Weather for New England and the Northeast

**Area Forecast Discussion, CORRECTED**
**National Weather Service Gray ME**
**314 AM EDT Sat Jul 18 2026**

**What Has Changed**

No major changes were needed for this forecast package. The main challenges continue to be the chance for isolated strong to severe thunderstorms this afternoon and evening, along with the return of smoke from distant Canadian wildfires.

**Key Messages**

1. Low pressure and an approaching cold front will bring a chance for rain and isolated strong to severe thunderstorms.

2. Widespread rain and thunderstorms are possible Tuesday through Wednesday, with locally heavy precipitation possible.

**Discussion**

**Key Message 1 Description**

A disturbance in the upper atmosphere, known as a shortwave, along with an approaching cold front, will move toward the region today. This will allow warmer, more humid air to spread into the area as winds higher in the atmosphere turn to the southwest.

High resolution forecast models suggest scattered morning showers across much of the region, with the greatest chances over southern New Hampshire and coastal Maine. How quickly these showers move away, along with how much wildfire smoke returns, will play an important role in determining how unstable the atmosphere becomes later today.

High temperatures are expected to range from the upper 70s across northern areas to the 80s across southern locations. Southern New Hampshire and southwest Maine could reach the middle to upper 80s.

During the afternoon, new showers and thunderstorms are expected to develop while additional storms approach from the west and north. The strength of these storms will depend on how much sunshine breaks through the clouds.

Forecast soundings from the High Resolution Rapid Refresh model, HRRR, indicate an atmosphere capable of supporting tall but relatively narrow thunderstorm updrafts, along with strong wind shear, which is a change in wind speed and direction with height. Another area of wildfire smoke is also expected to move into southern New Hampshire early in the day before spreading into central and coastal Maine during the afternoon. The combination of smoke and morning showers may reduce daytime heating and limit storm development.

Even so, the amount of wind shear present means only limited atmospheric instability may be needed for a few storms to become strong or severe. Damaging wind gusts are the greatest concern. There is also a small tornado risk across southern New Hampshire because of favorable low level wind shear and storm rotation potential.

Additional thunderstorms are expected to approach northern areas from Quebec around or shortly after sunset as the cold front arrives. However, forecast models indicate these storms should weaken as they move into the region because daytime heating will be fading. Even so, one or two stronger storms remain possible across northern areas during the evening.

Atmospheric moisture will be unusually high for mid July. Precipitable Water, PWAT, values are forecast to be around the 90th percentile for this time of year. In addition, Integrated Vapor Transport, IVT, indicates an enhanced flow of moisture into the region. This combination will support periods of heavy downpours.

Most showers and thunderstorms will move out overnight. A few lingering showers remain possible in the mountains on Sunday, but most locations will be dry. Cooler air behind the cold front will bring highs ranging from the 60s and lower 70s across the north, the middle to upper 70s across central New Hampshire and interior Maine, and the upper 70s to lower 80s across southern New Hampshire and coastal Maine.

Northwest winds will become gusty behind the cold front on Sunday, with gusts reaching up to 35 mph during the morning and afternoon.

A long period ocean swell continues to affect area beaches. Combined with increasing southwest winds and building seas, conditions are expected to produce a high risk of dangerous rip currents today. Because rip currents have occurred over the past several days and conditions remain favorable, a Rip Current Statement has been issued.

**Key Message 2 Description**

A slow moving but deep upper level trough will settle into the Northeast early next week. Strong southwest winds aloft will transport very humid air into the region.

Weather conditions appear favorable for widespread rain as an approximately 995 millibar area of low pressure slowly moves through Quebec. Some forecast models also suggest a secondary coastal low may develop near New England, which would increase moisture even further.

Ensemble Prediction System, EPS, and Global Ensemble Prediction System, GEPS, forecast atmospheric moisture, measured by Precipitable Water, PWAT, increasing to between 1.8 and 2.0 inches. This is a strong signal for this forecast range. Some forecast guidance also indicates enhanced Integrated Vapor Transport, IVT, meaning an unusually large amount of moisture flowing into the region.

The National Blend of Models, NBM, continues to forecast between 1.0 and 1.5 inches of precipitation across much of the region, although some individual ensemble forecasts produce considerably higher amounts.

Forecasters will be watching closely to determine how much of the precipitation develops from thunderstorms. The atmosphere appears favorable for efficient rainfall production, raising the possibility of prolonged periods of heavy precipitation. The best chance for thunderstorms will likely be Tuesday and Wednesday afternoons if enough sunshine develops to increase instability. However, thunderstorms embedded within larger areas of rain are also possible overnight because of the strength of the overall weather system.

Colorado State University, CSU, and Cooperative Institute for Precipitation Systems, CIPS, guidance shows a weak signal for severe thunderstorms, particularly on Wednesday, when forecast models indicate up to 1000 joules per kilogram of Most Unstable Convective Available Potential Energy, MUCAPE, may develop.

Temperatures should remain close to seasonal averages through the first half of next week. Nights will be somewhat warmer than average while daytime highs stay slightly below average because of extensive cloud cover and high humidity, with dew points remaining in the 60s and lower 70s. It is still uncertain how much Canadian wildfire smoke will affect temperatures, but ongoing fires north of the border mean air quality will need to be monitored through next week.