High Surf in Hawaii, February 18 to 20, 2006

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST SAT FEB 18 2006

.SYNOPSIS...
UNSTABLE WEATHER WILL REMAIN FOR THE WESTERN ISLANDS THROUGH
TODAY...THANKS TO AN UPPER LOW NORTHWEST OF KAUAI. EXPECT AFTERNOON
AND EVENING MAUKA SHOWERS WITH MOSTLY DRY CONDITIONS TONIGHT. LIGHT
TO MODERATE TRADE WINDS EXPECTED NEXT WEEK WILL NUDGE CLOUDS AND
SHOWERS BACK TO A TRADE WIND PATTERN...FAVORING WINDWARD AND MAUKA
AREAS.

&&

.DISCUSSION...
AN UPPER LOW MORE THAN 500 MILES NORTHWEST OF KAUAI CONTINUES MOVING
WEST AWAY FROM THE ISLANDS AND ITS IMPACT ON ISLAND WEATHER HAS
WANED SINCE YESTERDAY. HOWEVER...OVERNIGHT SOUNDINGS STILL SHOW AN
UNSTABLE AIR MASS OVER THE ISLANDS. THE LIHUE SOUNDING HAS A K INDEX
OF 22 WITH ABOUT 1 1/4 INCHES OF PRECIPITABLE WATER. CAPE IS
SLIGHTLY LOWER THAN YESTERDAY...BUT IS STILL ABOVE 1400 J/KG WITH NO
CAPPING INVERSION SEEN IN THE THERMAL PROFILE. IN CONTRAST TO THE
LIHUE SOUNDING...THE OVERNIGHT HILO SOUNDING SHOWS A HIGH-BASED
INVERSION NEAR 7300 FEET WITH MUCH LOWER CAPE.

SATELLITE LOOPS SHOW THAT DEEP CONVECTION AND LAYERED CLOUDS HAVE
LIFTED NORTHWARD SINCE YESTERDAY...FOLLOWING THE AREA OF UPPER LEVEL
DIFFLUENCE OR SPLIT FLOW TO THE EAST OF THE UPPER LOW. AN UPPER
RIDGE IS BEGINNING TO NOSE NORTHWARD OVER THE ISLANDS IN THE WAKE OF
THE RETREATING UPPER LOW...AND A BAND OF BROKEN HIGH CLOUDS ALONG
THE NORTHERN FLANK OF THIS HIGH IS MOVING NORTH OVER THE BIG ISLAND.
THESE HIGH CLOUDS WILL DIM THE SUNSHINE LATER TODAY FOR MUCH OF THE
STATE.

THE SURFACE TROUGH ASSOCIATED WITH THE UPPER LOW HAS PASSED WEST OF
KAUAI OVERNIGHT...LEAVING THE MAIN HAWAIIAN ISLANDS WITHIN LIGHT
SOUTH SOUTHEAST FLOW NEAR THE SURFACE. GFS75 SHOWS LIGHT TO MODERATE
TRADE WINDS RETURNING SUNDAY AND LASTING THROUGH THE REST OF THE
FORECAST PERIOD.

THE FORECAST CALLS FOR A TRANSITION TO A TRADE WIND DISTRIBUTION OF
SHOWERS BY SUNDAY...BUT ALSO FOR CONTINUED HIGH CLOUDINESS THROUGH
MONDAY AND INTO TUESDAY. CONVECTIVE SHOWERS MAY FORM THIS AFTERNOON
ACROSS THE CENTRAL AND WESTERN ISLANDS...BUT THE ENCROACHING THICK
HIGH CLOUDS WILL DECREASE THE EFFECT OF DAYTIME HEATING ON
CONVECTION FARTHER EAST.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...

NONE.

&&

POWELL