Lexington, Massachusetts, USA
000
FXUS61 KBOX 230550
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
150 AM EDT Tue Jun 23 2026
.WHAT HAS CHANGED...
No changes to the forecast at this time.
&&
.KEY MESSAGES...
- Widespread rain tonight into early Tuesday with periods of
heavy rain. Showers likely continue Tuesday. A few embedded
storms or downpours possible.
- Dry and warm temperatures Wednesday and Thursday. Shower and
storm chances increase for the end of the work week.
&&
.DISCUSSION...
KEY MESSAGE 1...Widespread rain tonight into early Tuesday with
periods of heavy rain. Showers likely continue Tuesday. A few
embedded storms or downpours possible.
Widespread rain has overspread southern New England this
afternoon. Expect this activity to continue for the remainder of
today into tonight as the first wave of low pressure moves
across the region. There will likely be just enough instability
to support embedded downpours and even a few embedded
thunderstorms. The highest risk for this will be tonight and
overnight into very early Tuesday morning as an axis of
instability shifts across the region. Precipitable water values
range 1.2-2.0" and model soundings show sufficient warm cloud
depths to support efficient rain processes, so pockets of
heavier rain rates are supported. The HREF 3-hour PMM QPF shows
3-hour amounts 0.5 to near 1.2" in 3 hours overnight into early
Tuesday morning. Given the instability and moisture amount,
1"/hr rates are possible, but would be fairly isolated and
within any embedded storms.
Confidence decreases with regards to the details Tuesday. A second
wave will track nearby Tuesday into Wednesday; however, the track is
still uncertain. How north or south this tracks will dictate the how
widespread the rain/showers will be as well as chances for any
embedded storms. It is likely showers continue Tuesday morning into
the afternoon slowly clearing from west to east in the late
afternoon and evening. HREF means track the main portion of the
system south of the region with the north shield of the
showers/embedded storms brushing across mainly the south coast of
southern New England and southeast MA through the evening. Some
hints of instability support a few embedded weak storms or
downpours and given the more likely track should keep the
highest risk south and east. In terms of totals, 1-2" continues
to be most likely for amounts. Given we have had an extended dry
period, flash flood guidance is fairly high is 2-3 inches/hour
in most areas. Therefore, widespread flash flooding is not a
concern. Urban and low drainage flooding is possible, especially
in areas that are impacted by the embedded heavier rain rates.
We will have to keep a watch on our more flashy areas
(Providence).
KEY MESSAGE 2...Dry and warm temperatures Wednesday and Thursday.
Shower and storm chances increase for the end of the work week.
Surface high pressure will keep the weather dry through the middle
of the week, after the rain comes to an end on Tuesday. High
temperatures will be in the low to mid 80s across the area, which is
near to a few degrees above seasonal normals, and overnight lows in
the 50s and 60s. High temperatures could be tempered a bit under
cloud cover and rain for Friday, but rebound over the weekend as the
front moves away from the region.
A low pressure system will move into the Great Lakes region
Thursday, then into southeastern Canada by the end of the week,
while a shortwave trough passes across the northeast. This system
will bring the next chances for rain to New England, beginning as
early as Thursday night, and continuing into Friday morning.
Coverage becomes more scattered by Friday afternoon, with isolated
to scattered thunderstorms are possible during those afternoon hours.
Ensemble and some machine learning guidance has low probability for
severe storms Friday, but how high that probability is and how much
of the region is covered varies fairly significantly among models.
Given this spread, and how far out in the forecast it is, confidence
on overall severe potential is low, but a couple strong
thunderstorms cannot be totally ruled out at this time.
High pressure and dry weather return for the weekend.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
06Z Update
Through 12z...Moderate Confidence.
Areas of IFR/LIFR have developed and should continue spreading
eastward heading into the morning hours. The risk for isolated
embedded thunder remains as showers moving across the region
continue to sporadically produce some flashes. Converted PROB30s
to TEMPOs to account for this risk. Visibilities towards the
Cape and Island terminals may periodically dip to 1/2SM or 1/4SM
in showers heading into the early morning. Winds will continue
to be mostly SE.
Tuesday...Moderate Confidence.
IFR/LIFR at least for the morning. Scattered showers through the
day with a few embedded downpours possible. Embedded storms
possible for SE MA terminals through mid-morning. Scattered showers
continue through much of the day. There is another risk for an
isolated storm by the afternoon into early evening; however,
confidence remains lower on this potential. Wind NW 5-10 kts,
shifting NE at BOS in the afternoon. Precipitation ends from
west to east gradually by around 18Z, with improving ceilings
after 20Z. Sub VFR conditions will linger the longest for Cape
and Island terminals.
Tuesday Night...Moderate Confidence
Confidence is lower regarding improvement to VFR from MVFR/IFR
conditions. NW winds should aid in clearing, VFR should be
common across the region by Wednesday morning. Light NW winds
around 5 kt.
KBOS Terminal...Moderate Confidence.
Rain. Moderate to heavy at times. LIFR ceilings are possible.
Potential for embedded thunder remains through 12Z. Scattered
showers continue Tuesday with NW winds shifting NE in the
afternoon at 8-12 kts.
KBDL Terminal...High confidence in TAF trends. Moderate
confidence in timing.
Outlook /Wednesday through Saturday/...
Wednesday through Thursday: VFR.
Thursday Night: VFR. Chance SHRA, slight chance TSRA.
Friday: VFR. Breezy. Chance SHRA, slight chance TSRA.
Friday Night: VFR. Slight chance SHRA.
Saturday: VFR. Chance SHRA, slight chance TSRA.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Through Tuesday...High confidence.
A Small Craft Advisory continues for the outer coastal waters
south of Block Island and east to Nantucket for this afternoon
into Tuesday morning. Gusts 22-25 kt possible for brief periods
across the Cape and islands, as well as the eastern outer
coastal waters.
Rain and a few embedded storms tonight before finally moving
off to the east Tuesday evening. Moderate to heavy rainfall at
times expected, resulting in poor visibility less than 1 mile at
times.
Outlook /Wednesday through Saturday/...
Wednesday: Winds less than 25 kt. Seas up to 5 ft.
Wednesday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft.
Thursday: Winds less than 25 kt.
Thursday Night: Winds less than 25 kt. Slight chance of rain
showers.
Friday: Winds less than 25 kt. Chance of rain showers, slight
chance of thunderstorms.
Friday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers.
Saturday: Winds less than 25 kt. Chance of rain showers, slight
chance of thunderstorms.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 AM EDT this morning for ANZ255-
256.
&&
$$
DISCUSSION...Mensch/Sava
AVIATION...Hrencecin/Mensch/Sava
MARINE...Mensch/Sava
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