It’s the Labor Day Weekend, the so-called final fling weekend, a 3-day or, for many, a 4-day weekend and, as per usual for a long holiday weekend, it is NOT one with an ultra high confidence forecast like last weekend. With that said, I am not anticipating any widespread bust on the prediction as the weather will be summery warm and muggy everywhere. The real trick is determining the extent of the showers and thunderstorms. Weak perturbations in the steering currents can easily generate batches of boomers in a tropical air mass. Yesterday’s expectations verified this morning as the first impulse triggered patches of activity migrating eastward across mainly northern MA. According to the WBZ WeatherBug Network, several areas received more than 0.25″ of rain with a few more than 0.50″ in downpours that lasted 10-20 minutes. The entire region needs a solid soaking of 2-3″ but, of course, that would not be appreciated by many on this special unofficial ending of summer weekend. Nevertheless, more showers and storms are in the forecast over the next couple of days. The area of highest risk will generally be located north and west of a Providence to Boston corridor especially through tomorrow. That doesn’t mean that I am completely ruling out any wet weather over southeastern MA and Cape Cod but the odds certainly favor the more inland terrain. As an upper air trough of low pressure amplifies into the eastern portion of the nation, the stage is set for more widespread showers and boomers on Monday as the surface cold front chugs closer to the Atlantic Seaboard.
In the meantime, plan on varying amounts of clouds over the weekend with more clouds than sunshine much of the time. Overall, the nicest weather may exist over the far northern mountains today and tomorrow. The brighter episodes of today and tomorrow across the rest of the region will launch the temperatures to the higher limits mainly closer to 85 degrees except at south-facing coastal areas where the southwesterly wind blows at 8-18 mph and restricts the numbers in the upper 70s such as the area of Newport to Nantucket and outer Cape Ann around Rockport/Gloucester. Boasters and the beach enthusiasts should keep an eye to the sky for changeable conditions. Roaming fog banks over the ocean may become more prevalent in this very muggy regime. With high to oppressive humidity, overnight lows will not slip below 70 in most places. On Labor Day, cloudier weather will result in slightly lower temperatures but no change in the high to oppressive humidity.
Looking ahead, the cold front will shift off Cape Cod Tuesday morning so the clearing will progress southeastward during the morning with most of the showers exiting the Cape around or just prior to dawn. The air will become less humid from northwest to southeast during that day as sunshine takes over between some passing clouds. High pressure builds south of the area late Tuesday to provide a nice brisk westerly flow of much drier air here on Wednesday yielding highs around 80 via ample sunshine. As this is happening, a stronger cold front will be diving out of Canada and it will push southward across New England late Wednesday night and Thursday morning. It will contain a broken strip of clouds and a sliver of mostly light showers. The shifting wind will herald the arrival of an autumnal air mass that will last into the first part of the weekend. Temperatures may rise to the middle to upper 70s early Thursday afternoon then start falling a bit later in the day with highs on Friday in the lower 70s around Boston and some upper 60s to near 70 north and west of the city.
Can you believe that today is August 31 and the final day of meteorological summer? in Boston, June was warmer than average with the mean temperature at +1.9 degrees. It was also extremely wet with almost triple the amount of average rainfall amounting to just over 10″! July had near average rainfall but it was the 5th hottest July on record while Worcester had the 4th hottest July and both Hartford and Providence checked in with the hottest July ever on record! August 2013 has delivered a mean temperature very close to the average but it has been very dry with a rainfall deficit of about 1.5″ in Boston. There were no days at 90 degrees or higher in the city compared to an average of 3. Last August, there were 2 days. Astronomical fall does not begin until the autumnal equinox at 4:44 pm on September 22nd.
Looking ahead, September begins tomorrow. For Boston, on average, the high temperature starts out at 77 at the beginning of the month and drops to 68 by the end. The low temperature falls from 61 at the start to 52 at the finish. Even more depressing is the loss of 81 minutes of daylight as the sunrise times become later from 6:09 to 6:40 am and the sunset times become earlier from 7:18 to 6:27 pm! On average, Boston receives 63% of the possible sunshine in September with about 3.8″ of rain and one day at 90 degrees or higher. The Full Harvest Moon occurs at 7:13 am on the 19th.
If there is any revision necessary in this synopsis and forecast, I will post a fresh update this evening. Otherwise, I will be on duty through this evening and Eric Fisher will be your Sunday meteorologist.
Have a happy and safe holiday weekend.