High Surf in Hawaii, November 19 to 21, 2007

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HONOLULU HI
500 AM HST MON NOV 19 2007

UPDATED TO EXPAND HIGH SURF ADVISORY TO NORTH FACING SHORES

.SYNOPSIS...
LIGHT TO MODERATE NORTHEASTERLY WINDS WILL PERSIST THROUGH
THANKSGIVING WITH LIGHT EASTERLY WINDS EXPECTED DURING THE WEEKEND.
AN UPPER LEVEL TROUGH WILL STALL EAST OF THE BIG ISLAND TODAY...
MAINTAINING SLIGHTLY UNSTABLE BUT SOMEWHAT DRY CONDITIONS FOR THE
NEXT SEVERAL DAYS. SHOWERS WILL FAVOR WINDWARD AND MOUNTAIN AREAS
THROUGH THE WEEK.

&&

.DISCUSSION...
AN UPPER LEVEL TROUGH STALLING EAST OF THE STATE TODAY WILL MAINTAIN
A SLIGHTLY UNSTABLE...THOUGH SOMEWHAT DRY NORTHEASTERLY FLOW ACROSS
THE ISLANDS THROUGH THANKSGIVING. AN UPPER LOW IS DEVELOPING WITHIN
THE UPPER TROUGH SEVERAL HUNDRED MILES NORTHEAST OF THE BIG ISLAND.
AS A RESULT...CONDITIONS ARE SLIGHTLY UNSTABLE OVER THE STATE.
OVERNIGHT AIRCRAFT DATA SHOWS A WEAK INVERSION AROUND 15000 FT...
HIGH ENOUGH TO ALLOW SOME LOCALLY HEAVY SHOWERS WITHIN A BAND NORTH
OF KAUAI AND OAHU. THIS BAND WILL BRING SHOWERS TO WINDWARD AND
MOUNTAIN PORTIONS OF KAUAI AND OAHU THIS MORNING...WITH SOME
SHOWERS REACHING LEEWARD AREAS. MAUI AND THE BIG ISLAND WILL START
THE DAY OFF RATHER DRY...BUT SHOWERS WILL DEVELOP DURING THE DAY
DUE TO LINGERING INSTABILITY.

FOR MUCH OF THE UPCOMING WEEK...THE ISLANDS WILL EXPERIENCE LIGHT TO
MODERATE NORTHEASTERLY WINDS AND SLIGHTLY UNSTABLE...BUT RATHER DRY
CONDITIONS. THE UPPER LEVEL TROUGH WILL STALL EAST OF THE ISLANDS
TONIGHT AND DEVELOP A SURFACE LOW SEVERAL HUNDRED MILES EAST OF THE
STATE. SURFACE TROUGHING WILL KEEP THE MODERATE WINDS OVER THE
ISLANDS OUT OF THE NORTHEAST WITH SLIGHT FLUCTUATIONS IN SPEED.
MOISTURE WILL BE LIMITED OVER THE ISLANDS...KEEPING SHOWERS MAINLY
ACROSS WINDWARD AND MOUNTAIN AREAS. TO THE WEST OF THE UPPER TROUGH
AXIS...THE FLOW ALOFT OVER THE ISLANDS WILL BE MAINLY STABLE...BUT
WEAK IMPULSES DROPPING INTO THE UPPER TROUGH MAY PRODUCE PERIODS OF
INSTABILITY THAT ENHANCE SHOWERS. MODELS INDICATE THAT ONE SUCH BOUT
IS POSSIBLE ON TUESDAY NIGHT AND WEDNESDAY. IF THIS OCCURS...THERE
IS A GOOD CHANCE THAT THANKSGIVING WILL FEATURE DRY AND STABLE
WEATHER.

FORECAST UNCERTAINTY INCREASES FOR THE WEEKEND AS THE NUMERICAL
MODELS DIVERGE. THEY ALL MAINTAIN A WEAK SURFACE RIDGE AND LIGHT
WINDS ACROSS THE REGION BUT VARY ON THE EXACT RIDGE POSITION. THE
ECMWF AND NOGAPS KEEP THE RIDGE NORTH OF THE ISLANDS AND PRODUCE
LIGHT TRADES...WHILE THE GFS PUSHES THE RIDGE TO THE SOUTH. WENT
WITH THE MAJORITY FOR NOW AND HAVE PLACED THE ISLANDS UNDER LIGHT
EASTERLIES. ALL MODELS KEEP THE UPPER TROUGH WELL EAST OF THE
ISLANDS...SO EXPECT STABLE CONDITIONS.

&&

.MARINE...
THE NORTH NORTHEAST SWELL THAT WE HAD BEEN EXPECTING BUILT RAPIDLY
AND LARGER THAN EXPECTED LATE TONIGHT. THE WAIMEA AND KAILUA
BUOYS HAVE REGISTERED ENERGY FROM THE NORTH IN EXCESS OF 11 FT WITH
PERIODS AROUND 12 SECONDS. THIS SWELL IS SLIGHTLY LARGER AND HAS A
LONGER PERIOD THAN WHAT WAS ANTICIPATED. THUS...THE HIGH SURF
ADVISORY HAS BEEN EXPANDED TO COVER NORTH FACING SHORES. A HIGH SURF
ADVISORY REMAINS FOR EAST FACING SHORES. THIS SWELL DIRECTION WILL
CAUSE HARBOR SURGES IN KAHULUI AND HILO HARBORS...AND A MARINE
WEATHER STATEMENT HAS BEEN ISSUED TO ADDRESS THIS. A SMALL CRAFT
ADVISORY IS ALSO IN EFFECT DUE TO HAZARDOUS SEAS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY THROUGH 4 AM TUESDAY DUE TO HAZARDOUS SEAS.

HIGH SURF ADVISORY FOR NORTH FACING SHORES OF NIIHAU KAUAI OAHU
MOLOKAI MAUI AND THE BIG ISLAND THROUGH 4 AM TUESDAY.

HIGH SURF ADVISORY FOR EAST FACING SHORES OF NIIHAU KAUAI OAHU
MOLOKAI MAUI AND THE BIG ISLAND THROUGH 4 PM TUESDAY.

&&

WROE