Heavy Rain in Hawaii, August 29, 2002

HAWAIIAN ISLANDS SYNOPTIC DISCUSSION AND GUIDANCE
NATIONAL WEATHER SERVICE HONOLULU HI
4 PM HST THU AUG 29 2002

SUMMARY...CLOUDS AND SHOWERS...SOME HEAVY...ARE IN STORE FOR THE BIG
ISLAND TONIGHT...THANKS TO A CONVERGENCE BAND ALONG THE LEADING EDGE
OF THE RETURNING TRADES. TRADE WINDS WILL RETURN FRIDAY STATEWIDE AS
LOW PRESSURE TO OUR NORTH MOVES AWAY TO THE NORTHWEST. THE CURRENT
CONVECTIVE PATTERN OF AFTERNOON CLOUDS AND SHOWERS WILL BE REPLACED
BY A TRADE WIND PATTERN. FRIDAY AND THEREAFTER...EXPECT ISOLATED
SHOWERS OVER WINDWARD AREAS...MAINLY AT NIGHT AND DURING THE MORNING
HOURS.

DISCUSSION...A CONVERGENCE BAND ALONG THE LEADING EDGE OF RETURNING
TRADES IS PASSING OVER THE BIG ISLAND THIS AFTERNOON. WEAK LOW
LEVEL CONVERGENCE...COMBINED WITH OROGRAPHIC EFFECTS OF TERRAIN AND
LOTS OF MOISTURE...HAVE CAUSED CONVECTION TO BLOOM ALMOST EVERYWHERE
ON THAT ISLAND OVER THE PAST FEW HOURS. OVERCAST SKIES AND
SHOWERS...SOME HEAVY ON THE WINDWARD SIDE...WILL PERSIST THERE
THROUGH THE EVENING. DRIER CONDITIONS WILL MOVE IN AS THE TRADE WIND
SURGE LINE MOVES WESTWARD OVERNIGHT AND THROUGH THE DAY TOMORROW.
THE SMALLER ISLANDS WILL SEE LIGHT PREVAILING WINDS TONIGHT...THEN
THE RETURN OF TRADES TOMORROW. THE DEEP LOW 650 MILES NORTH OF THE
MAIN HAWAIIAN ISLANDS IS FAR ENOUGH NORTH TO ALLOW HIGH PRESSURE TO
NOSE IN UNDER IT TO THE SOUTH. HAD THIS LOW BEEN CLOSER...THE TRADE
WINDS WOULD HAVE BEEN BLOCKED FOR MUCH LONGER. THERE IS LITTLE
CHANGE IN THE LONG RANGE FORECAST...GIVEN THAT MODELS SHOW THE
RETURN OF THE RIDGE AT THE SURFACE AND ALOFT OVER THE WEEKEND AND
INTO NEXT WEEK.

POWELL

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