ma discuss
Office: BOX
FXUS61 KBOX 061919
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
319 PM EDT Sun Jun 6 2021
.SYNOPSIS...
High pressure moving off the Eastern USA will bring increasing
heat and humidity through Tuesday. The heat likely breaks late
Wednesday night as a cold front sweeps across the region, with a
significant cool down to follow Thursday into Friday and
Saturday. Mainly dry weather this period, except a chance of
scattered showers and thunderstorms Tuesday into Wednesday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Southwest flow continues tonight. There may be enough of a northerly
component to the wind to bump some fog/stratus up against the
Islands. But at this time that seems at low confidence. Otherwise, a
fair weather humid night.
Water temps are 54 to 58 degrees. Dew points 60 to 65 and light
wind. This will allow min temps of 65 to 70, except 58 to 65 South
Coast where the wind advects off the ocean water.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Overview...
Surface high pressure at the surface will drift farther offshore.
Upper ridge lingers overhead. This should maintain the hot and humid
air Monday, with humidity lingering Monday night.
Details...
Mainly rain-free Monday and Monday night with high pressure in
control. Moisture in the air will increase...PW values around 1.25
inches during the day, increasing to near 2 inches in the evening
and overnight. As this moisture moves in, widely scattered showers
may develop over Western MA/CT during the late Monday
afternon/evening, then dissipate with sunset.
Mixing Monday will again climb to at least 750-mb, with temps at
that level similar to 19-20C at 850-mb and supporting max temps in
the mid 90s. Dew points will be a tad higher than today, reaching
the low to mid 60s. Heat index values will reach the mid 90s in much
of Eastern MA and the CT River Valley. Brief mid-90s were generated
in extreme NE RI and near Fitchburg in Worcester County, but the
rest of those areas had index values of 89 to 94. Based on this, the
existing Heat Advisory in Metro Boston and the Hartford-Springfield
area was expanded for Monday to include eastern Franklin County,
mainly for the CT River Valley. In addition, Tolland County in CT
was added, as well as Northern Bristol and Northern Plymouth
Counties were added in eastern MA.
Will be adding some light fog to the South Coast and Islands Monday
night. Monday night will mainly be quiet, with any showers
dissipating early. An approaching upper shortwave in NY may generate
a few showers/thunder late at night in Western MA, but the bulk of
any likely precipitation will hold off until after Monday night. Dew
points in the mid to upper 60s away from the South Coast. Expect min
temps in the upper 60s to low 70s, except near 60 along the South
Coast.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
335 AM update...
Highlights...
* Oppressive heat and humidity continue thru Wednesday
* A cold front late Wed/Wed night breaks the heat and humidity
* Trend toward cooler and less humid weather
Details...
Monday night through Wednesday...
Anomalous warm airmass remains over the region this period with
ensemble 850 mb temps +16C to +17C and 925 mb temps +22C to +24C
continuing. These temps aloft supportive of 90+ heat. The only
wrinkle here is moisture from closed low currently over TX/OK, will
be streaming northeast and arriving here Monday night/Tue, and
lingers into at least early Wed. This will likely translate into
increased cloud cover and scattered showers/T-storms, that may hold
down temps a few degs, albeit highs around 90 vs low to mid 90s
today and Monday. However heat indices (apparent temperature) will
likely be in the mid to upper 90s as dew pts rise to AOA 70F. Thus,
oppressive heat and humidity continue. Also, as PWATs surge to near
2 inches (almost 200% of normal) per ensembles and deterministic
guidance, some storms may contain tropical-like downpours. Not a
washout as there will be many hours of dry weather this period.
Pattern change looks to arrive late Wed/Wed night or early Thu
morning as a strong cold front sweeps across the area. This is in
response to a strong northern stream short wave moving thru
southeast Quebec.
Thu/Fri/Sat...
Ensembles suggest long wave trough sets up over southeast Canada
this period, suppressing summer heat and humidity south and west of
New England. This will support a trend toward cooler, more
seasonable and less humid weather. Ensembles advertise 1030 mb high
over Hudson Bay and 850 mb temps cooling off to +8C to +10C over New
England by Friday. This should support highs in the 80s Thu but
cooling off into the 70s by Fri and Sat, along with lows in the 50s.
Hence, warm/mild days and cool nights. Post frontal regime should
support mainly dry weather, but some uncertainty on amplitude of
short wave energy in the northwest flow, and how far south
boundary will be to Southern New England. Given the time range,
will lean towards a mainly dry forecast this period.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
Forecaster Confidence Levels.
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight...High confidence
VFR with light WSW to SW winds. MVFR/IFR stratus/fog over the
ocean shifts north toward the Islands overnight, but is expected
to stay offshore most of the night.
Monday...High confidence, except moderate confidence for the
Islands.
VFR with southwest winds 10 kts and gusts near 20 kt during the
afternoon. Widely scattered thunderstorms may edge into Western
MA late in the day with brief lightning and MVFR cigs/vsbys,
then dissipate.
Monday night...Moderate confidence.
Mostly VFR. Area of MVFR in fog is possible along the South
Coast late at night. Widely scattered showers/thunder may enter
Western MA toward morning with brief MVFR cigs/vsbys.
KBOS TAF...High confidence.
KBDL TAF...High confidence.
Outlook /Tuesday through Friday/...
Tuesday through Tuesday Night: Mainly VFR, with areas MVFR
possible. Chance RA, chance TSRA.
Wednesday: Mainly VFR, with areas MVFR possible. Chance RA.
Wednesday Night: Mainly VFR, with local MVFR possible. Chance
RA.
Thursday: VFR.
&&
.MARINE...
Forecaster Confidence Levels.
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /Tonight through Monday night/...
West-southwest winds 10 to 15 kt and seas 4 feet or less through
the period. Ocean fog/low clouds may affect the waters south
and east of Nantucket with 1 to 3 nm vsbys. This fog may move
to near Cape Cod and the South Coast Monday night.
Outlook /Tuesday through Friday/...
Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of thunderstorms, slight chance of rain.
Tuesday Night: Winds less than 25 kt. Chance of rain, chance of
thunderstorms.
Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of rain.
Wednesday Night: Winds less than 25 kt. Local rough seas.
Slight chance of rain.
Thursday: Winds less than 25 kt. Areas of seas approaching
5 ft.
&&
.CLIMATE...
With the toasty temperatures the next three days, let's crack
open the history books and look at the extremes of heat and
humidity for Sunday June 6 to Tuesday June 8.
Record High Temps
June 6
BOS 100 / 1925
PVD 96 / 1925
BDL 96 / 1925
ORH 94 / 1925
June 7
BOS 97 / 1999
PVD 96 / 1999
BDL 98 / 1999
ORH 94 / 1925
June 8
BOS 97 / 1984
PVD 94 / 2008
BDL 96 / 1984
ORH 91 / 1984
Record High Min Temps
June 6
BOS 80 / 1925
PVD 80 / 1925
BDL 76 / 1925
ORH 77 / 1925
June 7
BOS 68 / 1999
PVD 66 / 1922
BDL 67 / 1973
ORH 74 / 1899
June 8
BOS 77 / 2008
PVD 74 / 2008
BDL 70 / 2008
ORH 71 / 2008
Highest Dewpoint
June 6
BOS 71 / 2010
PVD 70 / 2010
BDL 71 / 2010
ORH 70 / 2010
June 7
BOS 74 / 1984
PVD 78 / 1984
BDL 73 / 2008
ORH 74 / 1999
June 8
BOS 73 / 1984
PVD 74 / 1984
BDL 73 / 2008
ORH 72 / 2008
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT Monday for CTZ002-003.
MA...Air Quality Alert until 11 PM EDT this evening for MAZ013-
016>024.
Heat Advisory until 8 PM EDT Monday for MAZ003-005-006-010-011-
013>018-026.
RI...Air Quality Alert until 11 PM EDT this evening for RIZ001>008.
MARINE...None.
&&
$$
SYNOPSIS...WTB/Nocera
NEAR TERM...WTB/Nocera
SHORT TERM...WTB
LONG TERM...Nocera
AVIATION...WTB/Nocera
MARINE...WTB/Nocera
CLIMATE...
FXUS61 KBOX 061921
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
321 PM EDT Sun Jun 6 2021
.SYNOPSIS...
High pressure moving off the Eastern USA will bring increasing
heat and humidity through Tuesday. The heat likely breaks late
Wednesday night as a cold front sweeps across the region, with a
significant cool down to follow Thursday into Friday and
Saturday. Mainly dry weather this period, except a chance of
scattered showers and thunderstorms Tuesday into Wednesday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Southwest flow continues tonight. There may be enough of a northerly
component to the wind to bump some fog/stratus up against the
Islands. But at this time that seems at low confidence. Otherwise, a
fair weather humid night.
Water temps are 54 to 58 degrees. Dew points 60 to 65 and light
wind. This will allow min temps of 65 to 70, except 58 to 65 South
Coast where the wind advects off the ocean water.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Overview...
Surface high pressure at the surface will drift farther offshore.
Upper ridge lingers overhead. This should maintain the hot and humid
air Monday, with humidity lingering Monday night.
Details...
Mainly rain-free Monday and Monday night with high pressure in
control. Moisture in the air will increase...PW values around 1.25
inches during the day, increasing to near 2 inches in the evening
and overnight. As this moisture moves in, widely scattered showers
may develop over Western MA/CT during the late Monday
afternoon/evening, then dissipate with sunset.
Mixing Monday will again climb to at least 750-mb, with temps at
that level similar to 19-20C at 850-mb and supporting max temps in
the mid 90s. Dew points will be a tad higher than today, reaching
the low to mid 60s. Heat index values will reach the mid 90s in much
of Eastern MA and the CT River Valley. Brief mid-90s were generated
in extreme NE RI and near Fitchburg in Worcester County, but the
rest of those areas had index values of 89 to 94. Based on this, the
existing Heat Advisory in Metro Boston and the Hartford-Springfield
area was expanded for Monday to include eastern Franklin County,
mainly for the CT River Valley. In addition, Tolland County in CT
was added, as well as Northern Bristol and Northern Plymouth
Counties were added in eastern MA.
Will be adding some light fog to the South Coast and Islands Monday
night. Monday night will mainly be quiet, with any showers
dissipating early. An approaching upper shortwave in NY may generate
a few showers/thunder late at night in Western MA, but the bulk of
any likely precipitation will hold off until after Monday night. Dew
points in the mid to upper 60s away from the South Coast. Expect min
temps in the upper 60s to low 70s, except near 60 along the South
Coast.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
* Very hot and humid through Wednesday.
* A cold front late Wed/Wed night brings relief from the heat and
humidity for the latter half of the week.
* Scattered showers and thunderstorms possible Tue into Wed, then
periodic rain chances late week into the weekend.
Details...
Tuesday and Wednesday...
A few more days of oppressive heat and humidity to deal with before
we finally get a break. Tuesday the ridge axis moves east placing
southern New England under southwest flow and a plume of moisture
over topping of the ridge. This is visualized well in precipitable
water which increases from ~1.25 inches on Monday to over 2 inches
in spots by Tuesday afternoon. The same can be said for dewpoints at
the surface which get pumped up into the low 70s. So, in addition to
the anomalous warmth it will also feel more muggy. Fortunately
temperatures will be moderating a bit thanks to a cooling airmass
(850 mb temps near 17C) and increased cloudcover/showers. Highs will
generally be in the upper 80s. The typically warmest locations like
the Merrimack Valley and Connecticut River Valley should make it
into the low 90s once more. Speaking of those showers, the
approaching shortwave will bring with it scattered showers and
thunderstorms. Plenty of instability around with several thousand
J/kg of CAPE, but fortunately mid level lapse rates and
environmental shear are negligible, so not expecting anything
severe. Showers continue through the overnight hours.
For Wednesday guidance continues to point to a late night backdoor
cold frontal passage, so another day of very warm (if a bit cooler)
temperatures is on tap. Clouds and scattered showers stick around
thanks to the mid level disturbance and surface trough extending
from northern New England. More garden variety thunderstorms are
possible, again not thinking anything severe given lack of shear
(better shear doesn't arrive until after the front when instability
is gone).
Thursday through Sunday...
Overall a much cooler and less humid airmass will be in place during
this period. A drier and cooler airmass moves in behind the
Wednesday night cold front with 850 mb temperatures dropping
precipitously. Some uncertainty as to just how cold the airmass
aloft gets each day, but by the weekend we're looking at potential
for air as cool as 7-10 C at that level. What this means at the
surface is high temps down in the low 70s by Friday-Sunday...right
around average for mid June. The broad longwave trough over the
northeast U.S. which brings these cooler temperatures will also mean
periodic unsettled weather as a few disturbances move through the
base of the trough; too soon to nail down the timing.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
Forecaster Confidence Levels.
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight...High confidence
VFR with light WSW to SW winds. MVFR/IFR stratus/fog over the
ocean shifts north toward the Islands overnight, but is expected
to stay offshore most of the night.
Monday...High confidence, except moderate confidence for the
Islands.
VFR with southwest winds 10 kts and gusts near 20 kt during the
afternoon. Widely scattered thunderstorms may edge into Western
MA late in the day with brief lightning and MVFR cigs/vsbys,
then dissipate.
Monday night...Moderate confidence.
Mostly VFR. Area of MVFR in fog is possible along the South
Coast late at night. Widely scattered showers/thunder may enter
Western MA toward morning with brief MVFR cigs/vsbys.
KBOS TAF...High confidence.
KBDL TAF...High confidence.
Outlook /Tuesday through Friday/...
Tuesday through Tuesday Night: Mainly VFR, with areas MVFR
possible. Chance RA, chance TSRA.
Wednesday: Mainly VFR, with areas MVFR possible. Chance RA.
Wednesday Night: Mainly VFR, with local MVFR possible. Chance
RA.
Thursday: VFR.
&&
.MARINE...
Forecaster Confidence Levels.
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Monday Night/...
West-southwest winds 10 to 15 kt and seas 4 feet or less through
the period. Ocean fog/low clouds may affect the waters south
and east of Nantucket with 1 to 3 nm vsbys. This fog may move
to near Cape Cod and the South Coast Monday night.
Outlook /Tuesday through Friday/...
Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of thunderstorms, slight chance of rain.
Tuesday Night: Winds less than 25 kt. Chance of rain, chance of
thunderstorms.
Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of rain.
Wednesday Night: Winds less than 25 kt. Local rough seas.
Slight chance of rain.
Thursday: Winds less than 25 kt. Areas of seas approaching
5 ft.
&&
.CLIMATE...
With the toasty temperatures the next three days, let's crack
open the history books and look at the extremes of heat and
humidity for Sunday June 6 to Tuesday June 8.
Record High Temps
June 6
BOS 100 / 1925
PVD 96 / 1925
BDL 96 / 1925
ORH 94 / 1925
June 7
BOS 97 / 1999
PVD 96 / 1999
BDL 98 / 1999
ORH 94 / 1925
June 8
BOS 97 / 1984
PVD 94 / 2008
BDL 96 / 1984
ORH 91 / 1984
Record High Min Temps
June 6
BOS 80 / 1925
PVD 80 / 1925
BDL 76 / 1925
ORH 77 / 1925
June 7
BOS 68 / 1999
PVD 66 / 1922
BDL 67 / 1973
ORH 74 / 1899
June 8
BOS 77 / 2008
PVD 74 / 2008
BDL 70 / 2008
ORH 71 / 2008
Highest Dewpoint
June 6
BOS 71 / 2010
PVD 70 / 2010
BDL 71 / 2010
ORH 70 / 2010
June 7
BOS 74 / 1984
PVD 78 / 1984
BDL 73 / 2008
ORH 74 / 1999
June 8
BOS 73 / 1984
PVD 74 / 1984
BDL 73 / 2008
ORH 72 / 2008
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT Monday for CTZ002-003.
MA...Air Quality Alert until 11 PM EDT this evening for MAZ013-
016>024.
Heat Advisory until 8 PM EDT Monday for MAZ003-005-006-010-011-
013>018-026.
RI...Air Quality Alert until 11 PM EDT this evening for RIZ001>008.
MARINE...None.
&&
$$
SYNOPSIS...WTB
NEAR TERM...WTB
SHORT TERM...WTB
LONG TERM...BW
AVIATION...WTB/BW
MARINE...WTB/BW
CLIMATE...
