High Surf in Hawaii, November 22, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST THU NOV 22 2012

.SYNOPSIS...
HIGH CLOUDS WILL PERSIST THROUGH TONIGHT...THEN DIMINISH FRIDAY.
WEAK SOUTHEASTERLY FLOW WILL ALLOW FOR ONSHORE SEA BREEZES DURING
THE DAY AND LAND BREEZES AT NIGHT. DAYTIME CLOUDS AND SHOWERS WILL
BUILD UP ACROSS THE ISLAND INTERIORS THROUGH THIS WEEKEND...WITH THE
POSSIBILITY OF SOME UNSETTLED WEATHER. STRONGER NORTHEAST TRADE
WINDS WILL FILL IN BEGINNING SUNDAY NIGHT.

&&

.DISCUSSION...
HIGH-BASED LAYERED CLOUDS ASSOCIATED WITH A JET STREAM OVER THE
STATE WILL PERSIST FOR ONE MORE DAY...THEN BEGIN TO BREAK UP ON
FRIDAY. THE HIGH CLOUDS WILL OCCASIONALLY BE THICK ENOUGH TO
PRECIPITATE DOWN TO THE BIG ISLAND SUMMITS...LIGHT RAIN/SNOW CHANCES
REMAIN IN THE FORECAST INTO FRIDAY.

WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL TROUGH WITH AN AXIS 675
MILES WEST-NORTHWEST OF KAUAI...MOVING EAST AT 15 MPH. A COLD FRONT
IS ASSOCIATED WITH THE TROUGH JUST EAST OF THE AXIS...ABOUT 375
MILES NORTHWEST OF KAUAI. THE TROUGH IS ENHANCING THUNDERSTORMS IN
AN AREA ABOUT 300 MILES SOUTHWEST OF LANAI. WHILE THIS CONVECTION IS
EXPECTED TO REMAIN SOUTHWEST OF US...DEBRIS CLOUDS PICKED UP BY THE
SUBTROPICAL JET WILL HELP TO KEEP THE STATE MOSTLY CLOUDY THROUGH
EARLY FRIDAY.

AT THE SURFACE...A HIGH IS FAR NORTHEAST OF THE STATE...WITH A RIDGE
EXTENDING SOUTHWEST FROM IT AND PASSING ABOUT 150 MILES NORTH OF
KAUAI. THE NEARBY RIDGE AND WEAK PRESSURE GRADIENT OVER THE STATE IS
CAUSING WEAK SOUTHEASTERLY FLOW. NIGHTTIME LAND BREEZES AND DAYTIME
ONSHORE SEA BREEZES WITH INTERIOR CLOUDS AND SHOWERS SHOULD DOMINATE
OVER THE BACKGROUND FLOW INTO THE WEEKEND. AVAILABLE MOISTURE FOR
CLOUDS AND SHOWERS OVER THE HAWAIIAN ISLANDS SHOULD BE HIGHER THAN
NORMAL ACROSS THE STATE. THE 12Z HILO SOUNDING SHOWS A FAIRLY
SATURATED ATMOSPHERE WITH PRECIPITABLE WATER VALUES AT 1.84
INCHES...WITH DRIER CONDITIONS OVER LIHUE THIS MORNING.

CURRENT RADAR THIS MORNING SHOWS A BIT OF SHOWERS AROUND THE STATE.
SOME OF THESE SHOWERS ARE MODERATE IN INTENSITY. MOST OF THESE
SHOWERS ARE OFFSHORE...EXCEPT FOR ALONG THE WINDWARD AND SOUTHEAST
BIG ISLAND AND THE EAST COAST OF HALEAKALA. EXPECTING THIS UNSETTLED
WEATHER TO CONTINUE INTO THE WEEKEND...WITH THE FOCUS ON THE ISLAND
INTERIORS DURING THE DAY AND OFFSHORE AT NIGHT. MODELS HAVE NOT BEEN
HANDLING THIS PATTERN VERY WELL IN TERMS OF LOCATION OF QPF.

WITH RESPECT TO THE OVERALL PATTERN...THE COLD FRONT NORTHWEST OF
THE STATE WILL STALL ABOUT 300-400 MILES NORTHWEST OF KAUAI AS A
WEAK LOW DEVELOPS ALONG IT. THIS FRONT WILL SUPPRESS THE RIDGE
SOUTHWARD TO NEAR KAUAI. AS A NEW UPPER LEVEL TROUGH DIGS FAR NORTH
OF THE STATE...THE LOW WILL STRENGTHEN AND TRACK NORTHEAST AWAY FROM
THE AREA BEGINNING SATURDAY...EVENTUALLY BRINGING THE REMAINS OF THE
FRONT ACROSS THE AREA SUNDAY NIGHT. STRONGER NORTHEAST TRADE WINDS
WILL FILL IN MONDAY AS HIGH PRESSURE PUSHES IN BEHIND THE FRONTAL
REMNANTS. THE TRADES WILL QUICKLY STRENGTHEN BY MONDAY NIGHT AND
TUESDAY.

&&

.AVIATION...
AIRMET ZULU IS IN EFFECT FOR ICING...LIGHT TO MODERATE RIME...FROM
18K TO 25K FEET FOR ALL THE MAIN HAWAIIAN ISLANDS EAST OF OAHU.

&&

.MARINE...
A NEW NORTH SWELL ARRIVED LAST NIGHT AND WILL PEAK TODAY. THE HILO
BUOY IS SHOWING SIGNIFICANT WAVE HEIGHTS 9 TO 10 FEET THIS
MORNING... WITH THE MAJORITY OF THE CONTRIBUTION FROM THE 14 SECOND
PERIOD SWELL. THESE WAVE HEIGHTS ARE EXCEEDING MODEL GUIDANCE AND
THROWS US TO ADVISORY LEVELS ALONG EAST FACING SHORES OF MAUI AND
THE BIG ISLAND WITH A NORTHERN EXPOSURE. THEREFORE...A HIGH SURF
ADVISORY GOES INTO EFFECT FOR THE MENTIONED AREAS UNTIL 600 PM HST
TODAY DURING THE SWELL/S PEAK. A MARINE WEATHER STATEMENT FOR HARBOR
SURGES INTO KAHULUI AND HILO HARBORS WILL ALSO REMAIN IN EFFECT FOR
TODAY. THE SWELL SHOULD BE LOW ENOUGH ALONG EAST SHORES OF OAHU AND
KAUAI FOR NO ADVISORY.

THE NORTH SWELL WILL DECLINE TONIGHT BUT WILL BOOST UP AGAIN FRIDAY
NIGHT / SATURDAY AS ANOTHER REINFORCEMENT SWELL COMES IN FROM THE
NORTH.

WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY
THROUGH THIS WEEKEND. NORTHEAST TRADES WILL BUILD BACK IN SUNDAY
NIGHT AND QUICKLY STRENGTHEN TO SMALL CRAFT ADVISORY LEVELS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 PM HST THIS EVENING FOR EAST FACING
SHORES WITH A NORTHERN EXPOSURE OF MAUI AND BIG ISLAND.

&&

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