436
FXUS61 KBOX 020720
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
320 AM EDT Wed Apr 2 2025

.SYNOPSIS...
Cooler today with continued dry weather, then an approaching warm
front will bring a period of light rain tonight into Thursday
morning, with pockets of mixed wintry precipitation possible across
the interior tonight. Milder conditions arrive Thursday into Friday
with a stalled front possibly bringing a few showers near the south
coast Thursday night into early Friday. Unsettled conditions
continue this weekend as a frontal system impacts the region, with
cooler temperatures Saturday followed by milder conditions Sunday.
Drying out early next week as the frontal system exits the
region.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Key Messages:

* Dry and cool with temps several degrees below normal

High pressure over eastern Canada shifts east of New Eng this
afternoon. The high pres and assocd low level dry air will keep
precip assocd with approaching warm front mostly to the west through
the day, with just a low risk a few light showers may spill into the
Berkshires toward evening. Sunshine will give way to thickening
afternoon clouds in developing warm advection pattern. Chilly
airmass across SNE as 925 mb temps this afternoon range from near 0C
CT valley to -4C across eastern MA. Highs will range from near 40
eastern MA coast to upper 40s CT valley. Some locations along the
immediate eastern MA coast may remain in the upper 30s with onshore
flow. Normal highs are 50-55.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Key Messages:

* Periods of rain developing tonight into Thu morning

* Pockets of mixed wintry precip tonight across the interior with
  spotty freezing rain possible over the higher elevations. Any
  travel impacts will be limited

* Milder Thu with rain becoming more spotty in the afternoon

Approaching warm front with good moisture advection aided by modest
low level jet will result in periods of light precip developing
tonight into Thu morning as PWATs increase to over 1.25". Axis of
the 850 mb jet will be to the north where best forcing for ascent
and heaviest precip will be. However, enough forcing combined with
deep moisture through the column for precip tonight, with steadiest
across northern MA closest to best forcing, with more rain more
scattered near the south coast.

Ptype in the coastal plain will be all rain, but there will be some
ptype issues in the interior as the precip moves in tonight.
Soundings show a pronounced warm nose 800-700 mb with low level cold
air below supportive of pockets of sleet, and spotty freezing rain
possible over northern MA higher elevations where temps will wet
bulb down to 32F for a time. Given warm ground and marginal temps,
any travel impacts will be limited and impacting a small area so no
advisories. Temps will rise above freezing before daybreak across
higher terrain so not expecting any impacts for the morning commute.

Periods of rain will linger into Thu morning, then should become
more spotty in the afternoon as the warm front lifts to the north.
Increasing SW flow will bring milder air with highs reaching the 60s
away from the south coast, with 50s along the south coast. 925 mb
temps are quite mild reaching 14-16C by late in the day, but low
level inversion will limit mixing. However, if some breaks of sun
can develop in the afternoon, temps could reach 70+ in portions of
the CT valley but confidence is low.

Low level jet will result in gusty SW winds developing. The low
level inversion will prevent the stronger winds from mixing down but
the potential exists for a few 30-40 mph gusts, especially inland
from the immediate south coast where milder temps will help to erode
the inversion.

&&

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

Key Messages

* Pleasant early spring day on Friday

* Cooler on Saturday followed by increasing warmth and shower
  chances Saturday night into Sunday

* Trending cooler again early next week

Thursday night and Friday

A dry cold front pushes through the region Thursday night into
Friday brining abnormally high 925 hPa temps near 15C down to values
closer to normal for early April in the 5 to 10 Celsius range. This
front will be accompanied by a dry northwest flow that will support
efficient mixing on Friday afternoon. As a result we can expect a
pleasant/sunny early spring afternoon with high temperatures in the
60s across southern New England. Expect the warmest temperatures in
east/southeast MA where downsloping on northwest flow may support
temperatures in the mid to upper 60s. A 70 degree observation can`t
be ruled out with ensemble probabilities suggesting a 10 to 20
percent chance of temperatures greater than 69 degrees on Friday
afternoon. The warmth will be accompanied by a northwest breeze with
some gusts of 20 mph possible across the region.

Saturday through Sunday night.

The warmth from Friday quickly cools down on Saturday as high
pressure is forecast to build north and east of southern New
England. This will allow a backdoor cold front to advect cooler air
back into the region with 925 hPa temps dipping near the freezing
mark by Saturday morning. This will support a cool/raw day with
highs peaking in the mid to upper 40s for much of southern New
England. Saturday will as mark the beginning of a wet/unsettled
period. As the aforementioned area of high pressure continues to
shift east, return flow from the south will support WAA driven
showers over southern New England likely beginning Saturday
afternoon. Expect precipitation to persist through Sunday as the
associated low-pressure system traverses over The Northeast Saturday
night through Sunday evening.

As warm sector air lifts over the region on Sunday, 925 hPa temps
rise dramatically to the 15 to 20C range. So while Sunday is
expected to be wet/rainy, it will also be on the warm/humid side
with temperatures in the low to mid 60s and dewpoints in the 50s.
Ensemble mean precipitation forecasts for Saturday afternoon through
Sunday night are ranging from 0.75 to 1 inch across southern New
England. Some of this precip may come in the form of convective
showers Sunday night as the associated cold front drives the warm
sector air out of the region. Model derived CAPE values are
unimpressive at this time, but with ensemble mean SBCAPE values
around 250 J/kg, a few showers could have a rumble of thunder,
particularly along the south coast.

Monday and Tuesday

Trending drier and more seasonable on Monday as a cold front ushers
a drier air mass over the southern New England. Ensemble mean high
temperatures on Monday afternoon currently ranging from the mid to
upper 50s across southern New England which is close to normal for
this time of year. Model spread increases on Tuesday with the
ECMWF/CMC models supporting a somewhat strong CAA pattern that would
feature high temperatures in the upper 30s/low 40s on Tuesday. The
GFS is less aggressive with cooler air and keeps high temps in the
mid to upper 40s next Tuesday. Stay tuned for further details...

&&

.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

Through 12z...High confidence.

VFR, dry weather and diminishing winds.

Today...High Confidence

VFR. NE wind 5-10 kt becoming SE-S in the afternoon.

Tonight...Moderate Confidence.

VFR trending to MVFR overnight. Local IFR across the higher
terrain late. Mostly -SHRA, but risk for -PL across the
interior with pockets of -FZRA higher elevations.

Thursday...Moderate Confidence

Mainly IFR/MVFR with -SHRA in the morning becoming more spotty
in the afternoon. Increasing SW winds with gusts to 25-35 kt
developing.

BOS TAF...High confidence.

BDL TAF...High confidence.

Outlook /Thursday Night through Sunday/...

Thursday Night: MVFR/IFR conditions possible. Breezy. Chance
SHRA.

Friday: Mainly VFR, with local MVFR possible. Breezy. Slight
chance SHRA.

Friday Night: VFR.

Saturday: Mainly MVFR, with local IFR possible. Chance SHRA.

Saturday Night: Mainly MVFR, with areas IFR possible. Breezy.
SHRA.

Sunday: Mainly MVFR, with areas IFR possible. Breezy. Chance
SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Today...High confidence.

Winds below SCA. N-NE wind will become SE this afternoon. Hazardous
seas over the outer waters will subside below 5 ft this afternoon.

Tonight and Thursday...High confidence.

Increasing southerly winds late tonight becoming SW Thursday. Modest
low level jet over the waters but strong low level inversion will
prevent stronger winds from mixing down. Expect gusts to 30 kt Thu.
SCA will be needed. Spotty light rain tonight into Thu.

Outlook /Thursday Night through Sunday/...

Thursday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Chance of rain showers.

Friday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Chance of rain showers.

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

Saturday: Winds less than 25 kt. Seas locally approaching 5 ft.
Rain showers likely.

Saturday Night: Winds less than 25 kt. Seas up to 5 ft. Rain
showers likely.

Sunday: Winds less than 25 kt. Areas of rough seas. Chance of
rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ250-
     256.
     Small Craft Advisory until 6 PM EDT this evening for ANZ254-
     255.

&&

$$

SYNOPSIS...KJC/RM
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...RM
AVIATION...KJC/RM
MARINE...KJC/RM