Marine Weather and Tide Forecast for Chatham, MA
May 21, 2024 4:11 PM EDT (20:11 UTC) Change Location
 | Sunrise 5:13 AM Sunset 8:01 PM Moonrise 6:22 PM Moonset 3:54 AM |
ANZ254 Coastal Waters From Provincetown Ma To Chatham Ma To Nantucket Ma Out 20 Nm- 403 Pm Edt Tue May 21 2024
Tonight - SW winds 10 to 15 kt with gusts up to 20 kt. Seas 3 to 4 ft. Wave detail: E 4 ft at 9 seconds and sw 2 ft at 3 seconds. Patchy fog. Vsby 1 nm or less.
Wed - SW winds 10 to 15 kt with gusts up to 20 kt. Seas 3 to 4 ft. Wave detail: sw 3 ft at 4 seconds and E 3 ft at 8 seconds. Patchy fog. Vsby 1 nm or less, increasing to 1 to 3 nm in the afternoon.
Wed night - SW winds around 15 kt with gusts up to 20 kt. Seas 3 to 4 ft. Wave detail: sw 3 ft at 4 seconds and E 2 ft at 8 seconds. Patchy fog. Vsby 1 to 3 nm.
Thu - SW winds around 15 kt with gusts up to 20 kt. Seas 3 to 4 ft. Wave detail: sw 3 ft at 4 seconds and E 2 ft at 8 seconds. Patchy fog in the morning with vsby 1 to 3 nm.
Thu night - SW winds 10 to 15 kt. Gusts up to 20 kt in the evening. Seas 2 to 3 ft. Wave detail: sw 3 ft at 4 seconds and E 1 foot at 7 seconds. A chance of showers. A chance of tstms in the evening.
Fri and Fri night - SW winds 5 to 10 kt. Seas 2 to 3 ft. Wave detail: sw 2 ft at 4 seconds and E 1 foot at 8 seconds.
Sat - SW winds 5 to 10 kt. Seas around 2 ft.
Sat night and Sun - S winds around 10 kt. Seas 2 to 3 ft. A chance of showers.
Sun night - S winds around 10 kt. Seas 2 to 3 ft.
winds and seas higher in and near tstms.
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.
winds and seas higher in and near tstms.
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 403 Pm Edt Tue May 21 2024
Synopsis for massachusetts and rhode island coastal waters - High pressure to the south will continue to support steady southwest winds over the coastal waters through Thursday afternoon. Wind speeds will be modest ranging from 10 to 20 knots with gusts up to 25 knots possible at times. Seas remain in the 0 to 1 foot range in the harbors and 2 to 3 feet over the outer marine zones. Warm moist air from southwest flow over the cooler waters may support periods of patchy dense fog during the evening and morning hours.
FXUS61 KBOX 211903 AFDBOX
Area Forecast Discussion National Weather Service Boston/Norton MA 303 PM EDT Tue May 21 2024
SYNOPSIS
A high pressure remains just south of New England, setting the stage for summerlike warmth through Thursday away from the immediate south coast. Generally dry weather is expected through Wednesday, but an approaching cold front may bring a round of scattered showers and thunderstorms Thursday afternoon and evening. A few strong to severe storms are possible. Still warm and mainly dry on Friday. Continued warm but unsettled through this weekend, then cooler early next week with more seasonable temperatures.
NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/
We continue to monitor some scattered convection which has been firing off in NY this afternoon and inching closer to SNE. However, due to lack of strong bulk shear these cells are going up and down fairly quickly without reaching severe levels. This is expected to be the case with a smattering of pop-up thunderstorms over northwest MA this afternoon and early evening, even as bulk shear is expected to increase marginally to 20-25kts lapse rates are poor and only sub severe activity is expected at this time. After a warm Tuesday temperatures will cool tonight but remain several degrees warmer than the night previous, in the mid to upper 50s and even low 60s thanks to increasing moisture/dewpoints on SW flow. The surface high pressure in place to our south will remain overnight leading to prolonged warmth and fog/low stratus on the immediate south coast and southeast MA. The more southwesterly trajectory of the wind should help the those low clouds/fog to be limited further south than last night, and is not expected to again extend into the CT Valley.
SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/
Wednesday expect more of the same, but starting off with a warmer low temp will help us achieve the hottest day of the week, with highs reaching into the upper 80s inland (low 90s in the hottest locations like the Merrimack Valley and northern CT valley). Those along the south coast will be spared the hot temps thanks to onshore flow keeping temps in the 70s. During the afternoon we may once again see a pop up shower or thunderstorm, but less coverage is expected than today; not seeing any strong source of forcing other than diurnal heating and shear is even weaker than today. Overnight lows temperatures will once again be quite mild owing to the high dewpoint airmass overhead, in the upper 50s and low 60s.
LONG TERM /THURSDAY THROUGH TUESDAY/
Key Points...
* A few strong to severe t-storms possible Thu. Damaging wind and large hail are the main threats
* Warm and dry Fri with above normal temps persisting
* Continued warm this weekend but turning more unsettled, then cooler early next week with risk of showers
Thursday...
The main forecast challenge revolves around the potential for severe weather as a cold front moves into a rather warm and humid airmass in place across SNE. While there is some uncertainty with extent of cloud cover and how that will impact instability, we expect at least partial sunshine which will allow temps to reach mid-upper 80s, except 70s near the south coast. Dewpoints will climb into the mid 60s. These conditions beneath decent mid level lapse rates will contribute to SBCAPES of 1000+ J/kg with a low prob of 2000 J/kg.
Effective shear is progged around 25-35 kt which is on the lower end of what would be considered sufficient for organized severe convection. The one negative factor which may limit areal coverage of severe storms is limited synoptic forcing as main shortwave energy and best upper jet dynamics will be well to the north. This is reflected in the NAM3k and FV3 simulated reflectivity which shows rather widely scattered storms. The CSU ML probs are still highlighting SNE for a low risk for severe. Still not within the window of the full suite of hi-res CAMs which will provide a better idea of coverage and intensity of storms. Current thinking is we will see a few strong to severe storms with best chance across interior MA into CT which is where NCAR ensembles show best updraft helicity swaths. Favorable low level lapse rates suggest damaging wind will be the primary threat with any severe storms, but hail is a secondary risk given decent mid level lapse rates and marginal shear. SW flow off cooler SST will limit instability and severe potential across RI and SE MA.
Weakening storms will move to the south coast Thu evening then drier air from the north will gradually overspread SNE overnight Thu night.
Friday...
SNE will be in between systems Fri with northern stream trough and attendant cold front well to the north and weaker shortwave to the south. Rather dry air in the mid levels will lead to lots of sunshine although clouds may linger along the south coast in the morning before sunshine increases. It will be another warm day as 925 mb temps reach 20-21C. Highs will reach well into the 80s, but sea breezes will keep coastal locations cooler. It also won't be quite as humid as mixing lowers dewpoints into the 50s.
This weekend into early next week...
Messy pattern sets up with numerous shortwaves within a quasi-zonal flow before pattern amplifies early next week. A few of these shortwaves will be rotating through New Eng and PWATs will be above normal which will result in an unsettled pattern with showers at times although no washouts are expected. Timing of these shortwaves will be a challenge but it looks like there will be a risk of showers somewhere in SNE each day. Warm pattern continues this weekend with above normal 925 mb temps leading to 70s and lower 80s for highs, then cooler early next week.
AVIATION /19Z TUESDAY THROUGH SUNDAY/
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
This afternoon...High confidence in trends, moderate in exact timing.
Winds out of the S/SW at 5-10 kts. Sea breeze will continue across eastern coastal locations roughly through 21Z, but some uncertainty in if winds will be light enough in lowest 2kft per RAP soundings.
Tonight...High confidence in trends, moderate in exact timing.
Conditions deteriorate to IFR/LIFR across the south coast, especially near and SE of the I-95 corridor. The only exception is for the Boston metro area where am anticipating the SWly component to keep the fog/stratus at bay. Some uncertainty if this stratus/fog moves up the CT River Valley, so have only hinted at BAF. Winds relatively light (<10 kts) out of the SW.
Wednesday...High confidence.
Should see any IFR/LIFR stratus and fog burning off roughly 10-13Z, though may linger longer for ACK. Elsewhere VFR with SW winds 5-10 kts and 15-20 kt gusts during the afternoon.
Wednesday night...Moderate confidence.
Light SW winds continue 5-10 kts. IFR/MVFR cigs in stratus/fog possible over southeast MA terminals but low confidence in areal extent.
KBOS TAF...High confidence in TAF, moderate confidence in timing.
VFR. Seabreeze expected through about 21Z but confidence in exact timing that winds switch back to S/SSW is low to moderate.
KBDL TAF...High confidence.
Not out of question stratus/fog comes back in tonight, but confidence not high enough to include in latest update. Winds S 5-10 kts today shifting to the SW tonight.
Outlook /Thursday through Sunday/...
Thursday: VFR. Breezy. Chance SHRA, chance TSRA.
Thursday Night: VFR. Slight chance SHRA, slight chance TSRA.
Friday through Friday Night: VFR.
Saturday: VFR. Slight chance SHRA.
Saturday Night: VFR. Chance SHRA.
Sunday: VFR. Slight chance SHRA.
MARINE
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Through Wednesday night...High Confidence.
High pressure south of the waters maintains relatively light winds and seas through Wednesday night. The main concern will be poor visibility in areas of fog reducing visibility to less than 1 mile at times tonight and Wednesday night.
Outlook /Thursday through Sunday/...
Thursday: Winds less than 25 kt. Slight chance of rain showers.
Local visibility 1 to 3 nm.
Thursday Night: Winds less than 25 kt. Chance of rain showers, chance of thunderstorms.
Friday through Friday Night: Winds less than 25 kt.
Saturday: Winds less than 25 kt. Slight chance of rain showers.
Saturday Night: Winds less than 25 kt. Chance of rain showers.
Sunday: Winds less than 25 kt. Slight chance of rain showers.
BOX WATCHES/WARNINGS/ADVISORIES
CT...None.
MA...None.
RI...None.
MARINE...None.
Area Forecast Discussion National Weather Service Boston/Norton MA 303 PM EDT Tue May 21 2024
SYNOPSIS
A high pressure remains just south of New England, setting the stage for summerlike warmth through Thursday away from the immediate south coast. Generally dry weather is expected through Wednesday, but an approaching cold front may bring a round of scattered showers and thunderstorms Thursday afternoon and evening. A few strong to severe storms are possible. Still warm and mainly dry on Friday. Continued warm but unsettled through this weekend, then cooler early next week with more seasonable temperatures.
NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/
We continue to monitor some scattered convection which has been firing off in NY this afternoon and inching closer to SNE. However, due to lack of strong bulk shear these cells are going up and down fairly quickly without reaching severe levels. This is expected to be the case with a smattering of pop-up thunderstorms over northwest MA this afternoon and early evening, even as bulk shear is expected to increase marginally to 20-25kts lapse rates are poor and only sub severe activity is expected at this time. After a warm Tuesday temperatures will cool tonight but remain several degrees warmer than the night previous, in the mid to upper 50s and even low 60s thanks to increasing moisture/dewpoints on SW flow. The surface high pressure in place to our south will remain overnight leading to prolonged warmth and fog/low stratus on the immediate south coast and southeast MA. The more southwesterly trajectory of the wind should help the those low clouds/fog to be limited further south than last night, and is not expected to again extend into the CT Valley.
SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/
Wednesday expect more of the same, but starting off with a warmer low temp will help us achieve the hottest day of the week, with highs reaching into the upper 80s inland (low 90s in the hottest locations like the Merrimack Valley and northern CT valley). Those along the south coast will be spared the hot temps thanks to onshore flow keeping temps in the 70s. During the afternoon we may once again see a pop up shower or thunderstorm, but less coverage is expected than today; not seeing any strong source of forcing other than diurnal heating and shear is even weaker than today. Overnight lows temperatures will once again be quite mild owing to the high dewpoint airmass overhead, in the upper 50s and low 60s.
LONG TERM /THURSDAY THROUGH TUESDAY/
Key Points...
* A few strong to severe t-storms possible Thu. Damaging wind and large hail are the main threats
* Warm and dry Fri with above normal temps persisting
* Continued warm this weekend but turning more unsettled, then cooler early next week with risk of showers
Thursday...
The main forecast challenge revolves around the potential for severe weather as a cold front moves into a rather warm and humid airmass in place across SNE. While there is some uncertainty with extent of cloud cover and how that will impact instability, we expect at least partial sunshine which will allow temps to reach mid-upper 80s, except 70s near the south coast. Dewpoints will climb into the mid 60s. These conditions beneath decent mid level lapse rates will contribute to SBCAPES of 1000+ J/kg with a low prob of 2000 J/kg.
Effective shear is progged around 25-35 kt which is on the lower end of what would be considered sufficient for organized severe convection. The one negative factor which may limit areal coverage of severe storms is limited synoptic forcing as main shortwave energy and best upper jet dynamics will be well to the north. This is reflected in the NAM3k and FV3 simulated reflectivity which shows rather widely scattered storms. The CSU ML probs are still highlighting SNE for a low risk for severe. Still not within the window of the full suite of hi-res CAMs which will provide a better idea of coverage and intensity of storms. Current thinking is we will see a few strong to severe storms with best chance across interior MA into CT which is where NCAR ensembles show best updraft helicity swaths. Favorable low level lapse rates suggest damaging wind will be the primary threat with any severe storms, but hail is a secondary risk given decent mid level lapse rates and marginal shear. SW flow off cooler SST will limit instability and severe potential across RI and SE MA.
Weakening storms will move to the south coast Thu evening then drier air from the north will gradually overspread SNE overnight Thu night.
Friday...
SNE will be in between systems Fri with northern stream trough and attendant cold front well to the north and weaker shortwave to the south. Rather dry air in the mid levels will lead to lots of sunshine although clouds may linger along the south coast in the morning before sunshine increases. It will be another warm day as 925 mb temps reach 20-21C. Highs will reach well into the 80s, but sea breezes will keep coastal locations cooler. It also won't be quite as humid as mixing lowers dewpoints into the 50s.
This weekend into early next week...
Messy pattern sets up with numerous shortwaves within a quasi-zonal flow before pattern amplifies early next week. A few of these shortwaves will be rotating through New Eng and PWATs will be above normal which will result in an unsettled pattern with showers at times although no washouts are expected. Timing of these shortwaves will be a challenge but it looks like there will be a risk of showers somewhere in SNE each day. Warm pattern continues this weekend with above normal 925 mb temps leading to 70s and lower 80s for highs, then cooler early next week.
AVIATION /19Z TUESDAY THROUGH SUNDAY/
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
This afternoon...High confidence in trends, moderate in exact timing.
Winds out of the S/SW at 5-10 kts. Sea breeze will continue across eastern coastal locations roughly through 21Z, but some uncertainty in if winds will be light enough in lowest 2kft per RAP soundings.
Tonight...High confidence in trends, moderate in exact timing.
Conditions deteriorate to IFR/LIFR across the south coast, especially near and SE of the I-95 corridor. The only exception is for the Boston metro area where am anticipating the SWly component to keep the fog/stratus at bay. Some uncertainty if this stratus/fog moves up the CT River Valley, so have only hinted at BAF. Winds relatively light (<10 kts) out of the SW.
Wednesday...High confidence.
Should see any IFR/LIFR stratus and fog burning off roughly 10-13Z, though may linger longer for ACK. Elsewhere VFR with SW winds 5-10 kts and 15-20 kt gusts during the afternoon.
Wednesday night...Moderate confidence.
Light SW winds continue 5-10 kts. IFR/MVFR cigs in stratus/fog possible over southeast MA terminals but low confidence in areal extent.
KBOS TAF...High confidence in TAF, moderate confidence in timing.
VFR. Seabreeze expected through about 21Z but confidence in exact timing that winds switch back to S/SSW is low to moderate.
KBDL TAF...High confidence.
Not out of question stratus/fog comes back in tonight, but confidence not high enough to include in latest update. Winds S 5-10 kts today shifting to the SW tonight.
Outlook /Thursday through Sunday/...
Thursday: VFR. Breezy. Chance SHRA, chance TSRA.
Thursday Night: VFR. Slight chance SHRA, slight chance TSRA.
Friday through Friday Night: VFR.
Saturday: VFR. Slight chance SHRA.
Saturday Night: VFR. Chance SHRA.
Sunday: VFR. Slight chance SHRA.
MARINE
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Through Wednesday night...High Confidence.
High pressure south of the waters maintains relatively light winds and seas through Wednesday night. The main concern will be poor visibility in areas of fog reducing visibility to less than 1 mile at times tonight and Wednesday night.
Outlook /Thursday through Sunday/...
Thursday: Winds less than 25 kt. Slight chance of rain showers.
Local visibility 1 to 3 nm.
Thursday Night: Winds less than 25 kt. Chance of rain showers, chance of thunderstorms.
Friday through Friday Night: Winds less than 25 kt.
Saturday: Winds less than 25 kt. Slight chance of rain showers.
Saturday Night: Winds less than 25 kt. Chance of rain showers.
Sunday: Winds less than 25 kt. Slight chance of rain showers.
BOX WATCHES/WARNINGS/ADVISORIES
CT...None.
MA...None.
RI...None.
MARINE...None.
| Stations | Dist | Age | Wind | Air Temp | Water Temp | Waves | inHg | DewPt |
| CHTM3 | 0 mi | 72 min | 62°F | 57°F | 29.96 | |||
| 44020 - NANTUCKET SOUND | 22 mi | 62 min | SSW 14G | 55°F | 2 ft | 29.96 | 54°F | |
| 44090 | 23 mi | 72 min | 60°F | 55°F | 1 ft | |||
| NTKM3 - 8449130 - Nantucket Island, MA | 29 mi | 72 min | SW 8.9G | 58°F | 57°F | 29.99 | ||
| 44018 - SE Cape Cod 30NM East of Nantucket, MA | 37 mi | 92 min | 53°F | 4 ft | ||||
| BZBM3 - 8447930 - Woods Hole, MA | 40 mi | 72 min | 57°F | 57°F | 29.98 |
toggle option: (graph/table)
| Airport | Dist | Age | Wind kt | Vis | Sky | Weather | Temp | DewPt | RH | inHg |
| KCQX CHATHAM MUNI,MA | 2 sm | 19 min | SSW 08G20 | 10 sm | Clear | 61°F | 54°F | 77% | 29.97 | |
| KHYA BARNSTABLE MUNIBOARDMAN/POLANDO FIELD,MA | 18 sm | 15 min | SSW 12 | 10 sm | Clear | 63°F | 54°F | 72% | 29.95 |
Chatham (inside)
Click for Map
Tue -- 12:11 AM EDT 3.60 feet High Tide
Tue -- 03:54 AM EDT Moonset
Tue -- 05:14 AM EDT Sunrise
Tue -- 06:57 AM EDT 0.20 feet Low Tide
Tue -- 12:41 PM EDT 3.30 feet High Tide
Tue -- 06:22 PM EDT Moonrise
Tue -- 07:04 PM EDT 0.46 feet Low Tide
Tue -- 07:59 PM EDT Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Click for Map
Tue -- 12:11 AM EDT 3.60 feet High Tide
Tue -- 03:54 AM EDT Moonset
Tue -- 05:14 AM EDT Sunrise
Tue -- 06:57 AM EDT 0.20 feet Low Tide
Tue -- 12:41 PM EDT 3.30 feet High Tide
Tue -- 06:22 PM EDT Moonrise
Tue -- 07:04 PM EDT 0.46 feet Low Tide
Tue -- 07:59 PM EDT Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Chatham (inside), Cape Cod, Massachusetts, Tide feet
| 12 am |
| 3.6 |
| 1 am |
| 3.5 |
| 2 am |
| 3.1 |
| 3 am |
| 2.5 |
| 4 am |
| 1.8 |
| 5 am |
| 1.1 |
| 6 am |
| 0.4 |
| 7 am |
| 0.2 |
| 8 am |
| 0.4 |
| 9 am |
| 1 |
| 10 am |
| 1.8 |
| 11 am |
| 2.7 |
| 12 pm |
| 3.2 |
| 1 pm |
| 3.3 |
| 2 pm |
| 3 |
| 3 pm |
| 2.6 |
| 4 pm |
| 2 |
| 5 pm |
| 1.4 |
| 6 pm |
| 0.7 |
| 7 pm |
| 0.5 |
| 8 pm |
| 0.7 |
| 9 pm |
| 1.2 |
| 10 pm |
| 2 |
| 11 pm |
| 2.9 |
Pollock Rip Channel
Click for Map
Tue -- 02:28 AM EDT 0.00 knots Slack
Tue -- 03:55 AM EDT Moonset
Tue -- 05:14 AM EDT Sunrise
Tue -- 05:59 AM EDT 1.95 knots Max Flood
Tue -- 09:00 AM EDT -0.00 knots Slack
Tue -- 11:44 AM EDT -1.55 knots Max Ebb
Tue -- 02:46 PM EDT 0.00 knots Slack
Tue -- 06:12 PM EDT 1.84 knots Max Flood
Tue -- 06:21 PM EDT Moonrise
Tue -- 07:58 PM EDT Sunset
Tue -- 09:11 PM EDT -0.00 knots Slack
Tue -- 11:58 PM EDT -1.69 knots Max Ebb
Tide / Current data from XTide NOT FOR NAVIGATION
Click for Map
Tue -- 02:28 AM EDT 0.00 knots Slack
Tue -- 03:55 AM EDT Moonset
Tue -- 05:14 AM EDT Sunrise
Tue -- 05:59 AM EDT 1.95 knots Max Flood
Tue -- 09:00 AM EDT -0.00 knots Slack
Tue -- 11:44 AM EDT -1.55 knots Max Ebb
Tue -- 02:46 PM EDT 0.00 knots Slack
Tue -- 06:12 PM EDT 1.84 knots Max Flood
Tue -- 06:21 PM EDT Moonrise
Tue -- 07:58 PM EDT Sunset
Tue -- 09:11 PM EDT -0.00 knots Slack
Tue -- 11:58 PM EDT -1.69 knots Max Ebb
Tide / Current data from XTide NOT FOR NAVIGATION
Pollock Rip Channel, Massachusetts Current, knots
| 12 am |
| -1.6 |
| 1 am |
| -1.2 |
| 2 am |
| -0.4 |
| 3 am |
| 0.5 |
| 4 am |
| 1.3 |
| 5 am |
| 1.8 |
| 6 am |
| 2 |
| 7 am |
| 1.7 |
| 8 am |
| 1 |
| 9 am |
| 0 |
| 10 am |
| -0.9 |
| 11 am |
| -1.4 |
| 12 pm |
| -1.5 |
| 1 pm |
| -1.3 |
| 2 pm |
| -0.6 |
| 3 pm |
| 0.2 |
| 4 pm |
| 1 |
| 5 pm |
| 1.6 |
| 6 pm |
| 1.8 |
| 7 pm |
| 1.7 |
| 8 pm |
| 1.1 |
| 9 pm |
| 0.2 |
| 10 pm |
| -0.8 |
| 11 pm |
| -1.5 |
Boston, MA,
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