FXUS61 KBOX 250557
Area Forecast Discussion
National Weather Service Boston/Norton MA
1257 AM EST Sat Jan 25 2020
High pressure over the Maritimes brings dry weather to New
England tonight and Saturday morning. Low pressure over the
Midwest redevelops over the Mid Atlantic states. This will
bring a period of heavy rain and gusty coastal winds late
Saturday and Saturday night as it tracks across interior
southern New England. It may be preceded by some light freezing
drizzle over the Berkshires. Mainly dry and mild conditions
return Sunday then dry and seasonable for much of next week.
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
915 PM update...
Ocean stratus has overspread much of eastern and central MA into
northern RI. With continued easterly flow expect the low clouds
to fill in across western MA and northern CT overnight per HREF
solution which indicates high probs of low cigs overnight. Some
patchy fog will also develop. Still a low risk for patchy
drizzle/freezing drizzle late tonight over upslope areas, but
most areas will remain dry. Temps not expected to fall much
from current readings and some locations may see temp increases.
Lows generally upper 20s to mid 30s.
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/...
Closed upper low over the Great Lakes with a 100-kt southern jet
feeding in. This will generate a secondary low during the night
that moves up over our area late Saturday and Saturday night.
Low level wind forecasts show a 50-60 kt low level jet moving
up over New York City early afternoon and along the South Coast
of New England late afternoon and early night.
The combination of these two jets will generate strong lift
over Southern New England during the late afternoon and early
night. This will generate rain from mid afternoon through
around midnight. PW values of 0.75 to 1.0 inches suggest some
heavy showers. The PW values are above normal for January, but
the system is moving fast enough to limit any flooding threat to
urban/poor drainage concerns. The rain tapers off a little
before midnight in the west and a little after midnight in the
That low level jet moves over the region early Saturday night.
The low level inversion will limit the amount of wind to reach
the surface, but gusts of 25-35 kt should be possible especially
along the South Coast and Islands. Winds will diminish after
midnight as the system moves past.
A 1 to 2 ft surge is expected along the south coast around the high
tide Sat evening as the low level jet is moving through.
Astronomical tides are rather low and no coastal flooding is
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
* Temperatures slowly trending downward through the extended.
* Dry and quiet through the extended. The only exception is across
the eastern slopes of the Berkshires Sunday into late on Monday
where light scattered rain and snow showers are possible.
Sunday AM through Tuesday AM...
Initially a cutoff low will be situated over the eastern Great
Lakes. The cutoff will gradually rotate northeastward into northern
New England by Sunday evening. Expect -5 to -8 degree Celsius
westerly cold air to advect in. Will see a mixture of sunshine and
clouds across the region on Sunday. There are chances of light rain
and snow showers across the eastern slopes of the Berkshires. Little
to no snowfall accumulation is anticipated. Temperatures will be
slightly warmer when compared to Saturday. Readings range from the
mid 30s across the Berkshires to the mid to upper 40s along
The cutoff low will rotate across northern New England on Monday. A
shortwave will rotate from the eastern Great Lakes late on Sunday
through southern New England on Monday. Winds will shift to the
northwest and continue advecting cold air into the region. Increased
cloud cover a bit compared to the previous forecast. There will be
chances of snow showers across the eastern slopes of the Berkshires.
Suspect that these chances could linger further east as suggested by
several GEFS members, especially during the day time. The
combination of the shortwave sliding through, cold air advection and
diurnal heating could bring scattered shower activity. Confidence is
low to moderate at this point in time, so have kept things dry at
this point in time. Temperatures on Monday range from the low 30s
across the Berkshires to the low to mid 40s along the coast.
Tuesday through Friday...
Confidence in the forecast significantly lowers Tuesday until the
end of the long term. Model guidance is all over the place with
several shortwaves sliding through with large differences between
individual models and run to run differences. At this point in time
it appears that we will remain dry, but under cyclonic flow aloft.
Temperatures should continue trending downward as colder air advects
Next shot for precipitation is late in the week and heading into the
weekend. High temperatures cool to the 30s by the end of the
extended. Low temperatures cool to the teens and 20s above zero.
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Sunday/...
Through tonight...Moderate confidence.
Widespread MVFR with areas of IFR today. Patchy drizzle or
perhaps some freezing drizzle over the higher elevations this
morning. A period of moderate to heavy rainfall moves across
western New Eng 21-00z and across eastern New Eng 00-04z.
Widespread IFR with areas of LIFR as heavier rainfall moves
through. Rain ends 03-06z from west to east, but areas of
IFR/LIFR stratus and fog persists overnight. E winds gusts 25-30
kt along the coast this afternoon peaking around 35 kt this
evening, then diminishing and becoming SW overnight. A brief
period of LLWS in eastern New Eng this evening as low level jet
Areas of MVFR cigs lingering in the morning in the east,
otherwise VFR. West winds gusting to 20 kt.
KBOS Terminal...Moderate confidence. A period of moderate to
heavy rainfall this evening with IFR/LIFR conditions. E gusts
peaking around 30 kt this evening.
KBDL Terminal...Moderate confidence. A period of moderate to
heavy rainfall late afternoon/early evening with IFR/LIFR
Outlook /Sunday night through Monday/ ...
Sunday Night through Monday: Mainly VFR, with local MVFR
Monday Night through Tuesday: VFR. Breezy.
Short Term /through Sunday/...High confidence.
Northeast wind around 10 kt tonight will increase to 20-25 kt by
late Saturday and early Saturday night. Wind gusts will be 30-40
kt at that time. Strongest gusts will be on the eastern MA
waters. Winds then diminish after midnight as the weather system
moves past. Winds at that time will shift out of the southwest.
Gale Watch continues on the waters east of Massachusetts for
Saturday and Saturday night. Small Craft Advisory continues on
all other waters through Sunday.
Outlook /Sunday Night through Wednesday/...
Sunday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 11 ft.
Sunday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 9 ft.
Monday: Winds less than 25 kt. Areas of rough seas.
Monday Night: Winds less than 25 kt. Seas up to 5 ft.
Tuesday: Winds less than 25 kt. Areas of seas approaching 5 ft.
MARINE...Small Craft Advisory from noon today to 7 PM EST Sunday for
Small Craft Advisory from noon today to 1 AM EST Sunday for
Small Craft Advisory from 3 PM this afternoon to 5 AM EST
Sunday for ANZ230.
Gale Watch from this evening through late tonight for ANZ231-
Small Craft Advisory from noon today to 11 AM EST Sunday for
Small Craft Advisory from 7 AM this morning to 7 PM EST Sunday
Gale Watch from this evening through late tonight for ANZ250-
Small Craft Advisory from 4 AM early this morning to 7 PM EST
Sunday for ANZ255-256.