Heavy Rain in Hawaii, May 21, 2005

Name: Heavy Rain in Hawaii, May 21, 2005
Start: 2005-05-21T05:20
End: 2005-05-21T11:20
Location: Hawaii

May 21, 2005 · NWS HFO · 1 event in 1 county or zone

Heavy showers caused ponding of roadways, and small stream and drainage ditch flooding in windward and southeast parts of Oahu. There were no reports of serious property damage or injuries.

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 caused ponding of roadways, and small stream and drainage ditch flooding in windward and southeast parts of Oahu. There were no reports of serious property damage or injuries.

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 May 21, 4:00 AM HST, 1 hour 20 minutes earlier.

Area forecast discussion, May 21, 4:00 AM HST, 1 hour 20 minutes before

HAWAIIAN ISLANDS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST SAT MAY 21 2005

.SYNOPSIS...LOCALIZED OVERNIGHT REMNANT SHOWERS SHOULD EASE LATER
 THIS MORNING. DRIER AND WEAKER WINDS ARE STILL EXPECTED THRU MUCH
 OF NEXT WEEK.

&&

.DISCUSSION...THE LOW LEVEL INSTABILITY OF WHAT WAS ONCE THE OLD
 SHEAR LINE IS HANGING AROUND LONGER THAN ANTICIPATED. INCOMING
 CLOUDS HAVE BLOSSOMED OVER THE WINDWARD SIDES OF OAHU AND
 MAUI COUNTY...ESPECIALLY OAHU. TRADE WINDS HAVE LIGHTENED JUST
 ENOUGH TO KEEP MOST OF THESE SHOWERS FROM DRIFTING OVER TO THE
 LEEWARD AREAS. THERE ARE MORE REMNANT SHOWERS UPSTREAM BUT STILL
 BELIEVE THESE WILL FURTHER DIMINISH AS WINDS LIGHTEN AND DAYTIME
 DAYTIME HEATING PROVIDES SOME BURNOFF. THE DRYING TREND SHOULD
 CONTINUE THRU THE WEEKEND AND MOST OF NEXT WEEK.

 THE TRADE WIND SUPPORTING RIDGE TO THE NORTH IS STILL EXPECTED TO
 BECOME WEAKER AND MOVE CLOSER TO THE ISLANDS BY THE PASSAGE OF
 LOWS TO THE RIDGES NORTH. ANOTHER LATE SEASON WEAK FRONT/SHEAR
 LINE SHOULD PUSH TOWARD US LATE NEXT WEEK AND PLACE THE STATE IN
 DRY AND STABLE AIR PRECEDING THIS NEXT SYSTEM. ITS ARRIVAL IS
 IFFY...SHOULD IT ARRIVE OVER THE NORTHERN ISLANDS IT WILL LACK
 UPPER AIR SUPPORT AND SHOULD PRODUCE LITTLE RAINFALL OR WIND.

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

&&

MATSUDA

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: May 21, 5:20 AM HST to 11:20 AM HST
Where: Honolulu County, Kahuku
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 2005 Every state in 2005 This day in weather history Warnings in Hawaii, May 2005

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: 5446175.