High Surf in Hawaii, February 6 to 7, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST THU FEB 5 2009

.SYNOPSIS...
MODERATE TO LOCALLY FRESH TRADE WINDS WILL CONTINUE THROUGH THE
MIDDLE OF NEXT WEEK AS SURFACE RIDGING HOLDS FAR NORTH OF THE STATE.
SHOWERS CARRIED BY THE TRADES WILL FAVOR WINDWARD AND MAUKA
LOCALES...WITH MOST LEEWARD AREAS REMAINING RATHER DRY. HIGH CLOUDS
WILL SLOWLY CLEAR THE ISLAND CHAIN FROM WEST TO EAST THROUGH FRIDAY
AS AN UPPER LOW SOUTH OF THE STATE WEAKENS AND DRIFTS TO THE
NORTHEAST.
&&

.DISCUSSION...
FORECAST IS ON TRACK WITH NO SURPRISES THIS EVENING. THE GRIDS ARE
HOLDING UP FINE SO DON/T ANTICIPATE ANY UPDATES AT THIS TIME.

PREVIOUS DISCUSSION FOLLOWS.

&&

.PREV DISCUSSION...
ISSUED AT 400 PM
THE SHIELD OF HIGH CLOUDS THAT HAS BLANKETED THE STATE FOR THE PAST
FEW DAYS HAS BEGUN TO THIN. THESE CIRRUS CLOUDS HAVE ALREADY
DISPERSED OVER KAUAI AND WILL GRADUALLY CLEAR THE SMALLER ISLANDS
FROM WEST TO EAST THROUGH TOMORROW. THE UPPER LOW GENERATING THE
HIGH CLOUDS...CURRENTLY CENTERED ROUGHLY 130 MILES SOUTH OF
HONOLULU...WILL WEAKEN AND OPEN INTO AN UPPER TROUGH AS IT DRIFTS TO
THE NORTHEAST THROUGH TOMORROW. THE HIGH CLOUDS WILL CLEAR THE BIG
ISLAND LATER FRIDAY OR SATURDAY AS THE UPPER TROUGH AXIS SLOWLY
SHIFTS EAST OF THE STATE.

MODERATE TO LOCALLY FRESH TRADE WINDS WILL PERSIST THROUGH THE
MIDDLE OF NEXT WEEK. A SURFACE RIDGE SEVERAL HUNDRED MILES NORTH OF
KAUAI EXTENDING FROM A STRONG HIGH CENTERED FAR NORTHEAST OF THE
STATE IS SUPPORTING THE TRADE WINDS. A FRONT...WHICH CLEARED MIDWAY
ATOLL THIS AFTERNOON...WILL PASS NORTH OF THE ISLANDS FRIDAY AND
SATURDAY...WEAKENING THE SURFACE RIDGE AND LEADING TO A SLIGHT AND
BRIEF DECLINE OF THE TRADE WINDS. ANOTHER HIGH MOVING ACROSS THE
NORTH PACIFIC BEHIND THE FRONT WILL REINFORCE THE SURFACE RIDGE
NORTH OF THE ISLANDS AND HELP TO MAINTAIN AT LEAST MODERATE TRADE
WINDS THROUGH NEXT THURSDAY.

A TYPICAL PATTERN OF WINDWARD AND MAUKA SHOWERS IS IN STORE FOR MUCH
OF THE STATE. AMSU SATELLITE DATA SHOW A RATHER DRY AIR MASS MOVING
WITHIN THE TRADE WIND FLOW TO THE EAST OF THE ISLANDS...BUT THE
CLOUD FIELD IN THIS AREA IS DOMINATED BY SHOWER-BEARING...OPEN
CELLED CUMULUS CLOUDS. AFTERNOON SOUNDINGS SHOW A LOW LEVEL
INVERSION CAPPING THE SHOWERS AT 5 TO 7 KFT...AND FORECAST MODELS
SHOW LITTLE CHANGE IN THE 700 MB HEIGHT THROUGH THE WEEK. AS A
RESULT...EXPECT THE CURRENT PATTERN OF WINDWARD AND MAUKA SHOWERS TO
PERSIST...WITH MOST LEEWARD AREAS EXPERIENCING MAINLY DRY
CONDITIONS. THE NOTABLE EXCEPTION WILL BE THE LEEWARD BIG ISLAND
SLOPES...WHERE AFTERNOON SHOWERS WILL PRODUCE MODEST RAINFALL
THROUGH THE WEEK. IN ADDITION...A SLIGHT CHANCE OF THUNDERSTORMS HAS
BEEN ADDED TO THE BIG ISLAND SLOPES FOR FRIDAY AFTERNOON AS THE
UPPER TROUGH MOVES OVERHEAD. ITS ASSOCIATED COLD POOL AND
INSTABILITY COMBINED WITH INCREASED DAY TIME HEATING UNDER THE
THINNING HIGH CLOUD SHIELD MAY CREATE FAVORABLE CONDITIONS FOR
ISOLATED CONVECTION ON THE UPPER BIG ISLAND SLOPES FRIDAY AFTERNOON.

&&

.MARINE...
SMALL CRAFT ADVISORIES HAVE BEEN EXTENDED THROUGH FRIDAY FOR ALL
CHANNELS AND WATERS FOR A COMBINATION OF WINDS AND SEAS. SMALL CRAFT
ADVISORY WINDS ARE IN STORE FOR THE USUALLY BREEZY CHANNELS AND
COASTAL WATERS...WHILE A NORTHWEST SWELL BUILDING TONIGHT SHOULD
CAUSE SEAS ACROSS MOST AREAS TO RISE ABOVE THE 10-FOOT SMALL CRAFT
ADVISORY LEVEL. THE NORTHWEST SWELL WILL ALSO PRODUCE ADVISORY LEVEL
SURF ALONG NORTH AND WEST FACING SHORES OF MOST SMALLER ISLANDS FROM
LATE TONIGHT THROUGH FRIDAY NIGHT.
&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY THROUGH FRIDAY AFTERNOON FOR ALL HAWAIIAN
WATERS.

HIGH SURF ADVISORY FOR NORTH AND WEST FACING SHORES OF NIIHAU KAUAI
OAHU AND MOLOKAI AND FOR NORTH FACING SHORES OF MAUI THROUGH FRIDAY
NIGHT.
&&