High Surf in Hawaii, February 16 to 17, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST MON FEB 16 2009

.SYNOPSIS...
A STRONG HIGH PRESSURE SYSTEM FAR NORTH OF HAWAII WILL MAINTAIN
MODERATE TO FRESH TRADE WINDS THROUGH MOST OF THE WEEK. A WEAK
SHEARLINE WILL PASS OVER THE ISLANDS WEDNESDAY CAUSING A SLIGHT
INCREASE IN THE TRADE SHOWERS. A LARGE LOW WILL MOVE INTO A POSITION
FAR NORTHEAST OF THE STATE WEDNESDAY AND CAUSE TRADE WINDS TO BECOME
NORTHEASTERLY BRINGING SLIGHTLY COOLER TEMPERATURES DURING THE
SECOND HALF OF THE WEEK.

&&

.DISCUSSION...
TONIGHT SHOWER ACTIVITY WILL REMAIN SCATTERED MAINLY FROM MAUI
THROUGH KAUAI AS A BATCH OF SHOWERY SC MOVE ACROSS THE AREA
REMAINING FOCUSED ON WINDWARD/MAUKA ZONES. RAINFALL ACCUMULATIONS
WILL BE LIGHT AND NOT EXCEED 1/10 INCH EVEN FOR THE WETTER AREAS.
SUSTAINED WINDS ON HALEAKALA SUMMIT ARE JUST OVER 30 MPH RIGHT NOW
AS THE MID LEVEL HIGH SLIDES TOWARD THE AREA FROM THE NW. FEEL THIS
INCREASE IS VERY TEMPORARY HOWEVER IT HAS PERSISTED AND DOES WARRANT
A WIND ADVISORY. WILL CARRY THIS THROUGH 10 AM TOMORROW MORNING.

WED...A RATHER UNIMPRESSIVE SHEARLINE WILL MOVE THROUGH THE FORECAST
AREA. IT WILL BRING SHALLOW FRONTAL REMNANTS WHICH WILL INCREASE
WINDWARD/MAUKA SHOWERS. OVERALL MOISTURE FIELDS LOOK UNIMPRESSIVE
WITH PWAT VALUES BARELY EXCEEDING 1 INCH AS THE SHEARLINE PASSES.

DISCREPANCIES STILL ARISE IN THE LONGER TERM REGARDING THE LARGE
OCCLUDED LOW THAT DEVELOPS NE OF THE STATE MID WEEK. BEGINNING FRI
THERE IS SIGNIFICANT DIVERGENCE IN MODEL SOLUTIONS AS TO THE
EVOLUTION OF THE LOW THROUGH THE REMAINDER OF THE FORECAST PERIOD.
THE CURRENT GFS...LIKE PREV RUNS...STILL SUGGESTS THE LOW WILL
FRAGMENT AND DROP SWWD TOWARDS THE STATE. THE 17/00Z GFS CONTINUES
TO KEEP THE LARGE LOW CONSOLIDATED MOVING IT SLOWLY NEWD BEGINNING
LATE SAT AS IT MERGES BACK WITH THE POLAR JET. THE ECMWF SOLUTION
HAS SIGNIFICANT SUPPORT FROM A MAJORITY OF THE GFS ENSEMBLE MEMBERS.
WILL LIKELY CONTINUE TO LEAN IN THIS DIRECTION GIVEN THE ENSEMBLE
SUPPORT...THE ECMWF TRACK RECORD WITH CUT-OFF LOWS AND BETTER RUN TO
RUN CONTINUITY.

&&

.PREVIOUS DISCUSSION 400 PM...
AFTERNOON SATELLITE IMAGERY SHOWS ONLY ISOLATED SHOWERS IN THE TRADE
WIND FLOW. THERE ARE FEWER CLOUDS UPWIND TO THE EAST OF THE BIG
ISLAND HOWEVER. A NORMAL WEATHER PATTERN OF LIGHT PASSING TRADE WIND
SHOWERS WILL AFFECT PRIMARILY WINDWARD AND MOUNTAIN AREAS THROUGH
THIS WEEK. THE GFS MODEL INDICATES SLIGHTLY MORE MOISTURE OVER KAUAI
AND OAHU THROUGH THE NIGHT. ALMOST NO PRECIPITATION ACTIVITY
REPORTED FROM THE AUTOMATED RAIN GAGES. A LARGE LOW WILL TAKE UP
RESIDENCE BETWEEN OREGON AND HAWAII AND REMAIN NEARLY STATIONARY BUT
IS NOT EXPECTED TO BE A FACTOR IN OUR WEATHER UNTIL THE ASSOCIATED
UPPER FLOW BEGINS ERODING THE UPPER RIDGE TO OUR NORTH THIS WEEKEND.
THERE COULD BE A CHANGE TO MORE UNSETTLED WEATHER SUNDAY OR MONDAY
WHEN A WEAK UPPER TROUGH DIGS DOWN OVER THE ISLANDS FROM THE NORTH.

&&

.MARINE...
THE BUOY NORTHWEST OF KAUAI PEAKED AROUND 11 FEET ABOUT MIDDAY. THIS
SWELL WILL SLOWLY DECLINE TOMORROW. LARGE SURF OF 12 TO 16 FT IS
EXPECTED TO CONTINUE THROUGH TOMORROW AFTERNOON. WE HAVE ADDED NORTH
FACING SHORES OF MOKOKAI AND MAUI TO THE HIGH SURF ADVISORY.

THE ABOVE MENTIONED LOW NE OF HAWAII WEDNESDAY WILL EVENTUALLY HAVE
A SWELL GENERATING FETCH AIMED TOWARD HAWAII DURING THE SECOND HALF
OF THE WEEK. THIS WILL LIKELY GENERATE A NE SWELL THAT WILL REACH
HIGH SURF ADVISORY LEVELS OF 8 FT ON E FACING SHORES THIS WEEKEND.

PREVAILING TRADES ARE EXPECTED TO CONTINUE NEAR 25 KT IN THE
TYPICALLY WINDY MARINE ZONES THROUGH MID WEEK AND THERE MAY BE
SUBSEQUENT EXTENSIONS OF THE SMALL CRAFT ADVISORIES FOR THESE AREAS.
THE NORTHWEST SWELL AND THE LOCALLY GENERATED WIND WAVES HAVE
COMBINED SEAS AROUND KAUAI..OAHU...AND MAUI COUNTY AT 10 FT OR
GREATER HENCE INCLUSION IN THE SCA.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 400 PM HST TUESDAY FOR NORTH AND WEST
FACING SHORES OF NIIHAU AND KAUAI...AND FOR NORTH FACING SHORES OF
OAHU...MOLOKAI AND MAUI.

WIND ADVISORY UNTIL 10 AM HST TUESDAY FOR HALEAKALA SUMMIT.

SMALL CRAFT ADVISORY UNTIL 600 AM HST WEDNESDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS- KAUAI
CHANNEL-KAIWI CHANNEL-MAALAEA BAY-PAILOLO CHANNEL- ALENUIHAHA
CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS.

SMALL CRAFT ADVISORY UNTIL 400 PM HST TUESDAY FOR OAHU WINDWARD
WATERS-OAHU LEEWARD WATERS-MAUI COUNTY WINDWARD WATERS-MAUI COUNTY
LEEWARD WATERS.

&&

PUBLIC/MARINE...DEJESUS
PREVIOUS DISCUSSION...HOAG