843 
FXUS61 KBOX 172053
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
353 PM EST Tue Jan 17 2023

.SYNOPSIS...
A weak disturbance may bring a few showers tonight, followed by 
mainly dry and mild weather Wednesday. A frontal system will bring 
mixed wintry precipitation Thursday afternoon into Friday, 
especially across northern Massachusetts with mainly rain near the 
coast. Drier conditions for the upcoming weekend along with 
near seasonable temperatures. Unsettled pattern returns late 
Sunday night into early next week as another storm likely
impacts the region.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Fast moving shortwave moves through this evening and will be 
accompanied by a few brief showers. Still plenty of dry air in the 
low levels to overcome as dewpoints in the teens and 20s which will 
limit areal extent of precip, but some spotty light precip possible 
through this evening. Will also to watch for patchy freezing 
rain over the higher terrain in northern MA as temps aloft are 
warm and wet bulb cooling could bring temps down to near 32 with
the precip. Any freezing rain would be spotty and limited in 
areal coverage. 

Shortwave moves to the east overnight so expect mainly dry 
conditions with partial clearing, although some upslope rain/snow 
showers to the west could spill into the east slopes of the 
Berkshires within WNW flow aloft. Lows will be mainly low/mid 30s. 

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Wednesday...

Another mid level trough passage with cold pool aloft and lingering 
low level moisture will yield lots of cloud cover, especially in the 
morning, with more sunshine developing in the afternoon. Not 
expecting much if any precip, although can't rule out a spot 
rain/snow shower in the morning over the higher terrain. Low level 
temps are cooling but somewhat deeper mixing and WNW flow will allow 
highs to reach well into 40s, to near 50 in the coastal plain. It 
will be a bit blustery with WNW gusts to 20-25 mph.

Wednesday night...

Upper trough moves to the east with shortwave ridging and surface 
high pres building in from the west. This will lead to clearing 
skies and diminishing wind, although high clouds ahead of next 
system will begin moving in overnight. A period of decent 
radiational cooling will allow low temps to drop to the mid 20s to 
lower 30s. 

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Highlights...

* Thursday afternoon a frontal system brings a wintry mix and cold 
  rain before changing over to accumulating snow across the interior 
  late Thursday night into Friday morning, increasing the threat for 
  a potentially slick morning commute. 

* Drier weather expected for the upcoming weekend along with near 
  normal temperatures Saturday and slightly above normal Sunday. 

* Unsettled weather potentially late Sunday night through Monday. 

Thursday through Friday night...

Dry for much of the first half of Thursday, trending wet, as a 
frontal boundary lifts north during the afternoon. As previously 
mentioned in the prior forecast discussion, the concern Thursday 
evening revolves around a winter mix of sleet/freezing rain for 
those locations along the northern border of Vermont/New Hampshire. 
While temperatures aloft are above freezing, producing rain, the 
temperatures at the surface are likely to be 30F to 33F for areas 
generally at or greater than 1,000 feet. 

Overnight into Friday a surface low associated with the system moves 
out of western New York, pulling colder air down as it moves east. 
The big question remains, how much cold air will rush in and how 
quickly. Ensembles show a tight gradient for the probability of 
greater or equal to 3". The GFS ensemble gives us a probability 
between 40 and 60 percent along the northern border of Massachusetts 
with Vermont/New Hampshire. Then nothing south of the Mass Pike. The 
Euro ensemble a little more robust, with a greater than 80 percent 
chance along the northern border with Vermont/New Hampshire. With 
the cut off, with less than 10 percent chance for areas south of the 
southern border with Connecticut/Rhode Island. 

For areas south of the Mass Pike, a cold soaking rain is in store. 
PWATs reach around 1.0" to 1.3". Not out of the question areas along 
the southern coast of Rhode Island and Massachusetts receive an inch 
of rain. 

There still remains a fair amount of uncertainty with precipitation 
types. At this time we have held off on issuing any NWS headlines. 
But, a Winter Weather Advisory could be needed for northern 
Massachusetts if confidence in snow and ice continues to increase. 

Saturday through Sunday...

A quieter period of weather with a 1025mb high building over the 
northeast. During this time expect more clouds, likely lower stratus 
as forecast soundings depict leftover low level moisture trapped 
below a surface inversion. As for temperatures, Saturday is pretty 
seasonable for mid-January, with 925mb temperatures between -4C/-6C. 
This will result in afternoon temperatures generally in the middle 
to upper-30s. A slightly warmer day for Sunday as WAA occurs aloft, 
925mb temperatures ranging between +1C and -2C, resulting in 
afternoon temperatures in the upper-30s to low-40s. 

Sunday Night through early next week...

Our next widespread weather system arrives sometime early Sunday 
evening or early Monday morning. While this part of the forecast is 
between 6 & 7 days out, did not spent too much time on it. As of 
now, global guidance shows a surface low pressure passing to our 
northwest and giving southern New England another drink of water and 
potential snow for interior New England. Once this system clears our 
Monday night, surface high pressures settles in for Tuesday. As for 
temperatures, next week looks to have slightly above normal 
temperatures in the upper-30s to low-40s. 

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels:

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

Through 00z...

VFR with gradually lowering cigs. A few showers possible toward
evening.

Tonight...High confidence.

VFR cigs with spotty MVFR cigs developing over the higher 
terrain. A few brief rain showers this evening. 

Wednesday...Moderate confidence. 

Cigs lowering to MVFR during the morning with spotty light
rain/snow showers possible in the interior, then partial
clearing and VFR developing in the afternoon. WNW wind gusts to
20-25 kt developing.

Wednesday night...High confidence.

Mainly VFR with diminishing wind. 

KBOS Terminal...High confidence in TAF. 

KBDL Terminal...High confidence in TAF.

Outlook /Thursday through Sunday/... 

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

Thursday Night: Mainly IFR, with areas MVFR possible. Breezy.
RA, chance SN, slight chance FZRA.

Friday: MVFR/IFR conditions possible. Breezy. SN likely, chance
RA.

Friday Night: Mainly VFR, with areas IFR possible. Breezy.
Slight chance RA, slight chance SN.

Saturday: Mainly VFR, with areas MVFR possible. 

Saturday Night: Mainly VFR, with local MVFR possible. 

Sunday: Mainly VFR, with local MVFR possible. Breezy. Slight
chance RA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Through Wednesday night...High confidence.

Tonight...SW wind gusts to 20 kt this evening will veer to the W 
overnight. Leftover easterly swell will result in 5 ft seas over 
outer waters where SCA will continue. 

Wednesday...Wind shift to WNW 15-20 kt, with occasional gusts to 
25kt at times. Mainly dry weather and good vsby. 

Wednesday night...NW gusts increasing to 20-30 kt in the evening, 
then diminishing late as high pres builds in from the west. SCA 
conditions persist over open waters. 

Outlook /Thursday through Sunday/... 

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain. 

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

Friday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft. Chance of rain. 

Friday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of
rain. 

Saturday: Winds less than 25 kt. Seas up to 5 ft. Slight chance
of rain. 

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

Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Slight chance of rain. 

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 7 AM EST Thursday for ANZ250-
     254>256.
     Small Craft Advisory until 4 PM EST this afternoon for ANZ251.

&&

$$
SYNOPSIS...KJC/Gaucher
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...Gaucher
AVIATION...KJC/Gaucher
MARINE...KJC/Gaucher