Forecast discussion: Once again, Thursday started in Boston a lot like Wednesday, weather wise. The day started with bright sunshine, which continued into the early afternoon. But, by the mid-afternoon, an upper level disturbance off the U.S.-Canada border near Maine began to drift southward. This helped create showers, periods of rain, and isolated thunderstorms.
By the late afternoon, some of the thunderstorms helped to create small hail and gusty winds. As of 6 p.m., there was an unconfirmed report that a pilot flying west of Martha’s Vineyard saw a developing waterspout. But, as we move closer to sunset, the thunderstorms moved further offshore and into the ocean. By the early evening, the activity will cease, as we will lose the daytime heating.
We will see clearing skies during the overnight hours, and the humidity will lower. A strong high pressure system north of the Great Lakes will dominate our weather pattern throughout the weekend. Also, rip currents at the south facing beaches will continue to lower, as the seas and swells continue to recede from Bertha. In fact, the next chance for any showers will be by Wednesday morning. A low pressure system will come down from central Canada and bring the risk of showers. It may combine with a stationary low from North Carolina, and its energy will give us the chance for heavier rainfall on Thursday.
Meanwhile, Hawaii is bracing for two hurricanes. It is the first time since 1993 that a Hurricane Warning is in effect for the islands. Hurricane Iselle will be hitting the island during the overnight, with maximum winds reaching 75 mph. Since 1949, when records were being kept, only one tropical storm ever hit the island. During the weekend, they will then have to brace for Hurricane Julio. At this time, the center of Julio will track about 100 miles northeast of the island.
72 hour forecast:
Tonight: Cloudy with showers and thunderstorms ending by 10 p.m. Clearing skies after 2 a.m. with a low of 60.
Friday: Mostly sunny with a high of 82. Winds will come from the north-northwest at 9-12 mph.
Friday night: Clear skies with a low of 63. Winds will come from the northwest at 7-10 mph.
Saturday: Mostly sunny with a high of 83.
Saturday night: Partly cloudy with a low of 64.
Sunday: Mostly sunny with a high of 82.
Sunday night: Partly cloudy with a low of 63.
Monday: Mostly sunny. Highs 81-84, lows 62-65.
Tuesday: Mostly sunny. Highs 79-82, lows 64-67.
Wednesday: Increasing clouds during the morning commute, with scattered showers by the late morning. Highs 77-80, lows 63-66.
Thursday: Cloudy with showers, periods of rain, and scattered thunderstorms until the mid-afternoon. Highs 77-80, lows 63-66.