BOX issues Area Forecast Discussion (AFD) at Apr 22, 1:11 AM EDT226
FXUS61 KBOX 220511
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
111 AM EDT Tue Apr 22 2025
.SYNOPSIS...
A warm front will spread increased cloudiness into Southern New
England through tonight, with passing showers around and after
midnight. Rain showers then taper off early on Tuesday with
decreasing cloudiness in most areas toward mild temperatures in
the 60s to low 70s, but cloud cover may linger into the
afternoon for the southern coast with cooler temperatures. Mild
and dry weather for the rest of the workweek, before our weather
pattern turns more unsettled again around the weekend.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Key Messages:
* Turning overcast tonight, with periods of rain showers around
and after midnight.
* Rain showers taper off overnight in western New England, but may
linger into the pre-dawn hours in eastern New England.
* Lows mid 40s to around 50.
Details:
Although we started the day with full sunshine with coastal
seabreezes, we're starting to see increased cloud cover in most
areas west of I-495 in MA. This is associated with increased
moisture from a warm front which trails from northern VT through
western RI; warm sector regime currently confined to much of the
eastern Gt Lakes, central/southern NY and western MA/CT precedes a
cold front now working its way through the Ohio Valley.
Cloud cover will only continue to gradually increase through tonight
and overnight, although many areas to remain dry thru midnight. Rain
showers then move into western New England around midnight, then
slowly progressing eastward into eastern MA and RI toward the pre-
dawn hours. Precipitable water values increase to around 1.2" with
the increased SW flow aloft; wouldn't rule out some very brief
downpours in a few showers but they're expected to pass through with
little overall fanfare. Through early Tuesday morning we should see
areal-average rain amts of up to a quarter-inch. Rain showers should
be coming to an end west of Worcester close to daybreak while
continuing into eastern MA, RI and the Cape and Islands. With the
warm advection (925 mb temps warm to around +12C) and increased
cloud cover, sided low temps toward milder side of guidance into the
mid to upper 40s.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
Key Messages:
* Overcast to start Tue; improvement away from the coastlines by mid
morning, but it may take until the afternoon before peeks of sun
break out for the South Coast, Cape and Islands. Temps range from
mid 60s to low 70s away from the southern coast, but only in the
50s to low 60s south coast, Cape/Islands.
* Dry cold frontal passage Tue night, with modest NW breezes.
Seasonable lows in the mid 40s.
Tuesday and Tuesday Night:
Rain showers from the overnight will be progressing off to the east
and offshore thru the early to mid morning hours. So while we start
off the day with overcast conditions, expect decreasing cloud cover
and warming temperatures away from the coasts into the 60s to low
70s. Forecast challenge for Tuesday resides along the south coast,
Cape and Islands; very limited mixing is progged given the cooler
marine boundary layer with moisture trapped beneath the warm airmass
aloft. This is visualized in forecast soundings at New Bedford,
Westerly, Falmouth/Hyannis and Nantucket. It could be quite a while,
potentially into the afternoon, before low clouds begin to erode
given those profiles. and that would cut into how warm temperatures
may get for the southern coast, with cooler SWly onshore flow for
these locations as well. Thus opted for highs only in the 50s,
perhaps near 60. If cloud cover does scatter out earlier, then temps
would be too cool and could reach up into low to mid 60s.
We then get a dry cold frontal passage for Tuesday evening, with
increased NWly breezes and falling dewpoint temps. However dry
weather is expected to accompany the front and in the intervening
hours behind its passage. Lows mainly in the 40s.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Key Messages:
* Warmer and drier Wednesday and Thursday with mostly clear skies.
* Pattern becomes more unsettled Friday through the weekend with
periodic chances for precipitation.
Wednesday through Weekend:
A cold front moves through Tuesday night into early Wednesday
morning, bringing a slightly cooler and drier airmass to southern
New England. Wednesday trends slightly cooler than Tuesday, although
still warmer than normal overall. Highs range in the 50s for the
Cape/Island and high 60s for the interior. Light NW winds expected
under broad high pressure with localized sea breezes in the
afternoon for the coastal areas.
A similar pattern stays in place through the end of the week with
zonal flow and 850mb temperature anomalies signaling at slightly
above normal temperatures. Ensemble guidance shows a transition to a
more unsettled pattern Friday into the weekend.
Heights fall across the region ahead of an upper level trough moving
over the Great Lakes. A weaker leading shortwave moves through
Friday evening with the main trough moving through by the end of the
weekend. This will bring a few rounds of spotty showers to the area;
however, still need to iron out the details with the timing/chances
of the first wave of showers on Friday. A more consistent round of
rain moves in overnight through Saturday. Slightly cooler for the
weekend as temperatures range around normal. Conditions gradually
drying out for Sunday.
&&
.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
06z TAF Update:
Through 12Z: Moderate confidence.
VFR east to start. Categories then continue to deteriorate to
MVFR, potentially IFR through 08z from W to E, in 4-6 SM -SHRA
and ceilings 010-020. Confidence in IFR is low. -SHRA should be
ongoing from ORH east by end of this period, while trending dry
for BAF/BDL. S winds around 10 kt, with areas of low level
shear as SW jet of 40 kt moves overhead.
Today: High confidence in trends but moderate on timing.
MVFR/IFR cigs early, quickly scattering out to VFR 13-16z. It
may take longer for south-coastal/Cape airports to scatter out
to VFR and showed MVFR-IFR ceilings thru at least 18z before
trending to VFR. SW winds around 5-10 kt then shift to WSW/W
around 10 kt, with occasional gusts to 20 kt for the interior.
Tonight: High confidence.
VFR. WNW winds around 5-10 kt.
Wednesday: High confidence.
VFR. Light NW winds 5-10 kts.
KBOS TAF...High confidence in TAF. VFR thru 07z, then
categories trend to MVFR with light showers. Improvement to VFR
anticipated by 15-16z.
KBDL TAF...High confidence in TAF. Improvement to VFR
anticipated by 12-13z.
Outlook /Wednesday Night through Saturday/...
Tuesday Night: VFR. Breezy.
Wednesday through Thursday Night: VFR.
Friday: VFR. Breezy.
Friday Night: Mainly VFR, with local MVFR possible. Breezy.
Chance SHRA.
Saturday: Mainly MVFR, with local VFR possible. Breezy. SHRA
likely.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight through Tuesday Night: High confidence.
Generally tranquil boating conditions through early tonight with
SE to S winds around 10-15 kt and seas 2-3 ft. Winds then
become S/SW around 15-20 kt tonight into Tuesday with passing
rain showers. SW gusts could reach near 25 kt over the far
southeast offshore waters, before becoming west late Tuesday
night.
Seas also begin to build to around 4 ft overnight tonight,
perhaps near 5 ft over the southern offshore waters. Seas
continue around that range through Tuesday night.
With the potential for limited mixing over the waters as a mild
airmass moves overhead, it will be close but felt conditions
were borderline for SCAs and refrained from hoisting at this
time. Later shifts could consider one to cover the Tuesday
timeframe if winds or seas increase further, but this does not
seem likely.
Outlook /Wednesday Night through Saturday/...
Tuesday Night: Winds less than 25 kt. Seas locally approaching
5 ft.
Wednesday through Friday: Winds less than 25 kt.
Friday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers.
Saturday: Low risk for Small Craft Advisory winds with gusts up
to 20 kt. Seas up to 5 ft. Rain showers likely.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.
&&
$$
SYNOPSIS...Loconto/McMinn
NEAR TERM...Loconto
SHORT TERM...Loconto
LONG TERM...McMinn
AVIATION...BW/Dooley
MARINE...Loconto/McMinn
Source:
BOX issues Area Forecast Discussion (AFD) at Apr 22, 1:11 AM EDT----------------
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