Weather for New England and the Northeast

**Area Forecast Discussion, National Weather Service Gray ME, 233 PM EDT Monday, August 24, 2026**

**What has changed**

No major changes were needed for this forecast package. Showers have started developing over the mountains a little earlier than initially expected, with only a couple of lightning strikes so far.

**Key Messages**

1. A slow moving upper level low will bring isolated to scattered showers and thunderstorms to the region this afternoon and Tuesday afternoon. A few strong storms are possible this afternoon.

2. Dry weather during the middle of the week will give way to a weak system late Thursday into Friday. Following this system, mostly dry weather returns for the weekend into early next week.

**Discussion**

**Key Message 1**

A closed upper level low, an area of colder air and lower pressure several miles above the ground, continues to slowly drift north northeast over Quebec this afternoon. A surface trough, an elongated area of lower pressure near the ground, extends south into New Hampshire. This boundary will help focus scattered showers and isolated thunderstorms this afternoon.

Atmospheric instability will be limited this afternoon. Current analysis suggests about 100 to 250 J/kg of MLCAPE, which is a measure of how much energy is available to fuel thunderstorms, across most of the area. A pocket of around 500 J/kg may develop over parts of the western Maine mountains during the mid to late afternoon.

Effective wind shear, which describes how much winds change with height and helps determine how storms organize, is currently around 40 to 50 knots across much of the forecast area. It should gradually decrease through the afternoon as the surface trough moves east.

Even with limited instability, storms could still produce some hail because of the unusually cold air several miles above the surface. The latest RAP analysis, a high resolution weather model and analysis system, suggests heights of roughly 20,000 to 23,000 feet across northern areas where the best environment for storms is expected. Freezing levels are also relatively low, so a marginally severe hail report cannot be ruled out with the strongest storms. Gusty winds will also be possible because temperatures decrease rapidly with height near the surface, creating a more unstable environment.

Showers and storms should diminish fairly quickly this evening as daytime heating is lost. Another foggy night is then possible, especially in the valleys and along the Midcoast of Maine.

The upper level low will drift farther northeast toward the Gulf of Saint Lawrence, but another surface trough will rotate into the region Tuesday afternoon. This will lead to another round of isolated to scattered showers and thunderstorms. Instability should remain limited and wind shear will be weaker, so the potential for stronger storms will be somewhat lower than today. Showers and storms should again diminish as daytime heating fades Tuesday evening.

**Key Message 2**

The trough axis shifts offshore Wednesday morning, with northwesterly winds bringing drier air into the region. High pressure builds at the surface, allowing temperatures to climb into the low 80s south of the mountains under mostly clear skies and downslope flow, meaning air sinking down the mountain slopes and warming as it does so.

North of the mountains, clearing may take a little longer, so temperatures should mainly reach the mid to upper 70s. Winds will begin bringing moisture back into the region Wednesday night, resulting in a cloudier and warmer night. Low temperatures should fall into the mid to upper 50s south of the mountains, with readings in the low 60s along the coast. North of the mountains, temperatures should drop into the low 50s.

High pressure moves east Thursday as another trough approaches from the Great Lakes region. Most of Thursday should remain dry with partly cloudy skies and southwest winds. Temperatures should be a few degrees warmer than Wednesday, with dewpoints climbing into the mid-60s south of the mountains. Dewpoint is a measure of how much moisture is present in the air, so the higher values will make Thursday feel more humid.

Looking at the 8 AM EDT NAM and RRFS model guidance from Monday, most of the precipitation should hold off until Thursday evening, although some afternoon showers could develop in New Hampshire as a warm front approaches.

The main round of precipitation is expected ahead of the cold front Thursday night into Friday. Forecast probabilities for more than one-half inch of precipitation have decreased since yesterday, with most of the area now having a 20 to 40 percent chance. This decrease may be related to higher resolution models being incorporated into the forecast and showing that heavier rainfall could be more localized around thunderstorms.

One of the computer forecasting systems also shows a low probability of severe weather during this period. However, around this region, the passage of a cold front can produce little weather activity if the front moves through too early or too late. Forecast trends will continue to be monitored, and additional model runs should provide a clearer picture of the timing and potential rainfall.

The series of fronts should move through the area by Saturday morning. Broad troughing, an area of lower pressure and cooler air aloft, will remain over the region, keeping temperatures seasonable.

High pressure will move eastward from the Great Lakes during the weekend, keeping the region generally dry despite an upper level trough. Global weather models suggest that an upper level low dropping southward from Quebec could influence the region Sunday night into Monday. There is still considerable uncertainty at this time range, so only a low chance of precipitation is included for now. This portion of the forecast could still change as we get closer to the weekend.