Thunderstorms back in the forecast

Most of us have heard the saying that timing is everything in life. From getting that choice job to picking the best week for vacation, timing has a lot to do with it all. So this evening after another fine summer day, though with more humidity, I am focused on the timing of a cold front for tomorrow.

So far this summer has been one of frequent breaks in the heat and humidity and plenty of showers to accompany those breaks. This time of year, most cold fronts, which end a period of heat and humidity, even a day or two of it, are accompanied by showers and thunderstorms. The severity of those storms is dependent on a number of factors including how warm and humid the air is to begin and how cool and dry it will be after the front passes.


Another major factor in thunderstorm development is the time of day a front approaches. If a front nears the area during the peak heat of the afternoon and early evening the chances of strong to severe storms is much higher than it would be if the front passes at 5AM during the coolest part of the day.

If you like big storms, tomorrow brings the opportunity for some strong storms because the front will be getting closer as the temperatures near the 90F degree mark after 2PM. The actual front won’t move through until late at night or in the early morning hours of Thursday, but there will be enough lift before the front so storms should form.


Tomorrow, the atmosphere will be such that strong winds, heavy downpours and even possible hail could accompany a storm. I’m only expecting a tenth to a quarter inch of rain, but if you see one of the storms that number could be significantly higher. The highest risk of storms will be west of Route 128 and the lowest risk is over Cape Cod and the Islands.

If you have outdoor plans Wednesday you it’s going to be a great beach day through 4PM or 5PM. The winds will not be coming off the water, like today, so even Boston will be hot reaching or even exceeding 90F.


The image below shows the position of the showers around 2PM Wednesday. Notice most of eastern areas are still shower free.

2pm weds.png

Once the front passes the showers will end and I believe any improvement will be very slow. I am not expecting complete clearing until the overnight hours Thursday setting the stage for a spectacular Friday and Saturday.

Sunday we will transition into a more unsettled pattern. While next week isn’t going to be a washout, it’s not going to be the accompanied by the mostly dry and sunny weather of the current 7 day stretch.

Finally, speaking of timing, check out the Doppler radar image from this past weekend over the Midwest.

mayflies loop2.gif

This loop is not of a few showers, but of a massive mayfly hatch. You can see the flies hatching and then moving north. It’s not what Doppler radar is intended for, but does show how sensitive the radar is.

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