11:39AM
With today’s (Sunday’s) weather pretty much set to be warm, muggy, but storm-free, it’s time to look ahead. Regarding today, however, we’ve seen much low cloudiness during the morning but breaks with sun coming out and going back in. As the sun heats the ground we’ve started to see these clouds make a transition into more cumulus type (puffy) clouds versus the stratus (flatter and less defined) that we had earlier across much of the RI, eastern MA, and southern NH area. A moderate breeze coming out of the south today is going to keep the atmosphere a little more stable than yesterday, and with the absence of a defined sea breeze boundary, getting showers and thunderstorms to form during the day today will be more difficult. The chance is not 0%, but it is low enough in my mind to leave them out of the forecast. If something does pop up during the day, I’ll update through comments underneath this post as well as on the WHW Facebook page.
Looking ahead…
A cold front will cross the region from west to east during the first half of Monday, bringing with it showers and thunderstorms. I’m not expecting severe storms as this front will be arriving at the time furthest away from maximum heating, and because of somewhat more stable air ahead of it than what would be seen if the wind were more from the southwest or west. Either way, some of the showers and storms may contain gusty winds and downpours with brief flash flooding possible. Hopefully most of this will take place before Monday morning commute time and impact will be minimal.
Once the front clears the region, a quick shot of cooler and drier air will move in for the end of the day Monday through Tuesday morning. The humidity may actually start to increase again later Tuesday but should not be too noticeable. This slow process of becoming more humid will continue Wednesday into Thursday. Wednesday looks like a fair weather day as weak high pressure remains in control. Starting Thursday and lasting into the weekend, things are a little less certain. A trough of low pressure is expected to drop into the Great Lakes Thursday and Friday. The question is, does it sit there for a while, move eastward right through the Northeast, or something in between? Obviously many people have outdoor plans, and also the nights of the 11th and 12th are important for star gazers as it will be time for the Perseid Meteor Shower. It’s too far away to start talking about detailed sky conditions. I hold out hope that if the trough holds back in the Great Lakes and high pressure off the East Coast is strong enough, we may see a pure tropical flow from the south, and though this often is a pattern of scattered showers and storms, we also see periods of clearer, haze-free sky as the air is coming from the tropics versus the more polluted Midwest. Plenty of time to figure out what will happen next weekend.
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Updated forecast for eastern MA, southern NH, and RI…
THIS AFTERNOON: Partly to mostly sunny. Humid. Highs 78-89, coolest around the Islands and immediate south-facing coastal areas, warmest interior MA and southern NH away from the Seacoast. Wind S 10-15 MPH with higher gusts.
TONIGHT: Clouds arriving west to east by midnight, some lower clouds from the south over Cape Cod and the Islands. Showers and thunderstorms arriving west to east after midnight. Any storms may produce gusty winds and heavy rain with brief flash flooding. Very humid. Lows around 70. Wind S 10-15 MPH with higher gusts.
MONDAY: Mostly cloudy with showers and thunderstorms ending west to east morning. Clearing west to east midday and afternoon. Humid morning, less humid in the afternoon. Highs 80-85. Wind S shifting to W 10-15 MPH.
MONDAY NIGHT: Clear. Cooler and drier. Lows upper 50s to lower 60s. Wind NW 5-15 MPH.
TUESDAY: Mostly to partly sunny. Dry morning, bit more humid later. Highs upper 70s to middle 80s. Wind variable becoming S up to 10 MPH.
WEDNESDAY: Mostly sunny. Low 62. High 88.
THURSDAY: Partly sunny. Low 66. High 84.
FRIDAY: Mostly cloudy. PM showers/thunderstorms. Low 66. High 80.
SATURDAY: Variably cloudy. Scattered showers/thunderstorms. Low 64. High 81.
SUNDAY: Partly sunny. Isolated showers/thunderstorms. Low 66. High 83.