Showers and tropical downpours in places this afternoon

1:30PM Update
As of early afternoon the rains are more showery in nature. This doesn’t mean you won’t see some torrential downpours, but it does mean there will be periods when it’s just breezy and muggy followed by very heavy rain. The radar loop below shows areas of rain moving up from the south. At times flash flood warnings have been issued south of Boston as the heavier elements of rain move through. I expect this trend to continue through the evening commute.

If you do see some sunshine this afternoon, that could fuel the atmosphere to develop some thunderstorms. I’ll be monitoring the radar for these as well.

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9:30AM UPDATE

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As of 9:15AM there are flash flood warnings for the areas in red and flood advisories for the areas in light green. The rest of the darker green areas are still under a flash flood watch. Many areas are closing in on an inch of rain, but there are some areas where little rain has fallen as of yet. There will be showers on and off throughout the day.
The rest of the earlier blog is below.


If you’re going to interrupt the nice stretch of weather, might as well do it in a big way. This morning we find a rather vigorous storm centered north of the region with a secondary storm developing south of the area. If this was winter I’d likely be forecasting a mess with rain, mixed precipitation and heavy inland snow. Of course it’s not cold enough for any of that (although we are less than 8 weeks away from our earliest snowfall ever).
Today we need to deal with water and quite a bit of it. All of us are definitely going to see 1 to 2 inches of rain and that isn’t enough to cause flooding. The problem is with the areas of torrential downpours which will develop this morning and continue through and past noon. Some of these elements of tropical rain might bring 1, 2 or even 3 inches in an hour and that’s why the flood watch is posted.

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Urban and Street Flooding
Already this morning there have been flash flood advisories south of here and this is an indication of the intensity of the rain. All of us are susceptible to the heavy rains. The type of flooding we are expecting isn’t big rivers or streams, rather it’s low lying roads, underpasses and small streams which can rise in level incredibly fast if they did receive 3 inches of rain in an hour.
Check out this tweet from the National Weather Service in New York just before 7AM. This amount of rain can do a lot of damage.

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Most of you will just experience a rainy day, but for those who do see the flooding, you’ll at least be aware of it’s possibility. Some areas will handle the heavy rain, while others will flood. Check your basement sump pump if you are susceptable to flooding in these heavy rain situations.
Coastal Flooding
There is also a coastal flood advisory posted for Cape Cod. This is due to possible minor coastal flooding at the time of high tide. When you see coastal flood watches posted it’s important to read the fine print. The watch is issued whether there is going to be major or minor flooding and in this case I am not concerned about the possible results from this storm.
Gusty Wind
There will be some gusty winds at times, especially along the coast, south of Boston. These winds will not be damaging, but could take down some larger limbs which in turn can always cut power to isolated homes and streets. I don’t expect the power issue to be widespread, but again like the flash flooding it might happen to you.
Severe Weather
There is the chance of severe weather as well, south of Boston. Severe thunderstorms generally need some heat to get going and it appears the air will stay cool from at least the Massachusetts Turnpike northward and perhaps even over all of southern New England. If the warm air did move up over southeastern Massachusetts and Rhode Island this afternoon, severe weather could result. I’ll be tweeting about that as it or if it occurs later today.
Skies will clear and humidity drops late tonight with an abundance of sunshine tomorrow at least to start the day. During the afternoon some clouds could build enough to yield a quick shower and this would be most likely inland if they occur.
Saturday is a great day with sunshine and seasonably warm afternoon highs. There also still won’t be noticeable humidity in the air which also will yield very comfortable sleeping weather through the weekend.
I’ll be updating the forecast @growingwisdom on Twitter.