Small Craft Advisory 16, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
330 AM HST THU MAR 12 2015

.SYNOPSIS...
LAYERED CLOUDS WILL COVER THE MAIN HAWAIIAN ISLANDS AND BRING
OCCASIONAL SHOWERS TO MAUI AND THE BIG ISLAND TODAY...WITH LESS
RAINFALL EXPECTED FARTHER WEST. LIGHT WINDS WILL TURN NORTHERLY AND
INCREASE FROM WEST TO EAST ACROSS THE AREA TODAY. TRADE WINDS WILL
RETURN BRIEFLY FOR THE WEEKEND.

&&

.DISCUSSION...
WATER VAPOR IMAGERY SHOWS AN UPPER LOW FAR NORTH OF THE STATE...WITH
AN UPPER TROUGH DIGGING SOUTHEASTWARD AROUND THE BASE OF IT. A
STRONG WEST-SOUTHWESTERLY JET IS LOCATED OVER AND TO THE NORTHEAST
OF THE MAIN HAWAIIAN ISLANDS. AT THE SURFACE...A WEAKENING FRONT IS
LOCATED SOUTHEAST OF THE BIG ISLAND WITH A RIDGE JUST TO OUR NORTH.
RADARS SHOW WIDESPREAD LAYERED CLOUD COVER...WITH THE THICKEST
PORTION GENERALLY ACROSS MAUI AND THE BIG ISLAND. GAGES SHOW SPOTTY
RAINFALL ACROSS BOTH OF THESE ISLANDS...UP TO ABOUT HALF AN INCH IN
PLACES OVER THE PAST 12 HOURS...WITH LESS REPORTED ACROSS THE
REMAINING ISLANDS.

THE UPPER LEVEL TROUGH NORTH OF THE STATE WILL SHARPEN A SURFACE
TROUGH TO OUR NORTH AS IT DIGS SOUTHEASTWARD TOWARDS US. LOW-LEVEL
WINDS ARE WESTERLY ACROSS MUCH OF THE STATE THIS MORNING...WITH
NORTHWESTERLIES NOTED AROUND KAUAI AND OAHU. NORTHWESTERLY WINDS
WILL SPREAD FROM WEST TO EAST THROUGH TODAY AS HIGH PRESSURE BUILDS
IN FROM THE NORTHWEST. WINDS AT THE BIG ISLAND SUMMITS ARE STILL
ABOVE BLIZZARD WARNING LEVELS AND THE DIGGING UPPER LEVEL TROUGH IS
EXPECTED TO KEEP WINDS HIGH THERE TODAY. PRECIPITATION IS ALSO
EXPECTED TO PICK UP AS SHOWERS NEAR MAUI SHIFT SOUTHEASTWARD. THE
BLIZZARD WARNING REMAINS IN EFFECT FOR THE BIG ISLAND SUMMITS
THROUGH TODAY.

THE HIGH NORTHWEST OF THE STATE WILL BUILD EASTWARD OVER THE WEEKEND
AND WINDS ARE EXPECTED TO RETURN TO A MORE TYPICAL TRADE WIND
DIRECTION ACROSS LOCAL WATERS. MODELS SHOW A DRIER WEATHER PATTERN
FROM LATE FRIDAY INTO SATURDAY. HOWEVER...THIS TRADE PATTERN MAY BE
SHORT LIVED AS A SERIES OF SYSTEMS TRACKING ACROSS THE NORTH PACIFIC
MAY SHIFT THE RIDGE SOUTHWARD OVER THE ISLANDS BY EARLY NEXT
WEEK...INTRODUCING A PERIOD OF LIGHTER AND POSSIBLY VARIABLE WINDS.
GFS SHOWS A FRONT APPROACHING THE ISLANDS FROM THE NORTHWEST BY LATE
NEXT WEEK.

&&

.AVIATION...
AIRMET SIERRA REMAINS IN EFFECT FOR MTN OBSC OVER PORTIONS OF THE
BIG ISLAND AND MAUI COUNTY DUE TO LAYERED CLOUDS ASSOCIATED WITH AN
UPPER TROUGH. THE AIRMET MAY BE DROPPED FOR THE PORTIONS OF MAUI
COUNTY IN EFFECT AS THE TROUGH SHIFT EASTWARD. ELSEWHERE...ISOLATED
MTN OBSC IS EXPECTED.

AIRMET ZULU IS IN EFFECT FOR ICING OVER MAUI COUNTY AND THE BIG
ISLAND...AND THE WATERS SURROUNDING BOTH.

AIRMET TANGO IS IN EFFECT FOR OCCASIONAL MODERATE TURBULENCE BETWEEN
FL250 AND FL350 FOR THE ENTIRE AREA.

&&

.MARINE...
WAVEWATCH GUIDANCE CONTINUES TO SHOW A NORTH-NORTHWEST SWELL
ARRIVING THIS AFTERNOON...BRINGING WARNING LEVEL SURF TO NORTH AND
WEST FACING SHORES BEGINNING TONIGHT. THIS SWELL WILL HAVE MORE OF A
NORTHERLY COMPONENT THAN NORMAL...AND WILL AFFECT NORTH AND EAST
FACING SHORES OF THE BIG ISLAND AS WELL. A HIGH SURF WARNING WILL GO
INTO EFFECT AT 6 PM HST TODAY FOR NORTH AND WEST FACING SHORES OF
NIIHAU...KAUAI...OAHU AND MOLOKAI AS WELL AS FOR NORTH FACING SHORES
OF MAUI. A HIGH SURF ADVISORY WILL GO INTO EFFECT AT THE SAME TIME
FOR NORTH AND EAST FACING SHORES OF THE BIG ISLAND. SURF WILL
GRADUALLY DIMINISH THROUGH THE WEEKEND. A SMALL SOUTHWEST SWELL WILL
ARRIVE ON FRIDAY AND CONTINUE THROUGH EARLY NEXT WEEK.

WINDS ARE EXPECTED TO TURN NORTHERLY AND INCREASE TODAY AND TONIGHT.
WINDS WILL EXCEED SMALL CRAFT ADVISORY LEVELS THROUGH THE WINDIER
CHANNELS TONIGHT AND FRIDAY. WITH THE BUILDING NORTH-NORTHWEST
SWELL...SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED OVER MOST
COASTAL WATERS DUE TO EITHER HAZARDOUS SEAS OR A COMBINATION OF SEAS
AND WIND BEGINNING TONIGHT.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 6 PM HST TODAY FOR HALEAKALA SUMMIT.

BLIZZARD WARNING UNTIL 6 PM HST TODAY FOR BIG ISLAND SUMMITS.

HIGH SURF WARNING FROM 6 PM HST TODAY TO 6 PM HST FRIDAY FOR NORTH
AND WEST FACING SHORES OF NIIHAU KAUAI OAHU MOLOKAI AND NORTH FACING
SHORES OF MAUI.

HIGH SURF ADVISORY FROM 6 PM HST TODAY TO 6 PM HST FRIDAY FOR NORTH
AND EAST FACING SHORES OF THE BIG ISLAND.

SMALL CRAFT ADVISORY FROM 6 PM HST TODAY TO 6 PM HST FRIDAY FOR ALL
HAWAIIAN WATERS EXCEPT MAALAEA BAY.

&&

DISCUSSION/MARINE...POWELL
AVIATION...FOSTER