• 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.

CAPE Index.... What does that mean?

jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
22,758
CAL 35 Cruiser #21 moored EVERETT WA
Before going to sea, many sailors, fearing thunderstorms, check CAPE.

Why?

CAPE — Convective Available Potential Energy — reflects the presence in the atmosphere of a certain amount of energy that can be used for convection.

Convection is the rise of heated warmer air surrounded by cooler air. Warm air is lighter than cold air, so it is displaced upwards.

The more available energy that can be used for convection there is, the more intensive convection will be.

More intensive means faster and higher. High CAPE values indicate a high rate of convection development.

Here is a look at 2 regions with different CAPE index values.
The Puget Sound 0 J/kg
Image 12-9-22 at 9.13 AM.jpeg

The Texas Coast 762 J/kg
Image 12-9-22 at 9.15 AM.jpeg
 
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jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
22,758
CAL 35 Cruiser #21 moored EVERETT WA
@ggrizzard
You will find it on Windy, as an item in the layer list on the right side of their screen.
Image 12-9-22 at 1.52 PM.jpeg
 
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JamesG161

JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
7,745
Hunter 430 Waveland, MS
Thermal Potential Energy or

Joules/Kilogram [J/Kg]

During the Tropical Storm season, we focus on the Ocean's Stored Heat as fuel.

CAPE is kinda the reverse, with that energy potential from Sky to Ground/Water.

Jim...
 
shemandr

shemandr

.
Jan 1, 2006
7,469
Slickcraft 26 Sailfish
There are three stages to a thunderstorm event while sailing:
1). You hear thunder. Crew member says "It's moving away from us."
2). Lightning is seen. Crew member says "It won't hit us."
3). All hell breaks loose. Wind, rain, lightning, waves, flapping sails, extreme heeling, noise and fear. Crew member shouts "Oh s**t it's here."
 
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