CRNW Forecast of 2021-0414 (Wed p.m.)

Yes, I think we will have some rather consistent swell. Winds should be cooperative. We may have some rainy afternoons with an early Green Season. Looks like several days could be overhead when I look at the raw numbers for swell size and periodicity.

 

I guess the model below had a brain fart!

 SURFLINE.COM Virtual Buoy Forecast    
  Model Cycle: 2021 APR 14 12Z          
  Time Zone: GMT - 6 hours              
-------------------------------------------------------------
             SURF    SURF DIR  SWELL  PERIOD   WIND    WND/DIR
             (m )       (deg)   (m )   (sec)   (kts)     (deg)
            -------  --------  -----  ------  -------  -------
4/14   6am   1 -  2   SW 219    1.1    17.8    5 -  7  ENE  66
4/14  12pm   1 -  2   SW 218    1.1    17.7    6 -  8  SSW 201
4/14   6pm   1 -  2   SW 217    1.2    17.0    4 -  6    S 182
 

4/15   6am   1 -  2   SW 218    1.2    16.6    7 -  9   NE  42
4/15  12pm   1 -  2   SW 218    1.3    16.3    2 -  3  WNW 283
4/15   6pm   1 -  2   SW 218    1.3    15.9    5 -  7  SSW 191
 
4/16   6am   1 -  2   SW 218    1.3    15.8   11 - 14   SE 140
4/16  12pm   1 -  2   SW 217    1.3    15.6    3 -  5   SE 147
4/16   6pm   1 -  2   SW 214    1.3    15.6    4 -  6  SSW 199
 
4/17   6am   1 -  2   SW 210    1.2    15.4    7 -  9  ESE 129
4/17  12pm   1 -  2   SW 213    1.3    14.9    7 -  9  SSE 169
4/17   6pm   1 -  2   SW 213    1.3    14.6    5 -  7  SSW 195
 
4/18   6am   1 -  2   SW 214    1.2    14.3    6 -  8  ESE 120
4/18  12pm   0 -  1  SSW 208    1.2    14.0    2 -  4  NNW 333
4/18   6pm   0 -  1  SSW 204    1.1    13.9    6 -  9  SSE 165
 
4/19   6am   0 -  1  SSW 206    1.1    14.0    3 -  4  ESE 111
4/19  12pm   0 -  1  SSW 207    1.1    13.8    1 -  1  WSW 254
4/19   6pm   0 -  1   SW 210    1.1    13.6    3 -  4  SSE 158
 
4/20   6am   1 -  2  SSW 207    1.2    19.1    4 -  5    E  88
4/20  12pm   1 -  2  SSW 208    1.2    18.9    6 -  8  SSW 199
4/20   6pm   1 -  2  SSW 196    1.3    17.9    5 -  7   SW 215
 
4/21  12am   1 -  2  SSW 198    1.3    17.5    2 -  4  ENE  79
4/21   6am   1 -  2  SSW 193    1.3    16.7    1 -  2    E  84

 

A secondary verdict confirms the first model output.

 

 

Periodicty and Swell Size Equal How Big a Wave?

 

The simple rules of periodicity and swell size... albeit I am a rank amateur here! But to quote the experts, in this example:

The longer the swell period, the more water gets pushed upward. A 3-foot wave with a 10-second swell period may only grow to be a 4-foot breaking wave, while a 3-foot wave with a 20-second swell period can jack up to be a 15-foot breaking wave given the right ocean floor bathymetry.

In our instance we have two potential examples, on the 20th and 22nd, but certainly on the 21st and 23rd as well. The angles of progress should be clear of Galapagos shadowing. So... we will just have to wait and see. Bathymetry is another factor but the water is deep out there. The swell direction is SSW and not extreme S, so it won't completely be flying past us.

The tide differentials are not great on the 20th to 23rd which to me is an important reason to consider paddling out. Later in the month when the tides move to the extremes I would err on staying inside around The Rock as so much water would be moving around... not to mention an outgoing tide combined with a 20mph Papagayo wind blowing! If you lost your mat it would be gone, gone, gone!!!

Here is a general table:

This table will help you estimate how big the waves will be based on the deep water swell height and period.
It is only a general guide based on a mathematical formula- every surf spot will take different heights and periods differently.
Reference: Airy wave theory and breaker height prediction, Komar & Gaughan. 1972

To quote swell matrix, "While this may seem like a disadvantage at first, it has several benefits for surfers. Every surfer knows:

• Some surf spots are bigger / better than others on a given day
• Tides make a huge difference on surf height and quality
• Wave period and direction are key factors in a spot going off
• Forecasts are never exactly right."