BOX issues Area Forecast Discussion (AFD) at Mar 16, 11:29 PM EDT
849
FXUS61 KBOX 170329
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
1129 PM EDT Sun Mar 16 2025
.SYNOPSIS...
A strong cold front will bring heavy rain and gusty southerly
wind gusts tonight into Monday morning, with rain lingering into
Monday night across SE New England. Mainly dry and mild weather
returns Tuesday into Thursday. Another frontal system will
likely bring a period of showers sometime late Thursday into
Friday, possibly changing to snow over higher elevations Friday
as colder moves back into the region. Dry and seasonable
conditions follow next weekend.
&&
.NEAR TERM /THROUGH MONDAY/...
Key Messages:
* A period of heavy rainfall late tonight into Mon morning may
result in areas of urban and poor drainage flooding
* Heaviest rainfall will impact the Monday morning commute along
the I-95 corridor to the south coast
* South wind gusts to 45 mph possible late tonight across SE MA
and southern RI
Only minor tweaks this evening. The main change was to rainfall
timing, which looked to be slower by about 1-2 hours. Overall
theme of widespread rainfall arriving overnight remained on
track. Brought temperatures back in line with observed trends.
Previous Discussion...
Upper level trough moves east from the Gt Lakes tonight, then
sharpens Mon as it approaches New Eng with favorable right
entrance region of the upper jet moving across SNE. Wave of low
pres expected to develop on the cold front which will slow its
eastward progress as it moves across SNE during Mon which will
keep rain going for much of the day Monday before gradually
tapering off in the west during the afternoon.
Deep moisture plume and low level jet ahead of the cold front
with axis of highest PWATs reaching 1.25-1.50" begin to move in
tonight, with forcing for ascent increasing ahead of the upper
level trough. This will lead to widespread showers developing
and moving W to E across the region through tonight and into
Mon, but rain may not reach eastern MA until after midnight.
Marginal instability to the west weakens as it approaches New
Eng, but there is some weak elevated instability which spills
into western New Eng tonight which could lead to an rumble of
thunder. PWAT anomaly 3-4SD above normal and low level wind
anomaly 2-3SD which is a strong signal for a period of heavy
rainfall. Timing of heaviest rainfall will be after midnight in
the west, and 5 am to noon from I-95 to Cape Cod. In fact, HREF
showing 30 percent probs of greater than 1" in 3 hours along the
I-95 corridor 09-12z before shifting to SE MA and Cape/Islands
12-18z. These rainfall rates will result in the potential for
some minor urban and poor drainage flooding which will impact
the morning commute along I-95 corridor. Rain will continue all
day across eastern New Eng but should become more scattered in
the in the west during the afternoon as PWATs decrease. However,
upper level trough axis remains to the west so at least
scattered showers will continue here through the afternoon.
We are looking at widespread total rainfall of 1-2 inches with
the potential for higher amounts somewhere from the I-95
corridor to the south coast where low risk for localized amounts
approaching 3 inches. Not expecting any river flooding with
these rainfall amounts, but combination of the rainfall and
snowmelt in the upper CT basin in northern New Eng may
eventually lead to minor flooding for some locations along the
CT river toward mid week.
Strong wind potential: Winds will be increasing tonight,
especially after midnight across RI and SE MA as the low level
jet moves across the region. Low level jet peaks around 65-70 kt
06-12z. Temps will be mild overnight holding in the mid-upper
50s across RI/SE MA which will help to weaken the inversion
somewhat and support a few hours of 40-45 mph gusts here after
midnight, which is about 50-60 percent of the LLJ. Gusty winds
will continue Mon morning over the Cape/Islands with the low
level jet overhead then diminish in the afternoon.
&&
.SHORT TERM /MONDAY NIGHT/...
Upper level trough axis finally moves east across New Eng Monday
night. Deep moisture axis and PWAT plume will be across SE MA
and Cape/Islands in the evening with frontal wave just to east.
Showers will be ending in the west during the evening, but rain
will continue across SE New Eng Mon night before gradually
tapering off and ending overnight as the frontal wave moves
offshore and drier air moves in from the west. It may take until
daybreak for rain to end over the Cape/Islands. Lows will drop
into the 30s late Mon night and Tue morning with North winds
increasing to 10-20 mph.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Key Messages:
* Drying out Tuesday under high pressure, but monitoring for river
flooding
* Another round of rain likely sometime Thursday night into Friday
morning
* Dry, but breezy and colder going into the weekend
Details...
Lingering showers push their way out to sea by midday Tuesday,
and a broad high pressure settles in behind the rain. The
majority of the associated cloud cover should begin to break up
a bit from west to east as Tuesday goes on. Winds shift more to
the north, but there is still a decent chance that temperatures
reach 55F towards the interior near the CT River Valley. Warmer
temperatures aloft (close to +10C at 850 mb) from ridging will
encourage these mild temperatures for midweek. High pressure
keeps the region dry for the rest of Tuesday into midweek;
however, we are monitoring the Connecticut River for the high
possibility of reaching minor flood stage from Northampton to
south of Hartford.
Easterly to northeasterly flow returns for Wednesday, which may
contribute to more clouds and will keep the eastern coastline of
MA cooler than the interior. South to SE flow Thursday will also
advect more moisture from over the Atlantic.
Another trough is expected to dig into the central US and move
northeast into the Great Lakes region Thursday into Friday.
While the associated surface low is likely to track northeast
across southern Ontario, most ensemble (and deterministic)
guidance is suggesting a secondary low will spin up along the
cold front in the Appalachian/Mid-Atlantic region.
With moisture being advected in Thursday, ensemble guidance
indicated about 150% of normal PWAT values ahead of the front
across southern New England for Thursday night. With the lift
provided from the cold front's passage, rain showers (and
possibly snow showers in the higher elevations) are likely to
develop just ahead of the front. As this front passes, winds
during the day Friday will increase and shift to the NW. Breezy
NW winds and cooler temperatures aloft will keep much of the
region in the 40s for Friday, with drier and colder post-
frontal air Friday night possibly bringing overnight lows down
to low 30s for Rhode Island and the South Shore and the upper
20s for interior MA and CT. Surface temperatures looks to
briefly sling shot back into the low 50s on Saturday with
southerly flow off the Atlantic under a ridge.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight: Moderate confidence.
MVFR, with IFR/LIFR ceilings along the immediate south coast.
MVFR likely to degrade inland to IFR between by 05-06z, with
IFR-LIFR ceilings holding near the southern coast. Light rains
move in from 03-06z from west to east, then becoming moderate to
heavy (visbys 2-3 SM) 08-12z from west to east. Could be a
rogue rumble of thunder overnight in the heaviest rains but
should be isolated if any develops at all.
Though there have been some southerly wind gusts in the 40 kt
range at times early this evening, gusts should be more in the
25-35 kt range during overnight. Low level wind shear likely
given a 60 kt low-level jet.
Monday...Moderate Confidence.
Rain begins to taper off from west to east. Guidance is slow to
clear the rain off the east coast with showers lingering for
eastern terminals into later Monday afternoon. CIGS should
remain IFR until winds turn more westerly, but guidance may be a
bit to slow on improving CIGS behind the wind shift.
Monday Night...Moderate Confidence.
CIGS should improve to VFR across the interior if they have not
already by Monday afternoon. Eastern terminals, esspically the
Cape and Islands may see lingering MVFR/IFR CIGS. Winds begin to
shift north at 10-20 knots.
KBOS TAF...Moderate confidence in TAF.
MVFR ceilings to deteriorate to IFR thru 04-05z. Light rain
moves in around 06z, becoming moderate to heavy between 09-10z
with visbys 2SM in RA+. Rain starts to taper off to a moderate
level (3-5 SM) tomorrow afternoon, but not trending dry until
late Monday. S gusts 25-35 kt with periods LLWS thru Mon AM,
then begin to shift to SW and decrease to 10-15 kt before a
windshift to NW Mon night.
KBDL TAF...Moderate Confidence in TAF.
MVFR ceilings to trend IFR as rain moves in this evening after
02z. Rain will become heavy between 07-12z. Rain and IFR CIGS
linger into late morning to early Monday afternoon before
improving to MVFR/VFR late Monday afternoon.
Outlook /Tuesday through Friday/...
Tuesday: Mainly VFR, with local MVFR possible. Breezy.
Tuesday Night through Wednesday: VFR.
Wednesday Night: Mainly VFR, with areas IFR possible.
Thursday: MVFR/IFR conditions possible. Breezy. Slight chance
RA.
Thursday Night: Mainly MVFR, with areas IFR possible. Breezy.
RA likely.
Friday: Mainly VFR, with local IFR possible. Windy with areas
of gusts up to 30 kt. Chance RA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Through Monday Night...High confidence.
We upgraded to Gale Warnings for tonight as low level jet ramps
up over the waters. Expect a period of marginal southerly gale
force gusts to 35 tonight, diminishing W to E Mon morning. Winds
becoming north Mon night and increasing with gusts to 25 kt
overnight. Vsbys lowering late tonight into Mon in rain and fog.
Outlook /Tuesday through Friday/...
Tuesday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Rough seas up to 10 ft. Slight chance of rain.
Tuesday Night: Winds less than 25 kt. Local rough seas.
Wednesday through Wednesday Night: Winds less than 25 kt. Seas
up to 5 ft.
Thursday: Winds less than 25 kt. Seas up to 5 ft. Slight chance
of rain.
Thursday Night: Winds less than 25 kt. Areas of rough seas.
Rain likely.
Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 25 kt. Rough seas up to 10 ft. Chance of rain.
&&
.HYDROLOGY...
A slow-progressing cold front interacting with an anomalously
high moisture plume for early March will be bringing a period of
heavy downpours, perhaps with embedded thunder serving to
enhance rain rates, to Southern New England tonight into Monday.
Current rainfall forecast shows rain amounts from 1-1.5 inches
mainly north and west of Interstate 95, with the heaviest
rainfall totals forecast in RI and portions of southeast MA with
amounts here ranging from 2-2.5 inches. Although the
location/placement of where the heaviest rainfall occurs is
pretty well agreed upon, there's only moderate confidence in
rain amounts and the potential exists for up to 3" totals in
spots in sustained, slow-moving downpours.
Although this is quite a slug of rain, especially in southeast
New England, significant and/or widespread flooding are not
expected at this time. NERFC 6-hourly flash flood guidance is
around 2.5-3" in interior Southern New England, and around 3 to
5 inches in southeast New England and we'll fall short of those
thresholds. Ponding of water and areas of minor street flooding
in some of the larger urban metro areas in southeast New England
which are especially flood- prone (Providence/Cranston, New
Bedford and Fall River) could develop Monday, although we don't
expect this to rise to significant levels.
However, we'll need to keep a close eye on creeks and larger
rivers not just with the initial slug of rainfall overnight into
Monday, but also as additional/higher flows up the CT River in
response to snowmelt occurring in VT/NH take place over the next
couple of days. Within-bank rises are expected on most rivers in
eastern and southeast New England, although we could have to
watch the Wood and Pawtuxet Rivers in RI if we do get higher
rainfall amounts. Further west in the CT River Basin, latest
NERFC forecasts as of early Sunday afternoon call for several of
our CT River forecast points to rise into Minor flood stage on
Tuesday (Montague MA and Northhampton MA around 5 AM Tuesday)
and Wednesday (Thompsonville CT and Hartford CT early Wednesday
morning). River flood warnings could be needed for these rivers
in the coming day(s).
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 11 AM EDT Monday for ANZ230.
Gale Warning until 11 AM EDT Monday for ANZ231-232-254-255.
Gale Warning until 8 AM EDT Monday for ANZ233>237-256.
Gale Warning until 8 AM EDT Monday for ANZ250-251.
&&
$$
SYNOPSIS...KJC
NEAR TERM...Belk/KJC
SHORT TERM...KJC
LONG TERM...McMinn
AVIATION...Loconto/McMinn/KP
MARINE...KJC/McMinn
HYDROLOGY...Loconto
Source: BOX issues Area Forecast Discussion (AFD) at Mar 16, 11:29 PM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202503170329-KBOX-FXUS61-AFDBOX)
----------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!