Forecast discussion: For the third straight weekend, Boston received a high pressure system which brought southerly winds and bright sunshine. However, in the coming days, the southwest winds are going to help increase the relative humidity in the air. This will also increase our heat index, especially as we reach the middle of the week.
We will still see one more day of nice sunshine and lower humidity on Monday. As we move into the middle of the week, a slow moving cold front now passing into Minnesota will help create some scattered showers starting early Wednesday morning. However, the real humid and heat arrives for Wednesday. At this time, the computer models are predicting the capital city will reach 90 degrees. This will make heat indexes feel like the upper 90’s. As the front passes through the area on Thursday, some thunderstorms may become strong. At the moment, the models show the atmosphere may be limited in creating these strong thunderstorms. But, if they do form, some areas may see heavy periods of rainfall in a short period of time.
Another factor that I am watching is a possible formation of a tropical depression off the Southeast U.S. coastline. Known as Invest 91-L, there is a 60% chance the system becomes a tropical depression within 48 hours, and an 80% chance within 5 days. At this time, the models do bring the low southeast of Southern New England Friday night into Saturday. There is the chance the system stays away from Rhode Island. At this time, the forecast track keeps the low close to the east coast, as there are no steering winds to give the system a formidable track. However, it will intensify rather quickly, as it remains in the warm waters of the Gulf Stream.
For now, I will have the system move off into the Atlantic and away from Southern New England on Saturday. However, my confidence in the forecast is extremely low. If the cold front stalls on Friday, this gives the low a better chance to move up the coastline and affect the region.
72 hour forecast:
Tonight: Partly cloudy with a low of 65.
Monday: Mostly sunny and more humid with a high of 86. Winds will come from the south-southwest at 13-16 mph.
Fenway Park Forecast (7:10 p.m. vs. Chicago Cubs): Partly cloudy, 79.
Monday night: Mostly cloudy with patchy fog after 2 a.m. and a low of 69. Winds will come from the southwest at 9-12 mph.
Tuesday: Partly sunny with a high of 88.
Tuesday night: Overcast with scattered showers by 5 a.m. and warm with a low of 72.
Wednesday: Overcast with scattered showers and a high of 90.
Wednesday night: Cloudy and very humid with scattered showers and thunderstorms with a low of 72.
Thursday: Scattered showers/thunderstorms. Thunderstorms may be strong. Highs 86-89, lows 67-70.
Independence Day: Scattered showers/thunderstorms end by 2 p.m. with partly sunny skies before sunset. Highs 80-83, lows 63-66.
A tropical depression has the possibility of moving south of Southern New England on Saturday. For now, I will call for mostly sunny skies. However, my confidence is quite low. Highs 76-79, lows 60-63.
Sunday: Mostly sunny. Highs 79-82, lows 61-64.