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000
FXUS61 KBOX 201817
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
217 PM EDT Sat Apr 20 2024

.SYNOPSIS...
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A ridge of high pressure will result in dry weather Sunday
through Tuesday with mild days and cool nights, along with
elevated fire weather potential. Unsettled, wet and cool on
Wednesday. Turning drier late in the week.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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First round of showers was still lingering around the Cape and
islands early this afternoon. Forecast still looks to be on
track, with this band of showers moving offshore by 3-4 PM.

Still liking the idea presented by the HRRR and RAP for a second
round of showers later this afternoon and evening as a mid
level shortwave passes by. Not as confident in the location,
which is not unusual with more convective rainfall in the near
term guidance. Have the greatest confidence in these showers
across the eastern half of southern New England between 4-8 PM.
Tried to place these showers in location and time using a more
ensembled approach between the last several runs of the HRRR,
RAP and NationalBlend.

Some brief clearing in a narrow band extended from southwest CT
into northeast MA. This clearing was already filling in. More
convective clouds were also popping up across eastern NY state.
Expecting the same across our region, where any breaks of
sunshine will fill in with diurnal clouds.

Once this mid level shortwave passes by, and with the loss of
daytime heating, expecting things to dry out rather quickly.
All showers should e gone by 10 PM, with clearing arriving from
west to east through this evening.

Light west to northwest winds should prevent ideal radiational
cooling. That said, some areas across the western half of
southern New England could see some patchy frost by Sunday
morning. Not thinking frost will be widespread enough to
warrant an advisory at this time, despite the season starting
tomorrow across northern CT, RI and mainly southeast MA.
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&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
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High pressure starts to build across southern New England
through Sunday night, providing dry weather. Expecting a period
of clouds Sunday afternoon and evening as a weak trough passes
by. This weak trough will also help generate gusty afternoon
west winds. Near to slightly below normal temperatures.
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&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
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Highlights

* Very seasonable weather next week with daily high/low temps
  close to the climatological normal

* Rainy on Wednesday


Monday through Saturday

No anomalous or impactful weather is expected in the extended
forecast for southern New England next week. The week begins
with the region largely dominated by high pressure building in
from the west. This should support a sunny/dry start to the week
with highs in the upper 50s/low 60s and lows in the upper
30s/low 40s. The only active period of weather this week will be
on Wednesday when a modest short-wave disturbance aloft
traverses over the region. Southerly flow ahead of this feature
will increase the moisture over southern New England allowing
for widespread stratiform precipitation during the day
Wednesday. With neither forcing nor moisture forecast to reach
impressive levels, the total rainfall accumulation with this
system is expected to be modest with amounts likely between 0.1
and 0.25 inches. As the associated surface cold front pushes
through the region behind this system Wednesday night, we`ll be
left with a dry but cooler air mass on Thursday which should
feature temperatures only slightly below normal. High pressure
then builds over The Northeast to end the week with more dry,
quiet, and seasonable conditions.
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&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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Forecast Confidence Levels:

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

Through 00Z...High confidence in trends, moderate in timing.

Mainly VFR with areas IFR west of I-495. Mainly IFR with pockets
of LIFR across RI and southeast MA. Thinking we see a second
round of hit-or-miss showers this afternoon, mainly across the
eastern half of our region. Low probability there is some
graupel in the heavier showers. Not as concerned about the risk
for thunderstorms. Winds out of the SW becoming more W at 5-15
kt. Could see some 20-25 kt gusts during the afternoon across
the interior.

Tonight through Sunday Night...High confidence.

Any lingering MVFR-IFR conditions across the Cape/Islands
clear to VFR this evening. VFR conditions expected into Sunday
Night. WNW generally 5-10 knots, shifting to the WSW Sunday at
10 to 15 knots with some afternoon gusts of 20 to 25 kt. Winds
turn WNW Sunday night and become less gusty.

KBOS TAF...High Confidence in TAF.

KBDL TAF...High Confidence in TAF.

Outlook /Monday through Thursday/...

Monday: VFR. Breezy.

Monday Night: VFR.

Tuesday: VFR. Windy with local gusts up to 30 kt.

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

Wednesday: Mainly VFR, with local IFR possible. Breezy. Chance
SHRA.

Wednesday Night: VFR. Breezy. Chance SHRA.

Thursday: VFR. Breezy.
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&&

.MARINE...
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Forecaster Confidence Levels:

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

Through Sunday Night...High Confidence.

A relatively weak pressure gradient should keep winds and seas
generally below Small Craft Advisory thresholds through Sunday
night. However, good mixing on westerly flow Sunday may yield a
few afternoon nearshore wind gusts of 20-25 knots creating some
chop.

Outlook /Monday through Thursday/...

Monday through Monday Night: Winds less than 25 kt.

Tuesday: Low risk for Small Craft Advisory winds with areas of
gusts up to 30 kt.

Tuesday Night: Low risk for Small Craft Advisory winds with
local gusts up to 30 kt. Seas locally approaching 5 ft.

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 25 kt. Seas up to 5 ft. Slight chance of rain
showers.

Thursday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft.
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&&

.FIRE WEATHER...
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Sunday...

Dry westerly flow in pre-greenup should allow for elevated fire
weather concerns on Sunday. The airmass will mix deeply and
allow for a large temp/dewpoint spread. Highs should reach the
upper 50s to near 60 with dewpoints dropping into the lower to
middle 20s. This should result in minimum afternoon relative
humidities between 20 and 30 percent. The deep mixing should
also produce some 20 to 25 mph wind gusts with perhaps a few
locales approaching 30 mph briefly. However, the rainfall today
was wetting for most locations. Will continue to monitor this
potential overnight.
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&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

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