Area Forecast Discussion
Issued by NWS Honolulu, HI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXHW60 PHFO 290612
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST THU AUG 28 2014

.SYNOPSIS...
TRADE WINDS WILL WEAKEN...BECOMING LIGHT BY EARLY NEXT WEEK. LAND
BREEZES WILL ENCOURAGE CLOUD BUILDUPS AND A FEW SHOWERS IN ISLAND
INTERIORS BY DAY...WHILE LAND BREEZES WILL PRODUCE CLEARING AT
NIGHT. THE TRADE WINDS MAY START TO RETURN BY THE MIDDLE OF NEXT
WEEK...THOUGH THEY WILL REMAIN ON THE LIGHT SIDE OF AVERAGE.

&&

.DISCUSSION...
SURFACE OBSERVATIONS AROUND THE MAIN HAWAIIAN ISLANDS REPORTED TRADE
WIND SPEEDS ON THE LIGHT SIDE OF AVERAGE...THOUGH STILL NOT QUITE AS
LIGHT AS GUIDANCE SUGGESTED EARLIER. THE GENERAL TREND TOWARD LOWER
SPEEDS DID APPEAR TO HOLD...THOUGH THE FORECAST MAY NEED A BIT OF
NUDGE UPWARD IF IT OUTPACES REALITY THROUGH TOO MUCH OF THE NIGHT.

PRECIPITATION ACROSS THE STATE WAS SPARSE...OR AT LEAST MOSTLY
MISSING THE RAIN GAUGES...BUT WHERE THEY DID OCCUR SOME OF THE
SHOWERS DROPPED OVER ONE QUARTER OF AN INCH IN THREE HOURS. ALTHOUGH
A MID-LEVEL RIDGE PREVAILED TO THE SOUTHEAST OF THE ISLANDS...A
BROAD TROUGH WAS PRESENT TO THE NORTHWEST THROUGH NORTHEAST. MOST
LIKELY IT WAS THIS FEATURE THAT ENCOURAGED ACTIVE TOWERING CUMULI TO
DEVELOP NEAR 30N...AND CONTRIBUTED TO SHOWER DEVELOPMENT HERE BY
RAISING THE INVERSION. ALSO...THOUGH PRECIPITABLE WATER OVER THE
STATE AND VICINITY WAS ON THE DRY SIDE OF AVERAGE...SATELLITE
ESTIMATES SHOWED A MOISTER PLUME APPROACHING MAUI COUNTY FROM THE
EAST. GUIDANCE PREDICTED SIMILAR MOISTURE SURGES TO REACH THE STATE
PERIODICALLY INTO NEXT WEEK...THOUGH WITH TIME THE DIFFERENT
SOLUTIONS ENDED UP FOLLOWING DIFFERENT PERIODS...COMPLICATING A
DETERMINISTIC FORECAST. WITH TRADE WINDS VERY WEAK BY MONDAY...
DIURNAL SHOWERS PRODUCED BY SEA BREEZES MAY DOMINATE WEATHER FROM
DAY TO DAY...WITH THE MOISTURE SURGES ONLY AMPLIFYING THE MAGNITUDE
OF THE DAILY EVENT.

IN ANY CASE...RIDGING ALOFT WILL EXPAND OVER THE ISLANDS FROM THE
SOUTHEAST DURING THE WEEKEND...SO BY NEXT WEEK SUBSIDENCE WILL START
TO CRUSH DOWN THE INVERSION. HOWEVER...A FRONT NORTH OF 30N WILL
KEEP THE SURFACE RIDGE ANCHORED NEAR THE ISLANDS WELL INTO NEXT
WEEK...SO THE TRADE WINDS WILL RECOVER ONLY VERY SLOWLY.

&&

.MARINE...
EASTERLY SWELL IS STILL FORECAST TO BUILD OVER THE HAWAIIAN COASTAL
WATERS TONIGHT AND FRIDAY...BUT CONFIDENCE REGARDING THE RESULTING
SURF HEIGHTS ALONG EAST-FACING SHORES WAS LOWER THAN EARLIER.
ADVISORY-LEVEL SURF ALSO WILL AFFECT SOUTH-FACING SHORES THROUGH
FRIDAY. INTERACTION BETWEEN THE LONG-PERIOD EAST AND SOUTH SWELLS
MAY PRODUCE STRONG CURRENTS IN SOME AREAS. THE SURF FROM BOTH SWELLS
WILL DECLINE SLOWLY THROUGH THE WEEKEND.

WITH TRADE WIND SPEEDS MORE LIKELY TO DIMINISH THAN TO INCREASE
THROUGH THE FIRST HALF OF THE FORECAST PERIOD...IT IS DOUBTFUL THAT
THEY WILL APPROACH THE CRITERION FOR A SMALL CRAFT ADVISORY.
HOWEVER...THE LONG-PERIOD EASTERLY AND SOUTHERLY SWELL COULD PRODUCE
LOCALLY LARGE AND CONFUSED SEAS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 AM HST SATURDAY FOR NIIHAU-KAUAI
WINDWARD-KAUAI LEEWARD-OAHU SOUTH SHORE-WAIANAE COAST-OAHU
KOOLAU-OLOMANA-MOLOKAI-LANAI MAKAI-KAHOOLAWE-MAUI WINDWARD WEST-
MAUI LEEWARD WEST-MAUI CENTRAL VALLEY-WINDWARD HALEAKALA-LEEWARD
HALEAKALA-KONA-SOUTH BIG ISLAND-BIG ISLAND NORTH AND EAST.

&&

$$

RYSHKO




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.