BOX issues Area Forecast Discussion (AFD) at Mar 5, 4:34 PM EST
675
FXUS61 KBOX 052134
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
434 PM EST Wed Mar 5 2025
.SYNOPSIS...
A frontal system brings a period of soaking rains, brief strong
southerly wind gusts, and unseasonably mild temperatures later
today into early Thursday morning. Then a strong but dry cold
front brings more seasonable temperatures, but also a period of
strong northwesterly wind gusts Thursday night through Friday.
Trending drier and slightly cooler than normal for this weekend
into early next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Key messages:
* Moderate to heavy windswept rain tonight across southern New
England is expected
* Gusts expected to remain below Wind Advisory criteria tonight
A strong 980 mb cyclone continues to make its way towards the
region tonight. Its associated warm/occluded frontal boundary
is expected to continue moving through southern New England
tonight into early Thursday morning, bringing with it moderate
to heavy rainfall. Breezy south to southeast winds tonight are
expected, but 12z HREF guidance and BUFKIT soundings,
particularly the NAM, don't favor widespread advisory-level
winds. Even with warmer than normal low temperatures sitting in
the 50s tonight, the nocturnal inversion is not expected to
budge as the marine layer will also be advected in. Latest HREF
guidance also does not have the LLJ strengthening or reaching
closer to the surface. If any 50 mph gusts occur, expect them to
be very isolated. Gusts should be in the range of 25 to 35 mph,
particularly across SE MA and the Cape and Islands.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Key messages:
* Mild day for Thursday before cold front passes through and
drops overnight lows back into the 20s and 30s
* Windy Thursday night into Friday morning
The bulk of the rain is expected to move out of southern New
England by 7-8 AM Thursday morning as the dry slot moves in.
Some low level moisture may hang around, but this would only
keep cloud cover overhead rather than produce any rain. Highs
are expected to sit in the 50s for Thursday. Clouds are not
expected to clear until after the passage of the low's cold
front. Cold air advection will not only drop temperatures, but
winds from the W to NW are expected to pick up after sunset.
There are no headlines out for this wind event at this time, but
future issuance of Advisories and even a High Wind Warning
across the higher elevations cannot be ruled out. Lows for
Thursday night will return to the 20s and 30s across the region.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Key Messages:
* Strong gusty west winds Friday
* Near normal temperatures through Monday, then trending above
normal
* Mainly dry during this time
A powerful low pressure over the Maritimes is expected to
continue to strengthen Friday, before finally moving farther
north by Sunday. This will maintain a tight pressure gradient
across southern New England Friday. Wind headline may be needed
Friday. At this time, have the greatest confidence in wind gusts
high as 35-45 mph. Could be higher depending on how deep the
boundary layer mixing can get. Gusts up to 55-60 mph are not
entirely out of the question. These would be mainly confined to
the higher terrain of the Berkshires and Worcester Hills, as
well as towards the Cape and islands.
Winds quickly diminish Friday evening as winds aloft decrease
and the nocturnal inversion sets in.
Mainly zonal flow this weekend into early next week, which
should keep storm tracks south of our region. A couple of
northern stream clipper systems move through northern New
England Saturday, and possibly again on Monday, which could
bring some light rain/snow showers to the region. High
temperatures this weekend don't rebound much with the
reinforcing shot of cold air from Saturday's clipper.
&&
.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Today: High confidence.
VFR ceilings except in parts of western MA early this afternoon.
MVFR ceilings spread eastward by mid-late afternoon. Rain
spreads from west to east in the 21-02z timeframe. SW winds
around 8-12 kt, with developing gusts 20-25 kt. Potential for
higher gusts up to 30 kts for south coast terminals (PVD, FMH,
HYA).
Tonight: Moderate Confidence.
Deteriorating conditions tonight into IFR/LIFR levels by 06z
with arrival of moderate to heavy rain from west to east. This
may also bring down visibilities to 2 SM (between 03-11z). S/SSE
winds overnight with gusts 25-35 kts. Higher end of that range
is more likely for SE Massachusetts with even some brief
localized higher gusts possible 04z-11z. Winds/gusts begin their
downward trend toward 12z. Rain ends from west to east between
10-13z with improving visibilities.
Thursday: Moderate confidence - Timing of improvement of
ceilings
Rain exits most the terminals by 14z with a chance of lingering
showers on the outer Cape. MVFR-IFR bases are likely in the
morning. There will be a slow improvement in ceilings through
the day. Confidence is lower on timing of improvements to VFR,
but late afternoon-early evening is the more likely timeframe.
SW winds around 8-12 kts. Cold front will move into western New
England late afternoon, flipping winds to W/NW and gusty (20-25
kt) with ceiling improvements behind it. Winds transition to W
for the east terminals by 00z.
KBOS TAF...Moderate confidence in TAF.
KBDL TAF...Moderate confidence in TAF.
Outlook /Friday through Monday/...
Friday: VFR. Strong winds with areas of gusts up to 40 kt.
Friday Night: VFR. Breezy.
Saturday: VFR. Windy with gusts up to 30 kt.
Saturday Night: VFR. Windy with local gusts up to 30 kt.
Sunday: VFR. Breezy.
Sunday Night: VFR.
Monday: VFR. Breezy. Slight chance RA, slight chance SN.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight through Thursday: High confidence.
S to SE wind gusts expected to pick up tonight, reaching Gale
force. Gale Warnings are in effect through 12z Thursday morning.
Seas expected to build up to 13 ft across the outer waters,
particularly in the south. Rain and fog also expected to impact
the waters tonight going into Thursday morning.
Gusts drop off to around 15 to 20 kt during the day Thursday,
shifting more to the WSW. Seas will remain elevated, though, so
Small Craft Advisories will be needed once the Gale-force gusts
end.
Thursday Night: High confidence.
Gale Watches are in effect for this timeframe from 00z Friday to
00z Saturday. W to NW winds are expected to gust up to 40 kt,
and some spots could reach Storm force, but widespread Gale
conditions are more likely. Seas expected to be from 7 to 12 ft.
Outlook /Friday through Monday/...
Friday: Strong winds with gusts up to 35 kt. Rough seas up to
13 ft.
Friday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas.
Saturday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Seas up to 5 ft.
Saturday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Areas of rough seas.
Sunday through Sunday Night: Winds less than 25 kt. Areas of
seas approaching 5 ft.
Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain.
&&
.TIDES/COASTAL FLOODING...
A period of strong southerly wind gusts and modest pressure
falls will result in a 1.5 to 2.5 ft storm surge with a low risk
for up to 3 feet along the south coast. This may result in a
period of splashover or perhaps very minor coastal flooding
during the late Wed night/early Thurs AM astronomical high
tide. One of the larger limiting factors to a greater coastal
flooding threat is that the astro tides are decreasing.
We opted to issue coastal flood advisories for the South Coast
of MA and RI, with coastal flood statements for the Cape and
Islands. The distinction between the two headlines was based off
the Stevens Institute and P-ETSS guidance. While these pieces
of guidance indicate high confidence of total water levels in
the Action Stage/"splashover" level, given a longer duration of
southerly flow preceding the period of highest surge, it's not
out of the realm of possibility that some areas in the coastal
flood advisory area could see total water levels reach into the
minor stage. Significant impacts are not likely even in the
advisory area, and fcst total water levels for Fox Point and New
Bedford barriers will likely fall short of decision point
thresholds.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Coastal Flood Advisory from 9 PM this evening to 6 AM EST
Thursday for MAZ020-021.
RI...Coastal Flood Advisory from 9 PM this evening to 6 AM EST
Thursday for RIZ002-004>007.
MARINE...Gale Warning until 7 AM EST Thursday for ANZ230>237-250-251-
254>256.
Gale Watch from Thursday evening through Friday evening for
ANZ230>237-250-251-254>256.
&&
$$
SYNOPSIS...Belk/Hrencecin
NEAR TERM...Hrencecin
SHORT TERM...Hrencecin
LONG TERM...Belk
AVIATION...Belk/Hrencecin/Mensch
MARINE...Belk/Hrencecin
TIDES/COASTAL FLOODING...Loconto
Source: BOX issues Area Forecast Discussion (AFD) at Mar 5, 4:34 PM EST (https://mesonet.agron.iastate.edu/p.php?pid=202503052134-KBOX-FXUS61-AFDBOX)
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