Big Picture
BIG Picture updated 12pm, Sunday, February 9
Monday, February 10th – Tuesday, February 18th
A mix of ESE, light and variable, and light Kona winds this period…
The synoptic scale pattern over the North Pacific remains quite active. For most of this period, very large, broad troughing will envelop the entire western North Pacific and extend well into the subtropics. A weak ridge of high pressure will mostly be anchored over the eastern North Pacific. This pattern favors a mix of weak trades and occasional bouts of light and variable to Kona wind. Light to moderate (5-15mph) ESE flow will hold into Monday. Speeds should drop a notch to light paces (5-10mph) for Tuesday and Wednesday as trough to the NW weakens the ridge over Hawaii. The wind will veer SE late Wednesday and then to light and variable to south Kona on Thursday. It should be light and variable on Friday. Models diverge for the weekend. The GFS model quickly brings in a cold front late in the weekend into early next week, which would keep winds light over the weekend. The ECMWF model is slower on the frontal approach and allows for a transient ridge to boost East trades on Saturday before veering SE on Sunday. The uncertainty persists into early next week with differences on the timing and strength of the front.
Mostly dry weather with a few light mauka showers will persist into the week. A trough approaching the state late in the week could bring a boost in shower activity on Friday. A potentially stronger system could bring more inclement weather late in the weekend or early next week.
Surf Outlook –
North Shore and West Shores: Increasingly large WNW-NW swells on the way…
Recent/Now (MODERATE TO LARGE): Surf on Sunday was 5-7’ Hawaiian scale on a dropping, 14 second period NW swell. The swell peaked at 7-8’ at 15 seconds overnight Saturday. The source was a trough embedded within a broad area of low pressure centered over the dateline south of the Aleutian Islands. The trough swung eastward along the southern periphery with a short fetch of 45-60mph winds aimed highest NE of the islands. Surf from this swell should drop to 2-3’+ early Monday as a slightly larger NW swell takes its place.
Next (MODERATE TO LARGE): Another trough became embedded within the broad cyclonic circulation centered over the dateline. Compared to the previous system, this developed a small area of storm-force winds from further away. The fetch was carried over a longer distance and had a slightly more southward extent. The result will be a slightly longer period, slightly larger event. 18-20 second period forerunners from the WNW should arrive late Sunday afternoon. Surf should rise to and peak Monday morning at 6-8’ and drop to 4-6’ early Tuesday.
Next (LARGE): Over the weekend, a very large trough began to merge with the gyre still centered over the dateline. A very long, wide fetch of 40-55mph winds developed during the merger on Saturday and Sunday. Satellite altimetry measured a massive region of seas to 25-30’+ to within 2,000 nautical miles of Hawaii. Fetch length, width, duration, and intensity will maximize wave generation and surf potential. It will also make for a long-lived event. 18-20 second period forerunners from the WNW should arrive overnight Monday. Surf should rise to 4-6’ at dawn Tuesday and peak in the afternoon at 8-12’. The Waimea Bay buoy should measure at least 8’ of swell at 15-16 seconds. Surf could drop a notch to 8-10’+ for the first half of Wednesday before rising back up to 8-12’ in the afternoon. Surf should drop to 6-8’ early Thursday and 4-6’ early Friday.
Finally (LARGE TO EXTRA LARGE): This episode will occur in two parts. First, a longwave trough is modelled to rotate around the broad gyre extending from the western to central North Pacific Feb 10-11. The trough will have a broad fetch of 35-45mph winds acting over pre-existing seas with an unusually southward extent. The second phase takes hold when the trough turns northward and deepens into a cyclone as it reaches the dateline Feb 13. It will stall roughly 1,400nm NNW of Hawaii and broaden. Fetch speeds should increase to 45-60mph. The system will gradually shift eastward and weaken on Feb 14-15. The first phase will feature increasing swell height within the 12-14 second period band from the WNW beginning late Friday. Surf could reach 6’+ before dark. The peak of the first stage will occur on Saturday at 6-10’ with energy centered within the 13-15 second period band. Longer period energy associated with the second portion of the event of 17-19 seconds from the NW should arrive pre-dawn Saturday. Surf will rapidly rise over the day and potentially reach 10-15’ before dark on Saturday when the outer reefs come into play. Surf should drop quickly to 8-12’ early Sunday and 3-5’ early Monday.
Outlook: Models hold the pattern through the third week of Feb. This suggests high potential for significant WNW-NW swells to continue deep into Feb. Stay tuned…
South Shores: Slight bump in surf likely this week, and possibly more on the way next week…
Recent/Now/Next: Surf on Sunday was 0-1’ on minimal background energy from the South Pacific. A rather potent subtropical storm formed 1,000nm ENE of New Zealand late Feb 3 into Feb 4. It tracked unfavorably ESE with winds of 40-50mph. On Feb 5-6, it stalled and broadened 1,200nm east of New Zealand, and the fetch winds aimed at Hawaii reached 45-55mph. The system gradually weakened Feb 7. Weak energy from the SSW could arrive Monday, which may bring surf up to 0-1.5 and hold into Tuesday. A more substantial bump should occur on Wednesday stronger, longer period energy from the SSW-S arrives. Surf should rise to 1-1.5’ early Wednesday and peak Thursday at 1-occ. 2’. Surf should slowly drop from 1-occ. 2’ early Friday to 1-1.5’ early Saturday. Seasonably tiny conditions should resume early next week.
Finally: Small wrap from the sizeable WNW swells later this week could contribute to surf at select locations, likely on Wednesday and early Thursday and again on Saturday. Surf at those spots could reach 1-2’.
Outlook: Models indicate that a series of systems will pass SE of New Zealand Feb 11-14. This could spell a slight increase in surf from the SSW-S Feb 18-21.
East Shores: Surf dropping to near flat by the weekend…
Recent/Now/Next/Finally: Surf on Sunday was 1-2’ occ. + on a dropping, 9-10 second NE swell and a 5-6 second period East trade wind swell. The NE swell was part of an exceptionally long-lived, sizeable event that generated peak surf of 6-8’ earlier in the week with fair conditions. East wind swell, primarily from stronger trades upstream of Hawaii, will maintain 1-2’ surf into Monday and then drop to 1-occ. 2’ for Tuesday-Thursday as the local East flow diminishes. Surf should drop to below 2’ on Friday and beyond. Depending on how the local ridging plays out this week, surf could briefly rise to 1-occ. 2’ on Saturday and Sunday before dropping back to below 2’ early next week.
Outlook: The large scale pattern does not favor significant wind swell. The WNW-NW angles of the larger swells impact the North Shores also do not favor wrap into the windward coast. Therefore, surf for most, if not all, of the week spanning Feb 16-22 should be minimal (less than 2’).
The next SNN Big Picture will be issued on Sunday, February 16.
Forecaster Jonathan Huynh
Surf Climatology HERE