Increased risk of flash flooding with more rain passing through tonight into Monday morning

BANGOR, Maine (WABI) - Good evening, and happy Sunday everyone. After an unstable afternoon and evening with showers and storms across northern, central, and western portions of the state, including a severe thunderstorm in southern Piscataquis County between 3:35-4:15pm, the severe weather risk is concluding. Skies are on the cloudier side for most with a few showers and isolated storms across northern and western locations. Temperatures vary from the mid 50s to low 70s as of 9pm. Dewpoints remain sticky to humid in the low to mid 60s.

The SPC’s excessive rainfall outlook has all of Northern and most of Western portions of the state under a 10-20% chance of flash flooding. A Flood Watch has been issued for Northern and Western Maine from 2pm this afternoon until 8am Monday due to today’s thunderstorms and the cold front tonight into Monday morning. This Flood Watch includes all of Aroostook, Piscataquis, Somerset, Franklin, and Oxford Counties. It also includes Northern and Central Penobscot County, Northern Washington County, as well as Interior Cumberland County. A Coastal Flood Advisory has been issued on the southern coast due to tonight’s rain timing up with astronomical high tide. Rainfall totals throughout the rest of Sunday and Monday will vary under a half an inch along the interstate and coast, while reaching 0.5 to 1.5 inches across the north and west.

The cold front has entered northern and western locations to start the night, with precipitation passing across Maine tonight into Monday morning. This will result in a quick soaking rain, which may be heavy at times, producing the risk of flash flooding. Skies will be cloudy tonight with precipitation holding mostly to the north and west before midnight. Rain will start to expand across Western and Northern locations during the early morning hours, reaching the Capital region between 2-4am. Rain will then fill out up to the Bangor region, Mount Desert Island, and Baxter State Park between 4-6am. Low temps will vary from the low 50s to low 60s tonight. Dewpoints will remain slightly sticky. South gusts will reach 20-30 mph in spots.

Rain will continue to expand into Downeast locations between 6-8am. Meanwhile, rain looks to peel out of Western locations shortly after sunrise. Rain will continue across Northern and Eastern locations, as well as the Bangor region, through 9am. However, during the late morning to midday hours, the cold front will continue to work east and exit most of these locations. Rain is only expected in Washington County by noon. However, that rain will exit by 12-2pm.

After the cold front passes through, sunshine will develop during the late morning to midday hours for most. Skies will be partly to mostly sunny in the afternoon on Monday. A few spots showers are possible Monday afternoon, but look unlikely as of now. Highs on Monday will reach the mid 60s to low 80s with sticky dewpoints dropping after the cold front works through. South to NW gusts will reach 20-30 mph.

The weather will finally quiet down on Tuesday and Wednesday, which are my two picks of the week. Sunshine will be abundant, with comfortable high temperatures reaching the 70s for most. Dewpoints will be dry to comfy. Winds will be on the lighter side.

However, by Thursday, more rain is expected to enter. Mostly cloudy skies in the morning on Thursday will give way to overcast skies and rain developing during the afternoon hours. A few thunderstorms are possible. High temps will be on the cooler side, from the mid 60s to mid 70s, but dewpoints will become slightly sticky again, reaching the low 60s. SE gusts will be breezy, reaching 25-35 mph on Thursday.

Showers remain possible on Friday, mostly across Northern portions of the state as Thursday’s low-pressure system spins up to the North of Maine in the Saint Lawrence River Valley. Gusts will remain breezy, and high temps will warm, reaching the upper 60s to low 80s. Dewpoints look to remain slightly sticky.

MONDAY: Highs from mid 60s to low 80s. Cloudier AM with rain & fog. Partly to mostly sunny PM. Sticky dewpoints drying out. South to NW gusts reach 20-30 mph.

TUESDAY: Highs from upper 60s to upper 70s. Sunny AM. Partly to mostly sunny PM. NW to SW gusts reach 20 mph.

WEDNESDAY: Highs from upper 60s to low 80s. Mostly sunny AM. Partly cloudy PM. Few late day showers possible West. South gusts reach 20 mph.

THURSDAY: Highs from mid 60s to mid 70s. Mostly cloudy AM. Cloudier PM with rain developing. PM t-storms possible. Slightly sticky dewpoints. SE gusts reach 25-35 mph.

FRIDAY: Highs from upper 60s to low 80s. Partly to mostly cloudy with showers possible. Cloudier North with rain. Slightly sticky dewpoints. WSW gusts reach 25-35 mph.