Surf Forecasting TodaySurf Forecasting TodayIn search of the perfect southern hemi sessionIn search of the perfect southern hemi session

Nathan Coolwww.NathanCool.com

AgendaAgenda

• 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 PondThe Pebble and the PondRipples across the oceanRipples across the ocean

• Wind (the pebble)Wind (the pebble)• Transfers energy to waterTransfers energy to water• Waves are createdWaves are created• Travel outwardTravel outward• Eventually reaching shoreEventually reaching shore

• Track ocean storms Track ocean storms • Measure energy Measure energy • Measure distance to shoreMeasure distance to shore• Wax your boardWax your board

The PrincipleThe Principle

The PracticeThe Practice

The Tools of the TradeThe Tools of the Trade

Wave Analysis Models (WAMs)

Model Data

Weather Models

Wave Analysis Models (WAMs)Wave Analysis Models (WAMs)

Your Tax Dollars at WorkYour Tax Dollars at Work• FNMOCFNMOC• NOAANOAA• NWSNWS

Dissecting a WAMDissecting a WAMWave HeightsWave Heights

Heights

Scale/Key

Date

Forecast Date

Dissecting a WAMDissecting a WAMPeriodsPeriods

Periods

Scale/Key

Date

Forecast Date

The WAM Crystal BallThe WAM Crystal BallA model look at the futureA model look at the future

Today

Tomorrow

48 Hours

144 Hours

Sacrificing Accuracy

Weather ModelsWeather Models

Your Tax Dollars, Still At WorkYour Tax Dollars, Still At Work• FNMOCFNMOC• NOAANOAA• NWSNWS

WAM Raw DataWAM Raw DataGrabbing the middle-manGrabbing the middle-man

Monitoring Mechanisms

Data

Model

• Wind data (wind fields)• Sea surface temperatures• Ice concentrations• Bathymetry/obstruction data

WAM Raw DataWAM Raw DataNumber Crunching Behind the ScenesNumber Crunching Behind the Scenes

For any point on the planetFor any point on the planet(“Virtual” Buoys)(“Virtual” Buoys)

Thus….

WAM Raw DataWAM Raw DataMaking a near-shore chartMaking a near-shore chart

DataCharts

(Near-shore estimates)

Monitoring Mechanisms

• Wind data (wind fields)• Sea surface temperatures• Ice concentrations• Bathymetry/obstruction data

Tracking A Southern HemiTracking A Southern HemiFrom the Southern Ocean to SoCalFrom the Southern Ocean to SoCal

The essentialsThe essentials• DistanceDistance• AngleAngle• TrajectoryTrajectory• Wave HeightWave Height• PeriodPeriod

Tracking A Southern HemiTracking A Southern HemiFrom the Southern Ocean to SoCalFrom the Southern Ocean to SoCal

• Distance: ~5200 nmDistance: ~5200 nm• Angle (A): ~210°Angle (A): ~210°• Trajectory (T): ~45°Trajectory (T): ~45°• Wave Height: ~36 feetWave Height: ~36 feet• Period: 15 secondsPeriod: 15 seconds

To

SoC

al

Trajectory

270

180~210

T

A

Tracking A Southern HemiTracking A Southern HemiThe Numbers for SoCalThe Numbers for SoCal

• Distance: ~5200 nmDistance: ~5200 nm• Angle (A): ~210°Angle (A): ~210°• Trajectory (T): ~45°Trajectory (T): ~45°• Wave Height (Wh): ~36 feetWave Height (Wh): ~36 feet• Period (p): 15 secondsPeriod (p): 15 seconds

To

SoC

al

TrajectoryT

A

• Distance Decay (dd) = >85%Distance Decay (dd) = >85%• Angular Decay (ad) = ~15%Angular Decay (ad) = ~15%

Height (h) = ((Wh – dd) – ad)Height (h) = ((Wh – dd) – ad)Face Height = h * (p * 0.1)Face Height = h * (p * 0.1)Time = Distance / (p * 1.5)Time = Distance / (p * 1.5)

Height = (35’ – 85%) - 15% = 4.4’Height = (35’ – 85%) - 15% = 4.4’Face Height = 4.4 * (15 * 0.1) = Face Height = 4.4 * (15 * 0.1) = 6.6 feet6.6 feetTime = 5200 nm / (15 * 1.5) = 231 hours Time = 5200 nm / (15 * 1.5) = 231 hours (~ 9 days)(~ 9 days)

The SW Next WeekThe SW Next WeekOriginating 2/17/08, Hitting SoCal 2/27/08Originating 2/17/08, Hitting SoCal 2/27/08

• Distance: ~5300 nmDistance: ~5300 nm• Angle (A): ~220°Angle (A): ~220°• Trajectory (T): ~30°Trajectory (T): ~30°• Wave Height (Wh): ~40 feetWave Height (Wh): ~40 feet• Period (p): 16 secondsPeriod (p): 16 seconds

To S

oCal

Trajectory

T

A

• Distance Decay (dd) = >87%Distance Decay (dd) = >87%• Angular Decay (ad) = ~10%Angular Decay (ad) = ~10%

Height (h) = ((Wh – dd) – ad)Height (h) = ((Wh – dd) – ad)Face Height = h * (p * 0.1)Face Height = h * (p * 0.1)Time = Distance / (p * 1.5)Time = Distance / (p * 1.5)

Height = (40’ – 87%) - 10% = ~4 - 5’Height = (40’ – 87%) - 10% = ~4 - 5’*Face Height = 4 to 5 * (16 * 0.1) = *Face Height = 4 to 5 * (16 * 0.1) = 6 to 8 feet 6 to 8 feet (based on 24h projection)(based on 24h projection)

Time = 5300 nm / (16 * 1.5) = 220 hours Time = 5300 nm / (16 * 1.5) = 220 hours (~ 9 days)(~ 9 days)

Height = (Height = (35’35’ – 87%) - 10% = ~ – 87%) - 10% = ~44’’*Face Height = *Face Height = 44 * (16 * 0.1) = * (16 * 0.1) = 6 feet max6 feet max (based on 0h projection)(based on 0h projection)

Time = 5300 nm / (16 * 1.5) = 220 hours Time = 5300 nm / (16 * 1.5) = 220 hours (~ 9 days)(~ 9 days)

The SW Next WeekThe SW Next WeekShoaling ConsiderationsShoaling Considerations

Face Height = Face Height = 4 * (16 * 0.1) = 6 feet max

Face Height ApproximationsFace Height ApproximationsSteep Shoaling: h * (p * 0.1) Steep Shoaling: h * (p * 0.1) Slow-sloped Shoaling: h * (p * 0.075)Slow-sloped Shoaling: h * (p * 0.075) So…So…Steep Shoaling: = 4 * 1.6 = 6 foot face heightSteep Shoaling: = 4 * 1.6 = 6 foot face heightSlow-sloped Shoaling) = 4 * 1.2 = 4-5 foot faceSlow-sloped Shoaling) = 4 * 1.2 = 4-5 foot faceOr…Or…4 to 6 foot face heights max (chest to head high max)4 to 6 foot face heights max (chest to head high max)

6’

4’

The SW Next WeekThe SW Next WeekEnergy as it moves across the PacificEnergy as it moves across the Pacific

• Calculate ForerunnersCalculate Forerunners• Reaffirm ETA by distanceReaffirm ETA by distance• Reaffirm angleReaffirm angle

IndicatorsIndicatorsNear-term verification by buoysNear-term verification by buoys

IndicatorsIndicatorsNear-term verification by CDIPNear-term verification by CDIP

9-Period BandsBuoy history

Now-cast ModelBut, initialized at Pt. Conception

Seasonal ForecastingSeasonal ForecastingJetstream (recent January swell)Jetstream (recent January swell)

•Low latitudeLow latitude•StrongStrong•But slight nudge northwardBut slight nudge northward

By comparison though…By comparison though…

Seasonal ForecastingSeasonal ForecastingJetstream (summertime pattern)Jetstream (summertime pattern)

•Higher latitudeHigher latitude•Weaker southWeaker south

Seasonal ForecastingSeasonal ForecastingJetstream (the SW next week)Jetstream (the SW next week)

• Bending northwardBending northward

Seasonal ForecastingSeasonal ForecastingENSOENSO

• La Niña: weaker southern hemi jetstreamLa Niña: weaker southern hemi jetstream• Better chance for storms to drift northBetter chance for storms to drift north• Fewer Pacific hurricanesFewer Pacific hurricanes• Better chance for Atlantic hurricanesBetter chance for Atlantic hurricanes

• ElEl Niño: stronger southern hemi jetstream Niño: stronger southern hemi jetstream• Less chance for storms to drift northLess chance for storms to drift north• More Pacific hurricanesMore Pacific hurricanes• Blows out Atlantic hurricanesBlows out Atlantic hurricanes

Q&AQ&A

• FNMOC WAMs and Wx Models: FNMOC WAMs and Wx Models: https://www.fnmoc.navy.mil/public/• NOAA WAMs: NOAA WAMs: http://polar.ncep.noaa.gov/waves/main_text.html• Surf Forecast Guide: Surf Forecast Guide: http://www.amazon.com/gp/product/059530365X• Swell Distance Calculator: Swell Distance Calculator: http://wavecast.com/guide/distance.shtml• Distance formulas: Distance formulas: http://www.meridianworlddata.com/Distance-Calculation.aspwww.meridianworlddata.com/Distance-Calculation.asp

ResourcesResources

Presentation available at: www.WaveCast.com/groundswell Presentation available at: www.WaveCast.com/groundswell

• WW3 Raw Data: http://polar.ncep.noaa.gov/waves/products.htmlWW3 Raw Data: http://polar.ncep.noaa.gov/waves/products.html• CDIP: http://cdip.ucsd.edu/CDIP: http://cdip.ucsd.edu/• Jetstream Analysis: http://squall.sfsu.edu/crws/jetstream.htmlJetstream Analysis: http://squall.sfsu.edu/crws/jetstream.html• National Data Buoy Center: http://www.ndbc.noaa.gov/National Data Buoy Center: http://www.ndbc.noaa.gov/• ENSO, Climate Prediction Center: http://www.cpc.noaa.gov/ENSO, Climate Prediction Center: http://www.cpc.noaa.gov/• Free Surf Forecasts: http://WetSand.comFree Surf Forecasts: http://WetSand.com