Forecast discussion: High pressure well offshore gave Boston one more day of hazy sunshine, with increasing clouds over the last couple of hours. However, it was the high humidity in the air that made today feel uncomfortable to be outside. The dewpoint temperatures rose into the upper 60’s to lower 70’s, which makes the air quite oppressive. However, a cold front will bring some relief by the weekend. However, we will have to tend with some strong thunderstorms and Tropical Storm Arthur over the next 48 hours.
Right now, a cold front over the Mid-Atlantic is creating strong thunderstorms and heavy rain for western Massachusetts and central Connecticut. We should see this activity reach eastern Massachusetts between 8:00 to 8:30 p.m. The cold front will move very slowly, so we will see showers, periods of heavy rain, and scattered thunderstorms now into Friday evening. Street flooding from heavy rainfall is possible, along with gusty winds and even the chance for some small hail. So, what are the chances we clear up in time for the Fourth of July?
The answer to that question right now is slim to none. A second cold front will sweep through the area on Friday, and we will begin to receive some of the effects of Arthur. At the moment, Tropical Storm Arthur is centered at 29.7N 79.1W, or about 435 miles south-southwest of Cape Hatteras, North Carolina. Maximum sustained winds are at 70 mph, and is moving north at 7 mph. The system should become a hurricane by the 11 p.m. forecast update. However, eastern Massachusetts will not take a direct hit from the storm. The latest spaghetti models show Arthur continuing to move in a northeast direction away from Southern New England. Instead, we will begin to see more moisture be feed into the cold front, keeping us wet with showers, rain, and isolated thunderstorms on Friday. Also, the Islands and the coastline will be seeing rough seas and surf throughout the weekend, thanks to the high swells Arthur will create south of us. This also means a high chance for strong rip currents.
Our holiday weekend will begin to look a lot brighter by Saturday morning. By then, the cold front will move offshore, and Arthur will soon to follow. High pressure in the Central Plains will begin to build over Southern New England, and our humidity levels will be quite low. By Monday, winds will once again switch to the southwest, helping to increase our humidity. There is the slight chance for some wet weather Monday afternoon, with a greater chance for showers and thunderstorms on Tuesday. A slow moving cold front will station itself west of the region, creating a tug of war with the cooler air to our west and the very warm, humid air over us at that time.
72 hour forecast:
Tonight: Warm and humid with scattered showers and thunderstorms. There may be locally heavy periods of rain. The low will only fall to 73.
Thursday: Patchy fog burning off by the late morning. Scattered showers and thunderstorms, with thunderstorms may be strong at times and create small hail. Heavy rain is possible, as well as street and river flooding. We will see a high of 85 with south-southwest winds of 10-13 mph.
Thursday night: Scattered showers with an isolated thunderstorm and a low of 70. Thunderstorms may produce heavy periods of rain and we will see patchy fog. Winds will come from the southwest at 9-12 mph.
Independence Day: Scattered showers and thunderstorms with winds increasing by the early evening. We will see a high of 79.
Friday night: Isolated showers and a possible thunderstorm. We will see a low of 66. Seas may become rough along the Islands and towards the entrance of Buzzards Bay.
Saturday: Showers ending by mid-morning, with partly to mostly sunny skies. We will see a high of 80.
Saturday night: Partly cloudy with a low of 62.
Sunday: Mostly sunny and less humid. Highs 81-84, lows 64-67.
Monday: A mostly sunny morning, with increasing clouds and possible showers/thunderstorms by the evening commute. The humidity will be increasing once again. Highs 85-88, lows 69-72.
Tuesday: Peeks of sunshine, otherwise mostly cloudy with scattered showers/thunderstorms. Highs 85-88, lows 68-71.
Wednesday: Partly sunny with possible afternoon thunderstorms. Highs 83-86, lows 66-69.