Area Forecast Discussion
Issued by NWS Boston, MA

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KBOX 290723
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
323 AM EDT Fri Mar 29 2024

.SYNOPSIS...
Dry but windy and cooler weather overspreads southern New England
Friday. However, rain will linger across RI and eastern MA in the
morning, possibly into early afternoon for Cape Cod and Nantucket.
Partial sunshine develops Friday afternoon, but clouds will be
slower to exit Cape and Islands. Sunny Saturday with winds
diminishing late in the day. Then a chance for a few showers
Saturday night into Sunday morning. Dry weather follows Sunday
afternoon along with a mix of sun and clouds and continuing into
Monday, with near to above normal temperatures. Very unsettled mid
next week perhaps a few chances for some accumulating snow!

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
2 AM Update...

Key Points Friday...

* Rain may briefly mix with snow before ending...but no impacts
* Rain ends this morning, except early aftn Cape Cod/Nantucket
* Partial clearing this aftn away from the Cape/Islands
* Windy with highs in the upper 40s to the middle 50s

Details...

Mid level trough taking on a negative tilt early this morning,
enhancing forcing for ascent over RI and eastern MA, resulting in
widespread rain for this region and moderate at times. Hourly
rainfall rates only on the order of 0.10 to 0.20 inches. Fairly
modest stratiform rainfall event, thus not expecting too much
impact for the morning commute across RI and eastern MA. The
Flood Watch continues early this morning for northeast CT, RI
and eastern- central MA, but this is mainly for river and Small
Stream flooding given all the rain we have had this month,
resulting in very little river/stream capacity.

Farther to the west across CT into western MA, NW flow on the
backside of the developing offshore cyclone, is advecting drier low
level air and resulting in much lighter rains across this area. As
for ptype, the NAM remains the most amplified of the models with
sufficient column cooling for rain to mix with snow later this
morning across eastern MA, before the qpf shield moves offshore by
midday or so. However, with surface temps remaining above freezing,
any wet snow mixing in at times will have no impact on road
conditions.

By midday, rain shield will be exiting offshore with the exception
of Cape Cod and Nantucket, where it may wait until 21z as model
trends have been more amplified and slower with evolving closed mid
level low just east of Cape Cod. Developing comma-head will delay
sunshine this afternoon. Partial sunshine should develop midday
across western CT/MA then slowly progressing eastward but may wait
until then just before sunset across eastern MA.

Given CAA and good boundary layer mixing along with downsloping NW
winds from strengthening offshore storm, temps will overachieve with
highs in the low to mid 50s, a few degs above normal for late March.
Although, it will feel much cooler given blustery NW winds 20-30
mph, gusting up to 40 mph at times.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
2 AM update...

Key Messages...

* Still quite blustery & cold Fri night with lows in the 30s
* Lots of sunshine Sat (inc clouds late) & diminishing winds

Details...

Friday night...

Sub 980 mb low lifts north through the Canadian Maritimes. This will
continue to result in quite blustery conditions to persist with
gusts in the 20 to 30 mph range and up to 35 mph or so in spots
during the evening. Lows will be seasonable for late March, in the
30s but gusty NW winds will combine to yield wind chills in the 20s.

Saturday...

Deep, cold mid level trough moves farther away from SNE,
resulting in rising heights and warming temps aloft across the
region. This will result in abundant sunshine and diminishing
winds in the afternoon. After a chilly start to the day, temps
will respond to the late March sun along with downsloping NW
winds, will push highs into the mid 50s. It will be pleasant in
the afternoon given ample sunshine and diminishing winds later
in the day. Mid/high clouds arrive late in the day across the
western horizon, as next short wave trough approaches.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Long Term

Highlights

* Dry and pleasant weather Sunday and Monday with a mix of sun and
  clouds and seasonable temperatures

* Unsettled Tuesday through Thursday next week with the potential
  for a long duration precipitation event and perhaps some elevation
  snow


Sunday and Monday

A mid-level ridge builds over The Northeast during the second half
of the weekend. This will bring the period of gusty northwest winds
to an end. Surface high pressure should support generally light
winds and a good amount of sunshine on Sunday afternoon. 925 hPa
temps are forecast to be slightly above the 0 Celsius mark. Cold air
aloft will support steep lapse rates all the way through the mid-
levels. The surface pressure gradient looks tight enough to support
at least some shallow mixing. Therefore with the 925 hPa temps just
above 0 Celsius, we can expect diurnal mixing to support surface
temps in the low to mid 50s on Sunday afternoon. This is pretty
close to the climatological normal in SNE for late March/early April.

Monday will feature similar conditions, but with some increasing
cloudiness across the western areas thanks to a plume of mid-level
moisture streaming into the Northeast. Areas that observe more
sunshine, mainly across eastern MA and RI may experience slightly
warmer temps than on Sunday with highs in the mid to upper 50s as
some modest warm advection will result in a marginally warmer air
mass.  Winds continue to remain on the lighter side. Low temps
Saturday and Sunday night close to normal as well ranging from the
low to upper 30s across the region.

Tuesday through Thursday

The forecast becomes more unsettled Tuesday through Thursday as a
deep upper level trough digs into the east CONUS. This is expected
to support the development of another robust low pressure system
that will likely result in another multi-day precipitation event
Tuesday through Thursday. Details are vague as the development of
the surface low-pressure system will be the product of northern and
southern stream PV anomalies merging over The Midwest. Thus,
confidence in storm track and potential impacts are low at this
time. Regardless of storm track, confidence is moderate to high that
this system will track somewhere over The Northeast and support
higher rain chances from mid to late week. NBM probs of 72 hour
precipitation exceeding 2 inches between Tuesday and Thursday
morning are 20 to 30 percent across southern New England, with a
higher bull eye over Rhode Island and southeastern MA in the 30 to
40 percent range. Furthermore, ensemble guidance reveals several
solutions that resolve a storm track that could support some
measurable snowfall across the higher elevations of The Worcester
Hills and The Berkshires. Probs of 24 hour snowfall exceeding 3
inches of snow over the higher elevations currently range from 20 to
30 percent with the higher probs focused closer to the MA/NH border.
We`ll have more details and higher confidence with respect to
impacts for our region by early next week.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
Forecast Confidence Levels:

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

06Z TAF Update...

Friday...High Confidence on trends, lower on exact timing of
details.

IFR/LIFR across RI and eastern MA in rain, slowly improves later
this morning and especially this afternoon as dry weather
returns. However gusty NNW winds develop as the day progresses.

For CT into western-central MA, MVFR/VFR in light rain predawn
gives way to dry weather later this morning along with VFR
conditions. Increasing NW winds.

Friday night...High Confidence.

VFR. NW wind gusts of 20 to 30 knots persist with even a few
gusts up to 35 knots possible during the evening.

Saturday...high confidence.

VFR, dry weather and gusty NW winds in the morning, slowly
slackening in the afternoon.

KBOS TAF...High confidence in trends, some uncertainty in exact
timing of details. Rain may briefly mix with some wet snow
09z-15z Fri before ending...but no accumulations expected.

KBDL TAF...High confidence in trends, some uncertainty in exact
timing of details.

Outlook /Saturday Night through Tuesday/...

Saturday Night: VFR. Breezy. Slight chance RA.

Sunday through Sunday Night: VFR. Breezy.

Monday: VFR. Slight chance RA.

Monday Night: VFR. Chance RA.

Tuesday: Mainly MVFR, with local IFR possible. Breezy. RA
likely.

&&

.MARINE...
Forecaster Confidence Levels:

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

2 AM update...

* NW Gales Friday/Fri night

Friday and Saturday...High Confidence.

Low pressure just SE of the 40N/70W benchmark intensifies into a
gale center today as it becomes a 980 mb low approaching Nova
Scotia late Fri. This will yield NW gales across the MA/RI
waters Friday and Friday night. As the low exits thru the
maritimes and into eastern Quebec Sat, winds slowly slacken
later Sat across MA/RI waters.

Outlook /Saturday Night through Tuesday/...

Saturday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Slight chance of rain.

Sunday through Sunday Night: Winds less than 25 kt.

Monday: Winds less than 25 kt. Slight chance of rain.

Monday Night: Winds less than 25 kt. Chance of rain.

Tuesday: Low risk for Small Craft Advisory winds with gusts up
to 30 kt. Areas of seas approaching 5 ft. Rain likely.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch until 6 AM EDT early this morning for CTZ004.
MA...Flood Watch until 6 AM EDT early this morning for MAZ004>007-
     012>024-026.
RI...Flood Watch until 6 AM EDT early this morning for RIZ001>007.
MARINE...Small Craft Advisory until 8 AM EDT Saturday for ANZ230-236.
     Gale Warning until 11 AM EDT Saturday for ANZ231-250-251-
     254>256.
     Gale Warning from 8 AM this morning to 11 AM EDT Saturday for
     ANZ232>235-237.

&&

$$

SYNOPSIS...Nocera
NEAR TERM...Nocera
SHORT TERM...Nocera
LONG TERM...RM
AVIATION...Nocera/KS
MARINE...Nocera/KS


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.