High Surf Advisory 28, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
918 AM HST TUE MAR 29 2016

.SYNOPSIS...
A WEAKENING COLD FRONT WILL MOVE ACROSS OAHU AND MAUI COUNTY
TODAY...DISSIPATING OVER THE BIG ISLAND THIS EVENING. SHOWERS WILL
BE FOUND ASSOCIATED WITH THE FRONT...BUT RAINFALL AMOUNTS ARE
EXPECTED TO REMAIN GENERALLY LIGHT. HIGH PRESSURE WILL MOVE OVER
THE ISLANDS WEDNESDAY THROUGH THURSDAY...WITH LIGHT WINDS AND
DRY WEATHER PREVAILING. THE HIGH WILL LIFT TO THE NORTH FRIDAY
THROUGH THE WEEKEND...ALLOWING TRADE WINDS TO RETURN ACROSS THE
ISLANDS.

&&

.DISCUSSION...
A WEAKENING COLD FRONT IS NEAR OAHU THIS MORNING...AND BRINGING A
FEW SHOWERS TO OAHU. OVERNIGHT THE FRONT BROUGHT SOME SHOWERS TO
KAUAI...WITH SOME GAGES ON THE GARDEN ISLE RECEIVING UP TO HALF
AN INCH OF RAIN. THE OVERNIGHT SOUNDING FROM KAUAI HAD 1.31 INCHES
OF PRECIPITABLE WATER /PW/ WHICH MATCHED WELL WITH THE SATELLITE
DERIVED PW.

THE MODELS ARE IN GOOD AGREEMENT WITH THE FRONT CONTINUING TO
WEAKEN OVER THE NEXT 12 TO 24 HOURS AS IT MOVES DOWN THE ISLAND
CHAIN. IN GENERAL...THE GLOBAL MODELS KEEP THE POPS A LITTLE
HIGHER THAN THE MESOSCALE MODELS. HAVE MADE SOME ADJUSTMENTS TO
THE POPS BASED ON THE MODELS AND SATELLITE DATA. DROPPED POPS FOR
KAUAI WHICH IS NOW BEHIND THE FRONT...AND FOR SOME AREAS TONIGHT
AS THE FRONT IS EXPECTED TO WEAKEN FURTHER.

AN UPPER LEVEL TROUGH PASSING NORTH OF THE ISLANDS IS KEEPING
ELEVATED WINDS ATOP THE BIG ISLAND SUMMITS. OVERNIGHT THE WINDS
DROPPED TO AT OR SLIGHTLY BELOW ADVISORY LEVELS. SINCE ABOUT 5
AM...WINDS AT THE SUMMIT OF MAUNA KEA HAVE INCREASED...MIRRORING
THE TREND IN THE GFS AT 600 MB. WINDS ARE BACK TO WHERE THEY WERE
24 HOURS AGO...AND THE GFS INDICATES WINDS AT 600 MB WILL INCREASE
THIS AFTERNOON OR THIS EVENING. IF THIS DOES PAN OUT...WE WILL
LIKELY NEED TO POST ANOTHER HIGH WIND WARNING FOR THE BIG ISLAND
SUMMITS.

OTHERWISE NO CHANGE IN FORECAST PHILOSOPHY. BEHIND THE FRONT A
HIGH PRESSURE SYSTEM MOVES OVER THE ISLANDS WEDNESDAY/THURSDAY...
BRINGING LIGHT WINDS AND A DRY AIRMASS TO THE REGION. THE HIGH
MOVES TO THE NORTHEAST FRIDAY/SATURDAY...ALLOWING TRADES TO BUILD
BACK IN ACROSS THE ISLANDS.

&&

.AVIATION...
A WEAKENING FRONT OVER OAHU THIS MORNING WILL SPREAD TO MAUI COUNTY
THIS AFTERNOON AND BIG ISLAND BY THIS EVENING. AIRMET SIERRA FOR
TEMPO MTN OBSC FOR OAHU NOW...WHICH WILL PROGRESS EASTWARD AS THE
CLOUDS ASSOCIATED WITH THIS FRONT PASS THE AFOREMENTIONED ISLANDS.
THE TOPS OF THE CLOUDS AND SHOWERS ASSOCIATED WITH THE FRONT ARE
NO HIGHER THAN 10 KFT.

AIRMET TANGO IS IN EFFECT FOR LOW LEVEL TURBULENCE FROM OAHU TO THE
BIG ISLAND DUE TO STRONG WESTERLIES ALONG THE FRONT. AS THE FRONT
MOVES EAST...OAHU IS LIKELY TO DROP OUT OF THE AIRMET...FOLLOWED BY
MAUI COUNTY AND THEN BIG ISLAND.

&&

.MARINE...
THE CURRENT LARGE NORTHWEST SWELL IS IN LINE WITH THE CURRENT
WAVE WATCH III MODEL DATA. THE SWELL ARRIVED AT BUOY 51101
NORTHWEST OF THE ISLAND IN THE PRE-DAWN HOURS...AND SHOULD BE
ARRIVING AT KAUAI BY MID DAY...AND TO SPREAD DOWN THE ISLAND CHAIN
THIS AFTERNOON. A HIGH SURF WARNING HAS BEEN POSTED BEGINNING AT
10 AM FOR THE BUILDING SURF ALONG NORTH AND WEST SHORES. EXPECT
THE SWELL TO PEAK WEDNESDAY...AND THEN GRADUALLY SUBSIDE THROUGH
THE END OF THE WEEK. A SMALL TO MODERATE SOUTH SWELL TODAY WILL
PEAK WEDNESDAY AND DIMINISH THURSDAY. A SMALL CRAFT ADVISORY IS
ALSO POSTED FOR THE INCOMING NORTHWEST SWELL.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF WARNING UNTIL 6 PM HST WEDNESDAY FOR NIIHAU-KAUAI
WINDWARD-KAUAI LEEWARD-WAIANAE COAST-OAHU NORTH SHORE-OAHU
KOOLAU-MOLOKAI-MAUI WINDWARD WEST-MAUI CENTRAL VALLEY-WINDWARD
HALEAKALA.

WIND ADVISORY UNTIL 6 AM HST WEDNESDAY FOR BIG ISLAND SUMMITS.

SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM HST THURSDAY
FOR OAHU LEEWARD WATERS-KAIWI CHANNEL-MAUI COUNTY WINDWARD
WATERS-MAUI COUNTY LEEWARD WATERS-ALENUIHAHA CHANNEL-BIG ISLAND
WINDWARD WATERS.

SMALL CRAFT ADVISORY UNTIL 6 AM HST THURSDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-
OAHU WINDWARD WATERS.

&&

DISCUSSION/MARINE...M BALLARD
AVIATION...FOSTER