Metro Boston, North Shore and Metro West: Overnight the rain intensity picked up with a windswept heavy rain greeting us Sunday morning. Many areas have already had between 1.25 to 1.5 inches of rain as of 9 am this morning. This has prompted the National Weather Service to issue a Flood Advisory for urban flooding, especially in poor drainage areas, flooding of underpasses and other vulnerable locations. There is the possibility of minor flooding from small streams as well. Also, a Coastal Flood Advisory is in place for the possibility of minor coastal flooding along the usual vulnerable shore roads at time of high tides late this morning and again around midnight.
With the recent snow melt and gusty winds of late the brush has begun to dry out and April is always a month of brush fires. This rainfall will put a damper on that possibility for the short term
All this havoc is the result of low pressure now centered over the Chesapeake Bay with a frontal boundary draped across extreme southern New England. The low will move slowly to a position near Cape Cod early tonight then east of Massachusetts Bay by Monday morning. Because it is a slow mover we can expect a continuation of rainfall through tonight and into Monday across the region. As the low pulls away enough cold air may be pulled in behind it to change the rain to a wintry mix across the area during Monday, possibly into Monday night as well.
Needless to say with the northeast to north winds it will remain unseasonably cold through Monday with temperatures running about 10 degrees below average for the end of March.
By Tuesday conditions will vastly improve with clearing skies and a moderate breeze to help dry out the area. A cold front approaches mid week but it now looks like the area only sees some clouds as the front approaches and slides through here.
Back to today and Monday. Rainfall through today will be heaviest this morning, tapering to lighter showers and misty conditions this afternoon as we get a respite from the heavy rain and urban flooding. Then, as the coastal low gets closer tonight the moderate and at times heavy rain will reemerge. Additional rainfall from mid morning through tonight could exceed 1 inch with locally higher amounts. Watch for the possibility of freezing rain well inland, especially to the west of Route 495, later tonight as temperatures there could flirt with the freezing mark. We mentioned yesterday that the possibility was there for a wintry mix Monday and that possibility still exists, first through the interior and then spreading all the way to the coastline before the precipitation winds down early evening or overnight.
Short Term Outlook:
Today: Heavy rain this morning transitioning to periods of lighter rain or showers and drizzle by this afternoon. Widespread fog. Cool and breezy with high temperatures only in the low 40s. Northeast to north winds 10 to 20 mph.
Tonight: Rain with areas of fog. Chance of freezing rain well inland. Cool and windy. Lows in the mid 30s, possibly low 30s across the interior. North winds 15 to 20 mph, gusting to near 30 mph.
Monday: Rain with pockets of sleet possible in the morning followed by a wintry mix of rain, sleet and snow later in the afternoon. Cold and raw. Temperatures remaining steady in the low to mid 30s. Gusty north winds.
Monday night: Precipitation winds down and ends early. Remaining mostly cloudy overnight. Cold, raw and windy. Lows in the 30s.
Tuesday: Improving skies with sunshine but still slightly below normal temperatures and a gusty breeze. Highs in the mid 40s.