Weather for New England and the Northeast

**Area Forecast Discussion**
**National Weather Service Gray ME**
**618 AM EDT Mon Jun 22 2026**

**What Has Changed**

No major changes were needed with this morning update. The latest observations have been incorporated and the aviation forecast was refreshed to reflect the 8:00 AM EDT aviation forecast package.

The forecast remains on track. However, some forecast guidance shifted the axis of heavier precipitation a bit farther southeast in overnight updates.

**Key Messages**

1. Soaking rainfall expected this afternoon through tonight. Some of this rain may be heavy and localized flash flooding is possible.

2. Temperatures rebound Wednesday and Thursday, but weak disturbances keep showers possible. A cold front nears the forecast area Friday.

**Discussion**

**Key Message 1 Description**

The first half of the day looks fairly quiet, but conditions begin to deteriorate by mid afternoon. Rain will move into the area from the southwest as a broad zone of warm air overruns cooler air at the surface, a process meteorologists call warm advection precipitation.

Some high resolution forecast models are weakening the rain somewhat as it moves northward, and there continues to be uncertainty regarding where the highest precipitation totals will occur. Recent guidance has shown a slight shift southward in the heaviest rainfall axis.

One thing that is becoming increasingly clear is that this will be a relatively strong low pressure system for late June, roughly the type of system seen about once per year during early summer. More notable is the amount of moisture being transported into the region, which is closer to a once every 5 to 10 year event.

The European Centre for Medium Range Weather Forecasts Extreme Forecast Index, or EFI, is highlighting southern portions of the forecast area for unusually high rainfall amounts compared to what is typical for this time of year. This supports the expectation of widespread soaking rain, especially south of the mountains.

While the rain itself is welcome given ongoing long term rainfall deficits, the concern is the potential for very heavy rainfall rates occurring on top of already wet ground from recent storms.

The 8:00 AM EDT June 21 High Resolution Ensemble Forecast, or HREF, showed maximum precipitation amounts in the 4 to 5 inch range. Recent High Resolution Rapid Refresh, or HRRR, forecast runs have produced similar rainfall amounts, although the exact location varies from run to run.

Local research suggests that these high resolution models often do a good job forecasting the maximum rainfall amount that may occur somewhere within the region, but they frequently struggle with pinpointing exactly where it will happen. As a result, forecasters are monitoring the possibility of isolated 4 to 5 inch rainfall totals. If those amounts fall on already saturated ground, flash flooding becomes more likely.

The greatest concern currently exists across the mountains, especially western Maine, and extending into the lower Kennebec River Valley. A few thunderstorms may develop within the rain shield, but the threat for severe weather is expected to remain southwest of the forecast area.

Rain should end fairly quickly Tuesday morning from west to east. A few isolated afternoon showers are possible, but they will be minor compared to the heavy rain expected tonight. Given the recent wet weather and the arrival of high pressure Tuesday night, valley fog is also likely to develop.

**Key Message 2 Description**

An upper level trough, an elongated area of lower pressure in the atmosphere, will move across the Northeast on Wednesday. Broad counterclockwise flow around this system will remain in place over the region, while northwest winds continue to transport somewhat drier air into New England.

Cloud cover may end up being more extensive than some forecasts currently indicate, particularly across areas northwest of the mountains where upslope clouds are likely to persist. Despite a cool start to the week, daytime temperatures should rebound Wednesday, with fairly similar temperatures expected along the coast and inland locations. Greater variability is expected in northwestern areas due to the increased likelihood of cloud cover.

West to east atmospheric flow, known as zonal flow, is expected to continue later in the week. This pattern can allow small disturbances to move through the region and produce occasional unsettled weather. That could result in scattered daytime showers on Thursday before a cold front approaches on Friday.

Current timing does not appear especially favorable for severe thunderstorms, but longer range machine learning forecast guidance continues to indicate at least some potential for stronger storms on Friday.