Heavy Rain in Hawaii, April 17, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
950 AM HST SUN APR 17 2011

.SYNOPSIS...
A WEAK SURFACE BOUNDARY WILL PROVIDE KAUAI WITH SOME SCATTERED
SHOWERS THIS AFTERNOON AND THIS EVENING. OTHERWISE..THE TRADE WINDS
WILL BE SPREADING ACROSS THE AREA FROM THE EAST DURING THE NEXT 36
HOURS AND REMAIN WITH US THROUGH THE REST OF THE WEEK. THE RETURN
OF THE TRADE WINDS WILL BE SUPPORTED BY RIDGING ALOFT WHICH WILL
LIMIT THE AMOUNT OF TRADE WIND SHOWERS.

&&

.DISCUSSION...
THE TRADE WINDS WILL BE SPREADING SLOWLY WESTWARD FROM THE BIG
ISLAND END OF THE STATE THROUGH MONDAY. SO FAR THE TRADES HAVE
REACHED EASTERN MOLOKAI...AND THE SATELLITE LOOP SHOWS EASTERLY
WINDS ACROSS THE LEEWARD WATERS FROM THE ALENUIHAHA CHANNEL TO THE
WATERS SOUTH OF OAHU.

KAUAI COUNTY IS CURRENTLY UNDER A LIGHT SOUTHERLY WIND FLOW WITH A
WEAK SURFACE BOUNDARY LURKING JUST OFF ITS NA PALI COAST. LOOK FOR
INTERIOR KAUAI TO CLOUD UP IN THE NEXT COUPLE OF HOURS WITH ISOLATED
TO SCATTERED SHOWERS AS THE BOUNDARY MOVES IN AND DISSIPATE EARLY
THIS EVENING. THESE CLOUDS AND SHOWERS WILL LINGER A LITTLER LONGER
INTO THE EVENING HOURS. BY MIDNIGHT OR SO...MOST OF THE EXPECTED
CLOUDS AND SHOWERS WILL HAVE DISSIPATED. OAHU IS MOST CLEAR THIS
MORNING. BUT WITH LIGHT WINDS ON TAP FOR THE REST OF THE DAY...LOOK
FOR SOME AFTERNOON CLOUDS AND ISOLATED SHOWERS OVER ITS LEEWARD AND
INTERIOR AREAS. HOWEVER...ANTICIPATING A MOSTLY FAIR NIGHT TONIGHT.

THE SURFACE BOUNDARY IS ACTUALLY PART OF A FRONT THAT EXTENDS
NORTHEASTWARD ACROSS 30N150W TO A LOW PRESSURE SYSTEM OFF THE
NORTHERN CALIFORNIA COAST. IT IS ANTICIPATED THAT THE SEGMENT OF THE
FRONT/BOUNDARY DISSIPATES OVER KAUAI BUT REMAINS INTACT OVER THE
WINDWARD WATERS OF KAUAI AND OAHU INTO TUESDAY NIGHT.

FOR MONDAY...BOTH KAUAI AND OAHU CAN EXPECT ONE MORE DAY OF
AFTERNOON CONVECTIVE CLOUDS AND ISOLATED SHOWERS. BY TUESDAY...THE
TRADE WINDS SHOULD HAVE A FIRMER GRIP. RIDGING ALOFT RIDGING WILL BE
SETTLING ACROSS THE AREA TUESDAY AND BE IN PLACE BY WEDNESDAY. THIS
WILL RESULT IN SLIGHTLY STRONGER TRADE WINDS AND A MORE STABLE AIR
MASS THAT WILL LIMIT THE AMOUNT OF TRADE WIND SHOWERS.

THE HAZE HAS BEEN REMOVED FROM THE FORECAST. IT HAS NOT BEEN A
FACTOR ACROSS THE CENTRAL ISLANDS DURING THE PAST 24 HOURS.

AN AREA OF LOW CLOUDS HAS KEPT MOST OF THE EAST FACING AND LEEWARD
DISTRICTS OF THE BIG ISLAND CLOUDY THIS MORNING WITH ISOLATED TO
SCATTERED SHOWERS. THE EAST FACING DISTRICTS CAN EXPECT SOME
CLEARING IN THE NEXT FEW HOURS AS THE AREA MOVES WESTWARD. HOWEVER
THESE CLOUDS WILL LIKELY PERSIST ACROSS THE LEEWARD AREAS INTO THE
EARLY EVENING HOURS BEFORE DISSIPATING.

THE REST OF THE WEEK LOOKS DRY WITH LIGHT TO MODERATE TRADES. THE
SUPPORT OF RIDGING ALOFT WILL LOWER THE INVERSION DOWN TO 5 TO 7
THOUSAND FEET.

&&

.MARINE...
WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY
CRITERIA AT LEAST THROUGH AT LEAST THURSDAY.

THERE WILL BE A SERIES OF SMALL TO MODERATE SIZE SWELLS FROM THE
SOUTH THROUGH TUESDAY. A LARGER...LONG PERIOD SOUTH SWELL IS
FORECAST TO ARRIVE TUESDAY NIGHT...AND PEAK WEDNESDAY NIGHT. SURF
HEIGHTS PRODUCED BY THIS SWELL WILL LIKELY CAUSE SURF TO REACH HIGH
SURF ADVISORY THRESHOLD ALONG SOUTH FACING SHORES AS EARLY AS
WEDNESDAY AFTERNOON. THIS SWELL WILL SLOWLY DECLINE INTO THE WEEKEND.

THERE WILL BE A SERIES OF SMALL TO MODERATE SIZE SWELLS FROM THE
NORTHWEST THIS WEEK. THE MODERATE SIZE SWELL IS SLATED TO REACH THE
NORTH AND WEST SHORES OF KAUAI NIIHAU AND OAHU MONDAY NIGHT AND PEAK
TUESDAY NIGHT. A FOLLOW UP SWELL IS SLATED FOR FRIDAY NIGHT. THIS
SWELL IS EXPECTED TO BE SLIGHTLY SMALLER.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

LAU