Heavy Rain in Hawaii, July 26, 2002

HAWAIIAN ISLANDS SYNOPTIC DISCUSSION AND GUIDANCE
NATIONAL WEATHER SERVICE HONOLULU HI
4 PM HST FRI JUL 26 2002

SUMMARY...RAIN SHOWERS ARE OCCURING ALONG WINDWARD COASTS AND OVER
MOUNTAIN AREAS OF THE ISLANDS FROM THE BIG ISLAND TO OAHU.  KAUAI IS
STILL MOSTLY SUNNY THIS EARLY AFTERNOON BUT SHOWERS WILL ARRIVE
THERE LATER THIS AFTERNOON AND EVENING.  TRADE WINDS ARE BLOWING IN
THE MODERATE TO LOCALLY FRESH RANGE THROUGHOUT THE STATE.

DISCUSSION...A CLUSTER OF TRADE SHOWERS IS AFFECTING WINDWARD AND
MOUNTAIN SECTIONS OF THE ISLANDS FROM BIG ISLAND TO OAHU. LEE AREAS
OFTHESE ISLANDS AND THE ISLAND OF KAUAI ARE MOSTLY SUNNY TO PARTLY
CLOUDY. THE LARGEST PORTION OF THE CLOUD/SHOWER CLUSTER IS STILL
LOCATED UPWIND OF THE BIG ISLAND FROM WHERE IT WILL SPREAD UP THE
WINDWARD SIDES OF THE SMALLER ISLANDS. THUS SHOWERY CONDITIONS ARE
APT TO LAST ALL NIGHT IN MANY WINDWARD SPOTS AND WELL INTO SATURDAY
FARTHER TO THE WEST ON KAUAI. LEE AREAS WILL ALSO GET SOME SHOWERS
AT NIGHT AND EARLY IN THE MORNING WHEN THE RELATIVE HUMIDITY IS
HIGH.

OUT TO THE EAST OF THE STATE A LARGE AND IMPRESSIVE VORTEX IS
APPROACHING THE ISLANDS. THIS IS THE REMNANT CIRCULATION OF
DOUGLAS. IT IS CENTERED NEAR 22N 139W AND MOVING WEST ABOUT 15 KT OR
A DEGREE EVERY 4 HOURS OR 6 DEGREES PER 24 HOURS. THE LEADING EDGE
IS NEAR 147W. ASSUMING FAIRLY STEADY MOVEMENT AND LITTLE CHANGE IN
THE SHAPE OF THE VORTEX THE LEADING EDGE IS FORECAST TO ARRIVE AT
HILO SATURDAY EVENING AND ON OAHU EARLY SUNDAY MORNING. THE SYSTEM
IS LARGE ENOUGH TO LAST ALMOST TWO DAYS AT ANY ONE PLACE. WITH THE
CENTER FORECAST TO PASS NEAR THE NORTHERN ISLANDS THE BULK OF THE
SHOWERS AND RAINFALL WILL BE OVER THE OCEAN TO OUR NORTH.

THERE IS AN UPPER LEVEL LOW PRESSURE CIRCULATION MOVING SLOWLY
WESTWARD TO THE NORTH OF THE ISLANDS TODAY. IT COULD AFFECT RAINFALL
AS THE UPPER DIVERGENCE ALONG THE EAST SIDE OF THE UPPER LOW MOVES
ACROSS THE REMNANTS MOISTURE NEAR THE ISLANDS ON SUNDAY AND MONDAY.
WERE THAT TO HAPPEN WE COULD GET AN ISOLATED HEAVY SHOWER WHERE LOW
LEVEL MOISTURER AND SOLAR HEATINGOVER LAND AREAS COMBINE TO PRODUCE
SUFFICIENT INSTABILITY.  AS IS USUALLY THE CASE WHEN TROPICAL STORM
REMNANT CIRCULATIONS PASS BY TO OUR NORTH THIS TIME OF THE YEAR...
WE SHOULD EXPECT THAT THE LACK OF TRADE WINDS COMBINED WITH HIGH
HUMIDITY AND SUNSHINE RATES WILL CAUSE UNCOMFORTABLE SULTRY
CONDITIONS OF THE SUMMERTIME DOG DAYS TO PREVAIL. ROSENDAL

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