BOX issues Area Forecast Discussion (AFD) at Sep 16, 1:44 PM EDT809
FXUS61 KBOX 161744
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
144 PM EDT Wed Sep 16 2026
.WHAT HAS CHANGED...
No significant changes to the forecast.
&&
.KEY MESSAGES...
- Warmer temperatures expected today with increased humidity levels.
- Scattered showers possible Thursday evening into Friday morning,
followed by dry conditions Friday.
- Rain chances return for the second half of the weekend. There
remains uncertainty in the details such as coverage, timing,
amounts.
&&
.DISCUSSION...
KEY MESSAGE 1... Warmer temperatures expected today with
increased humidity levels.
Patchy fog possible early this morning, but should burn off with
sunrise. High pressure in place will keep things mainly dry today.
The exception is a line of light showers moving through upstate NY
early this AM. At most this line may bring a sprinkle and period of
clouds as it moves through this morning.
Expect a warmer day with a touch more humidity. A strong upper level
ridge/high remains positioned across the southeast CONUS, subtly
building into the northeast. Warmer mid-level temperatures advect in
within the SW flow with 925mb temperatures 16-18C. This should yield
highs in the mid and upper 70s with low 80s in the valleys
(seasonably warm for mid-Sept). There will also be some moisture
advection as well within the SW flow which will bring dewpoints back
up into the low 60s. This will make it feel more humid than the
previous day or two.
KEY MESSAGE 2...Scattered showers possible Thursday evening into Friday
morning, followed by dry conditions Friday.
The first part of Thursday should remain dry with shower chances
increasing later in the day as a weak shortwave trough approaches.
Ahead of this shortwave, a plume of anomalous moisture advects in
from the west. PWATs run around 180-200 percent of normal or more
directly put, PWAT values 1.7-1.9". This has also been signaled as
anomalous across the NAEFS guidance. Despite the anomalous moisture,
the lift/forcing with this wave is weaker. Most guidance tracks the
better forcing further north (New England). Being further from the
stronger forcing will likely limit the potential for widespread
heavy rain across the region. For timing, showers become more
likely late afternoon into early evening, continuing through
early Friday morning. For rain totals, ensembles show low
probabilities (< 15%) for rain totals greater than 0.50".
Amounts generally range from a trace to a few tenths across the
GFS/ECMWF/Canadian are their ensembles. If this wave tracks
further south as a small portion of guidance has been
indicating, amounts will likely trend higher so this will
continue to be monitored. There is potential for some elevated
instability Thursday night which could result in an isolated
heavier downpour, but otherwise the model consensus leans toward
a period of showers with overall lighter amounts.
A drier airmass pushes in behind the exiting shortwave Friday which
will gradually clear clouds through the day. Temperatures are likely
to be in seasonable ranges in the 70s. A cooler airmass sinks across
the region by Saturday bringing the return of Fall-like
temperatures. Surface high pressure dominates bringing dry
conditions.
KEY MESSAGE 3... Rain chances return for the second half of the weekend.
There remains uncertainty in the details such as coverage, timing,
amounts.
Confidence in the pattern decreases for the second half of the
weekend into early next week. Ensembles continue to indicate
potential for a shortwave trough to drop southward across the
northeast Sunday into Monday. The strength/track of the trough and
how it interacts with a surface high over the Great Lakes has varied
across guidance leading to uncertainly in rain chances, timing,
and amounts. If the shortwave tracks closer to southern New
England the lift associated with the wave combined with a plume
of anomalous moisture will better support rain across the region
Sunday. However, there are also solutions that favor a stronger
high pressure that would suppress the system further south/west
resulting in more limited shower chances. Still plenty of
details to iron out, but should become more clear as we get
closer.
Surface high pressure shifts across eastern Canada into early
next week. There are indications across ensemble guidance for
another disturbance to push through potentially bringing a
period of showers in the Tue-Wed timeframe. Confidence remains
on the lower end with question on how the high pressure
suppresses the incoming system and moisture advection.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
18z TAF Update...
Through Tonight...High confidence.
VFR outside of areas of patchy fog, where MVFR/IFR visbilities
are possible. SW winds near 8-12 kts, with the higher end of
the range towards the Cape and Islands. Winds become lighter to
even calm for some areas in the interior tonight. Patchy fog in
the valleys and other terminals that often see fog (ORH, BED
mainly) may develop in the early morning hours between 08z and
12z, burning off quickly after sunrise. Mid- level cloud deck
begins to move in overnight into early Thursday morning.
Thursday...Moderate confidence.
VFR with areas of MVFR developing in the early afternoon/late
morning hours. Winds at 5-10 kt, shifting more S to SE across
the region towards 17z for most. Some could see winds more SSW,
particularly for Cape and Island terminals. Showers may start to
move into the region in the afternoon hours from W to E, with
chances continuing to increase through the evening.
Thursday Night...Moderate confidence.
MVFR with areas of IFR. Showers push across the region, clearing
towards Friday morning, though MVFR conditions could linger a
bit over the Cape and Islands. Winds generally at 5-10 kt from
the SW, shifting NW towards Friday morning.
KBOS Terminal...High confidence in TAF.
KBDL Terminal...High confidence in TAF.
Outlook /Thursday through Monday/...
Thursday: Mainly VFR, with local IFR possible. Slight chance
SHRA.
Thursday Night: Mainly VFR, with local MVFR possible. Breezy.
Chance SHRA.
Friday through Friday Night: VFR. Breezy.
Saturday: VFR.
Saturday Night: VFR. Chance SHRA.
Sunday: Mainly VFR, with local MVFR possible. Chance SHRA.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Surface high pressure continues with SW winds 10-15 kts today
and Thursday. Occasional gusts 18-22 kts are possible both days
in the afternoon/evenings.
Outlook /Thursday through Monday/...
Wednesday Night through Thursday: Winds less than 25 kt.
Thursday Night: Winds less than 25 kt. Chance of rain showers.
Friday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain showers.
Friday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of seas approaching 5 ft.
Saturday: Winds less than 25 kt. Areas of seas approaching
5 ft.
Saturday Night: Winds less than 25 kt. Slight chance of rain
showers.
Sunday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.
&&
$$
DISCUSSION...Mensch
AVIATION...Hrencecin/McMinn
MARINE...Mensch
Source:
BOX issues Area Forecast Discussion (AFD) at Sep 16, 1:44 PM EDT----------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
