Heavy rain with embedded thunderstorms are currently pushing due north into the Berkshires as of the time of this writing. This heavy rain is likely to be occurring across all of far Western Mass (areas west of I-91) by about 1:30-2 pm. Rainfall totals this afternoon across far Western Mass are likely to amount to at least 1 to 2 inches.
Those of you that either live in far Western Mass or are traveling that way, be aware that flooding of highways, roads and areas of poor drainage is likely this afternoon. Also, poor visibility in heavy rain will make travel very challenging.
Further East, the coverage of the showers and thunderstorms are expected to be very scattered this afternoon and during the first half of tonight across the rest of Western Mass and all of Central Mass. That said, any heavy showers or thunderstorms will be capable of producing torrential downpours that will lead to the potential for flooding of streets, highways and poor drainage areas.
Extremely heavy rain is still expected across the entire area beginning well after midnight tonight and continuing through all of Monday. Flash flooding is likely across the entire area and is something that's going to have to be monitored very closely.
In addition, scattered embedded thunderstorms are expected during Monday across the entire area and some of these storms may be on the strong side. Main threat will be very gusty winds and frequent lightning. That said, the low-level wind shear is likely to be quite robust during Monday due to a surface low pressure system lifting across the region. Because of this, a very isolated tornado or two is a very slight possibility. I want to emphasize though that the tornado threat is extremely low, but the environment will be somewhat favorable for thunderstorms to rotate. So this is something else that will be monitored very closely.
Rainfall totals through Monday evening are expected to range from 1.50 inches to 2.50 inches with locally higher amounts across Central Mass to 2.50 inches to 4 inches with locally higher amounts across Western Mass. Upwards of 6 inches of rain is quite possible across the Berkshires and this is the area I'm extremely concerned about in terms of flash flooding.