Alert archive / Hawaii / Flash Flood Warnings in 2024

Flash Flood Warning 21, NWS Honolulu, HI

October 26, 2024Honolulu County, Hawaii

NWS Honolulu, HI issued this flash flood warning at Oct 26, 2024, 6:40 AM HST for Honolulu County, Hawaii. It was in force for 6 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Oct 26, 2024, 6:40 AM HST (16:40 UTC)
Expired: Oct 26, 2024, 12:30 PM HST
In force: 6 hr
Issued by: NWS Honolulu, HI
Area: Storm-based polygon
Flood severity: None

County Honolulu County, HI

The radar

The Molokai radar (PHMO), 71 km from the middle of the area, began a volume at 16:41 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.

The nearest sounding before it

Lihue, (PHLI), launched 12:00Z, 4.7 hours before the alert went out and 173 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: 675 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 603 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: -8 m²/s²
0-3 km storm-relative helicity: 26 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

037 
WGHW50 PHFO 261640
FFWHFO
HIC003-261930-
/O.NEW.PHFO.FF.W.0021.241026T1640Z-241026T1930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Honolulu HI
640 AM HST Sat Oct 26 2024

The National Weather Service in Honolulu has issued a

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

* Until 930 AM HST.

* At 640 AM HST, radar indicated heavy rain over windward Oahu. Rain 
  rates as high as 1.5 to 2.5 inches per hour have been observed. 
  Periods of heavy showers over already saturated ground may quickly 
  lead to runoff and flash flooding. Water levels in streams are 
  expected to continue to rise. Flash flooding is ongoing or 
  expected to begin shortly.

  HAZARD...Flash flooding caused by heavy rain.

  SOURCE...Radar.

  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, Ahuimanu, Kaneohe, Kahaluu, Waiahole, Kalihi, Maunawili, 
  Moanalua, Aiea, Halawa, Waikane, Kaneohe Marine Base, Manoa, 
  Kailua, Salt Lake, Pearl City, Palolo, Waimanalo, Kaaawa and 
  Mililani.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

This warning may need to be extended beyond 930 AM HST if flooding 
persists.

This Flash Flood Warning replaces the previously issued Flood 
Advisory that was in effect for The island of Oahu in Honolulu 
County.

LAT...LON 2160 15797 2163 15790 2155 15783 2147 15783
      2143 15779 2144 15778 2147 15778 2147 15772
      2141 15773 2134 15769 2133 15765 2131 15764
      2126 15769 2125 15772 2127 15773 2125 15780
      2126 15784 2129 15787 2129 15788 2144 15798

FLASH FLOOD...RADAR INDICATED

$$

VAUGHAN

4 follow-up statements

704 
WGHW70 PHFO 261753
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
753 AM HST Sat Oct 26 2024

HIC003-261930-
/O.CON.PHFO.FF.W.0021.000000T0000Z-241026T1930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Honolulu HI-
753 AM HST Sat Oct 26 2024

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 930 AM HST THIS 
MORNING FOR THE ISLAND OF OAHU IN HONOLULU COUNTY...

At 753 AM HST, radar indicated heavy rain over windward Oahu. Rain 
rates as high as 1.5 to 2.5 inches per hour have been observed. 
Periods of heavy showers over already saturated ground may quickly 
lead to runoff and flash flooding. Water levels in streams are 
expected to continue to rise. Water could inundate some roads, 
including Kamehameha Highway. Flash flooding is ongoing or expected 
to begin shortly.

HAZARD...Heavy rain producing life threatening flash flooding.

SOURCE...Radar.

IMPACT...Significant and life threatening flooding in drainages,
         streams, rivers, roads, properties, and other low lying
         areas. Multiple public road closures expected, as well
         as landslides in steep terrain.

Some locations that will experience flash flooding include...
  Honolulu, Ahuimanu, Kaneohe, Kahaluu, Waiahole, Kalihi, Maunawili, 
  Moanalua, Aiea, Halawa, Waikane, Kaneohe Marine Base, Manoa, 
  Kailua, Salt Lake, Pearl City, Palolo, Waimanalo, Kaaawa and 
  Mililani.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 2160 15797 2163 15790 2155 15783 2147 15783
      2143 15779 2144 15778 2147 15778 2147 15772
      2141 15773 2134 15769 2133 15765 2131 15764
      2126 15769 2125 15772 2127 15773 2125 15780
      2126 15784 2129 15787 2129 15788 2144 15798

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

VAUGHAN

926 
WGHW70 PHFO 261816
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
816 AM HST Sat Oct 26 2024

HIC003-261930-
/O.CON.PHFO.FF.W.0021.000000T0000Z-241026T1930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Honolulu HI-
816 AM HST Sat Oct 26 2024

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 930 AM HST THIS 
MORNING FOR THE ISLAND OF OAHU IN HONOLULU COUNTY...

At 816 AM HST, radar indicated heavy rain over windward Oahu. Rain 
rates as high as 1.5 to 3.0 inches per hour have been observed. 
Periods of heavy showers over already saturated ground may quickly 
lead to runoff and flash flooding. Water levels in streams are 
expected to continue to rise. Water could inundate some roads, 
including Kamehameha Highway. Additionally, Manoa Stream at Woodlawn 
has reached 10.5 feet, which is known to cause impacts that include 
inundating nearby property. Flash flooding is likely ongoing.

HAZARD...Heavy rain producing life threatening flash flooding.

SOURCE...Radar.

IMPACT...Significant and life threatening flooding in drainages,
         streams, rivers, roads, properties, and other low lying
         areas. Multiple public road closures expected, as well
         as landslides in steep terrain.

Some locations that will experience flash flooding include...
  Honolulu, Ahuimanu, Kaneohe, Kahaluu, Waiahole, Kalihi, Maunawili, 
  Moanalua, Aiea, Halawa, Waikane, Kaneohe Marine Base, Manoa, 
  Kailua, Salt Lake, Pearl City, Palolo, Waimanalo, Kaaawa and 
  Mililani.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 2160 15797 2163 15790 2155 15783 2147 15783
      2143 15779 2144 15778 2147 15778 2147 15772
      2141 15773 2134 15769 2133 15765 2131 15764
      2126 15769 2125 15772 2127 15773 2125 15780
      2126 15784 2129 15787 2129 15788 2144 15798

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

VAUGHAN

971 
WGHW50 PHFO 261914
FFWHFO
HIC003-262230-
/O.EXT.PHFO.FF.W.0021.000000T0000Z-241026T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Honolulu HI
914 AM HST Sat Oct 26 2024

The National Weather Service in Honolulu has extended the

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

* Until 1230 PM HST.

* At 914 AM HST, radar indicated heavy rain over windward Oahu. Rain 
  rates as high as 1.5 to 2.5 inches per hour have been observed. 
  Periods of heavy showers over already saturated ground may quickly 
  lead to runoff and flash flooding. Water levels in already 
  elevated streams could rise rapidly with additional heavy rain. 
  Water could inundate some roads, including Kamehameha Highway. 
  Flash flooding is likely ongoing.

  HAZARD...Flash flooding caused by heavy rain.

  SOURCE...Radar.

  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, Ahuimanu, Kaneohe, Kahaluu, Waiahole, Kalihi, Maunawili, 
  Moanalua, Aiea, Halawa, Waikane, Kaneohe Marine Base, Manoa, 
  Kailua, Salt Lake, Pearl City, Palolo, Waimanalo, Kaaawa and 
  Mililani.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

This warning may need to be extended beyond 1230 PM HST if flooding 
persists.

LAT...LON 2160 15797 2163 15790 2155 15783 2147 15783
      2143 15779 2144 15778 2147 15778 2147 15772
      2141 15773 2134 15769 2133 15765 2131 15764
      2126 15769 2125 15772 2127 15773 2125 15780
      2126 15784 2129 15787 2129 15788 2144 15798

FLASH FLOOD...RADAR INDICATED

$$

VAUGHAN

533 
WGHW70 PHFO 261942
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
942 AM HST Sat Oct 26 2024

HIC003-262230-
/O.CON.PHFO.FF.W.0021.000000T0000Z-241026T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Honolulu HI-
942 AM HST Sat Oct 26 2024

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1230 PM HST THIS 
AFTERNOON FOR THE ISLAND OF OAHU IN HONOLULU COUNTY...

At 942 AM HST, radar indicated heavy rain over windward Oahu, the 
Koolau slopes, then spreading leeward and affecting communities in 
urban Honolulu. Rain was falling at a rate of 2 to 3 inches per 
hour, and was especially heavy the area from Manoa to Pearl City. 
Flash flooding is ongoing or expected to begin shortly.

HAZARD...Flash flooding caused by heavy rain.

SOURCE...Radar.

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, Ahuimanu, Kaneohe, Kahaluu, Waiahole, Kalihi, Maunawili, 
  Moanalua, Aiea, Halawa, Waikane, Kaneohe Marine Base, Manoa, 
  Kailua, Salt Lake, Pearl City, Palolo, Waimanalo, Kaaawa and 
  Mililani.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 2160 15797 2163 15790 2155 15783 2147 15783
      2143 15779 2144 15778 2147 15778 2147 15772
      2141 15773 2134 15769 2133 15765 2131 15764
      2126 15769 2125 15772 2127 15773 2125 15780
      2126 15784 2129 15787 2129 15788 2144 15798

FLASH FLOOD...RADAR INDICATED

$$

Birchard

The office that day

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

Issued	Product	Office	Counties	Lasted
Oct 26, 3:54 AM HST	Areal Flood Advisory	HFO	Honolulu	3 hr
Oct 26, 5:12 AM HST	Areal Flood Advisory	HFO	Kalawao	86 min
Oct 26, 6:38 AM HST	Flash Flood Warning	HFO	Kalawao	3 hr
Oct 26, 7:30 AM HST	Flood Watch	HFO	Hawaii, Honolulu, Kauai, Kalawao	61 hr
Oct 26, 10:16 AM HST	Flash Flood Warning	HFO	Honolulu	3 hr
Oct 26, 1:07 PM HST	Areal Flood Advisory	HFO	Kauai	3 hr
Oct 26, 1:12 PM HST	Areal Flood Advisory	HFO	Honolulu	3 hr
Oct 26, 1:27 PM HST	Areal Flood Advisory	HFO	Kalawao	72 min
Oct 26, 1:28 PM HST	Areal Flood Advisory	HFO	Hawaii	4 hr

Nearby

Flash Flood Warnings in Hawaii, 2024 Every flash flood warning in 2024

Sources

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