Old Res Weather

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 150115
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
915 PM EDT Sat May 14 2022

.SYNOPSIS...
Warm and humid weather will continue through Monday. Expect a
few showers tonight, then most of Sunday ends up dry aside from 
a brief afternoon shower or thunderstorm. A more widespread 
round of showers and thunderstorms is expected late Monday, 
especially across the interior as a cold front crosses the 
region. A return to cooler, but seasonable temperatures occurs 
Tuesday through Thursday. Warmer weather begins to return Friday
with the potential for near record heat by next Saturday.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
915 PM Update:

No changes from earlier update. Dense fog has crept northward
onto Islands and is expected to reach much of south coastal
RI/MA overnight. Some question as to whether or not dense fog
spreads farther north into PVD/PYM but high-res models don't 
bring it quite that far north. We'll leave the Dense Fog 
Advisory as is with this update.

Showers are lifting north tonight ahead of very subtle short
wave which is best seen around 850 mb. Instability is limited
with fairly deep southerly flow but most areas will see at least
some light rain showers overnight. Kept PoPs in line with
consensus of high-res models.

Forecast lows in 50s to mid 60s look good.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
.Tomorrow.

Short-wave energy meanders over southern New England tomorrow 
supporting a wet/unsettled day. The air will continue to have a 
summer like feel with temperatures and dewpoints in the 70s and 60s 
respectively. Scattered showers continue into the afternoon hours as 
short-wave energy slow exits east. Modest instability will be in 
place to the tune of a few hundred J/Kg of CAPE. With weak-forcing 
for ascent associated with the short-wave energy aloft, there exists 
the potential for a few mid-late afternoon thunderstorms across the 
interior. Hi-res model guidance suggests that western MA/CT will 
have the best opportunity to see some thunderstorms tomorrow 
afternoon. Thunderstorm chances diminish further to the east. Deep-
layer shear will be limited, not expecting any thunderstorms to 
become severe.

.Tomorrow Night.

Short-wave energy aloft finally exists east allowing for some 
partial clearing across southern New England tomorrow night. Deep-
southwest flow continues to support a warm/humid air mass over the 
region. Winds weaken overnight, thus expecting more areas of dense 
fog to develop on Monday morning, especially along the south coast. 
Lows once again bottom out in the low 60s across the interior and 
low-mid 50s along the coast.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Highlights...

* Warm Mon with a few strong-severe t-storms possible across 
  interior MA/CT if activity arrives early enough

* Cooler/Pleasant seasonable temps return Tue/Wed/Thu with perhaps a 
  few diurnally driven showers Tue, but otherwise mainly dry

* Potential for near record breaking heat into the 90s by next Sat?

Details...

Monday...

The main concern on Monday will revolve around the potential for a 
few strong to severe thunderstorms later in the day/early evening 
hours across the interior. A rather warm and somewhat humid airmass 
for this time of year will be in place on Monday. The surface flow 
will turn more meridional than what we had today; so temps will not 
get quite as high. That being said it still will be warm and a bit 
humid for this time of year with highs mainly in the upper 70s to 
the lower 80s. It will be cooler near the south coast as southerly 
flow brings a modified marine airmass northward. 

While we may see a few spot showers Mon morning, dry weather will 
dominate along with partial sunshine. A rather potent shortwave/cold 
pool aloft will lift northeast later Mon afternoon & early evening. 
The mid level lapse rates are rather poor, which will keep the 
instability in check. That being said; the SPC SREF and other 
guidance show about 1000 to 1500 J/KG of Cape developing across 
interior MA/CT. In addition, 0-6 KM shear will be approaching 50 
knots towards 00z across western MA & CT which is quite impressive. 
There are some timing issues and if the activity arrives early 
enough for a few strong to severe t-storms across the interior. 
Given rather poor mid level lapse rates and a likely advancing 
marine layer given southerly winds; an earlier arrival would 
increase the risk for a few severe t-storms across the interior. 
While a later arrival would limit this potential. We should have a 
better idea on this potential over the next 12 to 24 hours given 
will be in range of our high resolution CAM guidance. Main threat 
would be for localized strong to damaging wind gusts with hail being 
a secondary concern. Brief heavy rain and poor drainage street 
flooding would also be a concern. 

Meanwhile, across eastern MA and RI given the later arrival and an 
advancing marine layer may just looking at a few showers and perhaps 
a leftover rumble of thunder or two during the evening.

Tuesday...

A return to less humidity along with cooler/seasonable temps arrives 
Tue. We may have a few diurnally driven showers as an upper level 
shortwave/cold pool aloft crosses the region, but the vast majority 
of the day will be dry. High temps mainly between 70 and 75 with 
readings a few degrees cooler across the high terrain/portions of 
the coast, but a very nice day across the entire region.

Wednesday and Thursday...

A ridge of high pressure will cross the region Wed into Thu, 
bringing mainly dry weather with pleasant/seasonable temps. Low risk 
a few showers brief sneak up from the southwest with shortwave 
energy, but given west to northwest flow aloft think we pretty much 
stay dry. High temps mainly in the upper 60s to the lower 70s with 
comfortable humidity levels.

Friday and Saturday...

Upper level ridging across the southeast builds north Fri and Sat 
allowing height fields to rise across southern New England. It is 
still quite the ways off, but GEFS/EPS guidance showing the potential 
for near record heat arriving by next Saturday. Highs may be back 
into the 80s across portions of the region by Fri and perhaps into 
the 90s by Sat? The Ensemble situational awareness table from the 
ECMWF is indicating some upper level temperature fields to be 
outside the model/s climatology! In fact, the latest GFS/ECMWF 
operational runs indicate 850T around +20C and their 2 meter 
temperatures between 95 and 100 degrees Saturday afternoon! That is 
nearly a week out, so whether or not that comes to fruition remains 
to be seen. However, there certainly is a signal for at least the 
potential of record heat by next Sat with highs into the 90s.

&&

.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
Low - less than 30 percent. 
Medium - 30 to 60 percent. 
High - greater than 60 percent. 

00z TAF Update...

Tonight ...High confidence in trends, less in details and
timing.

Ceilings deteriorate to IFR/LIFR through 06z mainly across RI/SE
MA and after 06Z further northwest. Bulk of the fog/reduced
vsbys will be across RI/SE MA. Fog will again be most dense 
closer to the coast. Additionally expecting scattered showers 
later this evening into the overnight hours. Light S winds 5 to
10 knots.

Tomorrow...High confidence in trends, less in timing.

LIFR/IFR ceilings and visibility gradually improve to MVFR-VFR 
during the late morning/early afternoon except for Cape/Islands
and other areas near immediate coast where low clouds and fog
will continue to impact or flirt with those areas all day. 
There will be a possibility for a few showers and isolated
t-storms late in the day mainly across western MA and CT. 
South/southwest winds pick up to 10-15 knots by the afternoon 
with gusts to 20 knots possible. A sea breeze may impact
portions of the immediate coast for a time.

Tomorrow Night...

MVFR ceilings across the interior with more IFR/LIFR ceilings
and visibilities near the coast. Modest south/southwest winds
continue.

Saturday night....

LIFR/IFR become more widespread with widespread showers
overspreading the region along with stratus. Light SSW winds 
prevail.

Sunday...

Any scattered morning showers give way to a mostly dry day. 
IFR/LIFR in areas of fog early, then improving to MVFR/VFR. 

KBOS TAF...High confidence in trends, moderate in timing. 

KBDL TAF...High confidence in trends, moderate in timing. 

Outlook /Monday through Thursday/... 

Tuesday: Mainly VFR, with local MVFR possible. Windy with local
gusts up to 30 kt. Slight chance SHRA.

Tuesday Night through Wednesday: VFR. Breezy. 

Wednesday Night: VFR. 

Thursday through Thursday Night: Mainly VFR, with local MVFR
possible. Breezy. Slight chance SHRA.

Friday: Breezy. 

&&

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

Tonight through tomorrow night

Modest SSW winds continue to support a warm/humid air mass over the 
coastal waters through tomorrow night. Showers forecast tonight and 
tomorrow. Isolated thunderstorms will be possible tomorrow 
afternoon. Humid air mass will support persistent fog that will be 
locally dense at night and thinner during the day tomorrow.

Outlook /Monday through Thursday/...

Tuesday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft. 

Tuesday Night through Wednesday: Winds less than 25 kt. Seas up
to 5 ft. 

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

Thursday through Thursday Night: Winds less than 25 kt. Areas
of seas approaching 5 ft. Slight chance of rain showers. 

Friday: Winds less than 25 kt. Seas up to 5 ft. 

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Dense Fog Advisory until 10 AM EDT Sunday for MAZ020>024.
RI...Dense Fog Advisory until 10 AM EDT Sunday for RIZ005>008.
MARINE...None.

&&

$$
SYNOPSIS...Frank/RM
NEAR TERM...JWD
SHORT TERM...RM
LONG TERM...Frank
AVIATION...Frank/RM
MARINE...Frank/RM