BOX issues Area Forecast Discussion (AFD) at Aug 12, 1:19 PM EDT793
FXUS61 KBOX 121719
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
119 PM EDT Tue Aug 12 2025
.SYNOPSIS...
Somewhat drier Tuesday before heat and humidity peaks on
Wednesday. Scattered showers and thunderstorms are expected
ahead of a cold front later Wednesday and Thursday, then dry and
cooler weather follows Friday into the weekend, but heat could
return Sunday.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Tuesday
Key Message:
* Hot and dry today with clear skies
A mid-level ridge aloft coupled with low-level southwest flow will
continue to support above normal temperatures in southern New
England. Expect high temperatures to peak in the upper 80s to low
90s this afternoon under abundant sunshine. Deep diurnal mixing will
allow drier air aloft to mix to the surface helping to keep
dewpoints relatively low in the upper 50s to low 60s. Thus, max heat
indices this afternoon should be more or less on par with the actual
air temperature. We are not anticipating consecutive days of 95+
degree heat indices, thus no heat headlines are needed for southern
New England at this time. Winds will be 5 to 10 mph this
afternoon out of the southwest. A sea-breeze may develop along
the coast and help to keep temperatures slightly cooler in the
mid to upper 80s.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Key Messages
* Increasing heat and humidity on Wednesday
* Isolated to scattered thunderstorms possible Wednesday
afternoon and evening
Tonight
The weather will remain quiet again tonight with mostly clear skies
across the region. However, southwest flow will support increasing
dewpoints overnight with dewpoints rising to the mid to upper 60s by
day break. Light winds and clear skies should support efficient
radiational cooling, especially away from the urban areas. Expect
low temps in the low to mid 60s across the more rural locations and
mid to upper 60s in urban areas. There may also be some patchy
radiation fog or low-stratus development overnight, mainly along the
south coast and over The Cape/Islands.
Wednesday
Increasing heat and humidity on Wednesday with dewpoints in the
upper 60s to possibly low 70s and high temperatures in the mid 90s.
With the increased humidity we can expect heat indices in the mid to
perhaps upper 90s.
Some areas, mainly across the interior may have an opportunity for
some relief and much needed rainfall on Wednesday afternoon/evening
as a weak disturbance approaching from the west may trigger a few
isolated to scattered diurnal thunderstorms. Instability and low-
level lapse rates will be sufficient, but lack of strong forcing,
mid-level lapse rates, and wind shear will greatly limit the
potential for any severe thunderstorm development. Latest 00 HREF
supports highest thunder chances west of I-495, though some members
of the ensemble support convection as far east as Boston.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Key Messages:
* A cold front brings a risk for t-storms Wed late-day into
early Thurs.
* Cooler with lower humidity levels Fri/Sat with drier weather.
* Warming trend with rising humidity levels Sun.
Wednesday night/Thursday
Thunderstorm chances from Wednesday afternoon (see short-term
section) carries into Wednesday night/early Thursday as a weak
cold front crosses southern New England. This will bring a brief
period of unsettled weather on Thursday with increased
cloudiness and shower chances. Conditions remain muggy on
Thursday with highs in the mid to upper 80s and dewpoints in
the upper 60s to low 70s.
Friday and Saturday
High pressure builds over southern New England for Friday and
Saturday bringing cooler temperatures and lower humidity.
Onshore flow on Friday will support temperatures along the coast
in the mid to upper 70s with low to mid 80s across the interior.
Expect substantially cooler temperatures Friday night/Saturday
morning with light winds/clear skies supporting efficient
radiational cooling across southern New England. Latest model
guidance suggests very comfortable low temperatures in the
upper 50s to low 60s. High temps creep back into the mid to
upper 80s for Saturday.
Sunday and Monday
Heat and humidity returns on Sunday with ensembles supporting a
50 to 70 percent chance of high temperatures greater than 90
degrees across most of southern New England. Model spread
increases toward the end of the weekend, but the consensus is
for another frontal passage in the Sunday night/Monday time
frame that will provide the region with another opportunity for
precipitation. Ensembles currently support a 40% chance of
accumulating rainfall Sunday night through Monday night. Stay
tuned for further details.
&&
.AVIATION /17Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
18Z TAF Update:
Tuesday Afternoon: High confidence.
VFR. Light S/SW winds around 5-10 kt with sea breezes along
both coasts (starting at BOS around 15z and PVD around 16-18z).
Sea breezes kick out toward the S/SSW 23-00z at 5-10 kts.
Tuesday Night: High confidence.
Mainly VFR, though coastal fog/stratus could bring IFR-VLIFR for
the Cape and Islands and potentially as north as PVD. Most
likely timeframe for development after 08z. Can't rule
out the low chance for patchy BR in the CT Valley overnight. Light
SW winds less than 8 kts.
Wednesday: High confidence.
VFR. Southwest winds around 8-10 knots. Chance for localized
sea breeze at BOS. Chance for a few isolated to scattered
thunderstorms mainly after 18Z. Chances will be greatest west of
ORH.
KBOS terminal...High confidence in TAF. Seabreezes again
anticipated today around ~15z.
KBDL terminal...High confidence in TAF.
Outlook /Wednesday Night through Saturday/...
Wednesday: VFR. Breezy. Slight chance SHRA, slight chance TSRA.
Wednesday Night: VFR. Breezy. Chance SHRA, slight chance TSRA.
Thursday: VFR. Chance SHRA, chance TSRA.
Thursday Night: VFR. Slight chance SHRA.
Friday through Saturday: VFR.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
High confidence through the period.
South/southwest winds remain modest, generally below 10 knots.
This will keep seas on the lower side with significant wave
heights in the 2 to 3 foot range. Some fog/stratus may develop
over the south coast on Wednesday morning.
Winds increase out of the southwest to 10 to 15 knots on
Wednesday afternoon with a slight chance for an
afternoon/evening thunderstorm. SCY headlines may be needed east
of Boston where some gusts to 25 knots could be possible, though
confidence is low at this time.
Outlook /Wednesday Night through Saturday/...
Wednesday: Winds less than 25 kt. Patchy fog. Local visibility
1 to 3 nm.
Wednesday Night: Winds less than 25 kt. Chance of rain showers.
Thursday through Thursday Night: Winds less than 25 kt. Chance
of rain showers, slight chance of thunderstorms.
Friday through Saturday: Winds less than 25 kt.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Air Quality Alert until 11 PM EDT this evening for CTZ002>004.
MA...Air Quality Alert until 11 PM EDT this evening for MAZ004>021-
026.
RI...Air Quality Alert until 11 PM EDT this evening for RIZ001>008.
MARINE...None.
&&
$$
SYNOPSIS...RM
NEAR TERM...RM
SHORT TERM...RM
LONG TERM...RM
AVIATION...KJC/FT
MARINE...Frank/Loconto/RM
Source:
BOX issues Area Forecast Discussion (AFD) at Aug 12, 1:19 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!
