Weather for New England and the Northeast

Area Forecast Discussion
National Weather Service Boston/Norton MA
235 PM EDT Tue May 19 2026

**What has Changed**
No changes were made to this forecast package.

**Synopsis**

**Key Messages**

Lingering thunderstorm activity quickly winds down with the loss of daytime heating. Expecting very warm minimum temps tonight with lows in the 60s and low to mid 70s in more urban areas.

Final day of record warmth Wednesday with highs in the 90s away from the immediate coast. Chance for strong to severe thunderstorms by the afternoon with a risk for damaging winds and small hail.

Cooler temperatures through Memorial Day Weekend. Unsettled weather returns for the weekend with periods of rain possible, but confidence is low.

**Discussion**

**Key Message 1**
Lingering thunderstorm activity quickly winds down with the loss of daytime heating. Expecting very warm minimum temps tonight with lows in the 60s and low to mid 70s in more urban areas.

Showers and storms are expected to develop across western portions of our forecast area between 3 and 5pm and then quickly move east. Forecast guidance is showing the potential for storms to initiate over the Southern Adirondacks and Green Mountains and then gradually coalesce into a more organized line or cluster that generally moves west to east through the afternoon. Main threats with any organized storms will be strong to damaging straight-line winds given drier air in the low to mid-levels, resulting in soundings that show an inverted-V profile, which indicates a high risk for dry downbursts. Somewhat notably, the 1200 UTC weather balloon soundings from Albany and Upton featured a modified Elevated Mixed Layer, a layer of warm, dry air aloft that can trap storm energy, between 700 and 500 millibars with mid level lapse rates, the rate at which temperature decreases with height, between 6.5 and 7.5 degrees Celsius per kilometer. Thankfully, Rapid Refresh mesoanalysis indicates limited bulk wind shear, the change in wind speed and direction with altitude, around 25 knots this afternoon, so we are not looking at a widespread severe weather episode. Still, with Convective Available Potential Energy, a measure of atmospheric instability, values between 1200 and 1500 Joules per kilogram, there could be a severe storm or two north of the Massachusetts Turnpike. Activity quickly wanes with the loss of daytime heating this evening.

Bigger story tonight will be continued heat and humidity. Overnight lows remain in the upper 60s for much of the region and closer to the lower and even middle 70s across urban areas. These temperatures, paired with dewpoints in the 60s, will keep apparent temperatures, how hot it actually feels outside, in the upper 70s to low 80s even well into the night.
Those without adequate access to cooling and air conditioning are at greatest risk with the elevated overnight lows. There will not be much in the way of relief from winds as the boundary layer decouples, meaning the air near the ground separates from faster winds aloft, and winds calm to less than 5 mph for much of the forecast area.

**Key Message 2**
Final day of record warmth Wednesday with highs in the 90s away from the immediate coast. Chance for strong to severe thunderstorms by the afternoon with a risk for damaging winds and small hail.

An upper level ridge of high pressure begins to break down on Wednesday ahead of an approaching atmospheric trough. Despite the changes to the upper pattern, temperatures at the 850 millibar level, roughly 5000 feet up, will remain above 15 degrees Celsius south of the Massachusetts Turnpike and slightly cooler to the north. Forecast guidance has somewhat increased the speed of the incoming cold front, resulting in increased cloud cover over much of northern Massachusetts where temperatures have trended a few degrees cooler.

Even in these areas, we still think that valley locations see highs in the low 90s degrees Fahrenheit with downsloping from west winds, which warms the air as it sinks down mountain slopes. Further south, there is higher confidence in more widespread readings in the low to mid 90s degrees Fahrenheit away from the water. Greatest chance will be in the Hartford, Providence, and Boston urban corridor. Dewpoints in the low to mid 60s will make it feel humid but not tropical by any means.

An approaching cold front provides a much more robust lifting mechanism to trigger storms on Wednesday. With temperatures quickly warming into the 90s degrees Fahrenheit, expecting surface atmospheric instability values to rise to 1000 to 1500 Joules per kilogram. Bulk wind shear values in the lowest 6 kilometers of the atmosphere, while fine at 25 to 30 knots, are less favorable for organized severe weather than they are further north where the stronger mid level airflow resides.

So, the ingredients are there for some strong to severe storms. Wednesday the cold front will serve as a better lifting mechanism, timed coincident with peak daytime heating, so we would expect more coverage of storms. Any storms that do form have the chance to produce strong to damaging winds primarily given the dry, evaporation-driven air structures near the ground.
Greatest threat for any severe weather will likely be south of the Massachusetts Turnpike where higher instability exists.

**Key Message 3**
Cooler and unsettled weather is possible Memorial Day Weekend, but confidence remains low.

High pressure builds and mid-level atmospheric ridging builds in behind Wednesdays system, bringing near-seasonable temperatures and dry conditions for the end of the work week.

For Memorial Day weekend there is a signal for the weather pattern to become more unsettled, with a few atmospheric disturbances moving through bringing periods of rain. However, there is still a sufficient amount of uncertainty in the details of the track and timing of these weather waves, which will influence rain chances, timing, and precipitation amounts this holiday weekend.
Across traditional single-run computer models, there is plenty of spread in the track and details of a system that moves in from the Ohio Valley. This has led to a range of scenarios from a drier weekend with seasonable temperatures to a weekend with periods of rain and cooler temperatures.
What adds to the uncertainty is the lack of consistency of models from run to run as well. From a statistical and probabilistic view, average ensemble models, which combine multiple forecast runs, are keying in on moderate probabilities for rain across their respective members at this time, so the risk is there for periods of precipitation over the weekend into the holiday.
We will have to keep monitoring as we get closer and model guidance comes into better agreement.