Waves pass through the region High pressure will keep things hot and humid for one more day. A slow-moving cold front will move through the state Wednesday afternoon, bringing scattered showers and thunderstorms. Some storms may be strong to severe. The front will stall over southern New Hampshire on Thursday, supporting more widespread rain south of the mountains. Into the weekend, high pressure will build from the north, with below normal temperatures, much drier, and more pleasant conditions. Cooler temperatures with rain possible south Thursday A noticeable temperature drop will take place in southern and central Maine on Thursday, with daytime highs expected to be 10 to 16 degrees cooler compared to Wednesday. This shift is driven by a cold front that brings cooler marine air from the Gulf of Maine, tightening the temperature gradient across the region. Northern Maine will see little to no temperature change, remaining relatively stable under the influence of drier air and weaker frontal dynamics. Overall, high temperatures will range from the low to mid-70s in the south and high 60s to low 70s in the north.  Model guidance indicates that a frontal boundary will stall over southern New England, allowing clouds and scattered showers to spread into the region through the day. While most showers are expected to be light, increasing moisture, reflected by PWAT (Precipitable Water) values rising across southern New Hampshire and southwestern Maine, could lead to locally heavy downpours. By the afternoon, as low-pressure tracks along the boundary, a more widespread rain event may develop across southern areas, potentially featuring heavier showers. The latest 24-hour precipitation outlook from the WPC highlights southern Maine, particularly the far southwest region, as the most likely area to receive measurable rainfall through Friday morning, with amounts ranging from about 0.25” to 0.75”. However, central and northern Maine remain largely dry, with minimal or no accumulation expected. While this will not be a widespread soaking, locally heavy rainfall is possible at times in the southern portion. Cool and dry for Saturday, ridging warms on Sunday Friday 8 PM (00z Saturday) to Sunday 8 PM (00z Monday) Steering Level - High pressure will remain in place on Friday. At the same time, a broad longwave upper trough lingers to the north, resulting in mostly sunny skies and temperatures running slightly below normal for late July. As the weekend progresses, the flow aloft will begin to transition toward a more zonal pattern across the Northeast. On Saturday, Maine remains under the influence of a broad upper-level trough, which supports cooler-than-normal temperatures and a dry, stable air mass. Weak ridging will move in on Sunday as the trough begins to flatten and lift. Height anomalies will begin to stabilize across the region, signaling the beginning of a warming trend and a shift toward a more seasonal pattern. Wildfire haze may dim the sky by next week As we head into early next week, there is potential for haze and elevated smoke concentrations across Maine. With a broad ridge of high pressure building out west and extending into eastern Canada, airflow moving southeast may transport wildfire smoke from Western Canada and Alaska into the region. Numerous active fires, as shown on the AirNow map, are currently burning across western Canada and parts of Alaska, supplying a steady stream of smoke into the upper atmosphere. Temperature outlook through Tuesday Today's update prepared by Penn State graduate |
Mike Haggett
|
