Saturday, July11, 2020
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Marine Weather and Tides
West Chatham, MA

Version 3.4
NOTICE
12/16/2019 NOAA is having trouble with requests that include wind gusts. I am posting graphs without wind gusts until it gets fixed.
10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.

Sunrise 5:15AMSunset 8:17PM Saturday July 11, 2020 12:27 PM EDT (16:27 UTC) Moonrise 12:00AMMoonset 11:37AM Illumination 63% Phase: Waning Gibbous; Moon at 21 days in cycle
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.
Marine Forecasts
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ANZ254 Coastal Waters From Provincetown Ma To Chatham Ma To Nantucket Ma Out 20 Nm- 1016 Am Edt Sat Jul 11 2020
.small craft advisory in effect through Sunday evening...
This afternoon..S winds 10 to 15 kt with gusts up to 25 kt. Seas around 5 ft. Patchy dense fog. Vsby 1 nm or less.
Tonight..S winds 10 to 15 kt with gusts up to 25 kt. Seas 5 to 6 ft.
Sun..SW winds 10 to 15 kt with gusts up to 25 kt. Seas around 6 ft.
Sun night..SW winds 10 to 15 kt. Gusts up to 25 kt in the evening. Seas around 6 ft.
Mon..SW winds 5 to 10 kt, becoming S 10 to 15 kt in the afternoon. Seas around 5 ft.
Mon night..S winds 10 to 15 kt, becoming sw 5 to 10 kt after midnight. Seas around 6 ft. A chance of showers.
Tue..SW winds 5 to 10 kt. Seas 5 to 6 ft.
Tue night..W winds 5 to 10 kt. Seas around 5 ft.
Wed..W winds 5 to 10 kt, becoming S in the afternoon. Seas around 5 ft.
Wed night..SW winds 5 to 10 kt. Seas 4 to 5 ft. 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 1016 Am Edt Sat Jul 11 2020
Synopsis for massachusetts and rhode island coastal waters.. High seas and gusty winds from tropical storm fay will impact mostly the south coast and outer eastern waters today with high surf and dangerous rip currents. A cold front will cross the waters early Sunday and another cold front crosses the water Monday. Warm front lifts north on Wednesday. For information on possible hazardous weather beyond the 24-36 hour forecast period, please visit www.weather.gov/boston and follow the current hazards link above the map on the left.


7 Day Forecast for Marine Location Near West Chatham, MA
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location: 41.73, -69.97     debug


Area Discussion for - Boston, MA
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FXUS61 KBOX 111456 AFDBOX

Area Forecast Discussion National Weather Service Boston/Norton MA 1056 AM EDT Sat Jul 11 2020

SYNOPSIS. It will be quite warm and very humid today with a few afternoon thunderstorms possible across western Massachusetts and northern Connecticut. It will be dry and a bit less humid on Sunday, but highs will top out in the upper 80s to lower 90s during the afternoon. Slightly cooler and less humid conditions for Monday and Tuesday. Heat and humidity returns on Wednesday and Thursday.

NEAR TERM /UNTIL 6 PM THIS EVENING/. 1045 AM Update:

Forecast generally is holding up. However per obs and webcams and mariner reports in Nantucket Sound, added areas of patchy fog across Cape Cod and the adjacent waters. Areas of fog should start to burn off as southerly winds start to pick up, but still looking at mostly to partly cloudy conditions.

A continued very warm and very humid day is on tap, but also a fairly breezy day as well as Fay's remnants continue to lift northward. While southerly gusts may top out around 30 mph, peak heat indices are still expected to reach the mid to upper 90s in the interior. So the breezes may not appreciably help break the heat much. At least through mid-afternoon, it is likely that most if not all areas stay dry.

However focus shifts towards convective potential for this afternoon. Did note on the Simple Water Vapor RGB a shortwave trough, possibly one that was convectively enhanced from yesterday's storms in the Ohio Valley, now swirling over the eastern shore of Lake Erie. This feature advances eastward today into central NY/northern PA. 500 mb height falls related to this disturbance and downstream destabilizing air mass across eastern NY and interior western New England should foster thunderstorms developing to our west around mid-afternoon, and potentially fairly numerous at that per recent high-res CAMs. It is this activity that we'll need to keep watch on as the day progresses. Though the past couple runs of the HRRR have started to introduce isolated storms into our far western areas as early as 2 PM, timing of any storms at any greater net coverage into the CT Valley in MA/CT probably wouldn't begin until around/after 4 PM. Though the best chance at storms today lies along/west of I-91, it still is unclear how far east this threat may exist. Though it's highly unlikely storms make it all the way to the coast or even into RI, the eastern extent of the storm threat may extend as far as a Fitchburg-western Worcester suburbs-Willimantic line. Deep-layer wind shear is fairly poor at 30 kt or less, so storms may exhibit pulse character. Strong to locally damaging straight line winds/water-loaded wet microbursts appear to be the primary severe weather threat. Of some concern is that the low- level flow is fairly strong. If surface winds back to southeast in the CT Valley as indicated by some high res guidance winds, that could enhance the low- level hodograph and lead to a very low but non- zero tornado risk with 0-1 km SRH values around 100-200 units following the RAP model. Given the continued very humid air mass with elevated PWATs, heavy rainfall capable of localized street flooding also possible in this western MA/northwest CT area today. Opted to raise awareness of the strong/severe storm threat with an SPS that runs through noon.

Previous Discussion .

The remnants of Fay will lift into northern New England this morning. This will bring an end to most of the lingering scattered showers through about 12z. Subsidence behind the remnants of Fay will lead to partial sunshine developing this morning. This will result in a very warm and humid day. Given the warm start and the strong July sun angle, expect afternoon highs to reach in the upper 80s to near 90 in many locations away from the immediate south coast where it will be a few degrees lower. More importantly, it will be very humid with dewpoints in the lower 70s across the entire region. The result will be heat index values in the middle to upper 90s across much of the region. Southwest wind gusts of 20 to 25 mph with a few gusts near 30 mph may help a little, but nonetheless it will be very humid.

The biggest concern this afternoon will revolve around convective chances mainly near and west of the CT River Valley. Somewhat of a complex setup and guidance is split on whether or not this threat remains west of our region or spills into parts of western MA/northern CT. Initial subsidence behind Fay will be a limiting factor, but a shortwave will induce convection to our south and west later today. The issue is that the shortwave passes west of our region and some of the guidance indicates the activity out running the better support and weakening on approach. While some of the high resolution CAMs show all storms dissipating before entering our region, the global models are more aggressive. They seem to hint at a lead shortwave which may induce an earlier round of convection near and west of the CT River Valley between 17z and 22z. We will have to see how things evolve, but modest instability will be present along with a rather strong low level wind field from the remnants of Fay. Soundings actually do indicate decent 0 to 1 KM helicity, so if activity develops it will need to be monitored closely. Updraft helicity seems to be lacking though, so perhaps they will not be able to tap the modest instability.

So in a nutshell, a few strong to severe thunderstorms are possible near and west of the CT River Valley this afternoon along with localized torrential rainfall. However, the higher risk will be southwest of our region where better upper support will be present.

High Surf Advisory .

We have gone ahead and issued a High Surf Advisory for ocean exposed beaches along the south coast and Islands. 7 to 8 foot seas are currently being observed across our southern outer-waters early this morning form the remnants of Fay. This will result in High Surf and dangerous rip currents for beachgoers.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/. Tonight .

Any left over convection across western MA/western CT should dissipate this evening. Otherwise, a dry but muggy night is in store for the region. Many locations will not drop below 70 given the high dewpoint air in place. Low clouds will once again develop in some locations and while some patchy fog is possible, enough wind should prevent it from becoming widespread or dense.

Sunday .

A surface trough will cross the region and shift winds from the south to the southwest. This will allow for a bit less humidity as dewpoints will drop into the 60s as mid level drier air mixes down. High temperatures will reach into the upper 80s to the lower 90s, so while the humidity will be somewhat less it will be very warm to hot during the afternoon. There is just a low risk for an isolated spot shower/t-storm in western MA during the afternoon, but that would probably be the worst of it given the amount of mid level dry air present in the soundings.

Surf Forecast .

We will likely need to consider High Surf and/or a Rip Current Statement given long period southerly swell along with excellent beach weather.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/. Highlights .

* More widespread showers and thunderstorms return Monday into Tuesday before a drying trend mid week

* A bit of a break in the heat and humidity Monday - Wed before more heat and humidity return late in the week

Details .

Flow remains meridional through Tuesday as one final shortwave rotates through the broad upper trough centered over the northeast. This keeps things unsettled, with periodic rain chances. By mid to late week the pattern becomes more zonal from coast to coast, and more difficult to time disturbances moving through the steering flow. Generally building high pressure looks to bring drier conditions and warmer than average temperatures through the end of the week.

The first day of the week features by far the best chance of widespread rain and thunderstorms. This as a sfc low pressure beneath the upper trough forms and tracks over New England, lifting northeast. At the sfc a warm front will bring rain and thunderstorm chances during the day ahead of the cold front which swings through late in the day. Again we'll have to monitor for some strong to severe thunderstorms given ample instability (CAPE >1000 J/kg, LL lapse rates ~7.5 C/km) and shear (30-35 kts 0-6 km shear) ahead of the better cold frontal forcing.

Drier post frontal air moves in with PWATs down <1" for the first time in quite a while, giving us a break from the tropical airmass. Still some uncertainty on the timing of the drier air, but it's looking like Tuesday will feel nicer with dewpoints dropping into the low 60s, especially in the interior. Again on Tuesday we may get a round of scattered showers and thunderstorms in the interior on the back side of the exiting low as some better moisture swings back around with a final lobe of energy aloft. Temperatures Mon-Tue will be cooler than the weekend beneath the trough, in the low to mid 80s.

By mid week the trough finally lifts out and is replaced by mid level ridging and a building high pressure at the sfc. Thus expecting drier weather with building temperatures and humidity each day under southwest flow.

AVIATION /15Z SATURDAY THROUGH WEDNESDAY/. Forecaster Confidence Levels .

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

15z TAF Update:

Today: High confidence.

Mix of flight categories, generally MVFR-VFR but with lower IFR-LIFR across the Cape/ACK. Improvement towards VFR for most of the interior and towards BOS-BED, but continued IFR to MVFR across the Cape. Possible strong thunderstorms BAF-CEF-BDL-HFD as soon as 19z, but best chance after 20z. South winds 10-15 kt gusts to 25 kt.

Tonight . Moderate confidence. A period of MVFR-IFR conditions may return for a time tonight in some locations given cooling boundary layer and very high dewpoints in place. Winds will shift from the S to the SW overnight, which may allowed for many locations to improve back to VFR levels toward daybreak.

Sunday . High confidence. VFR conditions with SW wind gusts of 20 to 25 knots by afternoon.

KBOS Terminal . High confidence in TAF.

KBDL Terminal . Moderate to high confidence in TAF. VCTS for SCT TSRA threat after 20z.

Outlook /Sunday Night through Wednesday/ .

Sunday Night: VFR. Breezy. Chance SHRA, slight chance TSRA.

Monday through Tuesday: VFR. Chance SHRA, slight chance TSRA.

Tuesday Night through Wednesday: VFR.

MARINE. Today through Sunday . High confidence.

An active weekend on the waters for July standards. The remnant wind field from Fay will result in S to SW wind gusts of 25 knots at times though the weekend and a few gusts up to 30 knots are possible. The strongest of the winds will be nearshore during the afternoon with good mixing from diurnal heating. Rough seas anticipated through the weekend no the order of 3 to 7 feet. Highest of those seas will be across our southern waters.

Outlook /Sunday Night through Wednesday/ .

Sunday Night: Winds less than 25 kt. Areas of rough seas.

Monday through Monday Night: Winds less than 25 kt. Areas of rough seas. Chance of rain showers, slight chance of thunderstorms.

Tuesday: Winds less than 25 kt. Areas of rough seas. Slight chance of rain showers, isolated thunderstorms.

Tuesday Night: Winds less than 25 kt. Local rough seas.

Wednesday: Winds less than 25 kt. Seas up to 5 ft.

BOX WATCHES/WARNINGS/ADVISORIES. CT . None. MA . High Surf Advisory until 6 PM EDT this evening for MAZ020-023- 024. RI . High Surf Advisory until 6 PM EDT this evening for RIZ006>008. MARINE . Small Craft Advisory until 8 PM EDT Sunday for ANZ231>235-237- 250-251-254>256. Small Craft Advisory until 6 PM EDT this evening for ANZ230. Small Craft Advisory until 8 PM EDT this evening for ANZ236.

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


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
CHTM3 3 mi130 min S 8 G 11 68°F 1009.6 hPa
44090 20 mi31 min 69°F1 ft
44020 - NANTUCKET SOUND 23 mi38 min S 16 G 19 71°F 72°F2 ft1008.7 hPa
NTKM3 - 8449130 - Nantucket Island, MA 31 mi58 min S 8 G 13 75°F 74°F1010 hPa
WAXM3 - Waquoit Bay Reserve, MA 31 mi103 min ESE 2.9 77°F 1009 hPa74°F
44018 - SE Cape Cod 30NM East of Nantucket, MA 34 mi38 min SE 12 G 16 69°F 3 ft1008.9 hPa (-0.4)68°F
BZBM3 - 8447930 - Woods Hole, MA 40 mi58 min 76°F 71°F1009.1 hPa

Wind History for Nantucket Island, MA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chatham, Chatham Municipal Airport, MA2 mi36 minVar 69.00 miOvercast75°F70°F84%1010.2 hPa
Hyannis, Barnstable Municipal-Boardman Airport, MA17 mi32 minS 103.00 miOvercast with Haze78°F73°F85%1009.3 hPa
Provincetown Municipal Airport, MA23 mi32 minS 15 G 2010.00 miFair79°F73°F85%1009 hPa

Link to 5 minute data for KCQX

Wind History from CQX (wind in knots)
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Tide / Current Tables for Pleasant Bay, Quonset Pont, Massachusetts
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Pleasant Bay
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Sat -- 01:30 AM EDT     0.43 feet Low Tide
Sat -- 05:15 AM EDT     Sunrise
Sat -- 06:46 AM EDT     3.19 feet High Tide
Sat -- 11:37 AM EDT     Moonset
Sat -- 01:58 PM EDT     0.23 feet Low Tide
Sat -- 07:18 PM EDT     3.02 feet High Tide
Sat -- 08:14 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.90.50.50.91.62.433.22.92.41.91.510.40.20.511.82.632.92.62.21.8

Tide / Current Tables for Pollock Rip Channel, Massachusetts Current
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Pollock Rip Channel
Click for Map
Sat -- 02:35 AM EDT     -0.00 knots Slack
Sat -- 05:16 AM EDT     Sunrise
Sat -- 05:16 AM EDT     -1.56 knots Max Ebb
Sat -- 08:24 AM EDT     0.00 knots Slack
Sat -- 11:37 AM EDT     Moonset
Sat -- 12:00 PM EDT     1.93 knots Max Flood
Sat -- 03:09 PM EDT     -0.00 knots Slack
Sat -- 05:51 PM EDT     -1.55 knots Max Ebb
Sat -- 08:14 PM EDT     Sunset
Sat -- 09:02 PM EDT     0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.71.30.6-0.4-1.2-1.5-1.5-1.1-0.30.51.31.81.91.71.10.2-0.8-1.4-1.5-1.3-0.8-00.81.3

Weather Map
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GEOS Local Image of Northeast    EDIT
NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
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Wind Forecast for Boston, MA (12,3,4,5)
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Ground Weather Radar Station Boston, MA
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Disclaimer:
The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerous of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.