outlook
TRANSCRIPT
Outlook
FZHW52 PHFO
SRFHFO
SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST MON JUL 27 2015
OAHU-
400 PM HST MON JUL 27 2015
HIGH SURF ADVISORY FOR SOUTH FACING SHORES
Surf along south facing shores will be 6 to 9 feet tonight, and 4 to 7 feet on Tuesday.
Surf along west facing shores will be 3 to 6 feet tonight, and 2 to 4 feet on Tuesday.
Surf along east facing shores will be 1 to 3 feet through Tuesday.
Surf along north facing shores will be 2 feet or less through Tuesday.
Outlook through Sunday August 2: the current south swell will continue to gradually diminishthrough the week. Strengthening trade winds during the second half of the week will increase shortperiod choppy surf along east-facing shores.
Surf heights are forecast heights of the face or front of waves. The surf forecast is based on thesignificant wave height, the average height of the one third largest waves, at the locations of thelargest breakers. Some waves may be more than twice as high as the significant wave height. Expectto encounter rip currents in or near any surf zone.
FXHW52 PHFO
SRDHFO
COLLABORATIVE NEARSHORE SWELL AND WIND FORECAST FOR OAHU
NWS/NCDDC HONOLULU HI
300 PM HST MON JUL 27 2015
THIS COLLABORATIVE FORECAST WILL BE UPDATED MONDAY THROUGH FRIDAY AT
300 PM WHEN PAT CALDWELL IS AVAILABLE.
FORECAST
DATESWL
HGTDMNT
DIRDMNT
PDH
1/3H
1/10HGT
TEND
PROBWIND
SPDWIND
DIRSPD
TEND1PM
07/274E712SAME9-13ESAME4SSW15610DOWNTUE
07/284E712SAMELOW9-13ESAME4SSW1468DOWNMEDWED
07/295E623UPLOW11-16EUP3SSW1346DOWNLOWTHU
07/306E724UPLOW13-19EUP2S1223DOWNLOW1SSW1824UPLOWFRI
07/317E734UPLOW13-19ESAME1S1623SAMELOWSAT
08/017E734SAMELOW13-19ESAME1S1423DOWNLOW
LEGEND:
SWL HGTOPEN OCEAN SWELL HEIGHT MEASURED FROM TROUGH TO CRESTIN FEETLOCATED 20 NAUTICAL MILES OFFSHOREDMNT DIRDOMINANT DIRECTION TYPICALLY +/-10DEGREES IN 16 COMPASSPOINTSDMNT PDDOMINANT PERIOD IN SECONDSH1/3SIGNIFICANTWAVE HEIGHT IN THE SURF ZONEH1/10AVERAGE HEIGHT OF THE HIGHEST ONE-TENTHWAVES IN THE SURFZONEHGT TENDHEIGHT TENDENCY OF SWELL (VALID VALUES:UP/DOWN/SAME)PROBPROBABILITY OF OCCURRENCE (VALID VALUES: HIGH/MED/LOW)WINDSPDOPEN WATER WIND SPEED MEASURED IN KNOTS LOCATED20 NAUTICAL MILESOFFSHOREWIND DIRWIND DIRECTION IN 16 COMPASS POINTSSPD TENDWIND SPEEDTENDENCY (VALID VALUES: UP/DOWN/SAME)
Compass & Swell Shadow Lines for Hawaii
SURF HEIGHTS WILL VARY BETWEEN DIFFERENT BEACHES AND AT THE SAME
BEACH AT DIFFERENT BREAK AREAS.
Discussion: summary: South shores tapering down as east side builds.
Detailed: Mid Monday on southern shores has breakers above average from 185-200 degrees with14-19 second periods. Heights are expected to lower on Tuesday.
The secondary low pressure 7/19-21 which followed the first low pressure 7/18-19 east of NewZealand turned out to produce surf in Hawaii stronger than expected. The secondary pattern sent upa long fetch to severe gales that acted upon existing seas from the first system. The second patternalso nosed further into the subtropics closer to Hawaii, meaning less loss of size during travel. Theresult of the combined back-to-back low pressure systems was a long-lived, .well above averageevent locally 7/25-27, peaking 7/26. Fetches of both low pressure systems hugged the east side ofNew Zealand giving dominant direction locally from 190-200 degrees with lesser energy from 180-190 degrees.
The merged low pressures weakened steadily sub-gale 7/21-22 as the pattern shifted east. SouthernNOAA buoys 51002-3 Monday morning 7/27 remain elevated within 14-19 seconds, keeping breakersabout the same locally well into Monday night. With the large source and long travel distance overwhich the swell trains unravel into groups of similar wave period through dispersion, since longerwave periods travelling faster, the event should be long-lived and slowly changing. That should giveway to one more day of above average surf from 185-200 degrees. Heights should fall to near theaverage on Wednesday, then drop below average by Thursday.
A zonal jet stream near Antarctica steered a fast-moving severe gale eastward S to SE of NewZealand 7/22, with highest seas aimed at the Americas. This will likely be the dominant backgroundsource for Thursday into Saturday with below average breakers from within 180-200 degrees.
Mid Monday on eastern shores has breakers below the trade windswell average.
See the latest NWS state forecast discussion for an explanation of the evolving local trades.
Gentle to moderate trades over a large area to the E to NE of Hawaii have persisted 7/26-27. Below
average conditions are expected to continue on Tuesday.
Trades over and to the E to NE of Hawaii are modelled to build within moderate to fresh Wednesdayinto the weekend, which should trend breakers from windswell near the trade windswell average byFriday from within 60-90 degrees.
Into the long range, a gale to severe gale in the Tasman sea 7/26-28 should be the dominantbackground swell for 8/4-5 from 208-220 degrees. Wave watch iii only gives 3 feet at 15 secondsfrom 220 degrees at pago pago, american samoa 7/31 from this source, which suggests belowaverage locally about 4 days later.
Easterly windswell should hover around the average 8/1-4 with high uncertainty due to elusivetropical features within the latitudes of Hawaii for longitudes near Hawaii eastward 2000 nm.August is the peak month for tropical cyclonic development for the eastern and central north Pacific,and with the large scale, above average sea surface temperature pattern over and east of Hawaii tothe Americas, probabilities of cyclonic development are higher.
Long range forecasts are subject to major revisions.
This collaborative forecast will resume on Wednesday, July 29.
This forecast was produced through the collaborative efforts of NWS and NCDDC. Please sendsuggestions to [email protected] or call the Warning Coordination Meteorologist at 808-973-5275.
Additional resources: see /in lowercase/ http://www.prh.noaa.gov/hnl/pages/marine.php.
NWS and Pat Caldwell, Pacific/Hawaii Liaison Office, NCDDC
Additional Resources:
Latest North Pacific Surface Analysis
Upcoming tides for select Hawaii locations
Tides for Honolulu
Tide tables for Hawaii
