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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBOX 290559
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1259 AM EST Wed Jan 29 2020

.SYNOPSIS...

Skies will remain cloudy through much of tonight. With cold
northerly winds, scattered ocean effect rain showers will pass
across the mid and outer Cape to Nantucket. As temperatures fall
tonight, the rain will change over to light snow showers with
some light accumulations possible into early Wednesday morning
before tapering off. Dry, quiet conditions with near normal
temperatures are expected for the remainder of Wednesday and
into Thursday. This high moves offshore Friday with temperatures
moderating. Still watching a potential coastal storm which may
impact our region Saturday/Sat night. Dry, blustery and colder
weather likely follows Sunday into Monday.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...

1230 AM Update...

No changes in the latest update.

10 PM Update...

Slowed down the decrease in cloud cover overnight. Have bumped
up low temperatures a few degrees to reflect the higher cloud
cover. Decreased ocean effect chances across Cape Cod toward the
NMM as it is performing well based on radar over the past few
hours.

7 PM Update...

No major changes to the forecast this evening. Ocean-effect
showers continued to remain just offshore this evening. Minor
tweaks to sky condition and temperatures to reflect observed
trends.

Previous Discussion...

The majority of the model suite, especially the high res short
range models, have continued to signal the ocean effect band to
become better organized this evening E of Cape Cod, then shift
southwestward through around midnight or so. The rain early this
evening will change over to snow showers as temps fall back to
the lower 30s.

The best chance for any light snow accumulations will occur
across the outer arm of the Cape, but not expecting much more
than an inch in isolated spots, if that. Possible to see a
dusting of snow as far W as Hyannis. Also noting some possible
snow showers developing across the E slopes of the Berkshires as
another weak mid level short wave moves across. Should see any
precip taper off after 06Z- 08Z, though might linger across the
outer Cape until around daybreak.

Across the remainder of the interior, where dry conditions are
expected, skies will begin to clear after midnight. Northerly
winds will continue to 5-10 mph.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/...

Wednesday and Wednesday night...

Clouds across east coastal areas will shift SE as high pressure
slowly builds out of southern Ontario to central Quebec during
Wednesday. Overall, expect a mostly sunny day. Expect high
temps to be close to seasonal levels for late January, mainly
from 30 to 35 across the higher terrain to the upper 30s to near
40 across the coastal plain. It will feel chilly, though, as
north winds at 10-15 kt will bring wind chill values down to the
20s.

The high will remain across Quebec Wednesday night, but any
leftover pressure gradient will relax. So, expect mainly clear
skies across most areas with light northerly winds. Some clouds
may linger across SE Mass as well as Cape Cod and the islands.
It will be a cold night, however, with temperatures bottoming
out in the single digits to the mid teens inland, ranging to the
upper teens to mid 20s along the shoreline. These readings will
run up to 5 degrees below seasonal normals inland.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...

Highlights...

* Mainly dry Thu into Fri with near to slightly below normal
  temperatures rebounding above normal by Fri

* Still monitoring for a potential storm Saturday/Sat night, but
  forecast confidence remains very low on details

* Mainly dry with above normal temperatures early next week

Details...

Large high pressure late this week should lead to dry weather.
Near to below normal temperatures expected Thursday, until this
high pressure passes by our region into Friday. Then
temperatures are once again expected to be above normal.

Still monitoring the potential for a coastal storm sometime this
weekend. The energy expected to be a part of this system should
move over western North America tonight into tomorrow. Expecting
most of the details to emerge from the noise over the next
couple of days. There remains a large degree of spread in the
ensemble solutions, so it is important to not lock in on a
singular operational model run at this time.

The general idea from the 28/12Z guidance is for a low pressure
to move northeast along the eastern Seaboard Saturday into
Sunday. Still some question as to how close this low pressure
tracks to southern New England, as well as when does it
strengthen. The consensus solution is for a farther offshore
track, with the strengthening occurring after this low passes
us by. Only the operational GFS significantly deepened the low
pressure closer to our region.

At this point, will continue to mention a broad period with a
chance of rain and/or snow. Expecting changes with the details
in later forecasts. This remains a low confidence portion of the
forecast.

A drying trend should follow Sunday into early next week behind
this departing cyclone. Thinking above normal temperatures for
this portion of the forecast.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...

Forecaster Confidence Levels...

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

06Z Discussion...

Borderline MVFR conditions over roughly the next 6 hours. Models
still having a hard time with the cloud cover in place over the
region with a shortwave trough lifting offshore. Could see
clearing to VFR from NH southwestward as is currently occurring
over eastern NH via satellite. Ceilings will be between 2-5 kft.
Heavily utilized the GLAMP guidance in the latest update. Any
ocean effect snow showers will gradually taper off as drier air
moves in for Cape Cod.

Wednesday...

Expect any MVFR ceilings to clear to VFR roughly by 15Z across
Cape Cod. Will see N to NW winds at 5-15 kts with speeds being
the highest along E coastal terminals.

Wednesday night...

VFR conditions with light northerly winds.

KBOS Terminal...High confidence in the TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Thursday Night through Sunday/...

Thursday through Friday: VFR.

Friday Night: VFR. Slight chance SN.

Saturday: Mainly VFR, with local MVFR possible. Breezy. Chance
RA, with a slight chance SN.

Saturday Night: Mainly VFR, with local MVFR possible. Breezy.
Chance SN or RA.

Sunday: VFR. Breezy. Chance SN, with a slight chance RA.

&&

.MARINE...

Short Term /through Thursday/...High confidence.

Tonight...Winds becoming N 10 to 15 kt. Seas 3 to 4 ft.
Scattered rain/snow showers across the eastern waters from east
of Boston Harbor to near and east of Cape Cod and Nantucket.
Visibility of 1 to 3 miles in precipitation. Good visibility
elsewhere.

Wednesday...NW winds 10 to 15 kt gusts increasing to 15 to 20
kt during the afternoon. Seas 3 to 4 ft, approaching 5 ft
across the eastern waters. Good visibility.

Wednesday night...N winds 10 to 15 kt. Gusts up to 20 kt and
seas building up to 5 to 6 ft on the eastern outer waters. Good
visibility.

Outlook /Thursday Night through Sunday/...

Thursday: Winds less than 25 kt. Local rough seas.

Thursday Night: Winds less than 25 kt. Seas locally approaching
5 ft.

Friday: Winds less than 25 kt.

Friday Night: Winds less than 25 kt. Chance of rain or snow.

Saturday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Chance of rain.

Saturday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Local rough seas. Chance of rain, with a
slight chance of snow.

Sunday: Winds less than 25 kt. Areas of rough seas. Chance of
rain, with a slight chance of snow.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$
SYNOPSIS...Belk/EVT
NEAR TERM...Belk/BL
SHORT TERM...EVT
LONG TERM...Belk
AVIATION...BL
MARINE...BL