little more detailed where I can, we start today with extensive stratus and areas of fog. Ironically one of the areas with breaks of sun is the outer portion of Cape Cod, and while the South Coast and Cape will be in and out of low clouds and fog today and much of the week, they will also have “nicer” intervals. The stratus deck will break up across much of the region for at least partial sunshine today, but any sun will help fuel showers and thunderstorms, and today’s activity is most likely to occur during the afternoon over eastern CT, central MA, and southwestern to south central NH, while areas to the east are less likely to see them, at least until tonight. That’s when one of the aforementioned disturbances will swing into and across the region, keeping a shower and thunderstorm chance going through the night and into the early hours of Tuesday. I think if one day is to see the least amount of sun regionwide during this 5-day period, it will be Tuesday as we deal with a return of low clouds to start the day and above that an extensive canopy of mid to high level cloudiness associated with the remains of a Midwestern MCS (mesoscale convective system – aka a sizeable cluster of thunderstorms). Additional showers/storms can pop up in our area at any time regardless as another disturbance enters the region, courtesy our upper level low. Wednesday’s idea is more of a sun/cloud mix evolving as a slightly stronger southerly air flow tends to help the cloudiness line up with the wind in bands, but some of these can still evolve into bands of showers and thunderstorms. In this case you can get bands of showers staying over the same locations for longer periods of time as they line up with the wind flow, which will be southerly both at the surface and aloft. This set-up can lead to “training” or multiple shower and/or thunderstorm cells moving over the same region, which increases the chance of flooding, so we’ll have to watch for that. This activity should subside at night, but it may take its time doing so – will have to re-evaluate this based on monitoring short-range guidance leading up to it and then the radar that day and evening. By Thursday, the weakening upper low will be crossing overhead, and that day will feature a fair-weather start but pop up showers and thunderstorms possible anywhere during the afternoon and evening. These tend to cluster and then drive themselves via outflow boundaries when you have the upper low right overhead and no real strong steering wind, and then the activity diminishes with the lowering / setting sun. Also a higher hail potential can exist Thursday with the cold pool right atop the region. I’m optimistic that this low gets east of the region by Friday with a drier overall outlook, but still enough cyclonic flow and cold air aloft that we cannot rule out some pop up showers and storms, just with more isolated coverage and probably with a movement more to the southeast, in contrast to the more northward-moving showers/storms the first half of the week and the chaotic movement of any convection on Thursday. So you see, even within a pattern governed by the same system over several days, the details of certain things can change. There will be a lot to monitor as we go through these final June days.
TODAY: Extensive low clouds start the day, along with areas of fog especially South Coast. A sun/cloud mix follows but clouds may hang longer South Coast. Scattered afternoon showers and thunderstorms, some possibly strong to severe, are most likely in eastern CT, central MA, and southwestern to south central NH, with only isolated activity east of there. Highs 70-77 immediate coast, 77-84 elsewhere but warmest interior valleys. Dew point upper 60s to 70. Wind SE up to 10 MPH but can be variable, strong/gusty near any storms.
TONIGHT: Becoming cloudy. Areas of fog, likely most dense in coastal areas. Scattered to numerous showers and thunderstorms. Lows 63-70 Dew point 60+. Wind SE up to 10 MPH, can be variable/gusty around any showers/storms.
TUESDAY: Mostly cloudy with showers and thunderstorms likely. Areas of fog. Highs 71-78. Dew point middle 60s to lower 70s. Wind SE-S 5-15 MPH.
TUESDAY NIGHT: Mostly cloudy with showers likely. Chance of thunderstorms. Areas of fog. Lows 61-68. Dew point 60s. Wind S up to 10 MPH.
WEDNESDAY: Sun/cloud mix. Areas of fog, especially in the morning. Showers and thunderstorms likely, especially during the afternoon. Highs 72-79. Dew point middle 60s to around 70. Wind S 5-15 MPH.
WEDNESDAY NIGHT: Lots of clouds. Lingering showers, chance of thunderstorms, and areas of fog. Lows 60-67. Dew point 60+. Wind S up to 10 MPH.
THURSDAY: Variably cloudy. Scattered showers and thunderstorms mainly in the afternoon. Any heavier showers/storms may contain small hail. Highs 75-82. Dew point 60+. Wind variable up to 10 MPH, possibly gusty near any storms.
THURSDAY NIGHT: Partly cloudy. Isolated showers early. Patchy fog. Lows 60-67. Dew point 60+. Wind variable under 10 MPH.
FRIDAY: Partly sunny. Isolated showers and thunderstorms, mainly in the afternoon. Highs 76-83. Dew point near 60. Wind NW 5-15 MPH.
DAYS 6-10 (JULY 1-5)
Another but likely weaker upper low will be around for the July 1-2 weekend with a chance of showers and thunderstorms both of those days. Exit upper low and enter weak high pressure with less shower/storm chance, better weather, more seasonable but no major heat July 3-5. Moderate confidence on that forecast trend with fine-tuning to come.
DAYS 11-15 (JULY 6-10)
We should head to the 1/3 of the way through July mark with a pattern that features no sustained major heat, and a weaker version of the late June pattern, with the trough a little further west than we’ve seen it, reducing the shower/storm chance somewhat, but still with a few opportunities.