483 
FXHW60 PHFO 121330
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST TUE MAR 12 2013

.SYNOPSIS...
LINGERING MOISTURE...TOGETHER WITH A COLD LOW IN THE MIDDLE 
ATMOSPHERE...WILL PRODUCE SHOWERS OVER MOST OF THE STATE TODAY...AND 
POSSIBLY THUNDERSTORMS OVER HIGHER SLOPES OF MAUI AND THE BIG 
ISLAND. SLACK TRADE WINDS AND DRIER CONDITIONS WILL PREVAIL AROUND 
THE MIDDLE OF THE WEEK...BUT ANOTHER FRONT WILL SPREAD RAIN ACROSS 
THE STATE OVER THE WEEKEND.

&&

.DISCUSSION...
A BROAD AND DEEPLY STACKED TROUGH PERSISTED TO THE NORTH OF THE MAIN 
HAWAIIAN ISLANDS. THE AIR MASS MOISTENED AT LOWER LEVELS AROUND THE 
BIG ISLAND OVERNIGHT...WHILE LARGE SWATHS OF CIRRUS OBSCURED MOST OF 
THE STATE. THE HIGHER CLOUDS ALSO MAY HAVE BEEN SEEDING THE 
PROLIFERATING SHOWERS OFFSHORE. THUS...THE MORNING LIKELY WILL 
BECOME WETTER WITH TIME OVER MOST AREAS...THOUGH HEAVY RAIN SHOULD 
REMAIN RESTRICTED TO A FEW CONVECTIVE SHOWERS. BY THE AFTERNOON... 
THE AIR MASS MAY BE UNSTABLE ENOUGH TO PRODUCE A FEW THUNDERSTORMS 
OVER THE SLOPES OF HALEAKALA AND THE BIG ISLAND MOUNTAINS...THOUGH 
PERSISTENT CIRRUS COVER WILL REDUCE THE LIKELIHOOD OF THIS OUTCOME.

WINTER WEATHER HAD NOT MATERIALIZED OVER THE BIG ISLAND SUMMITS 
OVERNIGHT...AND OBSERVATIONS FROM THERE REPORTED INCREASINGLY DRY 
CONDITIONS. SOME WINTRY PRECIPITATION MAY BE POSSIBLE TODAY... 
ESPECIALLY IF THUNDERSTORMS DO DEVELOP ALONG LOWER SLOPES...BUT 
ACCUMULATION SHOULD BE LIMITED.

ON THE OTHER HAND...WINDS OVER THE SUMMITS REMAINED A CONCERN. 
GUIDANCE AGREED WELL IN PREDICTING THAT THE GRADIENT AT THE ALTITUDE 
OF THE SUMMITS WILL KEEP WIND SPEEDS HIGH THROUGH MOST OF THE WEEK. 
A SLIGHT LULL MAY OCCUR ON WEDNESDAY...BUT EVEN STRONGER WINDS ARE 
EXPECTED TO RESUME ON THURSDAY. INDEED...A HIGH WIND WARNING MAY BE 
WARRANTED BY LATE IN THE WEEK...AND THIS ISSUE WILL REQUIRE 
CONTINUED ATTENTION.

ELSEWHERE...WIND SPEEDS WILL REMAIN LOW. PREVAILING WIND DIRECTION 
WILL TURN AROUND TO A MORE TYPICAL TRADE-WIND ORIENTATION TODAY... 
BUT LOCAL SEA AND LAND BREEZES WILL PERSIST...AT LEAST WHERE CIRRUS 
COVER PERMITS THE LAND TO HEAT OR COOL SUBSTANTIALLY.

FROM THURSDAY INTO THE WEEKEND...LOW-LEVEL WINDS WILL START TO TURN 
SOUTHEASTERLY AND THEN SOUTHERLY AGAIN AHEAD OF THE NEXT INCOMING 
FRONT. GUIDANCE PREDICTS THIS FEATURE TO HAVE GOOD SUPPORT FROM 
ALOFT IN THE FORM OF A RAPIDLY DIGGING LOW WITHIN THE LARGER 
TROUGH...AND RECENT SOLUTIONS HAVE BEEN EXPECTING IT TO DROP 
GREATER AND MORE WIDESPREAD PRECIPITATION.

SOME DIFFERENCES REMAINED AMONG MODELS...MAINLY ON THE QUESTION 
WHETHER THE GREATEST PRECIPITATION WILL FALL FROM THE FRONTAL BAND 
ITSELF...OR FROM PRE-FRONTAL SHOWERS FIRING IN THE MOISTURE FROM THE 
PREVIOUS FRONT THAT FINALLY REACHES THE ISLANDS. BOTH MAY BE 
SIGNIFICANT...WITH MAUI COUNTY AND THE BIG ISLAND LIKELY TO RECEIVE 
MORE PRE-FRONTAL RAIN...BUT KAUAI COUNTY AND OAHU RECEIVING MORE 
FROM THE FRONT.

&&

.MARINE...
A SERIES OF NORTH AND NORTHWEST SWELLS WILL AFFECT THE ISLANDS 
THROUGH THE WEEK...THOUGH SURF HEIGHTS SHOULD REMAIN BELOW THE HIGH 
SURF ADVISORY CRITERIA. WIND SPEEDS ALSO SHOULD STAY BELOW SMALL 
CRAFT ADVISORY CRITERIA...WITH THE MAIN POSSIBLE EXCEPTION OCCURRING 
AFTER THE FRONTAL PASSAGE AROUND SATURDAY NIGHT.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 6 AM HST WEDNESDAY FOR BIG ISLAND SUMMITS.

&&

$$

RYSHKO