BOX issues Area Forecast Discussion (AFD) at Sep 14, 3:04 AM EDT857
FXUS61 KBOX 140704
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
304 AM EDT Sat Sep 14 2024
.SYNOPSIS...
Dry weather with above normal temperatures will continue for
the weekend and into next week. Low chance for rain comes mid to
late next week, but uncertainty remains high.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
230 AM Update:
Southern New England continues to be governed by high pressure
ridging, although METARs indicate its center is positioned in
far southeast Quebec. From a sensible wx perspective, there
really hasn't been too much change with clear skies and a light
northerly wind over most of the area. We were still seeing
patchy radiational fog develop too, both in the river valleys
but also in portions of RI and southeast MA. Though there are a
few more sites reporting fog compared to the past several
nights, but hasn't been too persistent. With more of a northerly
wind, if still light, it may be enough to keep it from becoming
too widespread, but will continue to monitor visbys. Current
temps ranged from the mid 50s to lower 60s.
For today, the high pressure area over southeast Quebec will
gradually shift southeastward and build intn the Gulf of Maine.
Althogh we are still expecting mostly sunny conditions for
today, the main change compared to the past few days is that
we'll see an onshore wind developing around mid morning into far
northeast MA, then gradually progress south and southwestward as
the day progresses. Heating will at least partially
modify/offset the cooler onshore flow. Highs should occur
earliest today along the eastern coast, in the low to mid 70s
before gradually cooling off into the afternoon. Further inland,
we should see highs reach into the lower to mid 80s, before
onshore flow sets in by the afternoon and brings modest cooling.
Northeast wind speeds around 5-10 mph once the onshore flow
develops, strongest near the coast.
More of a factor for tonight's forecast, but one thing that
we'll need to monitor is the area of marine fog and stratus that
is evident in obs and satellite imagery early this morning near
Nova Scotia/Bay of Fundy area. Most model forecasts indicate
this area expanding in coverage over the waters this morning,
then advecting southwestward through the Gulf of Maine to
offshore of the eastern MA coast by the afternoon. The heated
boundary layer over land should keep this stratus/fog bank
offshore, but we could see that layer expand into the coasts as
we move towards the late-afternoon/sundown timeframe.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
230 AM Update:
Tonight:
High pressure will continue to maintain dry weather tonight.
However, the marine stratus and fog bank that is forecast to be
offshore during the daytime hrs should expand westward and
landward as evening cooling takes place, along with a weakening
ENE flow. Unlike the past several nights where fog development
is driven by radiational cooling effects, this is instead more
of a shallow marine layer fog/stratus layer. Model-forecast
soundings show this moisture layer being a few hundred feet
thick and trapped underneath a strong inversion. So introduced
increasing cloudiness with stratus/fog advancing westward
through the evening hours; we probably wont't see fog become
locally dense, but it should be greater in areal coverage than
the patchy/serpentine coverage we've seen the last few nights.
Lows should range into the 50s to around 60.
Sunday:
It is a little unclear when the fog layer from the overnight
might dissipate, as it is trapped underneath a pretty strong
subsidence inversion, but it is also a pretty shallow moist
layer. It could linger into the mid morning hrs before we start
to see it disperse. However high confidence that the day will
again feature mostly sunny conditions with diurnal cumulus
development as the shallow boundary layer warms. Still have an
onshore E/SE flow for Sunday, which will again favor warmer
temps inland (lower to mid 80s), with mid 70s near the eastern
and southern coasts.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Highlights:
* Mild days and cool nights will continue Monday and Tuesday, will
have to watch for the potential of morning fog both days.
* System off the coast of the Carolinas, which is being monitored
by NHC, lifts north towards southern New England mid to late week,
bringing the next chance for any rains to the region.
Sunday Night through Tuesday...
Not to sound too much like a broken record, but, quiet conditions
prevail Monday and into Tuesday. The only weather to speak of are
the chances of morning fog both days. As mentioned in yesterday's
discussion, we would need to observe the outcome of Friday morning
and Saturday morning to gauge whether or not fog will form over the
subsequent mornings. Fog was limited Friday morning, mainly to the
river basins, but heading into this morning, fog seem to be more
prominent. BUFKIT soundings Monday morning shows saturation in the
lowest 500 to 1,000 feet of the atmosphere, practically ground
level. Will keep a mention of fog in the forecast for both mornings
for awareness.
Still, no significant weather is expected Monday and Tuesday with
high pressure firmly in place across the northeast. Skies are mostly
sunny Monday afternoon and Tuesday afternoon expecting an increase
in high clouds ahead of a developing system to our south. As for the
temperatures, mild afternoons in the upper 70s to low 80s, with
Tuesday possibly the warmer of the days as some interior locations
could top out in the middle 80s. At night, clear skies will promote
radiational cooling with overnight temperatures settling into the
50s. Did utilize the CONSMOS for overnight lows, waking up Monday
morning will be crisp as lows fall to the upper 40s and low 50s.
Will note if the fog holds off in southeastern MA, prone radiation
locations could drop as low as the mid 40s.
Wednesday through Friday...
There is still a bit of uncertainty mid to late week as to whether
or not a developing system off the coast of the Carolinas will bring
wetting rains to the northeast. In fact, NHC does give this area 50%
chance of development over the next 7 days. The last two nights,
deterministic guidance (GFS & GEM) shown ridge of higher pressure
breaking down and then shifting to the east, allowing this low
pressure system (or tropical remnants) to move towards southern New
England sometime late Wednesday into Thursday. While the ECMWF was
not on board with this solution, the latest 00z run does show a
northerly trend with moisture arriving around Thursday. This would
be the next best chance for any wetting rains, though there is still
pounds of time for things to change. Kept with the NBM POPs between
15 and 30 due to the uncertainty late Wednesday into Thursday. Given
this is day 6 and 7 did not want to deviate.
Afternoon temperatures decline from the upper 70s and the low 80s on
Wednesday to the low and middle 70s on Friday, due to the increase
in cloud cover and potential for precipitation, in addition overnight
lows will be noticeably warmer on either side of 60F.
Tropical Weather...
In addition to the area of interest off the coast of the Carolinas
the NHC continues to monitor T.S. Gordon, which is well east of the
Leeward Islands. NHC forecasts T.S. Gordon to remain a tropical
storm or possibly weaken to a depression over the next three to four
days as it slowly walks westward at 10mph. At this time, T.S. Gordon
poses no threat to land.
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
06z TAF Update:
Through 12z Saturday: High confidence.
Generally VFR; there may be temporary MVFR-LIFR visbys in fog for
RI and SE MA airports through sunrise, but is not expected to be
persistent. Calm winds become light NW to NNW by early morning,
becoming N/NNE by 12z.
Today: High confidence.
VFR. Windshift to NE/ENE and increase to around 5-10 kt,
starting soonest in eastern MA, then spreading westward through
the day. Stratus and fog should be offshore of the eastern coast
into the afternoon but should stay offshore until the evening.
Tonight: Moderate confidence.
VFR at least initially, but marine fog/stratus layer expected to
be off the eastern MA coast late in the afternoon to expand
westward through the evening. Categories to then become IFR-
LIFR mostly from low cloud bases, with visbys 1/2 to 4 miles in
fog. ENE to NNE winds ease to around 5 kt or less.
Sunday: High confidence.
Any sub-VFR conditions should improve thru 12-14z toward VFR
conditions. Winds become E/ESE around 5-10 kt.
KBOS TAF...High confidence in TAF. Windshift to NE/ENE around 10
kt by 14-16z Sat. Monitoring for possible marine stratus/fog
bank offshore of eastern MA around late-afternoon, but should
stay offshore until early evening with MVFR-IFR conditions for
the overnght.
KBDL TAF...High confidence in TAF. VFR; light N winds become E
later today. Stratus is possible overnight tonight but is more
uncertain on development.
Outlook /Sunday Night through Wednesday/...
Sunday Night through Monday: VFR.
Monday Night: Mainly VFR, with local IFR possible. Patchy BR.
Tuesday through Tuesday Night: VFR.
Wednesday: Mainly VFR, with local IFR possible. Slight chance
SHRA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Through Sunday: High Confidence.
Winds and seas below SCA levels.
Winds today become NE and increase to around 10 to 15 kt, then
ease tonight. Seas around 3ft or less all waters. It still looks
as though a fog bank may lurk off the eastern MA coast later
today into and tonight and that oculd reduce visibilities.
For Sunday, expect ESE winds around 10 kt or less with seas 2
ft or less all waters.
Outlook /Sunday Night through Wednesday/...
Sunday Night through Monday: Winds less than 25 kt.
Monday Night: Winds less than 25 kt. Patchy fog. Local
visibility 1 to 3 nm.
Tuesday: Winds less than 25 kt. Local visibility 1 to 3 nm.
Tuesday Night: Winds less than 25 kt.
Wednesday: 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...None.
&&
$$
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 Sep 14, 3:04 AM EDT----------------
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