Old Res Weather

Lexington, Massachusetts, USA

35°F

2/16/2025 7:17pm

Lexington Conditions: Clear
Temperature: 35.1°F / 1.7°C
Dew Point: 32.4°F
Relative Humidity: 90%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.00 in Falling Slowly
Visibility: 10 miles
Rain Today: 0.01 in
UV Index: $VPuv None

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 130541
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
141 AM EDT Fri Mar 13 2026

.WHAT HAS CHANGED...
Confidence continues to grow in the likelihood for at least some 
wind headlines Saturday. Otherwise, no significant changes.

&&

.KEY MESSAGES...

- Dry & seasonably cool today/Friday.

- Strong westerly wind gusts of 35-55 mph on Sat...Wind 
  Headline will likely be needed at least for parts of the 
  region.

- A period of heavy rainfall, strong winds and unseasonably mild
  temps Mon into Mon night. Some river and small stream 
  flooding expected.

- Trending colder with mainly dry weather Tue through Thu.


&&

.DISCUSSION...
KEY MESSAGE 1...Dry & seasonably cool today/Friday.

Post frontal/dry airmass overspreading the region early this 
morning, on gusty NW winds 25 to 35 mph during the predawn 
hours. Strong CAA with 850 mb temps lowering to -10C to -12C 
early this morning, yielding lows in the 20s before sunrise, 
along with colder wind chills. Although, partly to mostly sunny 
conditions later this morning, combined with diminishing winds 
will take the edge off the cool temps. Highs this afternoon will
be in the 40s, which is just about on track for this time of 
year. Fast/progressive flow aloft yields a WAA pattern 
overspreading the region this afternoon, yielding increasing 
clouds and SW winds increasing 15-20 mph. Hence, morning hours 
brighter than the afternoon. 

KEY MESSAGE 2...Strong westerly wind gusts of 40-50 mph on Sat.
Wind headlines will likely be needed at least for parts of the 
region. 

Mainly dry weather Saturday, with partly to mostly sunny 
conditions, but windy and chilly. Deepening low over the 
maritimes will yield a strong pgrad along with strong CAA. 
Increasing March sun angle will combine with strong CAA to 
yield steep low level lapse rates. Model soundings support WNW 
winds gusting up to 40 to 50. Thus, wind headlines may be 
required. Given the aforementioned attributes, our wind 
forecast incorporates some of the higher guidance (NBM 90 
percentile), supporting wind gusts up to 40-50 mph at times 
Sat. Seasonably cool with highs in the mid to upper 40s, but 
feeling much cooler given the strong winds. 

KEY MESSAGE 3...A period of heavy rainfall, strong winds and 
unseasonably mild temps Mon into Mon night. Some river and small 
stream flooding expected.

Guidance has trended a bit slower with the heavy rainfall and 
wind event and is more focused in the Monday to Monday night 
period. Initial wave of showers will overspread the region late 
Sun night into Mon associated with the low level jet and 
moisture transport lifting northward into the region. Winds will
also ramp up in this period but the period of strongest winds 
and heaviest rainfall will likely come late Mon and especially 
Mon night with the second and stronger LLJ ahead of the 
advancing cold front. Wind and PWAT anomalies are 3-4 SD above 
normal which is a pretty strong signal for heavy rainfall and 
strong winds. The other wildcard is the potential for convective
elements and a few t-storms and can't rule out a fine line of 
convection along the cold front Mon night given strong forcing 
for ascent and elevated instability. We are expecting 1-2 inches
of rain with localized 3 inch amounts if convection gets 
involved. 90th percentile of the ensemble guidance is indicating
up to 3 inches which would be a worst case scenario but think 
these higher amounts would be localized. 

The expected rainfall amounts would be enough to cause flood 
concerns along some rivers and small streams. MMEFS ensemble 
guidance from the NAEFS continue to show several rivers reaching 
flood stage, especially the Pawtuxet, Pawcatuck and Wood Rivers
in RI. Probs are 60-80% for minor flooding and there are even 
low probs (20-30%) of moderate flooding. Other rivers to watch 
for potential minor flooding include the Assabet River at 
Maynard, Deerfield River at West Deerfield and the lower reaches
of the CT River from Hartford to Middle Haddam. 

Regarding strong wind potential, while winds will be increasing 
Monday the greatest concern for a period of strong to damaging wind 
gusts will be Mon night ahead of the cold front. Some of the global 
guidance is indicating a 70-80 kt LLJ which is pretty impressive at 
this time range, but it's always a challenge determining how much 
wind will mix down to the surface with these southerly LLJ events. 
Temps will likely make a run at 60 or even lower 60s late Mon into 
Mon evening which would increase potential for strong to damaging 
gusts. Also, any fine line would help to mix down stronger winds. 
These are factors that we will have a better handle on this weekend. 

KEY MESSAGE 4...Trending colder with mainly dry weather Tue through 
Thu.

Looks mainly dry on Tue but this will depend on the cold front 
moving to the east by Tue morning. If timing of fropa is further 
delayed it's possible showers could linger into Tue morning, 
especially in the east. Otherwise, drying out and turning cooler and 
blustery Tue behind the cold front. Core of coldest air aloft will 
be over New Eng on Wed which will be the coldest day of the week 
with highs mostly in the 30s, with slight moderation on Thu.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
Forecaster Confidence Levels...

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

This Evening: Moderate confidence.

Mainly VFR, with areas MVFR in showers. Rain transitions to snow
during the evening push most likely, but doesn't linger long. 

Rest of Tonight: High confidence. 

Rapid improvement to VFR from west to east. By late evening,
just about all of southern New England should be VFR. Could be
closer to midnight for the Cape and islands. NW winds around 10
kt with occasional gusts to 20 kt. Even though temperatures 
will be subfreezing, rapid drying should limit any freeze-up on 
runways.

Friday: High confidence. 

VFR, though with increasing midlevel clouds late in the day. NW
winds become light and then shift to SW around 5-10 kt.

Friday Night: High confidence. 

Mainly VFR. Areas MVFR in rain and snow showers across northern
MA. Increasingly gusty S winds expected.

KBOS Terminal...Moderate confidence. Rain mixed with PL then 
brief SN. visibilities 2-4 SM in wintry precip, although 
runways should be wet. Rapid VFR improvement by late evening.

KBDL Terminal...Moderate confidence. Light snow developing by 
21Z, but should be over by 13/00Z. Mainly VFR, expected for
brief MVFR in precipitation late this afternoon and early
evening.

Outlook /Saturday Night through Tuesday/...

Saturday Night: VFR. Windy with local gusts up to 30 kt. 

Sunday: VFR. Breezy. 

Sunday Night: Mainly VFR, with local IFR possible. Windy with
gusts up to 35 kt. Chance RA, slight chance FZRA.

Monday: Mainly MVFR, with areas IFR possible. Strong winds with
gusts up to 40 kt. RA, isolated TSRA.

Monday Night: Mainly MVFR, with local IFR possible. Strong
winds with gusts up to 45 kt. RA.

Tuesday: VFR. Windy with gusts up to 35 kt. Slight chance RA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Rough seas linger across the outer coastal waters into Friday
morning. Winds expected to briefly diminish Friday afternoon,
before increasing once more from the south Friday night.

Outlook /Saturday Night through Tuesday/...

Saturday Night: Low risk for Small Craft Advisory winds with
areas of gusts up to 30 kt. Local rough seas. 

Sunday: Winds less than 25 kt. 

Sunday Night: Low risk for gale force winds with gusts up to
35 kt. Local rough seas. Chance of rain. 

Monday: gale force winds with gusts up to 45 kt. Rough seas up
to 16 ft. Rain, isolated thunderstorms. 

Monday Night: gale force winds with gusts up to 45 kt. Rough
seas up to 18 ft. Rain. 

Tuesday: Strong winds with gusts up to 35 kt. Rough seas up to
13 ft. Chance of rain.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 10 AM EDT this morning for ANZ235-
     237-250-256.
     Small Craft Advisory until 4 PM EDT this afternoon for ANZ254-
     255.

&&

$$

DISCUSSION...KJC/Nocera
AVIATION...Nocera
MARINE...Nocera