Sunrise 5:34 AM   Sunset 7:53 PM Moonrise 4:12 AM   Moonset 5:06 PM

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ANZ230 Boston Harbor- 105 Am Edt Sun May 5 2024
Rest of tonight - E winds around 5 kt. Waves 1 foot or less. Patchy fog. Vsby 1 to 3 nm. Sun - SE winds 5 to 10 kt. Waves around 2 ft. A chance of showers in the afternoon. Sun night - S winds 5 to 10 kt. Waves around 2 ft. Showers. Vsby 1 to 3 nm. Mon - SW winds around 5 kt, increasing to 10 to 15 kt in the afternoon. Waves 1 foot or less. A chance of showers. Vsby 1 to 3 nm in the morning. Mon night - SW winds 5 to 10 kt, becoming nw after midnight. Waves 1 foot or less. Tue - N winds 5 to 10 kt, becoming se 10 to 15 kt in the afternoon. Waves 1 foot or less. Tue night - S winds 5 to 10 kt, becoming N after midnight. Waves 1 foot or less. A chance of showers after midnight. Wed - E winds 5 to 10 kt with gusts up to 20 kt. Waves around 2 ft. Showers likely. Wed night through Thu night - NE winds around 10 kt. Waves 2 to 3 ft. Showers likely.
seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height.

ANZ200 105 Am Edt Sun May 5 2024
Synopsis for massachusetts and rhode island coastal waters - High pressure begins to move east tonight, but dry weather remains through Sunday morning. Weak low pressure system and cold front brings rain Sunday afternoon through Monday morning. Dry weather returns Monday evening through Tuesday. Low chance for showers mid to late next week as several disturbances pass over the waters.

FXUS61 KBOX 050506 AFDBOX

Area Forecast Discussion National Weather Service Boston/Norton MA 106 AM EDT Sun May 5 2024

SYNOPSIS
Cloudy and cool weather is on tap through Sunday with a period of widespread showers arriving from the west...mainly later Sunday into Sunday night. Mild and dry to start the work week before cooler and unsettled conditions Wednesday through next weekend

NEAR TERM /UNTIL 6 AM THIS MORNING/
730 PM Update...

Widely variable conditions across southern New England at this hour with temps in the mid 40s along the eastern MA coastline, thanks to onshore flow, and in the mid 60s in parts of CT that saw sunshine for the better part of the day. Cloud cover is variable as well, with several layers of clouds ranging from IFR to VFR, with the lowest clouds colocated with the coolest temperatures.

Low clouds will continue to spread inland this evening with some possible fog development along the south coast, Cape, and high terrain of central and western MA.

330 PM Update...

* Clouds continue to overspread the region off the ocean tonight * Overnight low temps mainly in the 40s

The upper level ridge axis will be shifting east of the region. This coupled with high pressure in the vicinity of the Canadian Maritimes will result onshore flow
As the boundary layer cools
expect low clouds to continue to develop and expand westward tonight. Dry weather will prevail tonight...but we may see a few spot showers develop near daybreak west of the CT River Valley. Overnight low temps will bottom out mainly in the 40s.

SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/
Key Points...

* Cloudy/cool Sun with showers arriving across the interior * A period of widespread showers Sun night across the entire region

Details...

Sunday and Sunday night...

High pressure will shift east of the Canadian Maritimes as shortwave energy approaches from the west on Sunday. Onshore flow low level flow will result in cloudy skies persisting and cool temperatures too. Highs will only be in the 50s even across the distant interior.

While a few warm advection spot showers are possible across the interior during the morning...the stronger forcing/deeper moisture does not arrive until the afternoon. So thinking the main threat for showers will be be Sunday afternoon across interior MA & CT...but should wait until late Sunday afternoon/evening across the coastal plain. Enough forcing exists for a period of widespread showers Sunday night. Modest forcing and Pwats 1-2 standard deviations above normal could result in a brief downpour or two. While we can not rule out a rumble or two of thunder with some marginal elevated instability...thinking it was not worth inserting into the forecast at this point. Low temperatures Sunday night will mainly be in the middle to upper 40s.

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/
* Generally dry with above normal temperatures Monday and Tuesday

* Persistent period of cool temps and heightened rain chances Wednesday through early next week.

Tale of two patterns for the upcoming work week with strong upper level ridging in place through Tuesday before a trough develops for the second half of the week.

Some residual showers may linger into Monday morning, primarily across far southeastern MA and the Cape. Weak frontal passage may initiate some shower activity come Monday evening but with drying flow aloft, questions remain on the geographic spread of this second round of showers. All in all, Monday looks to shape up as a primarily dry day, with above normal temperatures as boundary layer temperatures warm to around 15C. As noted by the previous forecaster, ensemble probabilities of 70F+ temps remain high, between 80-100%, across the interior. Tuesday continues to look like the pick of the week as temperatures soar well into the 70s.
Downsloping northwest flow that develops after the lunch hour and abundant sunshine should allow for a few localities in the CT River Valley to make a run at 80F. While ensemble probabilities remain low regarding temps hitting the 80F mark, conditions appear to be a recipe for an overachieving type day. For both Monday and Tuesday, weak pressure gradient will allow for seabreeze development, so while it may sound like a broken record, temps along the coastline will be significantly cooler.

Ridge breaks down as trough develops over the eastern CONUS Wednesday- Friday. CMC, GEFS, and ECMWF remain at odds regarding how potent the trough will be, but a series of shortwaves and persistent low pressure located over the Great Lakes and a stalled frontal boundary will bring rounds of showers to southern New England Wednesday through the weekend. Ensemble probs aren't particularly remarkable when it comes to QPF, with just 20-50% probs of 0.5" QPF over any 24 hour period, but onshore flow will make for a prolonged period of stratus and shower chances with temperatures locked in the upper 50s and low 60s.

AVIATION /05Z SUNDAY THROUGH THURSDAY/
Forecast Confidence Levels:

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

06z TAF Update...

Through 12Z...High Confidence in trends, but more uncertainty in regards to specific timing.

Borderline IFR/MVFR ceilings between 008-012 feet with light easterly winds.

Sunday...High Confidence.

IFR/MVFR ceilings will trend to mainly MVFR thresholds with some diurnal heating despite the cloudy skies. Some showers will work into mainly interior MA & CT during the afternoon hours, but will not reach the coastal plain until late Sunday afternoon/evening. SE winds 5 to 10 knots.

Sunday night...Moderate Confidence.

IFR/LIFR ceilings develop with light showers spreading west to east across southern New England overnight. SE winds shift to more of a S direction at 5 to 10 knots.

Monday...

IFR ceilings lifting to VFR levels by late morning/early afternoon. Though lower IFR ceilings may persist longer over The Cape Islands. Light southwest winds becoming more westerly.
Winds may be weak enough to support a sea-breeze circulation along the coastline.

KBOS TAF...High confidence

KBDL TAF...High confidence

Outlook /Monday Night through Thursday/...

Monday: Mainly VFR, with local IFR possible. Chance SHRA.

Monday Night through Tuesday: VFR. Slight chance SHRA.

Tuesday Night: VFR. Chance SHRA.

Wednesday: Mainly VFR, with areas MVFR possible. Chance SHRA, isolated TSRA.

Wednesday Night: MVFR/IFR conditions possible. Chance SHRA.

Thursday: Mainly VFR, with local IFR possible. Chance SHRA.

MARINE
Forecaster Confidence Levels:

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

Tonight through Sunday night...High Confidence.

High pressure in the vicinity of the Canadian Maritimes tonight will shift east of there on Sunday. This as a shortwave energy approaches from the west late Sunday and Sunday night
That being said
the pressure gradient remains rather weak so winds/seas will remain below small craft advisory thresholds through Sunday night. E winds 5 to 15 knots tonight shift to the SE Sunday and then more to the S on Sunday night.

Outlook /Monday Night through Thursday/...

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

Monday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers.

Tuesday: Winds less than 25 kt. Slight chance of rain showers.

Tuesday Night through Thursday: Winds less than 25 kt. Chance of rain showers.

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

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