The warm front that moved through here late Tuesday continues to lift north of us and should be draped across northern New England Wednesday. We are now in the warm and muggy air mass as high pressure to our south provides the heat pump. Dew points have increased to around 70 degrees overnight and it has become very sticky out there. Wednesday may be the first day we reach 90 in Boston since July 20th, as the heat and humidity really settles into the area. The National Weather Service has a Heat Advisory in effect for Wednesday, from 1 pm to 6 pm, as the combination of very warm temperatures and dew points in the low to mid 70s will likely produce heat index readings, or real feel temperatures, in the low 100s.
Meanwhile, a complex and sprawling area of low pressure across southern Canada and the Great Lakes will stay to our north, finally sweeping a cold front through here later Thursday night or early Friday. With the approaching front we can expect numerous showers and thunderstorms to develop Thursday afternoon and night. Some of the storms could be strong with locally heavy rainfall. This will need to be monitored as we approach Thursday as severe weather could occur. The shower and storm activity could expand into Friday morning as a weak area of low pressure may form along the slow moving cold front.
Behind this front Autumn returns as a flow of cool Canadian air follows Friday night and especially into the weekend with large high pressure expanding into the region as well.
Tropical Storm Gabrielle will pass well out to sea late this week and will have no impacts to the area except for swells along the east facing coastal beaches.
Five Day Outlook:
Wednesday: Early morning patchy fog, otherwise becoming mostly sunny, hot and very humid. High temperatures 89 to 93 degrees. South to southwest winds 5 to 10 mph.
Wednesday night: Becoming mostly cloudy overnight with a few scattered showers possible, chance of a thunderstorm. Patchy fog developing late. Warm and humid. Lows 70 to 74. Light winds.
Thursday: Patchy fog burns off early, followed by sunshine, giving way to partly then mostly cloudy skies through the afternoon. Chance of showers and thunderstorms developing in the afternoon. Warm and humid. Highs 85 to 89. Increasing south to southwest winds to 15 or 20 mph.
Thursday night: Showers and storms likely. Continued humid but not as warm. Lows 64 to 68. Southwest winds 8 to 15 mph.
Friday: Considerable morning cloudiness, chance of showers, followed by partly cloudy skies in the afternoon. Still a chance of an isolated afternoon shower. Cooler, slowly turning less humid. Highs 73 to 77.
Friday night: Partly cloudy skies, much cooler. Lows 47 to 51.
Saturday and Sunday: Mostly to partly sunny days. Fair skies overnight. Highs 65 to 69 Saturday, about 70 on Sunday. Nighttime lows 44 to 48 Saturday night.