Old Res Weather

Lexington, Massachusetts, USA

64°F

4/16/2024 11:24am

Lexington Conditions: Clear
Temperature: 64.0°F / 17.8°C
Dew Point: 38.7°F
Relative Humidity: 39%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 30.07 in Falling Slowly
Visibility: 10 miles
Rain Today: 0.00 in
UV Index: $VPuv Medium

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 100218
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1018 PM EDT Tue Apr 9 2024

.SYNOPSIS...
Increasing clouds tonight with passing light showers through
Wednesday night. Series of fronts bring several chances of rain
late week. Coastal flooding and blustery conditions will 
accompany the strongest cold front Thursday night into Friday. 
Unsettled but seasonal weekend before drier and seasonably mild 
conditions develop next week.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
1015 PM Update:

Easterly flow is established over SNE this evening with
increasing amts of high cloud cover; that said, still a pretty 
wide range in temps from the lower to mid 40s in eastern MA and
RI, to as mild as the lower 60s where flow is a bit stronger in
the CT Valley. Looks like winds should begin to slacken
somewhat in the CT Valley and that should bring temps closer to
forecast values, but did boost temps from Worcester westward
through early overnight using some the milder bias corrected
datasets. 

Though we still expect the balance of the overnight to be dry,
have to watch the cluster of convective showers and even a few
t-storms across the eastern Great Lakes/western NY/Ontario
vicinity associated with a warm front aloft. Appears steeper
lapse rates in the 850-500 mb layer is sustaining this activity
per the 00z BUF RAOB. Past couple runs of the hourly HRRR 
guidance and the 00z/10th NAM 3-km progress this activity 
eastward into eastern NY, southern VT and far northwestern MA
between 10-12z Wed, so more of an early-morning shower risk.
Will continue to assess trends and incoming guidance before
possibly introducing mention of showers a bit earlier into
western MA with later updates, but for now the overnight should
stay dry for all areas. 

Previous discussion:

Highlights: 

* Wonderful spring afternoon, turning seasonably cool overnight with 
  a very low chance of a rouge showers - otherwise dry. 

* Pockets of shallow coastal flooding for eastern Massachusetts 
  for the overnight high tide. 

A wonderful spring afternoon across the region, many locations hit 
the upper-60s if not the lower-70s. Surface high pressure has nosed 
in from the maritime, which brought an on shore component to the 
wind. This did limit how warm temperatures in eastern Massachusetts 
could achieve - early afternoon temperatures here are in the upper-
50s. But, earlier this morning a few areas did hit the low-60s 
before ahead of the wind shift from NNW to ENE. 

Rest of today very comfortable conditions. Increasing mid and high 
clouds overspread the region tonight with a warm front. Placement of 
the front is to the west, which should limit any rain chance across 
southern New England. Tonight is largely a dry night, outside of a 
rouge shower in far western Massachusetts or Connecticut. The added 
cloud cover should limit how low the overnight temperatures will 
fall. Given how dry the lowest part of the atmosphere, still expect 
a seasonably cool night with lows in the upper-30s to low-40s. Urban 
centers may remain a few degrees higher in the mid-40s. Winds are 
light from the ESE around 10 mph.

Lastly, tonight there could be nuisance coastal flooding for east 
coastal Massachusetts. High tide comes in shortly after midnight and 
the forecast does bring us VERY close to minor flood stage at 
Boston. Similar to the high tide this afternoon, we'd expect shallow 
pockets of flooding less than one foot deep affecting the most 
vulnerable coastal roads and lowest lying areas along the coast, 
such as Morrissey Boulevard in Boston. Roads remain passable. This 
will likely continue again on Wednesday as high astronomical tides 
lead to rounds of very shallow flooding. Moving forward, will handle 
this with Coastal Flood Statements.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Highlights: 

* Cooler with periods of light rain, especially Wednesday afternoon 
  with on and off shower activity Wednesday night into predawn hours 
  of Thursday. 

* Renewed chance for nuisance coastal flooding during the early 
  afternoon high tide for the east coast of Massachusetts. 

Wednesday: Warm front crosses southern New England increasing cloud 
cover across the region. PWATs climb 0.8 to 1.2 inch, but forcing is 
not the best, a mid-level shortwave rides the ridge - this gives 
enough lift for a few showers late morning into the afternoon. QPF 
is limited, generally less than 0.1 inch. Surface winds remain out 
of the southeast to south/southeast, this limits temperatures across 
southern New England to the low and middle 50s, slightly cooler 
along the immediate coast. Sea surface temperatures are low-40s, this 
will keep afternoon temperatures limited to the upper-40s.

Again, the high tide along the coast of eastern Massachusetts may 
near minor flood during the early afternoon. As there is a Coastal 
Flood Statement out for the overnight high tide, the overnight crew 
will need to reevaluate whether or not this product will be needed. 

Wednesday Night: Periodic showers overnight, the CAMS do show a lull 
in activity, shortly after midnight with an uptick in activity 
around sunrise on Thursday. Warmer overnight, lows range between the 
mid-40s to 50 degrees. Do to the increased dewpoints, it is possible 
there could be patchy areas of fog. Wind across the interior are 
less than 5 mph.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Key Points...

* Unsettled and wet conditions continue for the latter half of the 
  week into the first half of the weekend.

* Heaviest rain will be Thursday night into Friday with potential 
  for gusty winds, though odds of damaging winds are low. Minor 
  coastal flooding is possible for portions of the south facing 
  coast during this period. 

* Unsettled weekend before drier conditions may develop, but 
  monitoring another disturbance around Sunday/Monday which may 
  quash our chances of prolonged dry weather. 

Details...

Wednesday night through Friday...

Mid level ridging breaks down a bit Wednesday night as a shortwave 
rounds the top of the ridge bringing scattered rain showers to the 
region. We then see a brief lull in the rain toward Thursday morning 
as heights once again rise with the ridge building back in. This is 
a short lived reprieve, however, as it precedes a deep trough across 
the southern Plains which becomes negatively tilted as it slides 
into the northeast Thursday night into Friday. This will direct a 
plume of deep moisture (PWAT 1.5+ inches) into SNE ahead of a Friday 
mid level cold front. This will lead to widespread moderate rain, 
dropping 1-1.5 inches of rain on the region by Friday night. 
Ensembles continue to show little concern for any more rain than 
that (very low probs of AOA 2 inches) which should limit renewed 
river flooding; something to monitor as it approaches. As for the 
winds, there will be a substantial S/SW low level jet overhead (60-
80 kts) but model soundings continue to indicate the bulk of this 
wind will be kept aloft by a strong surface inversion. Even so, 
winds will still be gusty, especially for the Cape and islands 
Thursday night and Friday. This inversion should help minimize the 
threat for coastal flooding along the south coast Thursday night and 
Friday morning, but given where astronomical tides are, guidance 
indicates the potential for 1-2 feet of surge which could take 
places like Fox Point into minor flood stage. 

Saturday through Tuesday...

Even as the deep plume of moisture has moved east with the low by 
Saturday, the lingering cold pool aloft with cyclonic flow over SNE 
will keep clouds and periods of showers around through at least the 
first half of the weekend. Beyond that, though, we're not in the 
clear rain-wise. Another disturbance looks to round the base of a 
broader trough around Sunday or Monday with a surface low crossing 
New England which would keep rain chances in the forecast. 
Additionally, behind the Friday front a cooler airmass moves 
overhead, so highs previously in the 60s for Thu/Fri will drop into 
the 50s Saturday before rebounding Sunday and especially Monday. By 
Monday we may even see upper 60s to near 70 in the warm sector 
depending on the track of the aforementioned low. Overall, no 
prolonged truly dry stretch of weather looks to be in the cards at 
this point. Stay tuned.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Forecast Confidence Levels:

Low - less than 30 percent. 
Moderate - 30 to 60 percent. 
High- greater than 60 percent. 

00z TAF Update: 

Tonight... High confidence. 

VFR. Dry for the most part, though a rouge shower can't be ruled out 
across far northwestern terminals. Winds E but becoming SE between 5 
and 10 knots, slightly stronger winds possible 10 to 15 knots along 
and near the coast. 

Wednesday... High confidence in trends, but moderate in timing. 

VFR through early afternoon, trending to MVFR 18z-21z, along with 
chance -RA. Winds are SE 8 to 12 knots, with some gusts for coastal 
terminals to 20 knots possible. 

Wednesday Night... Moderate confidence. 

MVFR to start, trending IFR after 06z. Slight chance of -RA and 
patchy ground fog. Winds are SE to start, then become NE, though 
speeds are generally light 5 to 10 knots. 

KBOS TAF... High confidence.

KBDL TAF... High confidence.

Outlook /Thursday through Sunday/... 

Thursday: Mainly IFR, with local MVFR possible. Breezy. Chance
SHRA, patchy BR.

Thursday Night: Mainly IFR, with local VFR possible. Strong
winds with gusts up to 45 kt. SHRA, isolated TSRA, patchy BR.

Friday: Mainly IFR, with local MVFR possible. Strong winds with
gusts up to 55 kt. SHRA, isolated TSRA, patchy BR.

Friday Night: Mainly VFR, with local IFR possible. Strong winds
with local gusts up to 40 kt. Slight chance SHRA.

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

Saturday Night through Sunday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight through Wednesday Night... High confidence.

Winds and seas to remain below SCA levels through Wednesday
night. Winds become E/SE tonight through Wednesday with speeds 
around 10-15 kt. Seas through the period mainly 4 ft or less on 
the outer waters. Periods of light rain Wednesday afternoon
which becoming on and off overnight into the predawn hours of
Thursday. As a heads up later in the week, deepening low 
pressure is forecast to track through eastern Great Lakes Thu-
Fri. Confidence is increasing for Gale force S-SW winds and 
building seas offshore.

Outlook /Thursday through Sunday/... 

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers. Local visibility 1 to 3 nm.

Thursday Night: Low risk for gale force winds with gusts up to
45 kt. Seas up to 5 ft. Chance of rain showers, patchy fog.
Areas of visibility 1 to 3 nm.

Friday: Moderate risk for storm force winds with gusts up to
55 kt. Rough seas up to 14 ft. Rain showers, isolated
thunderstorms, patchy fog. Visibility 1 to 3 nm.

Friday Night: Low risk for gale force winds with gusts up to
40 kt. Rough seas up to 14 ft. Slight chance of rain showers. 

Saturday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 11 ft. 

Saturday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 25 kt. Areas of rough seas. 

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

SYNOPSIS...BW/Dooley
NEAR TERM...Loconto/Dooley
SHORT TERM...Dooley
LONG TERM...BW
AVIATION...Loconto/BW/Dooley
MARINE...Loconto/BW/Dooley