Alert archive / Hawaii / Flash Flood Warnings in 2021

Flash Flood Warning 34, NWS Honolulu, HI

March 15, 2021Honolulu County, Hawaii

NWS Honolulu, HI issued this flash flood warning at Mar 15, 2021, 2:28 PM HST for Honolulu County, Hawaii. It was in force for 4 hr. 3 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Mar 15, 2021, 2:28 PM HST (00:28 UTC)
Expired: Mar 15, 2021, 6:19 PM HST
In force: 4 hr
Issued by: NWS Honolulu, HI
Area: Storm-based polygon
Flood severity: None

County Honolulu County, HI

The radar

The Molokai radar (PHMO), 84 km from the middle of the area, began a volume at 00:30 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

Time	Report	Where	Remark
Mar 15, 4:28 PM HST	FLASH FLOOD	Kailua, HI	KAPAA QUARRY ROAD CLOSED DUE TO FLOODING.
Mar 15, 5:20 PM HST	FLASH FLOOD	Waianae, HI	LANE CLOSURE ALONG FARRINGTON HIGHWAY
Mar 15, 5:20 PM HST	FLASH FLOOD	Waikane, HI	KAMEHAMEHA HIGHWAY FLOODED WITH ONE FOOT OF WATER. TWO CARS DISABLED BY FLOOD WATER.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Lihue, (PHLI), launched 00:00Z, 0.5 hours before the alert went out and 159 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 408 J/kg
Mixed-layer CIN: -14 J/kg
Mixed-layer LCL: 764 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 1 m²/s²
0-3 km storm-relative helicity: 20 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

548 
WGHW50 PHFO 160028
FFWHFO
HIC003-160330-
/O.NEW.PHFO.FF.W.0034.210316T0028Z-210316T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Honolulu HI
228 PM HST Mon Mar 15 2021

The National Weather Service in Honolulu has issued a

* Flash Flood Warning for...
  The island of Oahu in Honolulu County

* Until 530 PM HST.

* At 228 PM HST, radar indicated heavy rain over central and 
  windward Oahu. Rain was falling at a rate of 2 to 3 inches per 
  hour. Flash flooding is occurring or expected to begin shortly.

  HAZARD...Flash flooding caused by heavy rain.

  SOURCE...Radar indicated.

  IMPACT...Flooding in drainages, streams, rivers, roads,
           properties, and other low-lying areas. Public road
           closures possible in some areas. Landslides are
           possible in steep terrain.

* Some locations that will experience flash flooding include...
  Honolulu, Mililani, Pearl City, Waikele, Wahiawa, Wheeler Field, 
  Waipahu, Kunia, Aiea, Halawa, Waiahole, Schofield Barracks, 
  Waikane, Salt Lake, Kahaluu, Moanalua, Ahuimanu, Iroquois Point, 
  Ewa Beach and Kaaawa.

The heaviest rain is over central Oahu with runoff north toward 
Waialua and Haleiwa and south toward Pearl Harbor and along the 
windward side from Kaneohe to Kahuku. This replases the previous 
Flood Advisory and Flash Flood Warning.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Stay away from streams, rivers, drainage ditches, and culverts, even 
if they are currently dry.

Do not cross fast flowing or rising water in your vehicle, or on 
foot. Turn around, don't drown.

&&

This warning may need to be extended beyond 530 PM HST if flooding 
persists.

LAT...LON 2158 15830 2160 15813 2173 15797 2155 15783
      2147 15783 2143 15779 2147 15778 2147 15771
      2141 15772 2131 15763 2125 15769 2125 15772
      2127 15772 2124 15782 2129 15787 2131 15797
      2129 15812 2136 15815 2148 15825 2153 15825

FLASH FLOOD...RADAR INDICATED

$$

DONALDSON

4 follow-up statements

748 
WGHW70 PHFO 160119
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
319 PM HST Mon Mar 15 2021

HIC003-160330-
/O.CON.PHFO.FF.W.0034.000000T0000Z-210316T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Honolulu HI-
319 PM HST Mon Mar 15 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 530 PM HST THIS 
AFTERNOON FOR THE ISLAND OF OAHU IN HONOLULU COUNTY...

At 319 PM HST, radar indicated heavy rain continuing over Oahu. Rain 
was falling at a rate of 2 to 3 inches per hour. Flash flooding is 
occurring or expected to begin shortly.

HAZARD...Flash flooding caused by heavy rain.

SOURCE...Radar indicated.

IMPACT...Flooding in drainages, streams, rivers, roads,
         properties, and other low-lying areas. Public road
         closures possible in some areas. Landslides are possible
         in steep terrain.

Some locations that will experience flash flooding include...
  Honolulu, Mililani, Pearl City, Waikele, Wahiawa, Wheeler Field, 
  Waipahu, Kunia, Aiea, Halawa, Waiahole, Schofield Barracks, 
  Waikane, Salt Lake, Kahaluu, Moanalua, Ahuimanu, Iroquois Point, 
  Ewa Beach and Kaaawa.

The heaviest rain began over the Wahiawa Schofield Barracks area 
this afternoon. The rain has spread out east and west from there, 
with the heaviest rain now over windward Oahu between Waimanalo and 
Laiea and over the east slopes of the Waianae Mountains near Kunia. 
Runoff is flowing north toward Haleiwa, south toward Pearl Harbor 
and east along the windward side of the island.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Stay away from streams, rivers, drainage ditches, and culverts, even 
if they are currently dry.

Do not cross fast flowing or rising water in your vehicle, or on 
foot. Turn around, don't drown.

&&

This warning may need to be extended beyond 530 PM HST if flooding 
persists.

LAT...LON 2158 15830 2160 15813 2173 15797 2155 15783
      2147 15783 2143 15779 2147 15778 2147 15771
      2141 15772 2131 15763 2125 15769 2125 15772
      2127 15772 2124 15782 2129 15787 2131 15797
      2129 15812 2136 15815 2148 15825 2153 15825

FLASH FLOOD...RADAR INDICATED

$$

DONALDSON

081 
WGHW70 PHFO 160228
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
428 PM HST Mon Mar 15 2021

HIC003-160330-
/O.CON.PHFO.FF.W.0034.000000T0000Z-210316T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Honolulu HI-
428 PM HST Mon Mar 15 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 530 PM HST THIS 
AFTERNOON FOR THE ISLAND OF OAHU IN HONOLULU COUNTY...

At 428 PM HST, radar indicated heavy rain over Oahu. Rain was 
falling at a rate of 1.5 to 2.5 inches per hour. Flash flooding is 
already occurring.

HAZARD...Flash flooding caused by heavy rain.

SOURCE...Radar indicated.

IMPACT...Flooding in drainages, streams, rivers, roads,
         properties, and other low-lying areas. Public road
         closures possible in some areas. Landslides are possible
         in steep terrain.

Some locations that will experience flash flooding include...
  Honolulu, Mililani, Pearl City, Waikele, Wahiawa, Wheeler Field, 
  Waipahu, Kunia, Aiea, Halawa, Waiahole, Schofield Barracks, 
  Waikane, Salt Lake, Kahaluu, Moanalua, Ahuimanu, Iroquois Point, 
  Ewa Beach and Kaaawa.

The heaviest rain on Oahu is now falling over the windward side 
between Waimanalo and Laie. Oahu Emergency Management reports Kapaa 
Quarry Road has been closed.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Stay away from streams, rivers, drainage ditches, and culverts, even 
if they are currently dry.

Do not cross fast flowing or rising water in your vehicle, or on 
foot. Turn around, don't drown.

&&

This warning may need to be extended beyond 530 PM HST if flooding 
persists.

LAT...LON 2158 15830 2160 15813 2173 15797 2155 15783
      2147 15783 2143 15779 2147 15778 2147 15771
      2141 15772 2131 15763 2125 15769 2125 15772
      2127 15772 2124 15782 2129 15787 2131 15797
      2129 15812 2136 15815 2148 15825 2153 15825

FLASH FLOOD...RADAR INDICATED

$$

DONALDSON

652 
WGHW50 PHFO 160324
FFWHFO
HIC003-160430-
/O.EXT.PHFO.FF.W.0034.000000T0000Z-210316T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Honolulu HI
524 PM HST Mon Mar 15 2021

The National Weather Service in Honolulu has extended the

* Flash Flood Warning for...
  The island of Oahu in Honolulu County

* Until 630 PM HST.

* At 524 PM HST, Flash flooding is already occurring. Oahu Emergency 
  Management a foot of water over the road in Waikane with two cars 
  stalled at 507 PM. They also reported one lane flooded on 
  Farrington Highway in Waiane near Waianae City Hall.

  HAZARD...Flash flooding caused by heavy rain.

  SOURCE...Emergency management.

  IMPACT...Flooding in drainages, streams, rivers, roads,
           properties, and other low-lying areas. Public road
           closures possible in some areas. Landslides are
           possible in steep terrain.

* Some locations that will experience flash flooding include...
  Honolulu, Mililani, Pearl City, Waikele, Wahiawa, Wheeler Field, 
  Waipahu, Kunia, Aiea, Halawa, Waiahole, Schofield Barracks, 
  Waikane, Salt Lake, Kahaluu, Moanalua, Ahuimanu, Iroquois Point, 
  Ewa Beach and Kaaawa.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Stay away from streams, rivers, drainage ditches, and culverts, even 
if they are currently dry.

Do not cross fast flowing or rising water in your vehicle, or on 
foot. Turn around, don't drown.

&&

This warning may need to be extended beyond 630 PM HST if flooding 
persists.

LAT...LON 2158 15830 2160 15813 2173 15797 2155 15783
      2147 15783 2143 15779 2147 15778 2147 15771
      2141 15772 2131 15763 2125 15769 2125 15772
      2127 15772 2124 15782 2129 15787 2131 15797
      2129 15812 2136 15815 2148 15825 2153 15825

FLASH FLOOD...OBSERVED

$$

DONALDSON

166 
WGHW70 PHFO 160419
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
619 PM HST Mon Mar 15 2021

HIC003-160429-
/O.CAN.PHFO.FF.W.0034.000000T0000Z-210316T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Honolulu HI-
619 PM HST Mon Mar 15 2021

...FLASH FLOOD WARNING IS CANCELLED FOR THE ISLAND OF OAHU IN 
HONOLULU COUNTY...

Flood waters have receded. The heavy rain has ended. Flooding is no 
longer expected to pose a threat. Please continue to heed remaining 
road closures.

LAT...LON 2158 15830 2160 15813 2173 15797 2155 15783
      2147 15783 2143 15779 2147 15778 2147 15771
      2141 15772 2131 15763 2125 15769 2125 15772
      2127 15772 2124 15782 2129 15787 2132 15794
      2129 15812 2136 15815 2148 15825 2153 15825

$$

LAU

The office that day

Everything else NWS Honolulu, HI issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 15, 5:13 PM HST	Areal Flood Advisory	HFO	Hawaii	3 hr
Mar 16, 3:41 AM HST	High Surf Advisory	HFO	Honolulu, Kalawao	6 days
Mar 16, 6:19 AM HST	Areal Flood Advisory	HFO	Honolulu	6 hr

Nearby

Flash Flood Warnings in Hawaii, 2021 Every flash flood warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.