Lexington Weather

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 060735
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
235 AM EST Fri Mar 6 2026

.WHAT HAS CHANGED...

No significant changes to the forecast.


&&

.KEY MESSAGES...

- Wintry mix along and north of I-90 and in the high terrain
  winds down by early-mid morning...as well the burst of
  plowable snowfall expected in north central/northeast MA. A
  slippery early morning commute in these locations.
  Otherwise...areas of fog, spotty very light rain/drizzle may
  persist at times today & tonight. Any light freezing drizzle
  confined mainly to the high terrain this afternoon, but black
  ice may become more of a concern across the rest of the region
  tonight. 

- Turning milder with a warming trend this weekend and with risk for 
  showers Sat night into early Sun.

- Potential for a few days of unseasonably mild conditions next
  week but have to watch a backdoor front to the north which
  would bring much cooler temps. Accelerated snowmelt will lead
  to steady rises on rivers and streams through the week. A
  period of showers accompany a cold front late Wed-Thu, then
  turning cooler towards the end of the week.

&&

.DISCUSSION...

KEY MESSAGE 1...Wintry mix along and north of I-90 and in the high 
terrain winds down by early-mid morning...as well the burst of 
plowable snowfall expected in north central/northeast MA. A Slippery 
early morning commute in these locations. Otherwise...areas of fog, 
spotty very light rain/drizzle may persist at times today & tonight. 
Any light freezing drizzle confined mainly to the high terrain this 
afternoon, but black ice may become more of a concern across the 
rest of the region tonight. 

The forecast remains on track early this morning. Rain and freezing 
rain have changed to mainly sleet along and north I-90 early this 
morning. This a result of 925T between -2C and -4C and the depth of 
the cold layer between 4-5K feet. So the main risk for a very 
localized areas of 0.25"+ of ice accretion will be in the southern 
Berks/southern Worcester Hills and the highest locations of the CT 
Hills. Fortunately...this risk looks to be very localized but power 
outages are possible if these higher ice amounts are realized.

High resolution CAMS still indicate a period of 20-30 units of lift 
in the snowgrowth region across north central and especially 
northeast MA until 5-6 am. Given the soundings are isothermal... 
intense lift will be needed to flip the sleet over to mainly snow. 
The HREF/HRRR/RRFS all indicating a window for brief 1" per hour 
snowfall rates possible through 6 am. A quick 2-4" of snow possible 
in this region with localized 5-6" amounts not out of the question 
in far northeast MA near the NH border. As we mentioned...the risk 
of the heaviest snow will be until 6 am with the threat of 
accumulating snow ending by 8-9 am in this region.

Otherwise...low pressure moves east of the region today but it will 
combined with high pressure over the Canadian Maritimes. So although 
the deeper/moisture forcing will have departed...persistent moist 
northeast flow will result in dreary weather continuing the rest of 
today into tonight. Spotty areas of very light rain/drizzle and fog 
will also remain possible at times. Temps will remain in the 30s 
today...but they should generally rise above freezing today outside 
the highest terrain so road conditions will improve later this 
morning and afternoon in areas impacted by the snow and ice early 
this morning. W still need to watch for spotty freezing drizzle and 
slippery travel into this afternoon in the highest terrain...mainly 
at elevations over 1000 feet in the Worcester Hills/Berks. Perhaps 
some black ice becomes more of an issue for the rest of the region 
tonight with temps dropping to near freezing. 

Key Message 2...Turning milder with a warming trend this weekend and 
with risk for showers Sat night into early Sun.

A mid-level ridge/surface high moves into the western Atlantic this 
weekend directing milder S-SW flow into the region. While mid level 
temperatures surge (850mb temps as high as 13C) poor mixing with an 
inversion just off the deck will keep us from tapping into the truly 
mild temps. Even so, compared to highs in the low to mid 30s on 
Friday, Saturday will be warmer simply thanks to the winds at the 
surface flipping from NE to S/SW. Expect a cloudy day with highs in 
the mid 40s. A cold front then swings through Sunday, and out ahead 
of that the combination of a 50-60 kts LLJ and a 1.25"+ PWAT plume 
will lead to scattered light showers. The best consensus for timing 
is overnight Saturday but still need to get some higher resolution 
guidance to increase confidence, as some guidance wants to keep 
shower chances around through the day on Sunday. The best chance
for this is southeast MA/coastal RI. For now sticking with 
thinking that showers and clouds clear out later Sunday allowing
temps to further increase well into the 50s. 

Key Message 3...Potential for a few days of unseasonably mild 
conditions next week but have to watch a backdoor front to the north 
which  would bring much cooler temps. Accelerated snowmelt will lead 
 to steady rises on rivers and streams through the week. A  period 
of showers accompany a cold front late Wed-Thu, then  turning cooler 
towards the end of the week.

The warm advection pattern continues through at least Tuesday before 
our next frontal system brings rain and colder temps mid week. We 
continue to see signals for highs well into the 60s by Tuesday but, 
as is fairly typical this time of year, a high pressure over eastern 
Canada may send a back door cold front into SNE around late Tuesday. 
This has the potential to spoil the warm temperatures early, 
especially for northeast MA. It could be a situation where we have a 
very large temperature gradient between northeast MA and southwest 
CT. Either way, confidence is higher that a cold front moves through 
with precipitation and a cooler airmass around Wednesday. Before 
that, though, increased temps and dewpoints will lead to significant 
loss of our snowpack, so will have to monitor for rises on rivers 
and streams. 

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
Forecaster Confidence Levels...

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

06z TAF Update...

Today...High confidence.

IFR/LIFR conditions dominate today. Lingering rain changes to freezing
rain and sleet in areas along and north of I-90 as well as 
parts of the high terrain over the next few hours. Sleet will be
favored over freezing rain to the north of I-90 overnight with 
a change over to a burst of snow across north central and 
especially northeast MA likely during the time of the heaviest 
precipitation. The threat of accumulating snow/sleet across 
north central and northeast MA will come to an end by 13z/14z. 
Meanwhile...south of I-90 in the lower elevation, ptype mainly 
will be rain but some sleet may be mixed in at times. 

All precipitation tapers to mainly spotty light rain/drizzle by mid-
late morning. However...IFR/LIFR conditions likely persist 
along with areas of fog due to continued onshore flow. Any 
spotty freezing drizzle will mainly be confined to the highest 
terrain by late morning and afternoon. NE winds 5 to 15 knots 
with some 20-25 knot gusts possible near the coast and up to 30 
knots or so for parts of the outer-Cape and Nantucket.

Tonight...High confidence.

IFR-LIFR persist. Winds slacken, but remain NE. Areas of spotty 
light rain/drizzle and fog persist at times. We may have to watch 
for spotty freezing drizzle/black ice with temps flirting with 32 
degrees. 

KBOS Terminal...High confidence in TAF. The threat for accumulating 
snow/sleet will come to an end by 13z/14z. 

KBDL Terminal...High confidence in TAF.

Outlook /Saturday through Tuesday/...

Saturday: Mainly IFR, with local MVFR possible. Breezy. Areas
BR, chance FZDZ, slight chance FZRA.

Saturday Night: Mainly IFR, with local MVFR possible. Breezy.
Chance RA.

Sunday: Mainly VFR, with local IFR possible. Breezy. Chance RA.

Sunday Night: VFR. 

Monday through Monday Night: VFR. Breezy. 

Tuesday: VFR. 

&&

.MARINE...
Forecaster Confidence Levels...

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

Today and tonight...High confidence.

Large high pressure over the Canadian Maritimes coupled with low 
pressure to the south of the waters will continue to generate NE 
wind gusts of 20 to 30 knots and 4 to 8 foot seas today. Small craft 
headlines posted for all open waters today. The gradient/NE winds 
slacken tonight...but will need to continue small craft headlines 
for all outer-waters given long NE fetch and lingering swell.

Outlook /Saturday through Tuesday/...

Saturday: Winds less than 25 kt. Areas of rough seas. Patchy
fog. 

Saturday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Rough seas up to 8 ft. Chance of rain. 

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

Sunday Night: Winds less than 25 kt. Seas up to 5 ft. 

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

Tuesday: Winds less than 25 kt. 

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory until noon EST today for CTZ002>004.
MA...Winter Weather Advisory until noon EST today for MAZ002>015-
     026.
RI...Winter Weather Advisory until noon EST today for RIZ001-003.
MARINE...Small Craft Advisory until 7 PM EST this evening for 
     ANZ231>235-237.
     Small Craft Advisory until 7 PM EST Saturday for ANZ250-251-
     254>256.

&&

$$

DISCUSSION...Frank/BW
AVIATION...Frank/BW
MARINE...Frank/BW