NWS Forecast Discussion


000
FXUS61 KBOX 150209
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1009 PM EDT Sun Apr 14 2024

.SYNOPSIS...
Showers end overnight, along with gradual clearing. Dry and
seasonably mild Monday through Wednesday. Another unsettled
pattern develops late this week, with near normal temperatures
and a few chances for rain Thursday into next weekend.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
1005 PM Update:

Low pressure near the Poconos in northeast PA will continue to
ride ENE along an elongated frontal boundary from its center
northeastward into Southern New England through late tonight.
This should gradually shift the effective frontal boundary
southward into the southern waters as time goes on tonight.
Though we had a few lightning strikes in CT a few hours ago, the
bulk of convective activity has remained well to the southwest.
Radar showing a fractured line of scattered showers located just
south of the Route 2 corridor, which will slowly progress
southeast toward the southern coastal waters thru midnight.
That will likely be the extent of it though over much of the
land with dry weather for the 2nd half of the overnight,
however it is possible we could see a rogue, garden-variety TS
develop over the southern waters (perhaps near MVY/ACK?) early
overnight per the HRRR and 18z/14th NAM-3km guidance. Rain amts
probably won`t amount to much more than a tenth of an inch as
showers should be passing and of generally light intensity.

Though the frontal boundary will be slowly sagging southward for
the 2nd half of the night well into the waters, cloud cover
could be a little slower to erode especially if the boundary
slows down. Did bump cloud cover up somewhat across the southern
half of Southern New England thru the pre-dawn hrs, essentially
a slower erosion of cloud cover. Further inland though, most
areas should trend mostly clear by overnight/pre-dawn period.

Previous Discussion...

A disorganized frontal wave will traverse over the Northeast
this afternoon and evening with scattered showers and a perhaps
a few thunderstorms. Latest SPC meso-analysis reveals no
significant surface based CAPE over southern New England within
the warm sector of the wave of low pressure moving through the
region. However, steep mid-level lapse rates are contributing to
elevated instability that could support a few rumbles of thunder
across western MA/CT and possibly over some locations near the
south coast this evening. Areas along and north of I-90 are
forecast to be in the cool sector, thus not expecting any
thunderstorm activity north of that mark. Any remaining showers
and thunderstorms are forecast to clear to the south and east
around or just before midnight. Thereafter we can expect gradual
clearing with winds shifting to the west/northwest. Low temps
bottom out in the low 40s across northwestern MA and mi to upper
40s elsewhere.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Tomorrow

A dry surface cold front pushes through the region during the
day tomorrow. This will support dry conditions and
west/northwest winds throughout the day. Skies will be clear to
start which will allow surface temps to warm to the upper 60s to
near 70 in some locations by the mid-afternoon hours. After a
sunny start, we will begin to see increasing diurnal cu during
the afternoon thanks to steep low- level lapse rates from cooler
air aloft. Overall a warm/dry afternoon. Warmest temps will be
focused in the CT River Valley and over southeastern MA where
downsloping from WNW winds should help temps over achieve.

Tomorrow Night

Very quiet tomorrow night. Clear skies and light west/northwest
winds. There is some question as to whether or not the
atmosphere decouples overnight. This will govern how far
temperatures are able to fall with radiational cooling. Will
have a better idea by tomorrow, but for now have leaned on a
blend of CONSMOS and NBM for low temps in the low to mid 40s on
Tuesday morning.

&&

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

* Broad trough settled over the region for much of the upcoming
  week, with a brief period of mid level ridging in the Tuesday-
  Wednesday timeframe

* Near to above normal temperatures, with an unsettled pattern
  developing late this week

Based on the latest guidance suite, still have the greatest
confidence in the forecast details into early Wednesday. After
then, there is little consistency with the timing and amplitude
of some synoptic features, leading to low confidence in the
forecast details. Kept a broad period of unsettled weather from
late Wednesday into Saturday, but not expecting this to be a
total washout this entire time. Expecting it will be a couple
more days before these details come into better focus. All that
said, there has been a consistent signal for near to above
normal temperatures through this portion of the forecast.

High pressure dominates our weather Tuesday into Wednesday.
Thinking we could get through most of Wednesday dry, especially
across the eastern half of southern New England. Just a low risk
for some showers during the afternoon farther west. More likely
to see rainfall arrive some time Wednesday night into Thursday
as a low pressure moves into the Great Lakes, with a secondary
low pressure possibly developing toward the Mid Atlantic coast.
This should move offshore Friday, with a lingering cold front
into Saturday. A large high pressure over the northern Plains
states should become more of a factor in our weather some time
Sunday.

Moisture is not particularly impressive, so not expecting a lot
of rainfall during the second half of this week. This should be
a good thing, by permitting area waterways a chance to drain
further.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Forecast Confidence Levels:

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

Tonight...High Confidence.

VFR. Any remaining SHRA diminish after 03Z across most of the
region. Some SHRA may linger near the south coast of RI/MA
through about 08Z. This will be followed by some gradual
clearing from west to east through 12Z. Southwest winds becoming
northwest from 5 to 10 knots.

Tomorrow...High Confidence.

VFR. W/WNW winds around 10 knots. Some gusts up to 20 knots
possible.

Tomorrow Night...High Confidence.

VFR. Steady WNW winds continue.

KBOS TAF...High confidence in TAF.

KBDL TAF...High confidence in TAF.

Outlook /Tuesday through Friday/...

Tuesday: VFR. Breezy.

Tuesday Night: VFR.

Wednesday: VFR. Slight chance SHRA.

Wednesday Night: VFR. Chance SHRA.

Thursday: VFR. Breezy. Chance SHRA.

Thursday Night: Mainly VFR, with local MVFR possible. Slight
chance SHRA.

Friday: Mainly VFR, with areas MVFR possible. Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight

Some showers and possible a rumble of thunder possible over the
south coastal waters before midnight tonight. Otherwise, expect
gusty southwest winds to diminish as winds shift to the
west/northwest overnight. Sustained speeds fall to 5 to 10 knots
by tomorrow morning with gusts less than 20 knots. Seas begin to
subside but remain high enough to warrant Small Craft Advisory
headlines for the outer marine zones.

Tomorrow and Tomorrow Night

Seas continue to subside to sub-Small Craft Advisory criteria by
tomorrow evening. Otherwise, expect relatively quiet conditions
over the coastal waters with modest 10-15 knot west/northwest
winds.

Outlook /Tuesday through Friday/...

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

Tuesday Night through Wednesday: Winds less than 25 kt.

Wednesday Night: Winds less than 25 kt. Slight chance of rain
showers.

Thursday through Friday: Winds less than 25 kt. Seas locally
approaching 5 ft. Slight chance of rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 2 PM EDT Monday for ANZ232>235-237-
     250.
     Small Craft Advisory until 8 PM EDT Monday for ANZ254>256.

&&

$$

SYNOPSIS...Belk/RM
NEAR TERM...Belk/Loconto/RM
SHORT TERM...RM
LONG TERM...Belk
AVIATION...Belk/Loconto/RM
MARINE...Belk/Loconto/RM

NWS BOX Office Area Forecast Discussion