Heavy Rain in Hawaii, September 3, 2002

Name: Heavy Rain in Hawaii, September 3, 2002
Start: 2002-09-03T14:15
End: 2002-09-03T17:00
Location: Hawaii

September 3, 2002 · NWS HFO · 1 event in 1 county or zone

Heavy showers produced ponding of roadways, and minor stream and drainage ditch flooding in West Maui. The areas most affected were the Waihee, Waiehu, and Iao valleys.

Where it happened

Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 1

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS HFO wrote it up.

Heavy showers produced ponding of roadways, and minor stream and drainage ditch flooding in West Maui. The areas most affected were the Waihee, Waiehu, and Iao valleys. No serious injuries or property damage were reported.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Honolulu, HI wrote its last area forecast discussion before the first event at Sep 3, 10:00 AM HST, 4 hours 15 minutes earlier.

Area forecast discussion, Sep 3, 10:00 AM HST, 4 hours 15 minutes before

HAWAIIAN ISLANDS SYNOPTIC DISCUSSION AND GUIDANCE
NATIONAL WEATHER SERVICE HONOLULU HI
10 AM HST TUE SEP 3 2002

SUMMARY...A WEAK SURFACE TROUGH WILL KEEP THE TRADES LIGHT TODAY.
LOW PRESSURE ALOFT WILL PROVIDE INSTABILITY...LIKELY SETTING OFF
SOME HEAVY SHOWERS OR THUNDERSTORMS. THE TRADES WILL PICK UP
WEDNESDAY...AS HIGH PRESSURE FAR TO THE NORTH MOVES CLOSER.

DISCUSSION...TYPHOON ELE...THOUGH WEST OF THE DATELINE...IS STILL
INDIRECTLY AFFECTING ISLAND WEATHER. AS IS USUALLY THE CASE IN
FORECASTING WEATHER...ONE HAS TO SEARCH THROUGH A NUMBER OF CAUSES
AND EFFECTS TO GET AT THE REASON FOR ONES WEATHER. IN THIS CASE...
THE CYCLONIC ELE PLACES AN ANTICYCLONIC RIDGE MORE OR LESS ALONG
170W...WHICH IN TURN PLACES AN UPPER LEVEL TROUGH OVER THE STATE.
THE TROUGH WITH EMBEDDED LOW SEVERAL HUNDRED MILES SOUTHWEST OF
KAUAI HAS WEAKENED THE PRESSURE GRADIENT ACROSS THE STATE. THE
FLATTENED GRADIENT SOUTH OF A SURFACE HIGH FAR TO THE NORTH IS IN
TURN THE REASON FOR THE LIGHT WINDS.

A SURFACE HIGH FARTHER NORTH THAN NORMAL TRANSLATES TO A WEAKER AND
HIGHER THAN NORMAL SUBSIDENCE INVERSION. OR LOOKING AT IT ANOTHER
WAY...A DEEPER THAN NORMAL MARINE LAYER. COOL TEMPERATURES
ASSOCIATED WITH THE UPPER TROUGH HAVE STEEPENED THE LAPSE RATE
RESULTING IN AN UNSTABLE ATMOSPHERE. FINALLY...WE HAVE A SLUG OF
MOISTURE MOVING SLOWLY IN ON THE LIGHT TRADE WINDS.

ALL THE NECESSARY INGREDIENTS ARE PRESENT...THOUGH IN A LIMITED
FASHION. THE WINDS ARE NOT QUITE LIGHT ENOUGH...AND THE MOISTURE IS
NOT THAT IMPRESSIVE. THE TEMPERATURES ALOFT ARE NOT QUITE COLD
ENOUGH...AND THE ATMOSPHERE IS NOT AS UNSTABLE AS IT CAN GET. THE
INGREDIENTS ARE...NEVERTHELESS...SUFFICIENT TO WARRANT THE MENTION
OF HEAVY SHOWERS AND THUNDERSTORMS IN THE FORECAST. ALSO...BECAUSE
OF THE ADDED KICK OF AFTERNOON HEATING...CONDITIONS ARE SUFFICIENT
TO WARRANT THE ISSUANCE OF A FLASH FLOOD WATCH FOR THE BIG ISLAND.

PROGS SHARPEN THE UPPER TROUGH AND MOVE IT FAR ENOUGH TO THE WEST TO
ALLOW THE TIGHTENING OF THE PRESSURE GRADIENT AND THE GRADUAL RETURN
OF MODERATE TRADES. ALSO...THE HIGH FAR TO THE NORTH IS FORECAST TO
MOVE CLOSER...WHICH WILL AID IN THE STRENGTHENING OF THE WINDS
WEDNESDAY. CRAIG.

.HFO...WARNINGS...ADVISORIES...NONE
.      WATCHES...FLASH FLOOD BIG ISLAND TILL 4 PM

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

1 heavy rain. Local standard time, as filed.

Heavy Rain, Maui

When: September 3, 2:15 PM HST to 5:00 PM HST
Where: Maui County, 5 mi W of Wailuku
Reported by: OFFICIAL NWS OBS.
Coordinates: 20.868, -156.617 (the zone’s center; the record gives no point)

What these are

Heavy Rain: Rainfall totals unusual for the place and season that did not produce a flood.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Hawaii in 2002 Every state in 2002 This day in weather history Warnings in Hawaii, September 2002

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5325053.