BOX issues Area Forecast Discussion (AFD) at Jul 3, 5:25 AM EDT264
FXUS61 KBOX 030925
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
525 AM EDT Fri Jul 3 2026
.WHAT HAS CHANGED...
No significant changes to the forecast.
&&
.KEY MESSAGES...
- Dangerous heatwave continues today and Independence Day. Heat
indices of 100-110 degrees today & 95-100+ on Independence Day.
- Isolated severe weather potential late today/tonight. Greatest
risk interior MA/CT. Main risk will be isolated pockets of
damaging straight line wind gusts.
- Low risk of severe weather and a few t-storms on Independence
Day, but greatest risk for more widespread activity right now
looks to be to our southwest.
- Relief from the heat with cooler and more seasonable
temperatures returning for the first half of next week.
Also...the potential for some much need rain may occur in the
late Sun-Tue time frame but that remains to be seen.
&&
.DISCUSSION...
KEY MESSAGE 1...Dangerous heatwave continues today and Independence
Day. Heat indices of 100-110 degrees today & 95-100+ on Independence
Day.
Near record high temperatures are once again on tap for the region
today. An anomalous airmass remains in place across southern New
England today with 925T on the order of +27C to +29C. This
coupled with a very warm start, mostly sunny skies and westerly
flow will result in temperatures soaring today. High
temperatures should top out in the 97 to 103 degree range and
once again challenge records. This combined with high dewpoints
will result in dangerous heat indices of 100 to 110 degrees.
Even across the Cape highs should reach into the 90s with heat
indices of 95 to 105 degrees given westerly flow.
There will be little relief tonight as low temperatures only drop
into the 72-77 degree range and probably only the upper 70s to near
80 in the urban heat island of Boston.
Independence Day will still feature dangerous heat and humidity.
Height falls and somewhat lower 925T will likely prevent triple
digit heat on the 4th. Nonetheless...we still expect highs in the 93
to 99 degree range in most location. This will bring heat indices
into the 95-100+ degree range and heat headlines remain in effect.
KEY MESSAGE 2...Isolated severe weather potential late today/tonight.
Greatest risk interior MA/CT. Main risk will be isolated pockets of
damaging straight line wind gusts.
The other concern will be the convective potential mainly late
today/tonight. This portion of the forecast remains tricky given
lack of large scale forcing but impressive instability.
We can not rule out a late afternoon isolated t-storm or two...But
high resolution CAMs indicated the greatest risk may come this
evening into the overnight hours. They tend to want to develop a few
thunderstorms to our west and north. Given ample instability
persisting well into tonight coupled with 0 to 6 KM shear of 30 to
40 knots...this activity will be capable of surviving into our region.
The greatest risk for this activity appears to be across interior MA
and CT where forcing is a bit more prevalent. This is also indicated
by the NADOCAST and CSU machine learning guidance. This will again
be more of a mesoscale/nowcast type of forecast...But the potential
for isolated severe weather exists again tonight. Low risk this
potential could end up a bit more widespread if a complex of storms
were to organize...which always has to be a concern in this type of
environment. But again the lack of overall synoptic scale forcing
will be a limiting factor.
KEY MESSAGE 3...Low risk of severe weather and a few t-storms on
Independence Day, but greatest risk for more widespread
activity right now looks to be to our southwest.
There will a low risk for severe weather on Independence Day as
a cold front works south across the region. At this time...most
of the CAMs and machine learning guidance indicate that the
greatest risk for more widespread thunderstorms and severe
weather will be to our southwest. This is where the best
instability will reside along with better forcing/shortwave
energy. In our region...winds shifting to the NW early in the
day may limit convergence and forcing for more widespread convection.
Nonetheless...given temperatures soaring well into the 90s
coupled with height falls there will be the risk for a few
thunderstorms and a low risk severe weather.
KEY MESSAGE 4...Relief from the heat with cooler and more seasonable
temperatures returning for the first half of next week. Also...the
potential for some much need rain may occur in the late Sun-Tue time
frame but that remains to be seen.
Long range ensemble guidance is in good agreement in the upper
level ridge breaking down and a tendency towards lower heights
next week. This will bring an end to the extreme heat, with readings
more in line with typical summer. A wave of low pressure will also
be approaching from the west. This may bring a period of much needed
over running rain to parts of the region sometime in the Sun night
to Tue time frame. Confidence in these setups is low this time of
year given mesoscale convective factors and limited baroclinicity.
Nonetheless...a period of two of much needed rainfall is possible
for the start of the next work week.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
06z TAF Update...
Today through Independence Day...High confidence.
VFR conditions will dominate today through Independence Day. We will
have to watch for low clouds/fog patches flirting with the
Cape/ACK...but this may tend to remain offshore.
Otherwise...isolated thunderstorms will be possible mainly tonight
and perhaps again on Independence Day. Confidence on areal
coverage/timing might be be limited so did not include in the TAFS at
this time...But something for later shifts to monitor.
Westerly winds may gust to 20+ knots later this morning and
afternoon with a few gusts near 25 knots possible. WInds shift to
the NW on Independence Day with some 20 knot gusts.
KBOS Terminal...High confidence in TAF.
KBDL Terminal...High confidence in TAF
Outlook /Saturday Night through Tuesday/...
Saturday Night: VFR. Isolated SHRA, isolated TSRA.
Sunday: VFR. Isolated SHRA.
Sunday Night: VFR. Chance SHRA.
Monday: Mainly VFR, with local MVFR possible. Chance SHRA,
slight chance TSRA.
Monday Night: Mainly VFR, with areas MVFR possible. Chance
SHRA, chance TSRA.
Tuesday: Mainly VFR, with areas MVFR possible. Breezy. Chance
SHRA, slight chance TSRA.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Today through Independence Day...High confidence.
Winds/seas should remain below small craft advisory thresholds today
through Independence Day. However...some 20+ knot wind gusts near
shore later this morning and afternoon will result in some chop in
some near shore sounds and Bays.
Outlook /Saturday Night through Tuesday/...
Saturday Night: Winds less than 25 kt. Scattered rain showers,
isolated thunderstorms.
Sunday: Winds less than 25 kt. Isolated rain showers.
Sunday Night: Winds less than 25 kt. Chance of rain showers.
Monday: Winds less than 25 kt. Chance of rain showers, slight
chance of thunderstorms.
Monday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers, chance of thunderstorms.
Tuesday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Chance of rain showers, slight chance of thunderstorms.
&&
.CLIMATE...
Record High Temperatures:
July 3:
KBOS: 102/1911
KBDL: 102/1966
KPVD: 98/2002
KORH: 96/1911
July 4:
KBOS: 104/1911
KBDL: 99/1911
KPVD: 99/1919
KORH: 102/1911
Record High Minimum Temperatures:
July 3:
KBOS: 80/2002
KBDL: 73/2018
KPVD: 78/2002
KORH: 72/2002
July 4:
KBOS: 77/2002
KBDL: 74/2018
KPVD: 77/2002
KORH: 73/2018
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Extreme Heat Warning until 8 PM EDT Saturday for CTZ002>004.
MA...Extreme Heat Warning until 8 PM EDT Saturday for MAZ002>021-
026.
Air Quality Alert from 11 AM this morning to 11 PM EDT this
evening for MAZ020>024.
Heat Advisory until 8 PM EDT Saturday for MAZ022-023.
RI...Extreme Heat Warning until 8 PM EDT Saturday for RIZ001>007.
Air Quality Alert from 11 AM this morning to 11 PM EDT this
evening for RIZ003-004-006>008.
MARINE...None.
&&
$$
DISCUSSION...Frank
AVIATION...Frank
MARINE...Frank
CLIMATE...FT
Source:
BOX issues Area Forecast Discussion (AFD) at Jul 3, 5:25 AM EDT----------------
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