Forecast Discussion for BOX NWS Office
FXUS61 KBOX 032028
Area Forecast Discussion
National Weather Service Boston/Norton MA
428 PM EDT Fri Jul 3 2020
Showers and a few thunderstorms across western Massachusetts
and northern Connecticut will come to an end by early to mid
evening. Dry weather is on tap for Saturday, but low clouds and
cool temperatures will persist on the coast while a partly
sunny and warm afternoon is on tap for interior southern New
England. A weak cold front moves through late Sunday/Sunday
night which may trigger a few showers or a thunderstorm. Weak
high pressure follows Monday, then a warm front approaches Tue
with chance of showers/thunderstorms in the interior. Hot and
humid conditions move in for the middle and end of next week
with scattered afternoon/evening thunderstorms each day.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
415 PM Update...
Showers and a few t-storms were still impacting western MA &
northern CT at late afternoon. This is where a backdoor cold front
combined with shortwave energy and modest instability to result in
some training and localized flooding. Parts of the Hartford metro
area received nearly 2.50 inches of rain in just an hour, which
Fortunately, the backdoor front has cleared our region and taken the
best instability with it. Showers and a few embedded t-storms across
western MA/northern CT will diminish by early-mid evening. Some
weakening showers may also briefly spill into RI/SE MA.
Otherwise, mainly dry weather is expected for the rest of tonight
outside a few showers/drizzle across southeast New England with
moist NE low level flow. We may see some patchy fog develop too.
Low temps will mainly be in the lower to middle 60s.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
High pressure over the Maritimes and low pressure to our south
will maintain low level NE flow. A bit of drizzle is still
possible into mid morning along the coast, but the main issue
will be low clouds. We should see partial sunshine develop
across the interior by afternoon, but it may take until mid to
late afternoon for some partial sunshine to emerge across
eastern MA/RI. In fact, the Cape/Islands may remain in the low
clouds until early evening.
Onshore flow and an abundance of clouds will hold high temps
into the 70 to 75 degree range across eastern MA as well as the
Cape/Islands. Meanwhile, enough sunshine should push parts of
western MA and northern CT into the lower to middle 80s.
Dry and pleasant weather is expected for Saturday night. Low temps
should drop between 60 and 65. Low probability of a shower or two
toward daybreak with some elevated instability, but forcing rather
limited so maintained a dry forecast. Some patchy fog is
.LONG TERM /SUNDAY THROUGH FRIDAY/...
* Few showers/t-storms possible Sunday
* Seasonably warm Mon/Tue with shower/t-storm risk interior on Tue
* Hot and humid Wed-Fri with sct afternoon/evening t-storms
Mid level shortwave drops across northern ME with 500 mb temps
dropping to -12 to -13C. This cold pool combined with surface
heating will contribute to CAPES 1000-1500 J/kg. Weak cold front
moving across SNE may provide a focus for a few showers/t-storms
developing. Guidance is not too bullish on convection so areal
coverage may be limited but do expect a few storms which may be
focused more in eastern half New Eng based on location of front.
850 mb temps around 16C which supports highs well into the 80s and
near 90 degrees in CT valley, but cooler immediate coastline where
sea breezes expected to develop.
Monday and Tuesday...
Cold front moves offshore by early Mon with weak high pres building
in bringing mostly sunny skies. Low level winds turn easterly which
will result in a cooler airmass Mon, especially in the east.
Instability axis gets pushed west of SNE so a dry day expected.
Highs Mon will range from the 70s eastern MA coast to the mid/upper
80s CT valley. Then on Tue, warm front will move in from the west
with risk of sct showers/t-storms in western MA/CT as instability
increases in the west. Seasonably warm temps Tue.
Wednesday through Friday...
SNE will be on the periphery of subtropical ridge which will result
in increasing heat/humidity moving into the region. Many locations
will likely see temps into the upper 80s and lower 90s. Series of
weak shortwaves traveling within the nearby polar jet combined with
unstable environment will lead to scattered afternoon/evening
showers/t-storms each day.
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
This afternoon...High confidence. MVFR-IFR conditions persist
in central/eastern MA and RI with just a few spot showers possible.
NE winds will gust into the lower 20 knots at times along the coast
plain. Meanwhile, in western MA/northern CT, showers and
embedded t-storms with heavy rain will be the main concern.
Tonight...High confidence. Cooling boundary layer tonight
allows for conditions to deteriorate to IFR-LIFR levels across
central/eastern MA & RI with lowest conditions along the coast.
May see a few spot showers and/or drizzle develop along the
coast too. Meanwhile, showers and embedded t-storms dissipate
this evening across western MA/CT, but ceilings should
deteriorate to MVFR levels.
Saturday...High confidence. Gradual improvement in ceilings to
mainly VFR by mid afternoon from west to east. However, lower
clouds may hang tough all day across the far southeast New
Saturday night...High confidence in mainly VFR conditions.
KBOS Terminal...High confidence in TAF.
KBDL Terminal...High confidence in TAF. Main concern will be
heavy showers and embedded t-storms in the vicinity of the
terminal through 21-22z.
Outlook /Sunday through Wednesday/...
Sunday through Sunday Night: VFR. Slight chance SHRA, slight
Monday Night: VFR. Slight chance SHRA.
Tuesday: VFR. Slight chance SHRA, slight chance TSRA.
Tuesday Night: VFR. Slight chance SHRA.
Wednesday: VFR. Breezy. Slight chance SHRA, slight chance TSRA.
Tonight through Saturday night...High confidence.
Marginal NE wind gusts of 20 to 25 knots and 3 to 5 foot persisted
late this afternoon, so will maintain SCA headlines across the
eastern waters early this evening. Weakening gradient will allow
winds/seas to drop below small craft advisory thresholds this
evening. NE winds of 10 to 15 knots Sat morning will shift to the
south at 5 to 15 knots Sat night as offshore low moves further away
from the region. Winds/seas will remain below SCA thresholds Sat and
Sat night. Areas of fog tonight and perhaps again Sat night will
reduce vsbys at times for mariners.
Outlook /Sunday through Wednesday/...
Sunday through Sunday Night: Winds less than 25 kt. Slight
chance of rain showers, slight chance of thunderstorms.
Monday through Tuesday Night: Winds less than 25 kt.
Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of rain showers, slight chance of
MARINE...Small Craft Advisory until 6 PM EDT this evening for
Small Craft Advisory until 8 PM EDT this evening for ANZ250-
NWS BOX Office Area Forecast Discussion