BOX issues Area Forecast Discussion (AFD) at Jul 29, 1:41 PM EDT202
FXUS61 KBOX 291741
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
141 PM EDT Tue Jul 29 2025
.SYNOPSIS...
Elevated heat and humidity will continue through Wednesday. A
frontal system brings scattered showers and thunderstorms late
Wednesday into Thursday, with possibly more widespread rain late
Thursday into Friday. Then followed by dry and much cooler/less
humid weather this weekend, with a touch of fall, as
temperatures closer to early September levels than early
August.
&&
.NEAR TERM /THROUGH TONIGHT/...
Key Messages:
* Peak of the heat and humidity, with feels-like temperatures
in the upper 90s and lower 100s
Despite a weak front pushing slowly across southern New England
today, not expecting much of an impact other than turning winds
W to NW and keeping seabreezes from developing. Even with the
heat and humidity, just about all model forecast soundings
maintained a subsidence inversion between about 800-700 mb.
Still favoring a rain-free forecast for today.
Heat Advisories continue for most of southern New England. Still
anticipating maximum "feels like" temperatures to range from the
mid 90s into the lower 100s.
&&
.SHORT TERM /WEDNESDAY/...
Key Messages:
* Not quite as hot and humid Wednesday
* Risk for showers and thunderstorms during the afternoon
A stronger cold front is expected to approach from the west on
Wednesday. This should provide the necessary focus to trigger
afternoon convection. A few thunderstorms could be on the
stronger side with the possibility of strong straight-line
winds.
Not much relief from the heat tonight and Wednesday. Heat
Advisories continue for one last day.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Key Messages...
* More showers and thunderstorms possible Thursday
* Cooler/unsettled for the second half of this week with a
return to pleasant temperatures for this weekend.
Ensemble guidance continues to indicate a substantial wave
moving through sometime in the Wed-Thu timeframe. Unfortunately,
there is still quite a bit of uncertainty in the details,
including timing of the wave and where this cold front will set
up. ECMWF ensembles show the front setting up over northern and
central MA, allowing for widespread showers and thunderstorms
to form south of the Mass Pike and sit over northern CT/RI. GFS
ensembles push everything farther south, into southern CT/RI and
Long Island. Regardless, high confidence that PWATs will be very
high, with guidance showing 1.6-2.0 inches across southern New
England, roughly 150-160% of normal. While exact timing and and
location of storm formation is still up in the air, confidence
is increasing in seeing high rainfall totals Thursday.
Once the showers move out Friday morning, expecting a much cooler
(and drier) airmass to push into southern New England allowing
for a break in the high heat and humidity. Ensemble guidance
showed good agreement with a transition to below normal
temperatures by Friday, with temperatures possibly in the mid
70s. Another high pressure system looks to move into New England
for this weekend and bring a return to seasonal temperatures.
&&
.AVIATION /18Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
18z update...
Rest of Today: High confidence for VFR, dry weather and west winds
around 10 kt, except SW along the south coast and islands.
Tonight: High confidence, except the south coast where fog bank and
low clouds southeast of ACK likely comes back onshore as a period of
IFR/LIFR. Light WNW winds this evening shift to the NE and then east
late toward morning.
Wednesday: Moderate confidence, some uncertainty if thunderstorms
develop and coverage.
IFR/LIFR possible across the Cape and Islands early. Otherwise, VFR
an dry thru 18z. After 18z, isolated to widely scattered
thunderstorms may develop. Low confidence on areal coverage. We
handled this uncertainty with a PROB30 after 18z. Low prob of a few
robust storms, with strong winds the main threat.
Wednesday night: low confidence on showers and thunderstorms.
VFR likely, except IFR/LIFR south coast, including Cape Cod and
islands in low clouds and fog. Isolated to widely scattered showers
possible along with isolated -TSRA.
KBOS terminal...High confidence in TAF through 18z Wed, with VFR and
west wind 10-15 kt. Winds then shift to NW this evening and then NE
toward morning. Wed, ENE winds early become SE then SW late in the
day. Dry weather thru 18z, then isolated/widely scattered
showers/thunderstorms possible after 19z/20z.
KBDL terminal...High confidence in TAF thru 18z. Then some
uncertainty on development and coverage of showers and thunderstorms
after 18z Wed.
Outlook /Wednesday Night through Saturday/...
Thursday: Mainly VFR, with local MVFR possible. Chance SHRA,
chance TSRA.
Thursday Night: Mainly MVFR, with local VFR possible. Breezy.
SHRA likely, slight chance TSRA.
Friday: Mainly VFR, with local MVFR possible. Breezy. Chance
SHRA, slight chance TSRA.
Friday Night through Saturday: VFR. Breezy.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Through Wednesday...High confidence.
A weak front is expected to approach the waters from the west
today, but likely not cross the waters until sometime Wednesday
morning, if at all. Areas of fog across some of the coastal
waters around the Cape and islands this morning, with reduced
visibility less than 1 NM. Pressure gradient remains weak, with
sea breezes more likely Wednesday.
Outlook /Wednesday Night through Saturday/...
Wednesday Night through Thursday: Winds less than 25 kt. Chance
of rain showers, slight chance of thunderstorms.
Thursday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Rain showers likely.
Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 25 kt. Seas up to 5 ft. Chance of rain showers, slight
chance of thunderstorms.
Friday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of seas approaching 5 ft. Slight
chance of rain showers.
Saturday: Winds less than 25 kt. Areas of seas approaching
5 ft.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT Wednesday for CTZ002>004.
MA...Heat Advisory until 8 PM EDT Wednesday for MAZ003>007-010>021-
026.
RI...Heat Advisory until 8 PM EDT Wednesday for RIZ001>007.
Air Quality Alert until 11 PM EDT this evening for RIZ006-007.
MARINE...None.
&&
$$
SYNOPSIS...Belk/McMinn
NEAR TERM...Belk
SHORT TERM...Belk
LONG TERM...McMinn
AVIATION...Belk/RM/Nocera
MARINE...Belk/McMinn
Source:
BOX issues Area Forecast Discussion (AFD) at Jul 29, 1:41 PM EDT----------------
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