Harmony, Rhode Island 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

694
FXUS61 KBOX 080817
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
417 AM EDT Thu May 8 2025

.SYNOPSIS...
Scattered showers and isolated thunderstorms possible today with
mild temperatures. Another heavy rainfall event with chilly
temperatures Thursday night into Friday night, especially across
western MA/CT where pockets of urban and poor drainage street
flooding could develop. Rain ends Saturday morning, then drier
on Sunday with a warming trend into early next week. Unsettled
pattern may return Tuesday night and Wednesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

Key Point

* Scattered showers and isolated thunderstorms possible this
  afternoon

Next shortwave trough begins to exit the Great Lakes. Pieces of
that shortwave energy begin to arrive in SNE this afternoon,
along with better mid-level moisture. With instability building
to around 300 J/kg, hi-res guidance is in good agreement that
there will be scattered showers and perhaps and isolated
thunderstorm. With the limited instability, not expecting any
severe weather today, but with skinny CAPE profiles and PWATS
around 1 inch, showers could drop a quick quarter to half an
inch of rain. Skies today will likely end up partly to mostly
cloudy, with diurnal stratocumulus quickly forming after
sunrise. Despite the cloud cover, high temperatures will still
reach the low to mid-70s. Winds remain light and variable today,
with localized sea breezes developing by mid-morning.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...

Upper-level shortwave deepens into the Ohio River Valley,
strengthening a surface low-pressure system over PA. WAA begins
to kick in ahead of the low pres, which will help maintain the
showers that formed in the afternoon even as instability wanes.
Better forcing from the short wave arrives overnight, allowing
more widespread moderate to heavy rain to move in from west to
east. With the WAA and rain, another mild night with lows only
dropping into the upper 40s to low 50s.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...

Key Points:

* Soaking rains Friday into Friday night with below normal
  temperatures. Heavy rainfall with possible hydro concerns across
  western MA/CT

* Rain gradually exits during Saturday morning with improving
  conditions in the afternoon

* Drying with a warming trend Sunday through Tue. Showers may return
  by Tuesday night or Wed

Details:

Friday into Saturday:

Slow moving upper low across the Gt Lakes gradually moves into New
Eng late Fri night before lifting to the NE Sat afternoon. Deep
southerly flow ahead of this upper low will transport elevated PWATs
1.25 to 1.5" northward into SNE Fri into Fri night. Meanwhile,
surface low pres will move across interior SNE with area of enhanced
low level frontogenesis along a warm front acting on deep moisture
to bring widespread rain to the region Fri into Fri night. Heaviest
rainfall will likely be focused across central/W MA and northern CT
near the axis of low level frontogenesis. Across eastern New Eng,
steadier rainfall may be delayed until later Fri and especially Fri
night as low level forcing and deep moisture moves east. Despite
cool low level airmass, cooling temps aloft as upper low moves
overhead may lead to some elevated thunder Fri night which could add
to the rainfall amounts.

Modest E-SE low level jet should enhance rainfall along east slopes
of the higher elevations. EPS ensembles are most bullish on heavy
rainfall with 60-80% probs of greater than 1 inch of rainfall and 20-
40% probs of greater than 2 inches focused in western MA/CT. GEFS
ensembles shift the axis of heavy rain probs (greater than 1 inch) a
bit further north and west but the Berkshires are within the axis of
highest probs. Generally looking at total rainfall amounts of 1-2
inches, heaviest in western MA/CT where localized amounts greater
than 2 inches possible, while rainfall amounts may be less than 1
inch across portions of eastern MA. This is not really a flash flood
scenario as rainfall rates will be somewhat muted. However, we may
see renewed flooding on the CT river at Hartford and Middle Haddam
with rainfall approaching 2 inches. NAEFS and GEFS ensembles
indicate about a 40 percent prob of renewed minor flooding along CT
river at Hartford and Middle Haddam with lower probs at other points
along the CT river.

It will be a chilly day on Fri with temps well below rainfall.
Easterly flow and rainfall will keep highs mostly in the 50s but
possibly remaining in the upper 40s across portions of northern MA.

Looking ahead to Sat, the dry slot will be overspreading SNE during
the morning with steadier rainfall tapering off, but lingering
showers in the comma head may continue in the morning before
gradually drying out in the afternoon. Increasing NW winds in the
afternoon as low pres pulls away. Temps remain below normal.

Sunday through Wednesday:

Mainly dry weather for much of the period as high pres builds into
the region before moving offshore early next week which will lead to
a gradual warming trend with above normal temps returning. Next
upper trough will be approaching from the west beyond Tue so
depending on timing of this system the risk of showers will
increase Tue night into Wed.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

06z TAF Update:

Thursday: High confidence.

VFR. Scattered to numerous showers form in the afternoon mainly
after 18z. There could be some thunderstorms esspically over the
CT river valley, but confidence was not high enough to include
in TAF yet. Localized sea breezes develop early to mid morning,
otherwise light and variable winds.

Thursday Night: Moderate confidence.

MVFR/IFR conditions. Left over rain from the afternoon
convection may continue through 04z, then the rain from the next
system reaches western MA and CT after 06z, and moves east
through the night. Rain may become moderate to heavy at times.

Friday: High Confidence

Continued IFR conditions with rain. East winds at 10-15 knots.

KBOS TAF...High confidence.

KBDL TAF...High confidence.

Outlook /Friday through Monday/...

Friday: Mainly IFR, with areas MVFR possible. RA, slight chance
TSRA.

Friday Night: MVFR/IFR conditions possible. RA, slight chance
TSRA.

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

Saturday Night through Monday: VFR.

&&

.MARINE...
Forecaster Confidence Levels:

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

Today through Friday: High Confidence.

Calm conditions today with light winds and calm seas due to
weak high pressure. Low pressure system will bring rain and
increasing southerly winds to the waters Friday. Seas begin to
increase to 3-5 feet in the open waters.

Outlook /Friday through Monday/...

Friday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain,
slight chance of thunderstorms.

Friday Night: Winds less than 25 kt. Seas up to 5 ft. Rain,
slight chance of thunderstorms.

Saturday: Winds less than 25 kt. Seas up to 5 ft. Slight chance
of rain showers.

Saturday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft.

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

Sunday Night through Monday: Winds less than 25 kt.

&&

.HYDROLOGY...

A flood watch has been issued for the CT river valley into the
Berkshires. Latest 00z HREF brings impressive rain totals to
the CT river valley into the east slopes of the Berkshires. the
24 LPMM shows a widespread 1.5-2.5 inches of rain with localized
spots up to 3 inches. Given the antecedent wet conditions from
the previous system earlier this week, there will be a renewed
threat for river flooding esspically in the southern portion of
the CT river. Not expecting flash flooding given the stratiform
nature of this event, but minor street and nuisance flooding are
likely with several hours with rain rates around 0.1 inches/hr.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch from late tonight through Saturday morning for
     CTZ002-003.
MA...Flood Watch from late tonight through Saturday morning for
     MAZ002-003-008>011.
RI...None.
MARINE...Small Craft Advisory from 5 AM to 8 PM EDT Friday for ANZ250.

&&

$$

SYNOPSIS...KJC/KP
NEAR TERM...KP
SHORT TERM...KP
LONG TERM...KJC
AVIATION...KJC/KP
MARINE...KJC/KP
HYDROLOGY...KP