BOX issues Area Forecast Discussion (AFD) at Jul 7, 3:42 AM EDT400
FXUS61 KBOX 070742
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
342 AM EDT Sun Jul 7 2024
.SYNOPSIS...
Very warm and humid weather conditions continue into next week.
Overcast conditions this morning gives way to partly to mostly
sunny skies today, except for the south coast. Other than a hit
or miss thunderstorms near Interstate 95, dry weather is
expected. Still fairly humid late week, though temperatures are
slightly less hot, along with better rain and thunderstorm
chances late week as the remnants of Beryl moves towards the
northeast.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
335 AM Update:
Another pea-soupy early morning across Southern New England,
and with few exceptions (northeast MA), most of the area is
blanketed in low clouds and/or fog. Fog is most persistent and
locally dense along the immediate coastline, with visbys
elsewhere in the 1 to 5 mile range. Not really seeing widespread
dense fog so SPS for fog issued early in the overnight still
looks valid. Otherwise, we're stuck in a weak sea-level pressure
pattern with surface trough axis from coastal ME/NH SSW through
the North Shore into northeast NJ. A rogue shower was near New
Bedford, but it is largely dry otherwise with scattered heavier
showers well south of the Islands. Current temps were in the low
to mid 70s. Similar dewpoints were observed as well, although
they were falling into the mid to upper 60s in the Berkshires
and eastern NY.
For today, we should see low clouds and fog gradually scattering
out, soonest in northern MA, and around mid to late morning to
the I-95 corridor. For the South Coast, Cape and Islands, there
looks to be little if any substantial improvement in lower
clouds; given those expectations, high temperatures are expected
to be cooler there in the upper 70s to lower 80s. However
dewpoints should be the highest for those locations today in the
low to mid 70s with southerly winds. Skies should trend toward
partly to mostly sunny conditions north and west of I-95 once
stratus erodes, with a drop in dewpoints into the mid to upper
60s and a lighter WSW flow. Highs elsewhere should reach into
the mid 80s to low 90s, though seabreezes keep the eastern
coastline on the cooler end of that range.
Generally dry for the vast majority of the area. But some
mesoscale signals of isolated to widely scattered thunderstorms
developing along a weak windshift boundary within the I-95
corridor, produced between the WSW winds in the interior and the
SSW winds in southeast New England. After low clouds dissipate
and heating gets going, NAM/RAP instability profiles near this
boundary are significant, to around 2000-3000 J/kg of surface
based CAPE. It may only be a couple storms if they develop at
all, but felt it was enough to sketch an area of isolated
thunderstorms around 1-8 PM from roughly northern portions of
Windham, Providence, southern Worcester, southern Norfolk and
northern parts of Bristol and Plymouth counties. That's where
there is some loose consensus on where that boundary sets up.
These storms could produce lightning and heavy downpours, but
severe weather at the moment seems unlikely from these storms.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
335 AM Update:
Tonight:
Lather, rinse and repeat: another very warm and muggy night for
Southern New England. Low clouds and fog over the south coast
are also expected to return back northward at least into the
southern roughly third of Southern New England. The exact
northward extent is in some question but could make it as far
north as the Mass Pike. Lows in the upper 60s to mid 70s.
Monday:
Low clouds and fog scatter out and/or retreat into the waters
again during the morning hours, giving way to mostly sunny
conditions for most of the area. The Cape and Islands should
still see periods of low clouds around, but there should be a
few more hours of sunny breaks. Monday is very warm to hot and
humid, with highs in the upper 80s to low 90s away from the
southern coast, bringing heat indices into the lower to mid 90s.
Along the south coast, Cape and Islands, highs should reach
into the upper 70s to mid 80s.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Highlights:
* Hot and humid conditions Tuesday and Wednesday, turning seasonably
warm and still quite humid towards later in the week.
* Daily shower chances Tuesday and Wednesday, potentially widespread
rainfall late in week with the arrival of the remnants of Beryl.
Little change to the forecast with the synoptic pattern featuring a
mid-level ridge of high pressure centered over Bermuda. This type of
setup continues the persistent southwest flow, which funnels higher
than normal moisture into southern New England. Additionally, 850mb
temperatures Monday through Friday do stay above normal, which boils
down to a warm/hot and humid week ahead. Getting caught up in this
deep southwest flow are bursts of shortwave energy that will ride the
outer periphery of the subtropical ridge, leading to periods of rain
and thunderstorms.
Temperatures:
There is fairly good model agreement that Tuesday and Wednesday will
be rather hot, with 925mb temperatures forecast between +24C to +26C
and this would lead to surface temperatures between the upper 80s
and lower 90s. That said, the southwest winds will lead to slightly
'cooler' temperatures along the southern coast of Rhode Island and
southeast Massachusetts around the lower 80s. And when you combine
the high dew points, it will feel much hotter. Heat Index values on
Tuesday are between 95F and 99F for much of the Connecticut River
Valley and I-495 corridor. More in the way of clouds on Wednesday
will probably result in somewhat lesser values, between 90F and 95F
in similar locations. Late week, 925mb settle at +20C to +22C with
slightly more seasonable highs in the lower to middle 80s. But will
not come with any relief from the high humidity.
Precipitation:
As we've discussed the past couple of days there is no large scale
forcing to be had due to vast mid-level/subtropical ridge. There are
bursts of shortwave energy on Tuesday and Wednesday that will
promote pop-up showers and thunderstorms. Given the high PWATs,
localized heavy downpours could be expected with any given cell
that develops.
Later in the week, PWAT anomaly are 2-3 standard deviation above
normal, much of this moisture is from remnant Beryl. At this point
in time there is more large scale lift, this should promote more
widespread rainfall Thursday into Friday. WPC does highlight our
region in a marginal risk for days 4 and 5 for excessive rainfall
which is something to monitor as we head late into the week.
&&
.AVIATION /08Z 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 Sunday: High confidence.
IFR to LIFR from stratus and fog. These conditions should remain
steady thru 12z for most, though we should start to see
improvement around after 10z Sunday for the western airports.
Light/calm winds north and west of I-95, otherwise southerly
winds 5-10 kt.
Today: High confidence overall, though moderate on timing
sub-VFR improvement.
IFR-LIFR to slowly improve to VFR for most thru 15z, with fog
retreating into the waters. IFR-LIFR is expected all day for the
South Coast, Cape and Islands. A chance for isolated/widely
scattered TS after 18z to sundown near I-95 with best chance at
PVD, but could slip as far north as ORH and BOS. Sub-VFR stratus
then starts to return northward slightly very late in the
period. Light W/WNW winds north and west of I-95, with
seabreezes at BOS as conditions trend VFR. SSW winds 5-10 kt for
PVD, Cape and Islands.
Tonight and Monday: Moderate confidence.
IFR-LIFR fog and stratus from the daytime hrs over the south
coast, Cape and Islands returns northward tonight; best chance
for PVD and the Cape/ACK, though it is possible it could slip
northward into the BOS-ORH-BDL areas. Where it does develop,
improvement should take place Monday morning, soonest north and
west and later/afternoon towards the southeast coast. Light
winds tonight and Monday, with seabreezes at BOS and PVD.
KBOS TAF...High confidence in TAF. IFR-MVFR stratus and fog
should improve to VFR by ~12-15z. VFR thereafter with
seabreezes likely to develop. Low (< 15%) chance at SHRA/TS
after 18z til sundown but best chance to the south. Stratus is
possible again after 04z Mon, but better chance southeast.
KBDL TAF...High confidence in TAF. IFR to improve to VFR by
10-12z Sunday. Stratus could return after 02z Mon but better
chance southeast.
Outlook /Monday Night through Thursday/...
Monday Night: Mainly VFR, with local MVFR possible. Patchy BR.
Tuesday: VFR. Chance SHRA, chance TSRA.
Tuesday Night: Mainly VFR, with local MVFR possible. Chance
SHRA, slight chance TSRA.
Wednesday through Wednesday Night: VFR. Chance SHRA, chance
TSRA.
Thursday: Mainly VFR, with local MVFR possible. Breezy. Chance
SHRA, chance TSRA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Today through Monday:
Still have a couple 5 footers near the southern waters, so will
maintain the SCA in effect for the southern outer waters thru
early this morning. Otherwise, S winds around 15-20 kt expected
today, and around 10-15 kt tonight and Monday. Fog will be
persistent over the waters today through Monday, with lowest
visbys more likely tonight. Could be a few showers at times too
but thunderstorms are not expected.
Outlook /Monday Night through Thursday/...
Monday Night: Winds less than 25 kt. Patchy fog. Local
visibility 1 to 3 nm.
Tuesday: Winds less than 25 kt.
Tuesday Night: Winds less than 25 kt. Slight chance of rain
showers, isolated thunderstorms.
Wednesday: Winds less than 25 kt. Slight chance of rain
showers, slight chance of thunderstorms.
Wednesday Night: Winds less than 25 kt. Chance of rain showers.
Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers, isolated thunderstorms.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 AM EDT this morning for ANZ254.
Small Craft Advisory until 11 AM EDT this morning for ANZ255-
256.
&&
$$
SYNOPSIS...Loconto/Dooley
NEAR TERM...Loconto
SHORT TERM...Loconto
LONG TERM...Dooley
AVIATION...Loconto/Dooley
MARINE...Loconto/Dooley
Source:
BOX issues Area Forecast Discussion (AFD) at Jul 7, 3:42 AM EDT----------------
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