Heavy Rain in Hawaii, August 28, 2005

HAWAIIAN ISLANDS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST SUN AUG 28 2005

.SYNOPSIS...
A TROUGH OF LOW PRESSURE JUST NORTH OF THE MAIN HAWAIIAN ISLANDS
CONTINUES TO TRACK WEST. IT WILL KEEP WINDS LIGHT OVER OUR
AREA...WITH LAND AND SEA BREEZES DEVELOPING DURING THE NIGHT AND
DAY. LIGHT TO MODERATE TRADE WINDS ARE EXPECTED TO SLOWLY RETURN TO
OUR AREA BY THE MIDDLE OF THE WEEK AND SHOULD PREVAIL THROUGH THE
REST OF THE WEEK AS HIGH PRESSURE REBUILDS NORTH OF THE ISLANDS.
&&

.DISCUSSION...
A SURFACE TROUGH OF LOW PRESSURE CONTINUES TO CROSS OVER THE AREA
THIS MORNING. IT SHOWS UP IN THE UPPER AIR SOUNDINGS AT LIHUE AND
HILO. WINDS IN THE BOUNDARY LAYER ARE SOUTHEAST AT HILO AND
NORTHEAST AT LIHUE. SURFACE OBSERVATIONS FROM THE OVERNIGHT HOURS
SHOW LAND BREEZES AT MOST LOCATIONS AROUND THE ALOHA STATE. 17Z
SCATTEROMETER PASS OVER THE ISLAND CHAIN SHOW 5 TO 10 KNOT NORTHEAST
FLOW FOR THE WESTERN ISLANDS RANGING TO 10 TO 15 KNOT SOUTHEAST FLOW
FOR THE EASTERN ISLANDS. ALL THIS SUPPORTS A SEA BREEZE REGIME TODAY
FOR THE REGION.

THE ASSOCIATED UPPER LEVEL LOW REMAINS WELL TO THE NORTH OF THE MAIN
ISLAND CHAIN KEEPING ITS ENERGY AWAY FROM THE AREA. HOWEVER AS THE
TROUGH PASSES THROUGH WE COULD SEE SOME SHOWERS DEVELOP IN THE
INTERIOR AND MOUNTAIN REGIONS. OVERNIGHT A MODERATE SHOWER DEVELOPED
ON WINDWARD OAHU WITH A SHORT PERIOD OF MODERATE TO HEAVY RAIN
REPORTED BY THE WAIHEE GAUGE. INVERSION DEPTHS THIS MORNING AT BOTH
UPPER AIR STATIONS CAME IN AROUND 8300 FEET...THE GFS75 MODEL
SOUNDINGS STARTED OUT PRETTY GOOD WITH THE REAL OBSERVATIONS AT THE
12Z RUN. THE FORECAST SOUNDINGS REACH 11000 FEET THIS AFTERNOON AND
EVENING AT BOTH LOCATIONS. WOULD EXPECT KONA SIDE OF THE BIG ISLAND
TO BE THE AREA TO WATCH THIS AFTERNOON FOR HEAVIER SHOWERS TO
DEVELOP WITH THE DAYTIME HEATING...HOWEVER ANYWHERE IN THE CHAIN
COULD POP A GOOD MODERATE SHOWER OR TWO. WILL HAVE TO KEEP A
WATCHFUL EYE ON RADAR FOR CONVECTION. WILL NOT PUT ENHANCED WORDING
IN THE ZONES SINCE ITS NOT LIKELY EVENT...WOULD LIKE TO SEE THE
INVERSIONS COMPLETELY GONE FOR THAT...HOWEVER MIGHT BE MORE LIBERAL
WITH SHORT TERM FORECASTS TO COVER ANY HEAVIER SHOWERS THAT DO
DEVELOP THIS AFTERNOON. THE SOUTHEAST WINDS ON THE HILO SOUNDING
BRING A CONCERN FOR THE KAU DISTRICT OF THE BIG ISLAND WITH UPSLOPE
FLOW FOR MORE WIDESPREAD SHOWER DEVELOPMENT. FOR NOW WILL HOLD WITH
THE CURRENT FORECAST...MIGHT HAVE TO DO A QUICK UPDATE AFTER THE
NOON HOUR IF THINGS START TO DEVELOP MORE RAPIDLY FOR THE
DISTRICT...RADAR RETURNS FROM SOUTH POINT SHOW OFFSHORE SHOWER
ACTIVITY DRIFTING FROM THE EAST NORTHEAST TO THE SOUTHWEST. IF THIS
TREND TURNS MORE SOUTHEAST MOVING NORTHWEST WILL BE MORE LIKELY TO
PRESS THE UPDATE BUTTON FOR THE DISTRICT.

OTHERWISE FOR THE REMAINING FORECAST PERIODS THE CURRENT TREND SEEMS
TO HAVE RIGHT IDEA WITH THE SLOW RETURN TO THE TRADES. GFS MODEL
SHOWS PRETTY GOOD AREA OF MOISTURE MOVING IN FOR WEDNESDAY EVENING
WHICH COULD BE GOOD TIMING FOR THE RETURN TO THE TYPICAL TRADE WIND
PATTERN FOR THE AREA.

&&

.MARINE...
A SERIES OF LOWS TO THE SOUTH OF NEW ZEALAND HAVE PRODUCED SWELLS
THAT ARE EXPECTED TO BEGIN ARRIVING IN OUR WATERS ON WEDNESDAY.
SURF ALONG SOUTH FACING SHORES WILL BE ELEVATED FROM WEDNESDAY
THROUGH NEXT WEEKEND DUE TO FACT THAT SEVERAL STRONG LOWS HAVE
TRAVERSED THE AREA SOUTH OF NEW ZEALAND. IN ADDITION...A SOUTH-
SOUTHEAST SWELL IS EXPECTED NEXT WEEKEND FROM A LOW CURRENTLY NEAR
30S 125W. AT THIS TIME SURF HEIGHTS ALONG SOUTH FACING SHORES ARE
EXPECTED TO BE BELOW ADVISORY LEVELS...BUT THE TRANSPOSITION OF
MULTIPLE SWELLS NEXT WEEKEND COULD BRING ADVISORY LEVEL HEIGHTS.
PINPOINTING SWELL ARRIVAL TIMES AND HEIGHTS WILL BE A LITTLE MORE
DIFFICULT THAN USUAL AS BUOY 51028 LOCATED ALONG THE EQUATOR TO THE
SOUTH OF THE ISLANDS IS NOT REPORTING WAVE HEIGHT INFORMATION AT
THIS TIME.

&&

.UPDATE...
HAVE GONE WITH A FEW MORE CLOUDS FOR THE EASTERN ISLANDS...AND
LESSER CLOUDINESS IN THE WEST FOR THE REMAINDER OF THIS MORNING. IN
THE AFTERNOON MADE SOME MINOR CHANGES IN THE EAST FOR CLOUD COVER
OVER THE HIGHER ELEVATIONS.
&&

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

PROTON