PAT CALDWELL
Mahalo for your Epic support.
All New Premium SNN sign ups get Pat’s forecasts Monday, Wednesday, and Friday.
Monday is FREE for all, and we offer Wednesday & Friday updates for Premium Members, just 5.00 a month (about a buck a week).
In addition to ALL Pat’s updates, you’ll also get the SNN 10-day forecasts plus our Multi Surf Cams free from Cam Ads & plenty viewing.
We are stoked for your support of all local surf companies!
Drop in Today! Aloha. SNN
SwellCaldWell Updated 3 PM Monday, March 18, 2024
DATE |
SWELL HGT |
SWELL DIR |
SWELL PER |
SURF H1/3 |
SURF H1/10 |
TREND |
PROB |
WIND SPD |
WIND DIR |
TREND |
12 PM |
5 |
WNW |
17 |
8 |
12 |
DOWN |
5-10 |
ENE |
SAME |
|
03/18 |
1.5 |
SSW |
17 |
3 |
6 |
SAME |
|
|
|
|
TUE |
4 |
NW |
12 |
6 |
8 |
DOWN |
MED |
9-14 |
ENE |
UP |
03/19 |
1.5 |
SSW |
15 |
3 |
5 |
DOWN |
LOW |
|
|
|
|
3 |
WNW |
19 |
6 |
8 |
UP |
LOW |
|
|
|
WED |
6.5 |
WNW |
16 |
10 |
14 |
UP |
LOW |
10-15 |
ENE |
UP |
03/20 |
1.4 |
SSW |
14 |
2 |
4 |
DOWN |
LOW |
|
|
|
THU |
5 |
NW |
14 |
6 |
10 |
DOWN |
LOW |
11-16 |
NE |
UP |
03/21 |
5 |
ENE |
6 |
1 |
2 |
UP |
LOW |
|
|
|
|
1.2 |
SSW |
12 |
1 |
3 |
DOWN |
LOW |
|
|
|
FRI |
3 |
NNW |
11 |
4 |
6 |
DOWN |
LOW |
13-19 |
NE |
UP |
03/22 |
6 |
ENE |
6 |
2 |
3 |
UP |
LOW |
|
|
|
SAT |
3 |
WNW |
18 |
5 |
7 |
UP |
LOW |
18-22 |
ENE |
UP |
03/23 |
8 |
ENE |
7 |
3 |
5 |
UP |
LOW |
|
|
|
Table Definitions given after Discussion
Summary
First day of spring arrives Tuesday, aloha winter, we’re going to miss you. Above average N shore midweek. Fresh to strong trades and building wind swell late in the week. SSW swell lingering
into midweek.
Discussion
Midday Monday 03/18 on northern shores has declining breakers near the seasonal average from 305-315 degrees of 14-20s periods under gentle trade winds. Heights should fall to moderate levels on Tuesday with a new, long-period, WNW building late in the day.
On this day, 03/18, in the historical H1/10 visual surf observation Goddard-Caldwell database (starting 9/1968) for the north shore of Oahu, the average is 7.0 Hs, (14’ peak face, Oahu Surf Climatology) and the largest surf on this date was 20 Hs (sets 40’ peak face top spots) in 2019 from NNW under 15 knot NE winds.
Moon’s view
- Series of lows coming off Asia spaced a few days apart last week into this week to winter-caliber strength, keeping the winter vibration in the Hawaiian surf.
Winter-caliber, NWPAC source 03/12-14—a Kuril hugger source on decline 03/18
- Backstory:
- A hurricane-force low deepened to 955 mb east of the Kuril Islands by early 03/13. The system was broad, with a wide long fetch over the 305-315 degree band 03/13-14 maintaining extreme winds. Seas grew over 35’ over a large area beyond 2300 nm away. The center stayed close to the Kuril Islands throughout.
- Pulse status:
- NOAA NW Hawaii buoy 51001 midday 03/18 has the dominant period down to 14s as energy levels slowly wane over the 12-16s band.
- PacIOOS/CDIP Waimea, Oahu buoy showed top readings near sundown Sunday 03/17 to the wee hours Monday 03/18. Deep water swell heights and dominant wave period are slowly shifting down into midday.
- Prognosis:
- Given the remote source, it takes time for the swell trains to unravel as the dominant wave period shifts down. This should ensure at least some moderate sets for Tuesday morning with a steady decline from 305-315 degrees.
NWPAC to Date Line source 03/15-18
- The next surface low formed 03/15 east of Japan. It tracked east near 40N, reaching about 2100 nm away (40N, 170E) with severe gales to storm-force winds 03/16 PM HST. Winds were strongest at this stage. The long-period energy from 300-310 degrees should be on the rise locally mid-afternoon Tuesday as heights slowly climb.
- The low center tracked ENE as it weakened 03/17, reaching the Date Line overnight. Seas were up to 30’ west of the Date Line, but mostly 20-25’ once in the western hemisphere. Models show it shifting N and fading 03/19-20.
- Surf should climb above average overnight Tuesday night. Peak of the swell is expected near noon on Wednesday from 305-320 degrees. Heights should remain moderate on Thursday morning from 310-330 degrees, then fall into the small bracket on Friday from the same direction.
Another Kuril hugger source 03/18-20
- The next low is east of Hokkaido 03/18. Models deepen the center to 976 mb on Tuesday with storm-force winds within 2400-2800 nm away. It weakens steadily on 3/20.
- This source is expected smaller in size and strength than the event that peaked locally Sunday night 03/17.
- It should have long-period onset Saturday, peak overnight likely below average from 300-310 degrees, and hold moderate through Sunday from the same direction.
Midday Monday 03/18 on eastern shores has breakers near an east side minimum. Heights should remain low on Tuesday.
Windward wind-head concerns —
- Surface high increasing through the week N of Hawaii, but Tuesday into Wednesday has some potential wind suppression from a nearby upper-level low. Better overhead stability going into the weekend, which should allow the pressure gradient across the islands to tighten. This would draw up some fresh breezes by late Thursday with a slow increase into the weekend.
East side surfer interests—
- Fetch too short and too weak early on this week, but a trend up Thursday into Saturday to near average for the weekend from 50-90 degrees.
Midday Monday 03/18 on southern shores has long-period swell from 185-200 degrees of 14-20s intervals with breakers near the seasonal average. Heights should hold about the same to a notch less on Tuesday (for the active spells at least, like any south swell—long lulls).
On this day, 03/18, in the historical H1/10 visual surf observation Goddard-Caldwell database (starting 1972) for the south shore of Oahu, the average is 1.7 Hs, (~3’ peak face) and the largest surf on this date was 4 Hs (8’ peak face) in 1995 from S under LV winds, sweet.
Moon’s view:
Pair of austral, midlatitude sources overlapping locally 03/18
Marginal source E of New Zealand 03/08-09
- This compact gale had a favorable track for Hawaii surf potential tracking to near 3800 nm away, though the magnitude was meek. Wave periods shorter, so travelled slower, allowing the following to catch up. It is likely in the mix 03/18, but should fade Tuesday.
Large, short-lived source S to SE NZ 03/10-11
- This low had severe gale to hurricane-force winds over a sizable area with 55-65S (~5000 nm away) with seas growing over 35’. Aim was highest toward the Americas.
- PacIOOS/CDIP American Samoa buoy is not operating. No Pulse status. NOAA southern buoy 51002 (south of Oahu, best indicator) is still inoperable. Local buoys overwhelmed by the large WNW energy. The eyes have it for pulse status.
- It filled in locally Sunday PM. Some spells pinch overhead Monday morning, wahoo, scored some nice ones, but some stinkin’ long lulls too, surfboard blues).
- Likely peaking 03/18. With the remote, large source, it ought to linger through Wednesday.
Into the long range, let’s see what Wooly Worm is up. Wooly’s in the kitchen listening to Irish music. What’s that he’s making, green something—keeping that St. Paddy’s day theme going. Oh, it’s wasabi piled on ahi rolled with lettuce into a wrap. Wasabi, must be the clue—more swell from Japan on the menu. Models show another winter-caliber low forming east of Tokyo 03/20 with a track towards the central Aleutians by 03/23. A new, long-period, WNW event is due Monday 03/25 to near average, holding moderate 03/26 and small 03/27 from 300-320 degrees.
The next SwellCaldWell forecast will be issued Wednesday, March 20.
Climatology update (March 4, 2024) to include through February 2024:
Summary (click below for details of each)
South shore, month of February 2024: Tail end of long-lived west on Feb 1; otherwise, slim pickens, ssstat02.
North shore, month of February 2024: Near average for counts of days in the big stuff ( High, XL, and Giant brackets), nsstat02. Bad timing on winds for some of those biggest days. For the 2023-24 season so far (Sep-Feb), hovering near average most categories, but below for Giant, nmstat09_02. Just like the disappointment for the 2023 south swell season with El Nino brewing, the winter got short-changed as well. Not every El Nino is alike, Ma Nature is a complicated lady with many moods.
Wind-heads: February 2024: Handful of fresh to strong N wind days, and oodles of fresh to strong trade wind days, wwstat02. It is common for above average trades as the El Nino pattern begins to transition towards neutral. Actually it is exactly that, the return of normal to above average trades in the tropical and equatorial Pacific is one of the primary mechanisms of whittling down an El Nino.
Climate Fun 1.
Monthly Stats
North Shore Oahu (1968-present):
January: nsstat01
February: nsstat02
March: nsstat03
April: nsstat04
May: nsstat05
June: nsstat06
July: nsstat07
August: nsstat08
September: nsstat09
October: nsstat10
November: nsstat11
December: nsstat12
South Shore Oahu (1972-present):
January: ssstat01
February: ssstat02
March: ssstat03
April: ssstat04
May: ssstat05
June: ssstat06
July: ssstat07
August: ssstat08
*Picts surf forecaster validation duties Big Wednesday 8/18/21
(photos Shredsniper.com, Mike Carroll)
September: ssstat09
October: ssstat10
November: ssstat11
December: ssstat12
Wind (1988-present, PC’s best guess):
January: wwstat01
February: wwstat02
March: wwstat03
April: wwstat04
May: wwstat05
June: wwstat06
July: wwstat07
August: wwstat08
September: wwstat09
October: wwstat10
November: wwstat11
December: wwstat12
Seasonal Stats
North Shore Oahu, 1968/69-2022/23; (full season, September to June): nmstat09_06
North Shore Oahu, 1968/69 to 2023/24 (Sept – Jan): nmstat09_02
South Shore Oahu, 1972-2023 (March thru Nov): smstat03_11
Helpful links,
Educational outreach: Waves 101– Why Surf Varies Time/Place
Table Definitions
DATE |
Represents daylight hours in zones of high refraction (biggest surf spots |
SWELL HGT |
Deep water swell (H1/3) height (feet) corresponding to a nominal (~3 mile) location |
SWELL DIR |
Deep water swell direction (from) centered on 16 point compass bands. |
SWELL PER |
Deep water swell period (seconds). |
SURF H1/3 |
Breaker H1/3 (defined above) height (feet, peak face) during most active envelopes. H1/3 |
SURF H1/10 |
Average of highest 1/10th of all breakers (feet, peak face) during active envelopes; |
PEAK FACE |
Trough to crest height (feet) on shoreward side of breaker at moment and location along |
Ocn H1/100 Cleanup or Sneaker set |
Waves arrive within a range of sizes. Surf zone enthusiasts emphasize the smaller percent |
TREND |
Breaker height (wind speed) tendency during daylight |
WIND SPD |
Wind speed (knots) for nominal coastal location on the windward side relative to |
WIND DIR |
Wind direction (from) centered on 16 point compass bands. LV refers to light and variable. |