COLLABORATIVE NEARSHORE SWELL AND WIND FORECAST FOR OAHU
NWS/NCDDC HONOLULU HI
245 PM HST WED FEB 6 2019
This collaborative forecast will be updated Monday through Friday at 300 PM when Pat Caldwell is available.
FORECAST
DATE | SWL
HGT | DMNT
DIR | DMNT
PD | H
1/3 | H
1/10 | HGT
TEND |
PROB | WIND
SPD | WIND
DIR | SPD
TEND |
1PM
02/06 | 5 | WNW | 15 | 8 | 12 | SAME | | 7-10 | SW | SAME |
| 7 | NE | 9 | 5 | 7 | UP | |
THU
02/07 | 5 | WNW | 14 | 8 | 10 | DOWN | LOW | 9-13 | NNW | UP |
| 4 | NNE | 14 | 6 | 8 | UP | LOW |
| 7 | NE | 9 | 5 | 7 | SAME | MED |
FRI
02/08 | 11 | NW | 18 | 24 | 32 | UP | MED | 19-23 | N | UP |
| 8 | NNW | 9 | 6 | 8 | UP | LOW |
| 3 | NNE | 12 | 4 | 6 | DOWN | LOW |
| 4 | NE | 9 | 3 | 5 | DOWN | LOW |
| 1 | SSW | 18 | 2 | 3 | UP | LOW |
SAT
02/09 | 13 | NW | 17 | 28 | 36 | DOWN | LOW | 22-27 | NNW | UP |
| 13 | NNW | 12 | 16 | 24 | UP | LOW |
| 3 | ENE | 9 | 3 | 4 | DOWN | LOW |
| 1 | SSW | 17 | 2 | 3 | SAME | LOW |
SUN
02/10 | 25 | NNW | 15 | 40 | 60 | SAME | LOW | 19-23 | NW | DOWN |
| 1 | SSW | 15 | 2 | 3 | DOWN | LOW |
MON
02/11 | 12 | NNW | 13 | 18 | 24 | DOWN | LOW | 13-19 | NW | DOWN |
| 1 | SSW | 14 | 2 | 3 | DOWN | LOW |
LEGEND:
| SWL HGT | Open ocean swell height measured from trough to crestin feet located 20 nautical miles offshore |
| DMNT DIR | Dominant direction typically +/-10 degrees in 16 compasspoints |
| 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 surfzone |
| 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 located20 nautical miles offshore |
| WIND DIR | Wind direction in 16 compass points |
| SPD TEND | Wind speed tendency (valid values: UP/DOWN/SAME) |
Oahu Surf Climatology
Surf heights will vary between different beaches and at the same beach at different break areas.
DISCUSSION: SUMMARY... Remote and nearby sources making for active surf from around the compass.
DETAILED:. Mid Wednesday on northern shores has dominant surf from 290-320 degrees with lower surf from 20-30 degrees. Similar mix of surf below the north shore winter average is predicted for Thursday.
The western North Pacific has had an active wave generation pattern over the past three weeks sending swell to Hawaii within the 280-320 degree band. The pattern began to change last weekend with dominant direction to veer more NW for the upcoming event.
The last in the series with abundant W to WNW component swell locally unfolded in the far west basin from east of Japan to east of the Kuril Islands 2/1-3. The winds were strongest 2/1-2 east of 165E or beyond 2400 nm away. The system weakened 2/3 west of the Date Line.
NOAA NW Hawaii buoys 51001 and 51001 shows the longer period phase of 16-19 seconds has peaked late 2/5 into early 2/6. With the large source and long travel distance, the event should change slowly into Thursday 2/7 from mostly 280-320 degrees.
Gales over the 15-30 degree band on the NW side of the large low pressure off the NW USA 2/2-4 is expected to add smaller surf building locally late 2/6, peaking 2/7 centered on 20 degrees, then dropping 2/8.
The next system in the western north Pacific formed 2/3-4 east of the Kuril Islands with the low center tracking ENE from near 40N, 160E. Storm- to hurricane-force winds kicked off the initial 24 hour period with seas growing above 40 feet late 2/4 into 2/5. The fetch was 300-320 degrees, without the more W to WNW component of the previous few weeks. Thus less Kauai shadow on Oahu is expected from this source. The head of the fetch crossed the Date Line centered on 310 degrees 2/6. The 12Z 2019-02-06 JASON altimeter showed seas over 30 feet. The system is expected to weaken sharply 2/6-7.
Long period swell are expected to fill in locally overnight Thursday night with surf building above the winter average by Friday morning from 300-320 degrees. By the mid afternoon, surf should build to extra-large levels, meaning high enough for outer reefs. The event should peak Friday night into Saturday morning as high, rough nearby seas build the breakers.
See the latest NWS State Forecast Discussion regarding the wintry weather pattern in the Hawaiian vicinity over the weekend.
Models show strong to near-gale winds over the 330-360 degree band setting up N to NNW within 600 nm nosing toward Hawaii late Thursday into Friday. Local winds are expected to increase Friday with a sharp rise Friday PM in breakers from windswell from 330-360 degrees, making for rough conditions given the large NW groundswell. The nearby- generated seas are expected to continue to build Saturday into Sunday making for extremely rough surf zones on exposed shores.
Models show a low center forming near 35N to the north of Hawaii late Friday. It is modelled to track SSW towards Hawaii. Gales with small pockets to storm-force are predicted to form on the west side of the low center, making for a captured fetch as the center jogs southward. This should allow long-period swell development from 330-350 degrees. This energy is due locally early Sunday, adding to the locally-generated rough seas, making for exceptionally high, rough surf for exposed shorelines.
A similar pattern of February 20-22, 2016 near Hawaii produced the highest wave readings by the PacIOOS/CDIP Waimea buoy locally to 28'. In the upcoming case, the low center could be closer, though the final judgement depends on the low center location longitudinally relative to Oahu. Further west would mean lower combined seas and swell. Stay tuned for updates.
Above average coastal wave wash is expected increase Saturday and peak on Sunday well above normal conditions. See the latest NWS coastal impact statements.
Models suggest the low to move slowly while it weakens Sunday into Monday with a downward trend into Monday though still rough and above the winter average.
Mid Wednesday on eastern shores has breakers from 10-90 degrees at levels above the trade windswell average. Heights are increasing.
See aforementioned comment on the NNE remotely-generated swell for Thursday. In addition, a broad area of strong winds with pockets to near gales to the immediate N to NE of Hawaii 2/4-6 out 800 nm is expected to keep surf elevated Thursday from 30-90 degrees. Models show the upstream source slowly weakening into Friday. This should result in a downward trend below average by late Friday into Saturday.
Refracting and diffracting NW to N seas and swell Friday into Monday should keep select more northerly exposures above average through the period.
Mid Wednesday on southern shores has near nil swell from the southern hemisphere. Similar surf is expected for Thursday.
A severe gale to the SW of New Zealand 2/1-3 tracked east sending highest seas toward the Americas. Angular spreading could bring in low swell to Hawaii Friday and holding into Monday 2/8-11 from 180-200 degrees.
Westerly exposures continue to have small breakers 2/6 from the western north Pacific sources aforementioned. Similar surf is expected for Thursday then fade out Friday.
Refracting and diffracting NW swell Saturday into Monday from the sources aforementioned could bring breakers to select corners and more westerly exposures.
Into the long range, a compact gale in the Kamchatka corner 2/8 is expected produce a low, long-period NW event locally 2/12-13. N to NE surf is expected to remain above average 2/12-13.
Long range forecasts are subject to high uncertainty.
This collaborative forecast will resume on Friday, February 8.
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 http://www.prh.noaa.gov/hnl/pages/marine.php
NWS Forecaster and NCEI Pat Caldwell
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