571 FXHW52 PHFO 290052 SRDHFO Collaborative Nearshore Swell and Wind Forecast for Oahu NWS/NCEI Honolulu HI 252 PM HST Mon Oct 28 2019 This collaborative forecast will be updated Monday through Friday at 300 PM when Pat Caldwell is available. FORECAST SWL DMNT DMNT H H HGT WIND WIND SPD DATE HGT DIR PD 1/3 1/10 TEND PROB SPD DIR TEND 1 PM 8 NNW 16 16 20 SAME 11-16 E SAME 10/28 1 SW 15 1 3 SAME TUE 8 NNW 15 14 18 DOWN LOW 9-13 ESE DOWN 10/29 5 NNW 11 6 10 UP LOW 3 NE 11 3 5 UP LOW 1 SW 14 1 3 SAME LOW WED 7 NNW 14 12 16 DOWN MED 4-6 VRB SAME 10/30 4 NNW 10 5 7 DOWN LOW 3 NE 12 4 6 SAME LOW 2 SSW 13 2 4 UP LOW THU 4 NNW 12 6 8 DOWN LOW 4-6 VRB SAME 10/31 3 NE 11 3 5 DOWN LOW 2 SSW 13 2 4 SAME LOW FRI 3 NNW 11 3 5 DOWN LOW 4-6 VRB SAME 11/01 2 NE 10 1 3 DOWN LOW 2 SSW 13 2 4 SAME LOW SAT 3 NNW 11 3 5 SAME LOW 4-6 VRB SAME 11/02 2 SSW 13 2 4 SAME LOW LEGEND: SWL HGT Open ocean swell height measured from trough to crest in feet located 20 nautical miles offshore DMNT DIR Dominant direction typically +/-10 degrees in 16 compass points DMNT PD Dominant period in seconds H1/3 Significant wave height in the surf zone H1/10 Average height in the highest one-tenth waves in the surf zone HGT TEND Height tendency of swell (valid values: UP/DOWN/SAME) PROB Probability of occurrence (valid values: HIGH/MED/LOW) WIND SPD Open water wind speed measured in knots located 20 nautical miles offshore WIND DIR Wind direction in 16 compass points SPD TEND Wind speed tendency (valid values: UP/DOWN/SAME) Surf heights will vary between different beaches and at the same beach at different break areas. DISCUSSION: SUMMARY... Transition season with surf from around the compass. DETAILED... Mid Monday on northern shores has breakers from 310-330 degrees at levels above the October average. Similar surf with a slow downward trend is predicted for Tuesday. A tropical cyclone a week ago off Japan was the nucleus for this above average surf event in Hawaii. The tropical moisture fed the mid latitude low pressure, that deepened to hurricane-force 10/23-24. The massive gyre maintained a long wide fetch of gales to storm-force winds, with the strongest winds further away hugging the Aleutians 10/24-26 over the 320-340 degree band. Marginal gales nosed to within 1200 nm away on 10/26. The system weakened sharply as the fetch aimed less at Hawaii 10/27. NW NOAA buoys 51001 and 51101 showed the peak of the longest period energy of 16-20s Sunday into Sunday night 10/27. The energy in the moderate period bands of 13-16s are holding steady mid Monday 10/28. The PacIOOS/CDIP Waimea, Oahu buoy showed a peakof long-period swell Monday morning 10/28. A secondary peak is expected Monday night, followed by a slow decline while remaining above average Tuesday into Wednesday from 320-340 degrees. Heights should drop below average by Thursday morning, with small breakers holding into Friday. A high pressure cell towards the Date Line and a low pressure trough immediately N to NNW of Hawaii have set up a long fetch of fresh to strong breezes, with pockets to near gale from 25-35N aimed slightly west of Hawaii. Buoys 51001 and 51101 rose sharply 10/28 from the 10-13s energy out of this fetch. Models show the fetch weakening 10/29. Proximity and angular spreading should overlay this shorter-period event below the remote moderate-period event for Tuesday into Wednesday. The most important result would be the increased surf zone currents from the more consistent arrival of sets 10/29-30. A weak low pressure approaching the Date Line 10/28-30 is expected to add short-period surf from 310-330 degrees building Saturday. Mid Monday on eastern shores has breakers from the trade wind belt out of 60-90 degrees at a minimum. An increase is predicted for Tuesday. A strong high pressure west of Washington State and low pressure near northern California set up strong breezes to gales over the 40-60 degree band with strongest winds closest to California but less near gales reaching to near 35N, 135W, or about 1500 nm away, 10/25-27. This is expected to bring in a remote windswell locally near the trade windswell average centered from near 50 degrees 10/29-31. It should fade 11/1. Mid Monday on southern shores has small breakers from 180-220 degrees at high refraction zones, while most breaker zones are near nil. Similar surf is predicted for Tuesday. A compact area of gales in the Tasman 10/20-22 was the source of the minimal SW swell 10/28. The low pressure area moved NE of New Zealand 10/22-24 with marginal gales. This should keep small breakers locally 10/30-31 from 190-210 degrees. A secondary area of marginal gales 10/22-24 SE of New Zealand should keep small breakers from 185-200 degrees. Into the long range, a compact gale south of French Polynesia 10/27-28 could keep small surf from 175-185 degrees 11/3-4. Models suggest more marginal gales SE to E of New Zealand this week that could make more surf below the average but above the approaching seasonal nil for the end of next week 11/8-10 from 180-200 degrees. The trade wind belt should remain weak to the E to NE of Hawaii with breakers from 60-90 degrees below the windswell average 11/3-5. A new gale is modelled to deepen about 1200 nm NNW of Hawaii 11/2 that could bring above average surf locally roughly 11/4-5 from 325-355 degrees. Long range forecasts are subject to low confidence. This collaborative forecast will resume on Wednesday October 30. This forecast was produced through the collaborative efforts of NWS and NCEI. Please send suggestions to w-hfo.webmaster@noaa.gov or call the Warning Coordination Meteorologist at 808-973-5275. ADDITIONAL RESOURCES: See https://www.weather.gov/hfo/marine $$ NWS Forecaster and NCEI Pat Caldwell