• 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.

Barometric Pressure statements, do you agree?

B

BAD ORCA

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Nov 6, 2020
511
Mariner 36 California
We are having a very windy day today at the work shop. 20-25 sustained winds all day with frequent gusts 30-35. Barometric pressure has been about 987 all day. Was reading a bit about barometric readings after dinner tonight and came across an article that made a few statements regarding short term trend as it relates to mariners. I am curious from those of you with lots of offshore sailing experience with barometers would you generally agree with t he following statements?

* a pressure drop of 3-5 millibars in about three hours suggests a strong weather system approaching.
* a slower, steady drop less than 3-5 millibars over a longer time frame indicates a low pressure far offshore.
* a fall of 6-8 millibars in three hours is serious and warrants immediate action and preparation, or to seek shelter as a serious storm is approaching.

I have a good barometer on the boat and a little sensor type i can use on my phone as a backup. I dont sail far offshore yet, but in anticipation of doing so in the future, am trying to learn how to properly develop an understanding of how to interpret what changes it makes, with regard to how fast those changes happen, and what to expect.

I know barometers are useful, and i think i have a good general understanding of the basic readings, but how much do you guys really rely on them offshore compared to just looking at a weather chart? I suppose their real value is when charts are not available, but in general, i'd be really curious to learn how many of you swear by them offshore, and what some of your personal observations from experience might be?
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,152
Catalina 34 224 Maple Bay, BC, Canada
In general, your observations are appropriate. Short time large drops of the barometer indicate bad things are on the way. Longer time slow drops means low pressure is coming, not necessarily "offshore" because this can happen in Kansas, too. :) The difference between isobars over distance indicates the strength of wind, as well as just pressure quantity.

However, most folks on this forum are coastal or lake sailors. I suggest asking your question on www.cruisersforum.com, where more of them are really offshore skippers.
 
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Likes: kloudie1 and jssailem
B

BAD ORCA

.
Nov 6, 2020
511
Mariner 36 California
Stu Jackson said:
In general, your observations are appropriate. Short time large drops of the barometer indicate bad things are on the way. Longer time slow drops means low pressure is coming, not necessarily "offshore" because this can happen in Kansas, too. :) The difference between isobars over distance indicates the strength of wind, as well as just pressure quantity.

However, most folks on this forum are coastal or lake sailors. I suggest asking your question on www.cruisersforum.com, where more of them are really offshore skippers.
Click to expand
Ha! yes good point. To me. everything within about a 1500 mile radius is 'offshore'. Ah yes cruiser forums. I forget about sailing anarchy as well. I think there is also many offshore sailors there.
 
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