• Sailing is all about the Weather.

    Big into the exploration of Atlantic Hurricanes since Katrina came uninvited into his world, James (Jim) Gurley (JamesG161) has followed every Tropical Storm birthed in Atlantic, Gulf and Caribbean waters since. Being a boater, he knows that we often need more time to prepare than we get from the TV weather folk. Jim relies on the science of storm development to share early warning info with friends and fellow boaters.

    Early in 2018, Jim and John Shepard, (JSSailem) started to chat about the weather data available. John asked Jim to help forecast Pacific NW storms, and this morphed into discussions on weather forecasting.

    For John, sailing in the PNW is sometimes hit and miss. One day is ugly, then a string of beautiful days but no wind, followed by a series of blue-sky days and 12 knot breezes. Being ready for those great sailing days means you need to look to the Pacific Ocean and what is brewing. John has been into Pacific NW Weather since the 1970’s when his first PNW November storm hit bringing more than 40 days and 40 nights of continual rain.

    Together we want to share information, new APPs, safety, and thoughts about letting the weather help you. Identify some of the resources for sailors and help prepare you for your next sailboat outing.

    It is far better to go out on the water knowing what to expect in weather terms, than to be out on the water and see dark ominous clouds suddenly appear, unprepared.

Windfinder VS Local Knowledge

john6206

john6206

.
Feb 19, 2008
508
Catalina 320 Tawas Bay Yacht Club
Hello,
We‘re a little later in the year than we’d hoped moving our boat from its winter home in Bay City, MI to it‘s summer home in Tawas, MI. It seems our schedules and the weather have been at odds.

Our last attempt was last Monday. Forecast called for 15mph wind with gusts to 20; with 1.5-2’ waves. Seems like a great sail, right?
We had trouble with our roller furling and a rigger met us at the dock at 8AM.

”You’re not going to Tawas today are you?” (It was pretty calm when he said that)

He said with the wind out of the NE it is uninterrupted from Canada to Bay City, and he expected much higher wind and waves than the forecast called for. I’m not sure what the wind and waves peaked out at, but by the time we packed up and went home, the wind was steady at 22.

Our next chance to move the boat is this coming Monday, and the forecast looks pretty similar. Both wind and waves a little milder, but direction is E to NE all day.

I would tend to believe local knowledge over Windfinder,
what’s your take?

Thanks,

John
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
24,453
CAL 35 Cruiser #21 moored EVERETT WA
John
Try WINDY.com
Use their “Distance & route plan”function. Choose your start and finish location. Choose the date and time. Set your boat speed. Then watch the wind conditions play out over the route.
1780615734539.png
 
D

dlochner

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Jan 11, 2014
13,947
Sabre 362 113 Fair Haven, NY
Wind patterns over the Great Lakes act more like ocean winds than wind over land. Wind aloft is always stronger than wind at the surface due to less drag. On a long fetch the stronger winds will drop down over the surface and are stronger, which is what you observed. The lakes also develop short steep waves which makes going to weather in stronger winds really uncomfortable.

Use both the general forecast from Windy or PredictWind, taking into account the local conditions, like fetch to make a go/no go decision. Had you been on the eastern shore of Lake Michigan the wind and waves would be much different. A NE wind would be dampened by the shore and waves would not build as high. And remember, long windward legs are challenging and tiring. The motion is not easy and it will be wet with spray.
 
Davidasailor26

Davidasailor26

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May 17, 2004
6,108
Beneteau Oceanis 37 Havre de Grace
When local conditions are a factor you can try using the higher resolution models, like the NAM 3km model on WindAlert. 3km means more localized points are modeled than with the broader global models like GFS or ECMWF. The broader models just project winds at farther apart points, and then some algorithm is used to blend the speeds between points. The higher resolution models can actually produce forecasts for specific locations, rather than just averaging between nearby places. In my experience that gives better results for some things like sea breezes or funneled winds. Of course your mileage may still vary depending on the local topography, how well the models match the actual local factors, and how good NAM’s projection of the overall weather patterns are to begin with.
 
  • Helpful
Likes: jssailem
D

dlochner

.
Jan 11, 2014
13,947
Sabre 362 113 Fair Haven, NY
In addition to using models to predict conditions, NOAA provides some real time data on wind and sea state for the Great Lakes and elsewhere.

On Lake Michigan there are 2 mid lake monitoring buoys that collect sea state data. Unfortunately they do not collect wind data.

NDBC - Station 45214 Recent Data

National Data Buoy Center - Recent observations from buoy 45214 (42.674N 87.026W) - South Michigan Spotter.
www.ndbc.noaa.gov www.ndbc.noaa.gov

NDBC - Station 45210 Recent Data

National Data Buoy Center - Recent observations from buoy 45210 (44.055N 87.050W) - Rawley Point East, WI (269).
www.ndbc.noaa.gov www.ndbc.noaa.gov

Here's one privately maintained buoy on the NOAA site. This is a near shore buoy displaying wind and wave data.

NDBC - Station 45199 Recent Data

National Data Buoy Center - Recent observations from buoy 45199 (42.702N 87.647W) - Salmon Unlimited Wisconsin.
www.ndbc.noaa.gov www.ndbc.noaa.gov

There are many shore based weather stations that can be accessed through the National Data Buoy Center.

National Data Buoy Center

The National Data Buoy Center's home page. The premier source of meteorological and oceanographic measurements for the marine environment.
www.ndbc.noaa.gov www.ndbc.noaa.gov

In addition to the NOAA buoys there are weather research buoys deployed by private organizations conducting research on the Lakes. These are a little harder to keep track of because of funding.

To build your knowledge of local weather, monitor the buoys watching for trends and the effect of wind on wave height.

One characteristic on the E-W oriented lakes is the lag between a wind shift and a shift in the wave train. On Lake Ontario as the wind backs from N to W following a frontal passage the wave train will build from the NW and continue travel across the lake while a new pattern is building from a more southerly direction. This can lead to really confused seas with steep pyramidal waves as the wave trains collide. There can be some dicey sailing.
 
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