Weather forecasting and routing for the 1st week/ はじめ1週間の天気予報とルート


Route: San Diego, CA to Japan

Departure: Sun, Feb 24, 2019

Prepared: 1500utc Sat, Feb 23, 2019


1) A broad and fairly weak area of high pressure is centered out near 35n/129w off of the California coast.

2) A weak and broad thermal low pressure trough is located along the Baja and the Sea of Cortez area.

3) Low pressure across the SW Gulf of Alaska has a front stretching to the SE and S with the tail end near eastern Hawaii.

4) This pattern does not have a lot of decent wind speeds off the coast and along your route for quite a distance out and we will need to head south toward the trade winds to start as this pattern will not be changing a whole lot over the next week.

5) Also will need to avoid heading too far west/SW early on as this will put you into more persistent light winds close to a high pressure ridge axis, and best to stay a bit more E and SE of the ridge for at least some breeze.

6) It looks okay to head directly off the coast Sunday getting west of the shipping channels with some NW breeze to carry you out.

7) Tue and Wed will feature a large area of light winds with high broad high pressure around 25-30n/120-125w.

a) There will be some NW to N to NNE wind east of 120w, so recommend staying east of there through


8) The high will dissipate and reform a bit to the west by Thu so you can be heading more SW by then.

a) The only issue is that winds will veer more into the NE and become more from behind, so you may

need to do some short gybes in dead downwind conditions.

9) It looks like we will need to continue SW for a few days and not turn west until likely south of 20n to avoid SW-W head winds north of 20n in the longer term as cold fronts continue to stretch well to the south this time of the year.

a) We will probably need to fine tune exactly when to turn more west as we get closer about a week

and a half from now.

10) Seas will not be too bad for most of the first week out with some long period NW swell but mainly in the slight range and limited or nil wind waves, then some building swells from the NW toward next weekend but this will continue to have a long period to it.

11) General weather will have a fair amount of cloudiness once offshore over the colder waters but otherwise not much going on the first week out.

12) We have noted to update you every 3 days to start for the first 9 days of the trip, so the next forecast will be on Tuesday the 26th.

13) Once underway please update us each day with your position, heading, boat speed and weather conditions so we can keep close track of you.


1) With it being late winter the storm track is still well to the south and bringing SW to W head winds along a direct route to Hawaii, so we will need to route well SE and S of rhumb line to avoid head winds.

2) Also best to try and stay east of persistent high pressure and associated light winds to the west of the route outlined below.

3) Once out away from the coast a bit and out of the main shipping channels head mainly south for a few days around 119-120w.

4) Then around 26n/120w it looks okay to start heading more SW toward persistent trade winds to around 20n/127 30w or so for now.

a) Depending on storm track and areas of light winds, we may have to adjust routing in the longer

term, but this looks like a good start.

5) Some estimated positions listed below.

Wind forecast

Time is UTC: Wind directions are TRUE / wind speed in kts

Sun, Feb 24

18: 310-330/ 6-12 approx departure

Weather…Fair to partly cloudy

Seas 2-4 ft

Mon, Feb 25

00: 290-310/10-16

06: 300-320/ 8-15

12: 310-330/ 8-14

18: 330-350/ 5-10 near 31 15n/118 50w

Weather…Partly to mostly cloudy

Seas 3-4 ft, long period NW swell

Tue, Feb 26 – large area of light winds near high

00: 300-320/ 7-13

06: 300-320/ 5-10

12: 300-320/ 4-8

18: 290-310/ < 7 near 29 15n/119w

Weather…Variable cloudiness

Seas 2-4 ft

Wed, Feb 27

00: 320-340/ 5-10

06: 350-010/ 5-9

12: 360-030/ 4-8

18: 030-050/ 6-11 near 27 10n/119 20w

Weather…Mostly cloudy

Seas 2-4 ft

Thu, Feb 28 – improving conditions getting south into the trades

06: 010-030/ 8-14

18: 030-050/13-19 near 25 15n/120 40w

Weather…Mostly cloudy

Seas building to 4-6 ft, long period NW swell

Fri, March 1 – winds lighter to the NW and W

06: 030-050/11-17

18: 360-020/ 7-14 near 24n/122 15w

Weather…Mostly cloudy

Seas building to 6-8 ft, long period NW swell

Sat, March 2 – winds lighter to the N and NW

06: 060-080/ 8-15

18: 060-080/10-16 near 22 50n/123 50w

Weather…Mostly cloudy

Seas diminishing to 4-6 ft, NW swell


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