BOX issues Area Forecast Discussion (AFD) at May 12, 1:40 AM EDT549
FXUS61 KBOX 120540
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
140 AM EDT Sun May 12 2024
.SYNOPSIS...
Increasing clouds tonight ahead of an approaching system across the
eastern Great Lakes. A few showers possible late tonight with a hit
or miss shower on Sunday, not expecting a washout. Another cooler
than normal day is expected Sunday. Milder next week with the
risk for showers increasing Tuesday into Wednesday, then mainly
dry and seasonable toward the end of next week.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1020 PM update...
Mid level low across eastern Gt Lakes with scattered showers
lifting across NY and PA. A few of these showers may spill into
western MA overnight as the mid level low drifts east with
cooling temps aloft. Otherwise, cloud cover will be increasing.
Temps have already dropped into the upper 30s across portions
of SE MA where enough breaks in the clouds with light winds,
while temps lower 50s in the CT valley. Lows will range from the
mid-upper 30s in eastern MA to low-mid 40s elsewhere.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
Highlights:
* Another cooler day with a few showers possible.
Sunday & Sunday Night:
A weak surface low pressure develops around the eastern Great Lakes
and moves southeast, promoting shower activity over New York, but a
few showers are possible in western Connecticut and Massachusetts.
While the day is mainly dry, an anomolously cold airmass aloft and
shortwave pushes across southern New England, the cold pool could
trigger a few spot/pop-up showers across all of southern New England
as seen on the 12z CAMs. Good news, not a washout, showers will be
isolated and brief. Winds are generally out of the southeast, but
along the east coast of Massachusetts do think a seabreeze develops
which will keep the wind direction out of the east. Another cooler
afternoon with highs in the upper 50s and low 60s away from the
coast, near the coast temperatures are in the mid 50s. Clearing sky
overnight with high pressure settling back into the region,
temperatures aloft are increasing, despite the clear sky don't
expect low temperatures to be much cooler than the night before, in
fact a few degrees warmer int he low and middle 40s.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Highlights:
* Warming up Monday and Tuesday with afternoon high temperatures
near or above 70 degrees
* A coastal low-pressure system is forecast to bring a period of
substantial rainfall and gusty winds to the region Tuesday night
into Wednesday
* Drying out late week with more seasonable temperatures in the 60s
and 70s
Monday and Tuesday
The week begins with an upper-level low and cold pool aloft shifting
east of southern New England. Behind this system a broad upper-level
ridge will build over the eastern US and replace the anomalously
cool air mass currently in place with a warmer and more seasonable
air mass for mid-May. 925 hPa temps rise to 10C on Monday afternoon
and 15C on Tuesday afternoon. This should support warmer
temperatures in the upper 60s on Monday afternoon and low to mid 70s
on Tuesday afternoon. Sea-breezes may keep the coastal areas a bit
cooler on Monday.
Precipitation chance begin to increase late Tuesday in response to
warm advect ahead of a fairly robust short-wave trough advancing
over The Midwest/Ohio River Valley. Most areas stay dry on Tuesday,
but can't rule out a few spot showers Tuesday evening.
Tuesday night and Wednesday
By Tuesday night, the short-wave over The Midwest will be traversing
east with a surface low-pressure system developing at the surface.
This system is forecast to bring a substantial amount of
precipitation to southern New England Tuesday night into much of
Wednesday. This system appears as though it will take a coastal-
storm track south of southern New England. This would presumably
support more stable conditions across the region and limit any
potential for spring convection. Nonetheless, strong synoptic
forcing/FGEN and PWATs approaching 1.5" will allow for precipitation
around an inch or greater by Wednesday night. Ensemble probabilities
of an inch or greater are about 50 percent across southern New
England with a 10 to 20 percent chance of up to 2 inches over the
south coast. Accumulations will be heavily dependent on storm track
and just how much moisture is available, but confidence is
increasing in a substantial precipitation event during this time
frame. Winds may be gusty at times as well with 20 to 30 mph gusts
possible Tuesday night and Wednesday. Latest guidance supports this
system being east of the region by Wednesday night leading to a dry
day on Thursday.
Thursday and Friday
Northwest flow behind a departing area of low-pressure will advect a
drier air mass over southern New England to end the week. This will
support plenty of sunshine on Thursday with highs in the upper 60s
to low 70s. A ridge axis overhead should keep the region dry with
warm/seasonable temperatures to end the week as well. As the ridge
axis shifts east late week, return flow from the south will support
increasing cloudiness and precipitation ahead of our next low-
pressure system which may bring more precipitation to the region
early next weekend.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
06z TAF Update...
Through 12z...
VFR, except patchy MVFR cigs over Cape/Islands
Today... Moderate confidence.
Mainly VFR cigs, but areas of MVFR over western MA. Widely
scattered showers developing, especially across western MA and
northern CT. Light winds turning S-SE in the afternoon with
sea-breezes along the coast.
Tonight... High confidence.
VFR. Low prob for patchy fog possible in prone radiator
locations. Light SW winds.
Monday...Moderate confidence.
VFR cigs. A few showers possible across interior MA into CT in
the afternoon. S-SW wind 10-20 kt.
KBOS TAF...High confidence in TAF. Sea-breeze develops by 14z.
KBDL TAF...Moderate confidence in TAF. We have low end VFR
cigs in the TAF today but could see some MVFR at times. A few
showers possible.
Outlook /Monday Night through Thursday/...
Monday Night: Mainly VFR, with local MVFR possible. Breezy.
Slight chance SHRA.
Tuesday: VFR. Windy with local gusts up to 30 kt. Chance SHRA.
Tuesday Night: Mainly MVFR, with local IFR possible. Windy with
local gusts up to 30 kt. SHRA, isolated TSRA.
Wednesday: MVFR/IFR conditions possible. Breezy. SHRA likely.
Wednesday Night: Mainly VFR, with areas IFR possible. Breezy.
Chance SHRA.
Thursday: VFR. Breezy. Slight chance SHRA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Through Sunday Night...
Pressure gradient brings east/northeast winds this afternoon across
the southern waters to 25-30 knots, becoming light and variable
overnight with high pressure settling over the waters. Residual seas
on the southern waters of 5 foot are the basis for the Small Craft
Advisory through portions of Sunday. A few spot and brief showers
possible Sunday morning then dry conditions into Sunday night.
Outlook /Monday Night through Thursday/...
Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Monday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of rain showers.
Tuesday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of seas approaching 5 ft. Slight
chance of rain showers.
Tuesday Night through Wednesday: Moderate risk for Small Craft
Advisory winds with gusts up to 30 kt. Seas up to 5 ft. Rain
showers likely.
Wednesday Night: Low risk for Small Craft Advisory winds with
gusts up to 20 kt. Areas of rough seas. Chance of rain showers.
Thursday: Winds less than 25 kt. Areas of rough seas. Slight
chance of rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ254-
255.
Small Craft Advisory until 2 AM EDT early this morning for
ANZ256.
&&
$$
SYNOPSIS...Dooley/RM
NEAR TERM...KJC/Dooley
SHORT TERM...Dooley
LONG TERM...RM
AVIATION...KJC/RM
MARINE...Dooley/RM
Source:
BOX issues Area Forecast Discussion (AFD) at May 12, 1:40 AM EDT----------------
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