Lexington Weather

Lexington, Massachusetts, USA

37°F

4/23/2024 6:00am

Lexington Conditions: Clear
Temperature: 37.0°F / 2.8°C
Dew Point: 33.3°F
Relative Humidity: 86%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 30.12 in Steady
Visibility: 10 miles
Rain Today: 0.00 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 212302
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
702 PM EDT Sun Apr 21 2024

.SYNOPSIS...
A ridge of high pressure will result in dry weather through 
Tuesday with mild days and chilly frost nights, along with 
elevated fire weather potential. Unsettled, wet and cool on 
Wednesday. Drier late in the week and heading into the weekend.

&&

.NEAR TERM /THROUGH MONDAY/...
Will have to contend with a weak surface trough and a cold front
overnight. While the trough should move offshore, expecting this
cold front to hang up somewhere across southern New England. 
Not a lot of low level humidity, so really only talking about 
mid and high clouds. Clearing skies and a reinforcing shot of 
colder air should mean low temperatures well into the 30s 
region-wide. Frost Advisory continues across northern CT, RI and
portions of southeastern MA. These are the areas where we are 
past the median time for the last freeze. Elsewhere, we have not
yet reached the median time of the last freeze, so no 
headlines. However, there is likely to be some frost regardless.

&&

.SHORT TERM /MONDAY NIGHT/...
This dry front lingers during the morning, before moving back
north as a warm front late in the day. High pressure moves
just offshore Monday night. Dry weather continues through this
portion of the forecast. Slightly below normal temperatures
expected.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Highlights

* Seasonable temperatures in the extended forecast

* Modest rain event on Wednesday with strong wind gusts 
  Wednesday night into Thursday

* High pressure and dry weather take over late week into next
  weekend 

Tuesday and Wednesday

High pressure remains in control on Tuesday but will shifting
east over the coastal waters. This will allow return flow from
the south to advect slightly higher temps over the region that
what should be observed on Monday. Nonetheless, temps will be
close to normal, maybe a few ticks above normal across southern 
New England with highs in the upper 50s to low 60s common.
Coastal areas may remain a bit cooler, especially if a sea- 
breeze circulation is able to develop (upper 40s to lower 50s).

Moisture continues to increase in response to southerly flow 
ahead of northern stream short-wave energy approaching from the 
Midwest. This system will bring our next chance for substantial 
rain, but there are no signals that this will be an impressive 
rain event by any means. Forcing for ascent associated with the 
system is rather modest and will be mainly driven by positive 
vorticity advection east of the short-wave trough axis. The 
trickier part of the forecast at this time range is just how 
much moisture will be available. Ensemble guidance reveals a 
rather large spread in PWATs ranging from 0.25 to 0.75 inches in
the column. This of course will play a role in just how much 
precip will be observed. The consensus is for anywhere from 0.1 
to 0.25 inches with the higher amounts focused to the north and 
west. However, should moisture over achieve, 0.25 to 0.5 inches 
could be in the cards as well. Regardless, confidence is 
moderate to high that Wednesday will feature wet/rainy 
conditions across much of the region. Temperatures will continue
to hover in the near-normal range, but slightly below normal 
given the precip and extensive cloud cover (low to mid 50s).

Wednesday night and Thursday

As the surface cold front associated with the aforementioned 
rainmaker on Wednesday pushes through the region Wednesday night
into Thursday, a CAA regime will support a period of gusty 
northwest winds over southern New England. There is uncertainty 
in how strong the low level jet will be, but ensemble
probabilities of wind gusts exceeding 30 mph are greater than
50 percent across much of the region Wednesday night into
Thursday. In addition to the wind, Wednesday night will feature 
chilly temperatures as a -5C 925 hPa air mass settles over the 
region by Thursday morning. Expect lows THursday morning to 
bottom out below freezing across much of southern New England. 
After a chilly start, efficient mixing in the CAA regime will 
allow temps to rebound to the mid to upper 50s. The column will 
behind the cold front will be very dry with PWATs less than 0.2 
inches. This should support dry weather and abundant sunshine on
Thursday.

Friday through Sunday

High pressure builds over the region by the end of the week. 
This will bring and end to the gusty post frontal winds that are
expected Wednesday night/Thursday. Expect the high pressure 
pattern to support dry/seasonable conditions Friday and Saturday
with highs/lows in the upper 50s/lower 60s and mid 30s - low 
40s respectively. As high pressure shifts east toward the end of
the weekend, increasing moisture may lead to some unsettled 
weather on Sunday, but confidence on what can be expected is low
at 7 days out.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Forecast Confidence Levels:

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

00Z TAF Update

Through Monday Night...High Confidence.

VFR. W to SW winds become NW overnight. Light NW winds Monday
open the door for late seabreezes along the coasts. Winds
expected to be more light and variable Monday night.

KBOS TAF...High Confidence in TAF. 

KBDL TAF...High Confidence in TAF. 

Outlook /Tuesday through Friday/... 

Tuesday: VFR. Breezy. 

Tuesday Night: VFR. Breezy. Slight chance SHRA.

Wednesday: Mainly VFR, with local IFR possible. Windy with
gusts up to 30 kt. Chance SHRA.

Wednesday Night: VFR. Windy with gusts up to 35 kt. Chance
SHRA.

Thursday through Thursday Night: VFR. Breezy. 

Friday: VFR.

&&

.MARINE...
Forecaster Confidence Levels:

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

Through Monday Night...High Confidence.

A relatively weak pressure gradient will keep winds and seas
below Small Craft Advisory thresholds through Monday night. 
Light northwest winds Monday could lead to late seabreezes along
the coasts. Light south winds developing Monday night.

Outlook /Tuesday through Friday/... 

Tuesday through Tuesday Night: Winds less than 25 kt. 

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

Wednesday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Seas up to 5 ft. Slight chance of rain
showers. 

Thursday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Local rough seas. 

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

Friday: Winds less than 25 kt.

&&

.FIRE WEATHER...
Today and Monday...

There will be elevated fire weather concerns Monday. Given that
we are in a pre-greenup, dry westerly flow will allow for 
minimum afternoon relative humidity values to drop to between 20
and 30 percent across the interior. Expecting wind speeds to be
lower Monday, but there could be W to NW gusts up to 20 mph.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Frost Advisory from midnight tonight to 7 AM EDT Monday for 
     CTZ002>004.
MA...Frost Advisory from midnight tonight to 7 AM EDT Monday for 
     MAZ013-016>023.
RI...Frost Advisory from midnight tonight to 7 AM EDT Monday for 
     RIZ001>008.
MARINE...None.

&&

$$

SYNOPSIS...Belk/RM
NEAR TERM...Belk
SHORT TERM...Belk
LONG TERM...RM
AVIATION...Belk/RM
MARINE...Belk/RM
FIRE WEATHER...Belk