Transcript Power Point Slide Show

Surf Forecasting Today
In search of the perfect southern hemi session
Nathan Cool
www.NathanCool.com
Agenda
• The pebble in the pond, forecasting principle
• Tools of the trade:
• WAMs
• Data Mining
• Weather models
• WAMs in-depth
• Forecast Accuracy
• Dissecting data (automatic data mining)
• Forecasting examples, tracking SW swells
• Near-term swell verification
• Seasonal Surf Forecasting
• Q&A and web resources
The Pebble and the Pond
Ripples across the ocean
The Principle
• Wind (the pebble)
• Transfers energy to water
• Waves are created
• Travel outward
• Eventually reaching shore
The Practice
• Track ocean storms
• Measure energy
• Measure distance to shore
• Wax your board
The Tools of the Trade
Wave Analysis Models (WAMs)
Model Data
Weather Models
Wave Analysis Models (WAMs)
Your Tax Dollars at Work
• FNMOC
• NOAA
• NWS
Date
Dissecting a WAM
Wave Heights
Forecast
Date
Heights
Scale/Key
Date
Dissecting a WAM
Periods
Forecast
Date
Periods
Scale/Key
The WAM Crystal Ball
A model look at the future
Today
Sacrificing Accuracy
Tomorrow
48 Hours
144 Hours
Weather Models
Your Tax Dollars, Still At Work
• FNMOC
• NOAA
• NWS
WAM Raw Data
Grabbing the middle-man
Data
Monitoring
Mechanisms
• Wind data (wind fields)
• Sea surface temperatures
• Ice concentrations
• Bathymetry/obstruction data
Model
WAM Raw Data
Number Crunching Behind the Scenes
For any point on the planet
(“Virtual” Buoys)
Thus….
WAM Raw Data
Making a near-shore chart
Data
Charts
(Near-shore estimates)
Monitoring
Mechanisms
• Wind data (wind fields)
• Sea surface temperatures
• Ice concentrations
• Bathymetry/obstruction data
Tracking A Southern Hemi
From the Southern Ocean to SoCal
The essentials
• Distance
• Angle
• Trajectory
• Wave Height
• Period
Tracking A Southern Hemi
From the Southern Ocean to SoCal
• Distance: ~5200 nm
• Angle (A): ~210°
• Trajectory (T): ~45°
• Wave Height: ~36 feet
• Period: 15 seconds
270
~210
180
Tracking A Southern Hemi
The Numbers for SoCal
• Distance: ~5200 nm
• Angle (A): ~210°
• Trajectory (T): ~45°
• Wave Height (Wh): ~36 feet
• Period (p): 15 seconds
• Distance Decay (dd) = >85%
• Angular Decay (ad) = ~15%
Height (h) = ((Wh – dd) – ad)
Face Height = h * (p * 0.1)
Time = Distance / (p * 1.5)
Height = (35’ – 85%) - 15% = 4.4’
Face Height = 4.4 * (15 * 0.1) = 6.6 feet
Time = 5200 nm / (15 * 1.5) = 231 hours (~ 9 days)
The SW Next Week
Originating 2/17/08, Hitting SoCal 2/27/08
• Distance: ~5300 nm
• Angle (A): ~220°
• Trajectory (T): ~30°
• Wave Height (Wh): ~40 feet
• Period (p): 16 seconds
• Distance Decay (dd) = >87%
• Angular Decay (ad) = ~10%
Height (h) = ((Wh – dd) – ad)
Face Height = h * (p * 0.1)
Time = Distance / (p * 1.5)
Height = (40’ – 87%) - 10% = ~4 - 5’
*Face Height = 4 to 5 * (16 * 0.1) = 6 to 8 feet (based on 24h projection)
Time = 5300 nm / (16 * 1.5) = 220 hours (~ 9 days)
Height = (35’ – 87%) - 10% = ~4’
*Face Height = 4 * (16 * 0.1) = 6 feet max (based on 0h projection)
Time = 5300 nm / (16 * 1.5) = 220 hours (~ 9 days)
The SW Next Week
Shoaling Considerations
6’
4’
Face Height = 4 * (16 * 0.1) = 6 feet max
Face Height Approximations
Steep Shoaling:
h * (p * 0.1)
Slow-sloped Shoaling: h * (p * 0.075)
So…
Steep Shoaling:
= 4 * 1.6 = 6 foot face height
Slow-sloped Shoaling) = 4 * 1.2 = 4-5 foot face
Or…
4 to 6 foot face heights max (chest to head high max)
The SW Next Week
Energy as it moves across the Pacific
• Calculate Forerunners
• Reaffirm ETA by distance
• Reaffirm angle
Indicators
Near-term verification by buoys
Indicators
Near-term verification by CDIP
9-Period Bands
Buoy history
Now-cast Model
But, initialized at Pt. Conception
Seasonal Forecasting
Jetstream (recent January swell)
•Low latitude
•Strong
•But slight nudge northward
By comparison though…
Seasonal Forecasting
Jetstream (summertime pattern)
•Higher latitude
•Weaker south
Seasonal Forecasting
Jetstream (the SW next week)
• Bending northward
Seasonal Forecasting
ENSO
• La Niña: weaker southern hemi jetstream
• Better chance for storms to drift north
• Fewer Pacific hurricanes
• Better chance for Atlantic hurricanes
• El Niño: stronger southern hemi jetstream
• Less chance for storms to drift north
• More Pacific hurricanes
• Blows out Atlantic hurricanes
Q&A
Presentation available at: www.WaveCast.com/groundswell
Resources
• FNMOC WAMs and Wx Models: https://www.fnmoc.navy.mil/public/
• NOAA WAMs: http://polar.ncep.noaa.gov/waves/main_text.html
• Surf Forecast Guide: http://www.amazon.com/gp/product/059530365X
• Swell Distance Calculator: http://wavecast.com/guide/distance.shtml
• Distance formulas: http://www.meridianworlddata.com/Distance-Calculation.asp
• WW3 Raw Data: http://polar.ncep.noaa.gov/waves/products.html
• CDIP: http://cdip.ucsd.edu/
• Jetstream Analysis: http://squall.sfsu.edu/crws/jetstream.html
• National Data Buoy Center: http://www.ndbc.noaa.gov/
• ENSO, Climate Prediction Center: http://www.cpc.noaa.gov/
• Free Surf Forecasts: http://WetSand.com