High Surf in Hawaii, January 1 to 6, 2016

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
800 PM HST THU DEC 31 2015

.SYNOPSIS...
LIGHT WINDS AND DRY CONDITIONS TONIGHT AND FRIDAY MORNING WILL YIELD TO
NORTHERLY WINDS AND A FEW SHOWERS AS A WEAK FRONT MOVES SOUTHEAST ACROSS
THE STATE FROM FRIDAY EVENING INTO SATURDAY. THE NORTHERLY WINDS WILL
BECOME NORTHEASTERLY...AND THEN EASTERLY BY LATE IN THE WEEKEND. LIGHT
WINDS AND DRY CONDITIONS THEN WILL RETURN AHEAD OF A SECOND FRONT MOVING
SOUTH OVER THE ISLANDS EARLY NEXT WEEK. A STRONGER FRONT HAS A CHANCE TO
BRING MORE SIGNIFICANT RAIN TO THE STATE LATE NEXT WEEK.

&&

.DISCUSSION...
LIGHT WINDS AND SCANTY PRECIPITATION PREVAILED OVER THE MAIN HAWAIIAN
ISLANDS AHEAD OF A WEAK FRONT APPROACHING FROM THE NORTHWEST. ALTHOUGH
SATELLITE IMAGES SHOWED CONSIDERABLE CLOUD COVER FORMING OVER THE OCEAN
AROUND THE STATE...MOST OF IT CONSISTED OF SHALLOW...STABLE STRATUS. THE
FRONTAL CLOUD BAND HELD TOGETHER SURPRISINGLY WELL DURING ITS PASSAGE
THROUGH THE SUBTROPICAL RIDGE. SUPPORT FROM ALOFT WAS LIMITED...WITH
ONLY A SHALLOW TROUGH ALOFT DIGGING WEAKLY INTO THE MOSTLY ZONAL...BUT
QUITE SOLID...MID-LEVEL RIDGE PREVAILING OVER THE AREA.

SCATTEROMETER DATA AND CLOUD MOTIONS DID SUGGEST FAIRLY STRONG WINDS
BEHIND THE FRONT THOUGH...SO THESE AND THE COOLER AIR MASS WILL
REPRESENT THE MOST NOTICEABLE CHANGES AS THE FEATURE PASSES OVER THE
ISLANDS ON SATURDAY. WIND DIRECTION SHOULD START OUT NORTHERLY...BUT
WILL BECOME NORTHEASTERLY FAIRLY QUICKLY AS RIDGING BUILDS FURTHER
THROUGH A DEEP LAYER. INCREASED SHOWERS WILL ACCOMPANY THE FRONT...BUT
SUBSIDENCE AND LIMITED WATER VAPOR SHOULD KEEP MODERATE ACCUMULATION TO
ONLY A FEW LOCATIONS.

A CLOSER LOOK AT THE TEMPERATURE FIELD SHOWED THAT THE LIKELY EFFECTS OF
THE FRONT HAVE NOT BEEN INCLUDED IN THE FORECAST YET. GUSTY WINDS SHOULD
KEEP MINIMUM TEMPERATURES UP...BUT DAILY HIGHS THROUGH THE WEEKEND MAY
NEED A TWEEK DOWNWARD.

IN ANY CASE...GUIDANCE PREDICTED ANOTHER FRONT TO APPROACH FROM THE
NORTHWEST BY SATURDAY NIGHT. MOST SOLUTIONS DEPICTED BOTH A DEEPER
SUPPORTING TROUGH ALOFT...AND A STRONGER FRONT AT THE SURFACE. HOWEVER...
THE BEST-SUPPORTED PART OF THE FRONT SHOULD PASS TO THE NORTHEAST OF THE
ISLANDS...LEAVING ONLY A SHALLOW TAIL TO SAG SOUTHWARD OVER THE STATE
THROUGH THE EARLY PART OF NEXT WEEK. THUS...EFFECTS SHOULD BE SIMILAR TO
WHAT THE FIRST FRONT BRINGS.

TRADE WINDS WILL RETURN BRIEFLY BY THE MIDDLE OF NEXT WEEK...BUT WIND
DIRECTION WILL BECOME SOUTHEASTERLY AGAIN FAIRLY QUICKLY AHEAD OF A MUCH
STRONGER FRONT. GUIDANCE LEANED TOWARD FAIRLY IMPRESSIVE SUPPORT
DEVELOPING FOR THIS THIRD FRONT ALOFT...SO THIS FEATURE MAY HAVE A
CHANCE TO BRING MORE SIGNIFICANT RAIN TO THE STATE BY THE END OF NEXT
WEEK.

&&

.AVIATION...
LIGHT WINDS OVERNIGHT WILL BE REPLACED BY GUSTY NORTHERLY WINDS ON
FRIDAY AS A WEAK FRONT MOVES THROUGH THE ISLANDS AND A NEW HIGH
BUILDS IN BEHIND THE FRONT. WINDS WILL LIKELY REMAIN LIGHT ENOUGH
INTO LATE FRIDAY MORNING TO PRECLUDE THE NEED OF ANY AIRMET TANGO
FOR LOW LEVEL TURB. AIRMET TANGO MAY BECOME NECESSARY FRIDAY
AFTERNOON AS WINDS INCREASE.

OVERNIGHT...EXPECT MINIMAL SHOWER ACTIVITY AND PREVAILING VFR
THROUGHOUT THE STATE. THE APPROACHING FRONT IS NOT FORECAST TO BRING
WIDESPREAD SHOWERS...BUT WINDWARD AREAS MAY SEE A MODEST INCREASE IN
CLOUDS AND SHOWERS WITH ISOL MVFR AND MTN OBSCURATION POSSIBLE AS
THE FRONT SLIDES THROUGH THE ISLAND CHAIN DURING THE DAY ON FRIDAY.

&&

.MARINE...
THE CURRENT NORTHWEST SWELL WILL BE REINFORCED WITH A LARGER
NORTHWEST SWELL FRIDAY...CONTINUING THROUGH SATURDAY. EXPECT THE HIGH
SURF ADVISORY TO CONTINUE THROUGH THE WEEKEND...WITH SURF REACHING
WARNING LEVELS. WITH THE REINFORCING SWELL...ADVISORY-LEVEL SURF MAY
REACH THE BIG ISLAND. AN EVEN LARGER NORTHWEST SWELL IS FORECAST TO
ARRIVE SUNDAY NIGHT INTO MONDAY.

A SMALL CRAFT ADVISORY /SCA/ REMAINED IN EFFECT FOR MANY COASTAL
WATERS FOR COMBINED SEAS FROM THE LARGE SWELL. SOME ADDITIONAL AREAS
MAY NEED TO BE ADDED AS THE NEWER SWELLS ARRIVE.

&&

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

SMALL CRAFT ADVISORY UNTIL 8 PM HST FRIDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-
OAHU WINDWARD WATERS-KAIWI CHANNEL-MAUI COUNTY WINDWARD WATERS-
ALENUIHAHA CHANNEL-BIG ISLAND WINDWARD WATERS.

&&

DISCUSSION/MARINE...RYSHKO
AVIATION...JACOBSON