BOX issues Area Forecast Discussion (AFD) at Feb 1, 3:30 AM EST885
FXUS61 KBOX 010830
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
330 AM EST Sat Feb 1 2025
.SYNOPSIS...
Light freezing drizzle may lead to slippery conditions this
morning. Cold front moves through today bring blustery
conditions and dropping temperatures into the 20s for this
afternoon, and near zero for overnight lows. Still chilly on
Sunday, but less windy. A fast- moving Alberta Clipper low
pressure area brings light snow accumulation north of the
Massachusetts Turnpike Sunday night into Monday morning.
Temperatures then trend near to above normal through the middle
of next week, with our weather pattern turning more unsettled
again by the middle of next week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Key Points
* light freezing drizzle possible this morning
* Dropping temperatures today with wind chills in the low teens
to single digits
* Ocean effect snow bands may bring light accumulations to the
Cape and Islands.
The remaining precipitation moves offshore this morning as a cold
front brings drying conditions. Expect clearing conditions from west
to east this morning into the afternoon. Before skies clear, low-
level cloud cover could bring periods of freezing drizzle with
surface temperatures dropping below freezing. High temperatures
peaked overnight and will only drop throughout the day. Afternoon
temps will be in the upper 20s to low 30s. Gusty northerly winds
between 20-30mph will make it feel like the single digits to low
teens. With the cold northerly flow, guidance indicates that ocean-
effect snow showers are possible today, mainly for the Cape and
Islands. There is a low chance the Ocean effect could get into
Boston if surface winds turn more ENE. Accumulations with ocean-
effect snow showers will be light, under a half-inch.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Key Points
* Very Cold Sunday night with lows near 0F for the interior
* Cold Sunday with less wind
Winds quickly diminish this evening as surface high pressure builds
from the Great Lakes and the boundary layer decouples. Ocean effect
snow bands will gradually dispute this evening as winds diminish.
Clear skies and calm winds will lead to excellent radiational
cooling conditions. Overnight lows will drop near zero for much of
the interior and low teens for coastal areas.
Increasing cloud cover on Sunday ahead of a shortwave over the Great
Lakes. The lift associated with said Shortwave wont arrive until
Sunday night, which, combined with surface high pressure still
departing to the east, will keep conditions dry. There is no real
change in airmass on Sunday as surface winds remain light. High
temperatures will only top out in the upper 20s to low 30s.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Key Messages:
* Minor accumulation of snow (C-2") north of the Mass Pike Sun night
into early Monday, with possible minor impact to Monday AM commute.
* Near to above normal temps thru midweek, though turning unsettled
around Wed/Thu.
Details:
Sunday Night and Monday:
An Alberta Clipper low pressure area still looks to move through
Southern New England Sunday night and into early on Mon. Noted in
the overnight forecast guidance that the system's warm-frontal QPF
was slightly greater and further southward to the Mass Pike. Temps
at onset should be cold enough to support steady light snows to the
Mass Pike overnight into early Monday, but further southward in the
CT-RI-SE MA area, temps here still look more borderline and could
support more of a snow to rain mix. Again noted a modest uptick in
QPF, and latest ensemble snowfall probabilities now show high (>80%)
probs of 24 hr snows of 1 ore more the Mass Pike, but probs of 24 hr
snow totals of 3" or more are still very low to nil. Minor impacts
to the Monday morning commute still look to be the case, although
forecast snow accums still look closer to the sub-Advisory range
based on ensemble probs.
Conditions then improve later Mon AM, and actually turns blustery
and rather mild, with highs Mon into the mid 40s and lows in the 20s.
Tuesday through Thursday Night:
500 mb pattern transition to one of quasi-zonal flow with a rather
sharp 850 mb thermal gradient lying near or south of Southern New
England to begin this period.
Overall a lower-confidence forecast as it pertains to precip chances
in this period, which will be determined by the timing of embedded
vort maxima coming across the Northern Plains/Gt Lakes region.
International suite of guidance shows one such fast impulse possibly
around Tue night or Wed, but this doesn't have much support in
ensemble members or in the GFS. Were anything to develop in this
period of time, it would likely not be much of a precip-maker given
the fast embedded zonal flow regime and its weak amplitude. A
potentially stronger 500 mb wave and associated frontal system then
sets its sights on the Northeast around Wed night and/or into
Thurs/Thurs night. This system has a better chance at being a
stronger precip-maker, although with warmer air advection, precip
types are uncertain. Will continue to take a blended approach to
PoPs/Wx in this period but it is looking like midweek would be our
next chance for significant precip after Sun night.
Temps should be more seasonable to start this period, but should
trend toward above normal, with perhaps significantly above normal
temps (40s/spot 50?) around Wed/Thurs if warmer solutions verify.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
06z TAF Update:
Through 12z Saturday: High confidence in trends, moderate on
exact timing.
IFR-LIFR cigs with visbys ranging from 1 to 6 SM in rain, snow,
fog. Steadier precip gradually decreases 07-11z with areas of
drizzle or freezing drizzle, soonest north and west and later
south and east. Light snow accums up to 2" for BAF-ORH-BED and
perhaps a light coating at BOS, with little to nil icing from
any freezing drizzle. By daybreak, ceilings should start to
trend to IFR-MVFR range. Light northerly winds then to become
NW and increase to around 10-12 kt by daybreak.
Today: High confidence.
Ceilings improve to VFR during the morning, but we may see MVFR
ceilings and a period of ocean effect snow/rain showers along
the immediate eastern MA coast ~12-15z. VFR by late-AM in all
areas. NW winds 12-15 kt with gusts to 25 kt, up to 30 kt Cape
and Islands.
Tonight: High confidence.
VFR. NW winds around 10-12 kt early, though speeds decrease thru
the overnight to under 5 kt for most, up to 10 kt Cape and
Islands.
Sunday: High confidence.
VFR, though with increasing midlevel cloud cover late in the
day. Low risk for flurries or light snow showers toward early
Sun night. Light NW winds become SE around 5-10 kt late in the
day.
KBOS TAF...High confidence in TAF. IFR with mix of rain/snow to
trend to period of light snow 07-10z. Snow may become mixed with
freezing drizzle 10-12z. Accums C-1". Gradual improvement to
MVFR-VFR Sat, but possible period of ocean effect -SHSN 12-15z
before trending VFR. Light NE/N winds to trend NNW around 10-12
kt/gusts to 25 kt.
KBDL TAF...High confidence in TAF. IFR cigs with light RA/DZ
thru 10z before conditions slowly trend MVFR-VFR by 13z. N/NW
winds increasing to around 10-13 kt with gusts to 20 kt.
Outlook /Sunday Night through Wednesday/...
Sunday Night: Mainly IFR, with local MVFR possible. Breezy. SN
likely, chance RA, slight chance FZRA.
Monday through Tuesday Night: VFR. Breezy.
Wednesday: VFR. Chance SN.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High- greater than 60 percent.
Today through Sunday...High Confidence.
A cold front will gradually clear out low clouds and fog this
afternoon. Winds will be near gale force this afternoon out of
the north. With cold air in the 20s this afternoon, dropping to
the low teens overnight, moderate freezing spray is possible
mainly across eastern waters this afternoon and evening. Winds
gradually diminish overnight, allowing for freezing spray
concerns to decrease. Winds flip south on Sunday remaining
light around 10 knots.
Outlook /Sunday Night through Wednesday/...
Sunday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Rain likely, snow. Local
visibility 1 to 3 nm.
Monday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain.
Monday Night: Winds less than 25 kt. Seas up to 5 ft. Slight
chance of rain.
Tuesday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft.
Tuesday Night: Winds less than 25 kt. Local rough seas.
Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of snow.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Winter Weather Advisory until 7 AM EST this morning for MAZ002-
008.
RI...None.
MARINE...Small Craft Advisory from 7 AM this morning to 7 PM EST this
evening for ANZ230-236.
Small Craft Advisory until 4 AM EST Sunday for ANZ231-251.
Freezing Spray Advisory from 1 PM this afternoon to 1 AM EST
Sunday for ANZ231>234-251-255.
Small Craft Advisory until 10 PM EST this evening for
ANZ232>234.
Small Craft Advisory until 1 AM EST Sunday for ANZ235-237.
Small Craft Advisory until 10 AM EST Sunday for ANZ250.
Small Craft Advisory until 1 PM EST Sunday for ANZ254>256.
&&
$$
SYNOPSIS...Loconto/KP
NEAR TERM...KP
SHORT TERM...KP
LONG TERM...Loconto
AVIATION...Loconto/KP
MARINE...Loconto/KP
Source:
BOX issues Area Forecast Discussion (AFD) at Feb 1, 3:30 AM EST----------------
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