National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBOX 070920
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
420 AM EST Tue Feb 7 2023

.SYNOPSIS...
-- Changed Discussion --
Dry, seasonable conditions today give way to mixed precipitation
overnight. Light freezing rain is possible across much of the
area. A period of mainly rain is expected later Thursday into Thursday
night as low pressure passes well to our northwest. Unseasonably
mild temperatures follow on Friday and record highs may be
challenged. Seasonable temperatures return this weekend. We also
will have to watch an offshore low pressure system for a period of
rain and/or snow this weekend...but this may remain south of the
region.
-- End Changed Discussion --

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

-- Changed Discussion --
Lingering clouds over the Cape will decrease as a maritime low
continues to pull out to sea. Mostly sunny conditions this morning,
thanks to high pressure overhead, will gradually give way to
increasing clouds this afternoon ahead of our next precipitation
maker. Northerly flow will keep temperatures near normal. Winds
gradually shift to the south this afternoon.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...

-- Changed Discussion --
A complex but quick hitting mid/upper level shortwave will bring
mixed precipitation to southern New England after 00Z this evening
as its` parent low sweeps through southern Quebec. While
progressive, this system looks to bring a headache, in terms of
precipitation forecasting, to our area between 00Z and 06z from west
to east. A significant layer of dry air aloft ahead of the system
will allow for evaporational cooling at the surface as the column
begins to saturate; dropping surface temperature to near or below
the freezing mark. With a strong warm nose between 800-850mb,
freezing rain and sleet are likely to fall across western portions
of our CWA. As the system moves east, the entire column will
gradually saturate, which will allow more of a rain/snow mix to
develop. Locations south of the I-90 corridor, specifically across
SE MA and southern RI, will stay above freezing through the column
for the entire event, yielding light rain in these areas.

The 00Z model suite was much more aggressive regarding the
geographic distribution of freezing rain compared to earlier model
runs, with the NAM, GFS, and ECWMF showing light accumulations of
freezing rain across most of Massachusetts north of the I-90
corridor. Given confidence has grown in the potential for freezing
rain, we elected to hoist a Winter Weather Advisory for all of
Massachusetts north and west of the I-495 corridor. The day
shift will be able to evaluate the need to expand this advisory
into our metropolitan areas, like Hartford, Providence, and
Boston as it is possible that these locations see light
accumulations of FZRA, especially if current model trends
continue. In any case, FZRA/Sleet/Snow accumulations are
expected to be very minor, with less than an inch of snow/sleet
possible. With that said, we are all too familiar with what a
trace/glaze of ice can do to roadways, so drivers this evening
should take extra precautions to avoid slick roadways.

Fortunately, this progressive system will be out of our hair before
sunrise on Wednesday, with some clouds lingering during the morning
hours. The afternoon will bring abundant sunshine with high pressure
overhead, and mild temperatures in the upper 40s to near 50 degrees!
Breezy WSW winds will gradually shift to the NW and diminish through
the day.
-- End Changed Discussion --

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...

-- Changed Discussion --
Highlights...

* A period of mainly rain later Thu into Thu night
* Dry/Unseasonably mild Fri with near record high temps possible
* Seasonable temps return this weekend
* Period of unsettled weather possible this weekend or may stay south

Details...

Thursday & Thursday night...

Low pressure over the midwest will lift northeast into the eastern
Great Lakes and then Quebec Thu & Thu night. In response...a modest
southwest LLJ will develop and increase the forcing for ascent. This
will allow for a period of rain to overspread the region sometime
later Thu into Thu night. Antecedent cold air will be lacking ahead
of this system and with the low passing well to our
northwest...Ptype will mainly be rain. It is possible that just
enough cold air will be present in northwest MA for a bit of
snow/ice at the onset.

Friday...

Southwest flow coupled with anomalous mid level warmth in place will
set the stage for unseasonably mild temperatures to close out the
work week. 850T on the order of +3C to +6C coupled with good mixing
should yield highs well up into the 50s...to perhaps 60+ in a few
spots. The potential exists for record highs depending on the amount
of solar insolation. A modest LLJ will also allow for it to become
quite breezy to windy across the region.

This Weekend...

A more seasonable airmass will return to the region this weekend
behind as high pressure builds over Quebec and into northern New
England...sending cooler air southward. We also will have to watch
an offshore low pressure system for the potential for a period of
rain and/or snow. However...the upper level pattern is not very
amplified. This may allow the precipitation in association with this
offshore system to remain to our south. A lot of spread in the
ensembles...so will just have to keep things probabilistic until the
models come into better agreement.
-- End Changed Discussion --

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
Forecaster Confidence Levels:

Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.

09Z update...

Tuesday... High confidence.

VFR, but may see persistent MVFR cigs Cape/Islands in the
morning as low pressure pulls out to sea. N wind gusts to 25 kt
Cape/Islands diminishing by mid morning. Winds turn southerly in
the afternoon, increasing late in the day.

Tuesday Night...High Confidence in timing, Moderate Confidence
in precipitation type.

Mixed precipitation moves through the region between about 00Z
and 06Z from west to east. P-Type will vary significantly, from
the possibility of -SN and -FZRA at western terminals, to all
rain at terminals in RI and across the Cape and Islands. Low
confidence in P-Type along the I-90 corridor, as precipitation
likely starts as -FZRA before transitioning to -IP/-RASN.
Breezy southerly winds diminish as they turn WSW winds
overnight.

Wednesday... High Confidence.

MVFR ceilings and reduced visibilities become VFR by 12Z
Wednesday except across the high terrain where MVFR cigs will
hang on through mid morning; meaning MVFR cigs possible at ORH
for a period Wednesday am. Cigs become VFR at all terminals by
about 16Z. Breezy conditions redevelop after sunrise; WSW
winds, gusting to 20 kt, diminish to between 5-15kt as they
gradually shift to the NW by Wednesday afternoon.


KBOS Terminal...Moderate Confidence in TAF.

VFR today as northerly winds shift to the south by this
afternoon. Mixed precipitation likely between 03-06Z this
evening, high confidence in the timing but low to moderate
confidence in P-Type. Chance for IP to mix in closer to 03Z
before precipitation becomes more of a RA/SN mix. Little to no
accumulation expected.

KBDL Terminal...Moderate Confidence in TAF.

VFR today. Mixed precipitation moves in between 00-03Z this
evening, likely as a rain/sleet mix. Little to no accumulation
of frozen precipitation expected, but a glaze of freezing rain
is not out of the realm of possibilities.

Outlook /Wednesday Night through Saturday/...

Wednesday Night: VFR. Breezy.

Thursday: Mainly VFR, with local IFR possible. Breezy. RA
likely, chance FZRA.

Thursday Night: Mainly IFR, with local MVFR possible. Windy
with gusts up to 35 kt. RA likely.

Friday: VFR. Windy with gusts up to 35 kt.

Friday Night: VFR. Breezy. Chance RA.

Saturday: Mainly VFR, with local MVFR possible. Windy with
gusts up to 30 kt. Chance RA.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
Forecaster Confidence Levels:

Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.

09Z Update...

Today through Wednesday ...

All gale warnings have been converted to small craft advisories
as winds have fallen below Gale criteria and are expected to
remain below for the next 24-36 hours. North/northeast winds
will shift to the south by late this afternoon. Winds gradually
shift to the SW and eventually NW through Wednesday afternoon.
as a cold front moves across the waters push through the region
overnight tonight with scattered showers and 20 to 30 knot wind
gusts out of the west.

Seas will gradually diminish through the period from 7-10 feet
to near or just below 5 feet but Wednesday afternoon.

Outlook /Wednesday Night through Saturday/...

Wednesday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft.

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain. Local visibility 1 to 3 nm.

Thursday Night: Moderate risk for gale force winds with gusts
up to 40 kt. Seas up to 5 ft. Rain likely. Visibility 1 to
3 nm.

Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Areas of rough seas. Slight chance of rain.

Friday Night: Winds less than 25 kt. Local rough seas. Chance
of rain.

Saturday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Local rough seas. Chance of rain.
-- End Changed Discussion --

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
MA...Winter Weather Advisory from 7 PM this evening to 2 AM EST
     Wednesday for MAZ002>012-014-026.
RI...None.
MARINE...Small Craft Advisory until 7 PM EST this evening for ANZ230-
     236.
     Small Craft Advisory until 7 AM EST Wednesday for ANZ231>235-
     237-251.
     Small Craft Advisory until 7 PM EST Wednesday for ANZ250-
     254>256.
-- End Changed Discussion --

&&

$$
SYNOPSIS...Frank/KS
NEAR TERM...KS
SHORT TERM...KS
LONG TERM...Frank
AVIATION...Frank/KS
MARINE...Frank/KS