Big Picture
BIG Picture updated 1pm, Sunday, January 19
Monday, January 20th – Tuesday, January 28th
Major change in the weather pattern with potentially strong Kona winds midweek…
A wildly different synoptic-scale pattern will come for the North Pacific between the second half of January and early February. Over the past two months, a series of powerful systems raced across the ocean from Honshu to the dateline, and a ridge of high pressure persisted over the eastern Pacific. For this period and beyond, models agree that high pressure will attempt to build over the western Pacific and the one over the eastern Pacific will strengthen even more. Closer to the dateline and Hawaii, a series of deep troughs or closed lows could form. This will have strong implications for the local wind and weather. On Sunday, a weak ridge extended SW to Hawaii from the NE, and a disturbance was deepening NE of the islands. This led to moderate (10-20mph) NE-ENE trades. It should be similar on Monday. By Tuesday, a rather potent cold front, characterized by strong cold air advection, will approach the state from the NW. The local winds will drop off to light paces from the NE-East (5-10mph). Models indicate a near 990 millibar low pinching off the front and centering itself within 600 nautical miles due North of Oahu. Fresh to strong Kona winds (20-30mph) could develop through the day, and the direction will shift from the SW to W-NW on Wednesday. The Kona low will linger and gradually fill North of the islands through Friday, so SW-W Kona winds should continue but weaken to moderate to fresh paces (10-25mph) on Thursday and light to moderate paces (5-15mph) on Friday. The flow should become light (5-10mph) for the weekend. Models diverge early next week, with the GFS model pushing another powerful front through the state while the ECMWF model holds off on that scenario until later in the week.
Dry, pleasant weather will continue into Tuesday. The approaching front on Wednesday should sweep through the islands through the day and manifest as a line of showers and/or thunderstorms. A few showers could linger on Thursday, especially for Kauai. It should be dry on Friday. Weak trades to the east could push remnant moisture from the front in the form of showers back over the islands for the weekend. Confidence plummets for early next week as models diverge.
Surf Outlook –
North Shore and West Shores: Active surf continues with stormy, high surf conditions midweek…
Recent/Now (LARGE): Surf on Sunday was 6-8’+ Hawaiian scale on a slowly dropping 14-15 second period NW swell. There were still lingering 10’ sets. The source was a near hurricane-force low with 55-70mph winds that tracked straight east from off the coast of Honshu to the dateline Jan 13-15, driving seas to 40’. The Waimea Bay buoy peaked at 11’ of swell at 18 seconds Friday afternoon, which was large enough for XL surf of 15-18’ at the outer reefs. This swell had a very strong westerly component, and there was evidence of shadowing by Kauai for Oahu. The NW buoy peaked at around 18’, which would suggest a Waimea Bay buoy peak of at least 12-13’. The Kalaeloa buoy measured the same peak as that at Waimea Bay, which was a very unusual observation. Most leeward coasts observed highly elevated surf, including areas that typically remain small under wintertime events that cannot be accounted for in size solely from the ongoing, moderate SSW swell discussed below. Surf should drop to 4-6’ on Monday and 2-4’ on Tuesday.
Next (MODERATE TO LARGE): A strong, compact storm emerged from northern Honshu Jan 16 and began to broaden and deepen further Jan 17-18. It gained winds of 45-55mph as it slowly tracked eastward. A satellite altimeter pass around 3:30pm HST Jan 18 measured seas to 28’, which compares well to WaveWatch 3 output. By Jan 19, it nearly reached the dateline, and it should be east of the dateline by Jan 20. Compared to the previous system, this storm was weaker, smaller, and more distant. Long period forerunners of 18-20 seconds from the WNW-NW should arrive Tuesday morning. Surf should rise to 2-4’ by late Tuesday afternoon and 5-7’ by early Wednesday. It should peak in the afternoon at 6-8’.
Finally (EXTRA LARGE): A powerful storm will form in close proximity to Hawaii Jan 22. Centered just 600nm North of the islands, the system will achieve peak intensity on Jan 23 with 40-50mph winds reaching to within 500nm of Hawaii. These winds will also blow over seas and swell generated by the previous storm. These factors should support a rapid rise in surf from the NNW overnight Wednesday. Surf could reach 8-12’ by Thursday morning and 10-15’ later in the day. The peak should occur towards or after dusk at 12-18’ (30’ faces). Proximity will cause the wave energy to span the 11-16 second period band and be centered at 13-14 seconds, making for less organized surf and frequent sets. Heights could hold similar or even a notch higher early Friday. The Kona winds will ensure that surf will be rough and unrideable for most spots during this time. There is significant uncertainty in size and timing with systems that are this close to Hawaii, so these numbers will likely change in the next few days. Surf should rapidly drop to 5-7’ early Saturday and 2-4’ early Sunday.
Outlook: Confidence is exceptionally low due to a fast-changing environment over the North Pacific, and it is not possible to distinguish any single event with fidelity past Sunday. Confidence is moderate that active surf from the WNW-NNW (likely more NNW than WNW) will continue into early February. Stay tuned…
South Shores: Surf from the rare SSW swell drops but rises midweek from Kona low with victory-at-sea conditions…
Recent/Now/Next: After peaking slightly above the summer average on Friday at 2-3’ occ. +, surf from a 13-15 second period SSW swell dropped to 1-2’ occ. + on Sunday. Atypical for this time of the year, the source was a sizeable, stationary system east of New Zealand that aimed 40-50mph to the NE Jan 9-11. The area of low pressure filled on Jan 12, which weakened the fetch. Surf should drop to 1-occ. 2’ on Monday, 1-1.5’ on Tuesday, and 0-1.5’ on Wednesday. Storm activity over the South Pacific was minimal Jan 14-15, so surf should be seasonably flat to tiny on Thursday.
Next: A powerful Kona low just north of Hawaii could induce strong SW-W flow that could bring in a mix of WSW wind swell and longer period West swell. 4-7 second period WSW wind swell should pick up locally over the second half of Wednesday with rough surf reaching 1-2’+ by nightfall. This chop should persist into at least Thursday and drop Friday. Longer period West energy should arrive earlier on Wednesday and peak on Thursday at 1-3’+ at select spots. Many other spots will deal with 1-2’+ wind chop. The unfavorable wind direction will result in victory-at-sea, storm surf conditions. The surf quality should remain poor on Friday under continued, albeit lighter, Kona wind with surf dropping at the same time. Confidence is low in size and timing because of proximity of the dynamic situation to the islands.
Finally: An NE-SW elongated system stalled slowly tracked eastward from south of Tasmania Jan 16-17. It had winds of 40-50mph aimed mostly to the ENE. It could bring a trace of SW swell late Friday through Sunday with surf no larger than 1.5’ and more than likely just 1’. Things go quiet again into early next week.
Outlook: A strong, better aimed system should pass south of the Tasman Sea Jan 20-21, which could bring a tiny SW swell around Jan 28-30. Seasonably quiet conditions should continue well into February.
East Shores: A mixed plate of different swells through the period with better than average wind conditions…
Now/Next: Surf on Sunday was 1-2’ occ. + on a mix of 5-7 second period NE wind swell and tiny North wrap. Surf should be a half notch smaller at 1-2’ on Monday as the local wind eases slightly.
Next: A disturbance 900nm NE of Hawaii will weaken as it rotates towards the islands on Jan 20. The fetch winds aimed at Hawaii should reach only 25-30mph. An 8-10 second period NE swell should arrive late Tuesday and rise through the night. Surf should peak at 1-2’+ early Wednesday and steadily drop overnight. It should be mostly gone by early Thursday.
Finally: A large NNW swell will bring some wrap to the windward coast on Thursday. Surf should rise to 1-2’ occ. + as the swell angle begins with a stronger West component. As the swell angle shifts even more NNW, heights should peak on late Thursday or early Friday potentially at 2-4’ or larger with excellent offshore wind. Surf should steadily drop to 1-3’ early Saturday and 1-2’ on Sunday.
Outlook: Confidence is very low after the weekend. Climatology and model trends call for at least small to perhaps near average ENE-E trade wind swell to return for the last week of January and holding into the start of February.
The next SNN Big Picture will be issued on Sunday, January 26.
Forecaster Jonathan Huynh
Surf Climatology HERE
