Heavy Rain in Hawaii, August 17, 2004

Name: Heavy Rain in Hawaii, August 17, 2004
Start: 2004-08-17T15:03
End: 2004-08-17T18:00
Location: Hawaii

August 17, 2004 · NWS HFO · 1 event in 1 county or zone

Heavy showers caused ponding of roadways, and small stream and drainage ditch flooding in western parts of Oahu. No serious injuries or property damage were reported.

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
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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 caused ponding of roadways, and small stream and drainage ditch flooding in western parts of Oahu. 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 Aug 17, 10:00 AM HST, 5 hours 3 minutes earlier.

Area forecast discussion, Aug 17, 10:00 AM HST, 5 hours 3 minutes before

HAWAIIAN ISLANDS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST TUE AUG 17 2004

.SYNOPSIS...A SURFACE RIDGE OF HIGH PRESSURE CONTINUES TO APPROACH
THE MAIN HAWAIIAN ISLANDS...BEING SUPPRESS SOUTHWARD BY A LOW
PRESSURE AREA WELL NORTH OF THE MAIN HAWAIIAN ISLANDS. THE RIDGE
WILL STOP SHORT OF KAUAI WEDNESDAY MORNING. BUT ITS ACTION HAS
ALREADY RESULTED IN LIGHTER WINDS OVER THE SMALLER ISLANDS. BY
THURSDAY THE LOW PRESSURE AREA WILL HAVE MOVED AWAY WITH HIGH
PRESSURE FILLING IN AND SUBSEQUENTLY ALLOWING TRADE WINDS TO RETURN
TO THE MAIN HAWAIIAN ISLANDS. THE TRADES ARE EXPECTED TO
STRENGTHENING TO MODERATE LEVEL FRIDAY.

&&

.DISCUSSION...NO REAL CHANGE TO THE REASONING BEHIND THE CURRENT
FORECAST PACKAGE. THE RIDGE OF HIGH PRESSURE SOME 200 NM NORTH OF
THE KAUAI THIS MORNING WILL CONTINUE TO MOVE SOUTH UNTIL IT REACHES
SOME 70 MILES SHORT OF KAUAI BY LATE WEDNESDAY MORNING.  THE RIDGE
IS BEING SUPPRESS SOUTH BY A LOW PRESSURE AREA SOME 600 TO 800 MILES
NORTH OF OAHU. THE LOW VACATES THE AREA BY WEDNESDAY THUS ALLOWING
THE RIDGE TO MOVE NORTH AND HENCE THE RETURN OF THE TRADES
COMMENCING LATE WEDNESDAY NIGHT. THE TRADES WILL RETURN TO MODERATE
STRENGTH BY FRIDAY. ONLY THE WINDWARD BIG ISLAND WILL NOT BE TOTALLY
AFFECTED BY THE RIDGE MOVING SOUTH.

THE EFFECTS OF THE LIGHT WINDS WILL BE FELT PRIMARILY ON THE ISLANDS
OF MOLOKAI...OAHU AND KAUAI. THE CURRENT FORECAST FOR THESE ISLANDS
FOR AFTERNOON CLOUDS AND ISOLATED TO SCATTERED SHOWERS IS OKAY. WE
ARE MONITORING THE BROKEN AREA OF LOW LEVEL CLOUDS SOUTH OF OAHU AND
KAUAI. SO FAR THE RIDGE AT THE LOWER LEVELS ARE PREVENTING THEM FROM
MOVING NORTH TOWARDS THOSE TWO ISLANDS. SHALL THE RIDGE BREAKS
DOWN...WELL HAVE INCREASE THE POPS AND CLOUDS. THE GFS SO FAR
REMAINS FIRM IN KEEPING THE RIDGE IN AND THESE CLOUDS TO PASS SOUTH
OF THESE TWO ISLANDS. ADDITIONALLY THE ENERGY ASSOCIATED WITH THE
UPPER LEVEL TROUGH THAT INSTIGATED THE WET WEATHER ON NORTHEAST MAUI
YESTERDAY AND PARTS OF WINDWARD OAHU LAST NIGHT HAS NOW MOVED AWAY.
THE LOSS OF THE UPPER LEVEL SUPPORT LESSENS THE CHANCES FOR ANY
SURPRISE HEAVY SHOWERS.

A TROPICAL DISTURBANCE NEAR 13N 153W OR ABOUT 460 MILES SOUTH
SOUTHEAST OF SOUTH POINT BIG ISLAND IS MOVING WEST AT ABOUT 17 MILES
PER HOUR. IT WILL BE PASSING WELL SOUTH OF THE MAIN HAWAIIAN ISLANDS
WEDNESDAY AND WEDNESDAY NIGHT...AND IS NOT EXPECTED TO INFLUENCE THE
LOCAL WEATHER.

&&

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

&&

LAU

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, Honolulu

When: August 17, 3:03 PM HST to 6:00 PM HST
Where: Honolulu County, Waialua
Reported by: OFFICIAL NWS OBS.
Coordinates: 21.455, -157.961 (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 2004 Every state in 2004 This day in weather history Warnings in Hawaii, August 2004

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: 5431604.