Chatham, MA Marine Weather and Tide Forecast
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Marine Weather and Tide Forecast for Chatham, MA

April 20, 2024 11:11 AM EDT (15:11 UTC) Change Location
Sunrise 5:50 AM   Sunset 7:28 PM
Moonrise 4:23 PM   Moonset 4:33 AM 
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NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.

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Marine Forecasts
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ANZ254 Coastal Waters From Provincetown Ma To Chatham Ma To Nantucket Ma Out 20 Nm- 1001 Am Edt Sat Apr 20 2024

This afternoon - SW winds 5 to 10 kt, becoming w. Seas 2 to 3 ft. Wave detail: se 3 ft at 7 seconds and E 2 ft at 10 seconds. Patchy fog. Showers. Vsby 1 nm or less.

Tonight - SW winds 5 to 10 kt, becoming nw after midnight. Gusts up to 20 kt. Seas 2 to 4 ft. Wave detail: se 3 ft at 7 seconds and W 1 ft at 2 seconds. Patchy fog in the evening. A chance of showers in the evening with vsby 1 nm or less.

Sun - NW winds 5 to 10 kt, becoming sw with gusts up to 20 kt in the afternoon. Seas 3 to 4 ft. Wave detail: se 3 ft at 7 seconds and W 2 ft at 4 seconds.

Sun night - W winds 10 to 15 kt with gusts up to 20 kt. Seas 2 to 4 ft. Wave detail: W 2 ft at 4 seconds and se 2 ft at 7 seconds.

Mon - NW winds 10 to 15 kt with gusts up to 20 kt, becoming N in the afternoon. Seas 2 to 3 ft. Wave detail: nw 2 ft at 4 seconds and se 2 ft at 7 seconds.

Mon night - SE winds 5 to 10 kt. Seas 2 to 3 ft. Wave detail: nw 2 ft at 4 seconds and se 1 ft at 7 seconds.

Tue and Tue night - S winds 10 to 15 kt with gusts up to 25 kt. Seas 2 to 3 ft.

Wed and Wed night - S winds around 15 kt, becoming sw. Gusts up to 25 kt. Seas 3 to 5 ft. A chance of showers.
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 1001 Am Edt Sat Apr 20 2024

Synopsis for massachusetts and rhode island coastal waters - A cold front brings showers and a period of breezy conditions for today. High pres then returns for Sun and Mon bringing westerly winds. The high moves overhead on Tue.


7 Day Forecast for Marine Location Near Chatham, MA
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Area Discussion for - Boston, MA
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FXUS61 KBOX 201339 AFDBOX

Area Forecast Discussion National Weather Service Boston/Norton MA 939 AM EDT Sat Apr 20 2024

SYNOPSIS
A round of showers mainly this morning will persist into early afternoon across parts of Rhode Island and southeast Massachusetts, but partial sunshine should develop across the interior later today. A ridge of high pressure will result in dry weather Sunday through Tuesday with mild days and cool nights along with elevated fire weather potential. Unsettled, wet and cool on Wednesday. Turning drier late in the week.

NEAR TERM /UNTIL 6 PM THIS EVENING/
Last several runs of the HRRR and RAP looked to have a good handle on the showers this morning, and the possibility for a second round later this afternoon into this evening. Thus, used the consensus of that guidance for rainfall chances and timing with this update.

First round of showers was moving east, and should be largely offshore by noon. Could be as late as 3-4 PM before the risk for showers from this band clears the Cape and islands. By that time however, thinking a second round of showers will be underway across the western half of southern New England. Eventually, these showers should move across the eastern half of our region, before moving offshore later this evening.

Only minor tweaks to temperatures. Tricky forecast, as current forecast is predicated on seeing a brief period of sunshine.
Starting to see hints of some breaks developing across NE PA into eastern NY state. Will continue to monitor. Latest near term guidance has trended slightly cooler, but thinking even a little bit of sunshine will have a quick impact on temperatures.

Previous discussion...

* Showers develop this morning with a few downpours too * Bulk of the showers come to an end late morning into mid afternoon * High temps this afternoon in the upper 50s to the middle 60s

A shortwave and its associated cold front was approaching from the west this morning. In advance of this front, increasing low level moisture has allowed low clouds to overspread much of the region very early this morning. A few showers were starting to develop across western MA very early this morning. We expect the activity to increase in areal coverage & intensity as the front pushes east into an environment where PWATS will exceed 1 inch.
So expect showers to blossom across the region through daybreak with a few brief downpours too.

This front is progressive and we expect the showers to pretty much come to an end from northwest to southeast by mid afternoon in most locations and earlier across the interior. Partial sunshine will develop by mid to late afternoon northwest of I-95 and towards evening along the I-95 corridor. The partial sunshine coupled with the upper trough will result in enough diurnal instability to trigger a few additional showers later today, but the vast majority of this time will feature dry weather in a given locations. Given the cold temps aloft its not out of the question that a few of the late day showers contain some graupel.

The relatively mild start coupled with some partial sunshine later today should allow areas northwest of I-95 to reach the lower to middle 60s. Southeast of I-95 where clouds/showers linger a bit longer...highs will be in the middle 50s to the lower 60s. The coolest of those readings will be across the Cape and Islands.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/
Key Points...

* Clearing tonight with lows in the 30s to the lower 40s * Partly sunny a bit breezy Sunday with highs upper 50s/near 60

Details...

Tonight...

Lingering clouds across eastern New England should push east of the region this evening as drier air works in from the west.
This should yield mostly clear skies and diminishing wind will allow for a good night of radiational cooling. Some locations will see low temps bottom out well down into the 30s. If the winds diminish enough there also could be areas of frost, particularly in the typical low-lying locations. The mild spot will be the urban heat Island of Boston where overnight lows should bottom out in the lower 40s.

Sunday...

A weak ridge of high pressure will be nosing in from the southwest, resulting in a mixture of clouds and sunshine. 850T are fairly chilly around -3C...but good mixing on westerly flow should allow for high temps to reach the upper 50s to near 60 in most locations. Westerly winds will gust to between 20 and 25 mph by afternoon.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/
Highlights

* Dry, breezy and mild on Mon and Tue. Elevated fire weather concerns possible.

* Shower chances return Wed and could linger into Thu. Temps trending colder.

* Temps trending milder late in the week into early next weekend.
Dry on Fri, but we may turn unsettled over the weekend.

Sunday Night through Tuesday...

Stuck under persistent cyclonic flow throughout this period. A ridge axis builds from the Mid/Upper Mississippi River Valley Sun Night into the Great Lakes by early Mon. The ridge builds into the Mid Atlantic by late Mon and offshore on Tue. Another trough digs into the Great Lakes Region by late Tue. High pressure nudges into our region through this period. The high builds overhead Mon Night into early Tue before shifting offshore later on Tue.

Not a lot of change from the past couple of days. Dry and quiet weather expected through this timeframe. Main concern will be elevated fire weather concerns. For both days the boundary layer will be well mixed, but on Mon flow will be out of the W to NW and on Tue winds turn southerly as the high shifts offshore.
Both the NAM and GFS continuing to show the boundary layer mixing to approximately 800 hPa per Bufkit soundings. This should mix down the drier air aloft fairly easily. In these situations guidance tends to perform poorly as temps, min RH and dew points overperform. Opted to increase temps to the 75th percentile of guidance for both days. High top out in the mid 50s to the low/mid 60s. Though Tue appears to be the milder of the two days given the southerly flow.

Lowered dew points/RH values during the daytime due to the excellent mixing to the 10th percentile of guidance for Mon and 25th for Tue. Not as confident in being much drier on Tue given the wind shift to southerly flow, which tends to pump a bit more moisture in. At this point have minimum relative humidities of 15 to 35 percent on Mon and 25 to 45 percent on Tue. Could see some 20-25 mph gusts during the day.

Tuesday Night through Thursday...

Still stuck in cyclonic flow. A trough over the Great Lakes Tue Night digs into the eastern Great Lakes/New England on Wed. The trough may lift out of our region by Thu. This will be our next shot for unsettled wet weather as a system slides into our region.

A cold frontal system swings through New England mostly on Wed bringing widespread rain showers. The PWAT plume not appearing overly impressive with PWATs below 1 inch per EPS/GEFS and GEPS nil probs of values AOA 1 inch. Deterministic guidance showing we generally we be under roughly 0.75 to 0.85 inches. This is around the 75th percentile for this time of year per SPC Sounding Climo for CHH. We do have a deeper S/SWly low level jet at 850 hPa, which could help squeeze out the moisture available. At this point deterministic guidance shows roughly 30-40 kt jet in place. So we are trending a bit weaker of a system compared to 24 hrs ago. Should remain mild/seasonable on Wed. Temps will be above 0 C as the system is initially moving in, so should stay all rain. However, as things are winding down much colder air may filter in late Wed into early Thu. This is especially if the GFS is correct with a deep cutoff parking itself over the area. At this point the GFS is the outlier with the ICON/UKMET/ECMWF and GEM guidance all milder. So, have backed away from snow mixing in as things are winding down.

At this juncture we've still got mod to high probs (30-80 percent) of totals AOA 0.1 inches. Whereas the probs of have lowered for 0.5 inches to low (around 10 percent). The best shot is across the interior per GEFS/EPS and GEPS guidance. Still just sticking with WPC for now.

High temperatures on Wed range from the mid 50s to the low 60s.
As for Thu we will be cooler in wake of the system with highs in the low to mid 50s. There could be isolated showers across the interior.

Friday through Saturday...

Ridge axis builds into the Great Lakes region on Fri and into Sat, but a shortwave may ride the ridge as we head into Sat.
High pressure generally in control through this period, but a frontal boundary may lift toward us as we head into the weekend.

Dry and quiet weather anticipated with temperatures rebounding nicely as we head into the weekend. Do have some uncertainty as we head into the weekend with that shortwave lifting toward us.
Given it is spring time there could be some convective influences. Have just stuck with the NBM for now. Highs around seasonable levels on Fri and slightly warmer than normal on Sat.

AVIATION /14Z SATURDAY THROUGH WEDNESDAY/
Forecast Confidence Levels:

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

Today...High confidence in trends, moderate in timing.

MVFR to IFR with localized LIFR as showers slide through.
Anticipate activity ending NW of I-95 by 15-17Z with improvement to VFR. Southeast of I-95 the lower conditions persist until roughly 21-03Z with the latest across the Cape/Islands. Could see a second round of hit/miss showers this afternoon mainly ORH/PVD/BED and BOS. Low prob there is some thunder as well along with graupel in these showers, but given the coverage have stuck with VCSH for now. Winds out of the SW becoming more W at 5-15 kts as day progresses. Could see some 20-25 kt gusts during the afternoon across the interior.

Tonight and Sunday...High confidence.

Any lingering MVFR-IFR conditions across the Cape/Islands clear to VFR this evening. VFR conditions expected into Sunday.
WNW generally 5-10 knots shifting to the WSW Sunday at 10 to 15 knots with some gusts of 20 to 25 knots.

KBOS TAF...High Confidence in TAF.

IFR conditions this morning with rain. Will gradually improve to MVFR by 15-17Z and showers end. Could have another round of hit/miss activity around 20Z. Could see some graupel or a rumble of thunder, but given coverage have kept VCSH for now. Winds out of SW shift to the WSW/W late with gusts of 15-20 kts.

KBDL TAF...High Confidence in TAF.

MVFR/IFR to start, but showers will slide through by roughly 14Z. Should improve to VFR around 16-18Z. Winds out of the S shifting to the SW/W late and eventually the NW this evening.
Will become gusty around 18-20Z.

Outlook /Sunday Night through Wednesday/...

Sunday Night through Monday: VFR. Breezy.

Monday Night: VFR.

Tuesday: VFR. Breezy.

Tuesday Night: VFR. Breezy. Slight chance SHRA.

Wednesday: Mainly VFR, with local IFR possible. Breezy. Chance SHRA.

MARINE
Forecaster Confidence Levels:

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

Today through Sunday...High Confidence.

A relatively weak pressure gradient should keep winds and seas generally below Small Craft Advisory thresholds through Sunday.
However, good mixing on westerly flow Sunday may yield a few afternoon nearshore wind gusts of 20-25 knots creating some chop.

Outlook /Sunday Night through Wednesday/...

Sunday Night through Monday Night: Winds less than 25 kt.

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

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

Wednesday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Chance of rain showers.

FIRE WEATHER
Sunday...

Dry westerly flow in pre-greenup should allow for elevated fire weather concerns on Sunday. The airmass will mix deeply and allow for a large temp/dewpoint spread. Highs should reach the upper 50s to near 60 with dewpoints dropping into the lower to middle 20s. This should result in minimum afternoon relative humidities between 20 and 30 percent. The deep mixing should also produce some 20 to 25 mph wind gusts with perhaps a few locales approaching 30 mph briefly.

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




Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesinHgDewPt
CHTM3 0 mi54 min 48°F 50°F
44020 - NANTUCKET SOUND 22 mi42 min WSW 7.8G12 47°F 48°F29.9447°F
44090 23 mi102 min 47°F 46°F
NTKM3 - 8449130 - Nantucket Island, MA 29 mi54 min SW 5.1G8.9 48°F 50°F29.96
44018 - SE Cape Cod 30NM East of Nantucket, MA 37 mi62 min 45°F2 ft
BZBM3 - 8447930 - Woods Hole, MA 40 mi54 min 47°F 47°F29.96


Wind History for Nantucket Island, MA
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Airport Reports
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AirportDistAgeWind ktVisSkyWeatherTempDewPtRHinHg
KCQX CHATHAM MUNI,MA 2 sm19 mincalm1 smOvercast Lt Rain Mist 48°F48°F100%29.94
KHYA BARNSTABLE MUNIBOARDMAN/POLANDO FIELD,MA 18 sm15 minSSE 045 smOvercast Lt Rain Mist 46°F46°F100%29.91
Link to 5 minute data for KCQX


Wind History from CQX
(wind in knots)
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Tide / Current for Chatham (inside), Cape Cod, Massachusetts
   
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Chatham (inside)
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Sat -- 04:33 AM EDT     Moonset
Sat -- 05:51 AM EDT     Sunrise
Sat -- 06:05 AM EDT     0.43 feet Low Tide
Sat -- 11:52 AM EDT     3.35 feet High Tide
Sat -- 04:22 PM EDT     Moonrise
Sat -- 06:29 PM EDT     0.31 feet Low Tide
Sat -- 07:26 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Chatham (inside), Cape Cod, Massachusetts, Tide feet
12
am
3.2
1
am
3
2
am
2.6
3
am
2.1
4
am
1.3
5
am
0.7
6
am
0.4
7
am
0.6
8
am
1.1
9
am
1.9
10
am
2.7
11
am
3.2
12
pm
3.3
1
pm
3.2
2
pm
2.8
3
pm
2.3
4
pm
1.6
5
pm
0.8
6
pm
0.4
7
pm
0.4
8
pm
0.8
9
pm
1.5
10
pm
2.4
11
pm
3



Tide / Current for Pollock Rip Channel, Massachusetts Current
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Pollock Rip Channel
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Sat -- 01:48 AM EDT     0.00 knots Slack
Sat -- 04:33 AM EDT     Moonset
Sat -- 05:16 AM EDT     1.85 knots Max Flood
Sat -- 05:51 AM EDT     Sunrise
Sat -- 08:07 AM EDT     -0.00 knots Slack
Sat -- 11:04 AM EDT     -1.55 knots Max Ebb
Sat -- 02:00 PM EDT     0.00 knots Slack
Sat -- 04:22 PM EDT     Moonrise
Sat -- 05:35 PM EDT     2.03 knots Max Flood
Sat -- 07:26 PM EDT     Sunset
Sat -- 08:33 PM EDT     -0.00 knots Slack
Sat -- 11:30 PM EDT     -1.64 knots Max Ebb
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Pollock Rip Channel, Massachusetts Current, knots
12
am
-1.3
1
am
-0.7
2
am
0.2
3
am
0.9
4
am
1.5
5
am
1.8
6
am
1.7
7
am
1.1
8
am
0.1
9
am
-0.8
10
am
-1.3
11
am
-1.5
12
pm
-1.4
1
pm
-0.8
2
pm
-0
3
pm
0.9
4
pm
1.5
5
pm
2
6
pm
2
7
pm
1.5
8
pm
0.6
9
pm
-0.4
10
pm
-1.2
11
pm
-1.6




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Boston, MA,



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