Weather Tools for Passage Planning

[mvweebles]

Nerd Alert/Warning - this is a pretty geeky discussion on weather intended as a spin-off thread from “Waiting for weather in Panama” thread. Recall, this was a 1200nm nonstop 7-day trip up the Caribbean Sea into head seas the entire way. While we had a bail-out options (Cayman Islands), it was essentially open ocean the entire way. Not a typical cruise by any means.

CAVEAT: the lists below are applicable for a fairly technical run into prevailing seas up the Caribbean Sea and includes dancing with the Gulf Stream much of the way. It's a pretty rare use case so you'll have to adjust for your style of cruising.

My objective here is to describe the weather tools we used (I say ‘we’ because the owner/captain is very experienced with 20k miles of cruising experience between Alaska and no Florida. We view one another as peers – so we discussed a LOT though final decision was his). Please keep in mind that due to the challenging nature of a 1200nm open ocean passage, we used every tool we could muster or pay for. Much of what follows is overkill for what I needed to get from San Francisco to Panama.

First, here is a list of all the weather tools used roughly in order from most frequent to least frequent:

• PredictWind (Standard Package - $250/yr) and (Pro Package - $500/yr – includes currents).
• Windy.com ($29/yr subscription)
• Chris Parker Weather Router ($550/yr subscription - he has shorter duration subscriptions too)
• TimeZero Weather Overlay (part of upgraded TZ package)
• Synoptic Charts (48-hr surface especially) from NOAA Ocean Prediction Center (free)
• Passageweather.com (free)
• Pilot Charts for seasonal trends – free (PredictWind has a useful function for this).

Other weather tools I’ve used in the past (no particular order)

• Dashews “Mariners Weather Handbook” old be useful (and it’s free!).
• FastSeas ($60/yr – provides routing and currents; 3-free forecasts per month). It's a bit clunky but decent value.
• BuoyWeather (it’s been several years but was my go-to for day-trips)
• Sirius Weather ($50/mo – seems similar to TZ Weather)
• VHF/NavTex Radio Wx (close to obsolete)
• WeatherFax (obsolete)
• SSB (obsolete)

For the most part, Starlink is the connective tissue for current weather information.

Some random notes and thoughts:

• PredictWind Standard Package is a good deal even at $250/yr. Why? It provides routing meaning it will predicts a moving forecast based on departure time and speed. It also helps plan when is best to depart with up to four forecasts. We used them at 24-hour intervals to decide when was best to leave Panama.
• PredictWind Pro ($500) is probably only a good value when dealing with heavy currents such as the Gulf Stream. I’ll add that I am highly suspect of where the data comes from – I don’t think anyone has good source data for currents.
• Windy is a good ‘spot’ tool to check conditions. Used it a lot.
• Euro vs US models. Pick one and stay with it. I like the US/GFS model only because I once when I was talking with a NOAA meteorologist and noted that many cruisers think the ECMWF (Euro) is more accurate, he responded “Do you really think if we had access to better data we wouldn’t use it?” I hear a lot of people who ‘model shop’ meaning they talk about which model is this or that. To me, it’s technical butt-sniffing.
• Whatever model you chose, view Wind GUSTS and make sure you view Wind Waves and Swell information. And if you’re near the Gulf Stream, look for wind against current. More than about 15-kts of wind against a couple knots of current can get messy.
• Using a weather router (Chris Parker in this instance). Mixed bag for a powerboat. Parker hosts a Zoom call each morning for subscribers and will discuss general weather patterns. He also sends a morning weather forecast for the areas relevant to your passage plan. I found his information most useful for mid-term planning – when to expect the next general weather window which is especially useful coming up the Caribbean as weather windows can be many weeks apart. I personally found his daily updates less useful for two reasons: First, I am fairly comfortable with <72-hour forecasting. Second, once you’re underway, not much you can do so you have to deal with whatever is coming anyway. Also, forecasts can be highly perishable – when were going to cross the Gulf Stream after rounding west end of Cuba, Parker advised crossing at a right angle due to winds out of the NE against the Gulf Stream. He did not accurately calculate our boat speed so by the time we arrived at Cuba’s west end (San Antonio), we were 12-18 hours behind his schedule. Conditions were fairly benign so we made a decision to abandon Parker’s guidance and ride the stream with a 3-kt bump in speed. It was the right decision for us at the time. My biggest takeaway when using a professional router (I’ve used one three times) is: They are a data point, not a guidepost or recipe.
• I feel strongly that if anyone wants to cruise any distance in open waters (say, more than 50-miles at a clip in open water), NOAA/OPC Synoptic Charts are useful to understand. Why do you need them when Windy/PredictWind does the work for you? Because the Synoptic Charts help understand why the forecast is what it is. Also, surface charts have a human overlay to them – an adult in the room vs a pure algorithm (each chart is ‘signed’ by a NOAA meteorologist). I find the 48-hour surface chart the most intuitive visual on how pressure gradients will move - h/l pressures, cold fronts, etc.

There’s a ton more to say on this topic but wanted to at least collect my thoughts on what we used and how we used the tools. I have monitored this region for over a year in contemplation of bringing my tiny Willard 36 Weebles to Florida. I cannot over-estimate my focus on weather. Pilot Charts to pick the right month, PredictWind to pick the right day. Surface charts to monitor changes in pressure gradients. On my list to learn are 500mb charts as they pre-sage surface activities and give ‘high beams’ to see further down the weather highway.

Hope this helps someone.

Peter