Sunday July 6, 2025

7/6/2025

Outlook for the week ahead

Hot and humid conditions will persist tonight, with temperatures only dropping into the upper 60s to low 70s. As the cold front arrives in the northern half of the state Monday, we will see a chance of showers in the morning and a few scattered thunderstorms in the afternoon and evening hours. Variable amounts of rainfall are expected along this slow-moving frontal boundary, with a risk of flash flooding in areas where downpours occur. There is a continued chance of scattered storms as the front moves southward on Tuesday. As the remnants of Tropical Storm Chantal approach the region early in the week, we may see PWATs (Precipitable Water, water vapor in a column) over 2", boosting rainfall totals in some areas. The remnants of Chantal may also cause some swells in the Mid-Coast and Down East areas, creating unsettled conditions on the water. By the middle of this week, a low-pressure wave is expected to follow the front, bringing the chance for unsettled conditions and relatively cooler temperatures.

Humid on for Monday, heat south,
showers and storms possible north

A heat advisory is in effect until 8 PM Monday for York, Oxford, Cumberland, and Androscoggin counties. Make sure to drink plenty of fluids and take extra precautions if you plan to spend time outdoors.

Monday looks to be another humid day with muggy conditions south of the mountains (Dew Points in the low 70s). With temperatures in southern parts of the state remaining in the upper 80s, conditions will feel quite uncomfortable, as heat indices are expected to climb into the low 90s. In the northern half of the state, conditions will begin to cool as storms move through, with daytime highs only reaching the mid-70s. Areas along the coast will get some relief from the heat as an afternoon sea breeze develops.

Monday 8 AM (12z) to Tuesday 2 AM (06z) - As the cold front sags into the region, the northern half of the state will experience showers and thunderstorms. A few scattered showers are likely in the late morning, before a second wave of storms moves in during the afternoon and continues into the overnight hours. Storms will be primarily concentrated north of Bangor during the day, as the front remains nearly stationary over the northern half of the state. The primary threats associated with these storms are strong wind gusts and heavy rain, due to the significant amount of available moisture. The WPC has issued a Day 2 Marginal Risk for excessive rainfall across northwestern parts of the state due to the risk of isolated flash flooding from local downpours.

Chantal's moisture enters the region Tuesday,
showers and storms slowly move south

Monday 8 PM (00z Tuesday) to Tuesday 8 PM (00z Wednesday) - As the remnants of Tropical Storm Chantal move up the Atlantic coast early this week, increased moisture associated with it is expected to move into the region. Current models show PWATs (Precipitable Water values) exceeding 2" associated with the storm remnants, potentially boosting rainfall totals as the frontal boundary shifts southeast toward the coast. This system is still relatively far out, so the timing of its approach remains uncertain; however, current guidance indicates that the remnants will be near the region by early Tuesday. These remnants may also generate swells along the coast. Confidence in the exact timing and location remains low, so please stay tuned for updates as we move forward.

Tuesday 8 AM (12z) to Wednesday 8 AM (12z) - The cold front is expected to remain stalled over the region for most of Tuesday, gradually moving southward. Storms are expected to develop in the southern and DownEast areas by late morning, continuing into the overnight hours, although model guidance remains inconsistent on the exact timing. CAPE (Convective Available Potential Energy, the fuel for thunderstorms) values are expected to be relatively high, ranging from 1500 to 1800 J/kg. Development of these storms will depend on the amount of available moisture, though moisture is expected to be abundant (very humid dew point temperatures around 75°). Any additional moisture from the remnants of Tropical Storm Chantal is likely to impact rainfall totals and the potential for localized flash flooding. The Weather Prediction Center has issued a Day 3 Marginal Risk for excessive rainfall across the southern half of the state due to the threat of flash flooding from localized downpours. Stay tuned for more on that potential. With the cold front having passed through much of the state, temperatures should be more comfortable, reaching the mid-70s to low 80s during the day.

Cooler and unsettled at times Wednesday to Friday

The cold front will FINALLY move out of the region Wednesday, with a wave of low pressure moving into the area behind the front. This will bring cloudy skies to the region, along with a chance for continued showers and storms in the latter half of the week. This low will also bring a cooling trend, with highs Wednesday and Thursday peaking in the upper 70s. Friday will mark the peak of this cooling period, with highs in the southern half of the state reaching only the low 70s in the south and the mid-60s in the north.

Temperature outlook through Saturday

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Today's update prepared by Michigan State student intern Harry Fuess

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