The look from above A warm front brings showers to the area today, followed by building heat and humidity through midweek as a ridge settles over the region. A strong cold front is expected to approach on Wednesday, bringing the potential for thunderstorms and marking a shift in the pattern. Behind the front, a cooler and drier air mass settles in as a broad Canadian high builds in. This high-pressure pattern is expected to persist into next weekend, supporting dry weather and a gradual warming trend. Summer heat to start the week Monday will be mostly sunny and hot across a good portion of the region as high pressure moves in behind a departing front. A light northwest breeze will help keep humidity levels manageable despite the heat. A few showers may develop in the mountains late in the day as a weak disturbance approaches, but most areas will stay dry. Skies remain mostly clear overnight with some patchy fog possible in valleys.  Tuesday will be a hot day across the region, with heat indices (“feels-like” temperatures) climbing into the upper 80s to low 90s in southern areas and mid-to-upper 80s farther north. This burst of heat and humidity is being driven by a ridge of high pressure aloft and warm southwesterly flow ahead of an approaching cold front, which is allowing warmer air and moisture to build across the region. The combination of heat and some lingering humidity will make it feel hot during the afternoon. While not extreme enough for widespread advisories at this time, those working or spending time outdoors should take precautions and stay hydrated. Sharp cold front passes through Wednesday Even though temperatures on Wednesday may not be particularly high, the humidity will make it feel noticeably uncomfortable across Maine. Dew points are forecast to reach the upper 60s to low 70s in many areas, especially in the south and central parts of the state. This level of moisture in the air will not only make it feel muggy but also contribute to a more supportive environment for thunderstorms if they develop later in the day. The combination of high humidity and brief periods of sun could help destabilize the atmosphere, despite modest air temperatures.  Storm potential across Maine on Wednesday afternoon depends heavily on how much clearing occurs behind the cold front. If skies brighten even briefly, lingering heat and humidity could lead to enough instability for isolated thunderstorms to develop. The above graphic shows elevated CAPE values in parts of southern and central Maine, which suggests the atmosphere may be primed for storms if surface heating is realized. However, one possible bust scenario is if cloud cover remains thick for most of the day. That would limit warming and reduce the energy available for storms to form. This setup introduces some uncertainty to the forecast, and conditions will need to be closely monitored as the day approaches.  The Weather Prediction Center has indicated a marginal risk for excessive rainfall is in place over parts of Maine, with isolated flash flooding possible, particularly in central and southwestern areas such as Augusta and Portland. This risk is associated with a secondary cold front and an upper-level disturbance that will bring showers and thunderstorms, some of which could become strong with gusty winds due to moderate to strong instability and strengthening westerly winds aloft. While widespread flooding isn’t expected, localized flash flooding could occur in areas with poor drainage or where storms repeatedly track. Cool down on the way late week Thursday 11 PM (03z Friday) to Saturday 2 PM (18z Saturday) - This ECMWF temperature anomaly map for late next week highlights a clear shift in the pattern over Maine, signaling a cooldown as an extensive Canadian high-pressure system builds in from the northwest. This change comes in the wake of a strong cold front expected to move through midweek, followed by the weakening of an upper-level trough over eastern Canada. As this trough slides east and surface winds turn northwesterly, a more stable and cooler air mass settles over the region. This pattern will bring a noticeable break from the recent heat and humidity, supporting a stretch of drier, more comfortable conditions heading into the weekend. Temperature outlook through Saturday Today update prepared by NC State student intern |
Mike Haggett
|
