Alert archive / Hawaii / Flash Flood Warnings in 2021

Flash Flood Warning 44, NWS Honolulu, HI

December 5, 2021Kalawao County, Hawaii

NWS Honolulu, HI issued this flash flood warning at Dec 5, 2021, 9:16 PM HST for Kalawao County, Hawaii. It was in force for 12 hr. 2 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: Dec 5, 2021, 9:16 PM HST (07:16 UTC)
Expired: Dec 6, 2021, 8:55 AM HST
In force: 12 hr
Issued by: NWS Honolulu, HI
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Kalawao County, HI

The radar

The Molokai radar (PHMO), 90 km from the middle of the area, began a volume at 07:16 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
Dec 5, 9:40 PM HST	FLASH FLOOD	Kula, HI	KULA HWY FLOODING AT LOWER KULA RD.
Dec 6, 8:02 AM HST	FLASH FLOOD	Kula, HI	LOWER KULA ROAD CLOSED DUE TO FLOODING.

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

The nearest sounding before it

Hilo, (PITO), launched 00:00Z, 7.3 hours before the alert went out and 189 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: 154 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 626 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 192 m²/s²
0-3 km storm-relative helicity: 307 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.9

Open this sounding in Storm Lab

The text

As transmitted.

944 
WGHW50 PHFO 060716
FFWHFO
HIC009-061015-
/O.NEW.PHFO.FF.W.0044.211206T0716Z-211206T1015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Honolulu HI
916 PM HST Sun Dec 5 2021

The National Weather Service in Honolulu has issued a

* Flash Flood Warning for...
  The island of Maui in Maui County

* Until 1215 AM HST.

* At 916 PM HST, radar indicated heavy rain over all of Maui. Civil 
  Defense reports significant flooding in the Kihei area near Maui 
  Meadows subdivision, where several homes have been flooded, and 
  cars have been washed away. Additional flooding impacts are being 
  reported in some upslope communities.

  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...
  All of the island of Maui. 

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 1215 AM HST if flooding 
persists.

LAT...LON 2093 15672 2102 15668 2105 15660 2100 15652
      2091 15647 2096 15633 2095 15624 2087 15612
      2084 15611 2081 15599 2076 15597 2071 15598
      2064 15604 2061 15614 2057 15642 2063 15647
      2077 15648 2076 15654 2080 15663 2088 15670

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

$$

BIRCHARD

8 follow-up statements

074 
WGHW70 PHFO 060828
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
1028 PM HST Sun Dec 5 2021

HIC009-061015-
/O.CON.PHFO.FF.W.0044.000000T0000Z-211206T1015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maui HI-
1028 PM HST Sun Dec 5 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1215 AM HST MONDAY 
FOR THE ISLAND OF MAUI IN MAUI COUNTY...

At 1028 PM HST, radar indicated that rainfall was gradually 
diminishing in intensity, but significant flooding and runoff from 
earlier heavy rain continues.

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...
All of the island of Maui. 

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.

&&

LAT...LON 2093 15672 2102 15668 2105 15660 2100 15652
      2091 15647 2096 15633 2095 15624 2087 15612
      2084 15611 2081 15599 2076 15597 2071 15598
      2064 15604 2061 15614 2057 15642 2063 15647
      2077 15648 2076 15654 2080 15663 2088 15670

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

$$

BIRCHARD

376 
WGHW50 PHFO 061001
FFWHFO
HIC009-061315-
/O.EXT.PHFO.FF.W.0044.000000T0000Z-211206T1315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Honolulu HI
1201 AM HST Mon Dec 6 2021

The National Weather Service in Honolulu has extended the

* Flash Flood Warning for...
  The island of Maui in Maui County

* Until 315 AM HST.

* At 1201 AM HST, radar indicated that heavy rain had eased in 
  coverage and intensity over the island of Maui, with a few 
  fast-moving heavy showers producing rain rates near 1 inch per 
  hour. However, significant flooding from earlier heavy rain is 
  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...
  All of the island of Maui, but especially Wailea and Makena. 

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 315 AM HST if flooding 
persists.

LAT...LON 2093 15672 2102 15668 2105 15660 2100 15652
      2091 15647 2096 15633 2095 15624 2087 15612
      2084 15611 2081 15599 2076 15597 2071 15598
      2064 15604 2061 15614 2057 15642 2063 15647
      2077 15648 2076 15654 2080 15663 2088 15670

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

$$

BIRCHARD

912 
WGHW70 PHFO 061136
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
136 AM HST Mon Dec 6 2021

HIC009-061315-
/O.CON.PHFO.FF.W.0044.000000T0000Z-211206T1315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maui HI-
136 AM HST Mon Dec 6 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 315 AM HST EARLY THIS 
MORNING FOR THE ISLAND OF MAUI IN MAUI COUNTY...

At 136 AM HST, radar indicated a cluster of heavy showers moving 
over leeward Maui from the south, producing rainfall rates of 2 to 3 
inches per hour.

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...
mainly leeward areas. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

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.

&&

LAT...LON 2093 15672 2102 15668 2105 15660 2100 15652
      2091 15647 2096 15633 2095 15624 2087 15612
      2084 15611 2081 15599 2076 15597 2071 15598
      2064 15604 2061 15614 2057 15642 2063 15647
      2077 15648 2076 15654 2080 15663 2088 15670

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

$$

BIRCHARD

469 
WGHW50 PHFO 061240
FFWHFO
HIC009-061615-
/O.EXT.PHFO.FF.W.0044.000000T0000Z-211206T1615Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Honolulu HI
240 AM HST Mon Dec 6 2021

The National Weather Service in Honolulu has extended the

* Flash Flood Warning for...
  The island of Maui in Maui County

* Until 615 AM HST.

* At 240 AM HST, radar indicated a renewed area of very heavy 
  showers moving over Maui from the south, with even more heavy 
  showers developing further upstream. Localized rainfall rates of 2 
  to 3 inches per hour will exacerbate ongoing flooding from earlier 
  rainfall. Portions of leeward Maui have received over 6 inches of 
  rain over the past 6 hours, and runoff remains high.

  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...
  the entire island of Maui. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

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 615 AM HST if flooding 
persists.

LAT...LON 2093 15672 2102 15668 2105 15660 2100 15652
      2091 15647 2096 15633 2095 15624 2087 15612
      2084 15611 2081 15599 2076 15597 2071 15598
      2064 15604 2061 15614 2057 15642 2063 15647
      2077 15648 2076 15654 2080 15663 2088 15670

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

$$

Birchard

140 
WGHW50 PHFO 061550
FFWHFO
HIC009-061915-
/O.EXT.PHFO.FF.W.0044.000000T0000Z-211206T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Honolulu HI
550 AM HST Mon Dec 6 2021

The National Weather Service in Honolulu has extended the

* Flash Flood Warning for...
  The island of Maui in Maui County

* Until 915 AM HST.

* At 550 AM HST, radar indicated a cluster of heavy showers moving 
  over Maui from the south, producing rainfall rates of 1 to 2 
  inches per hour. Leeward Maui has received 6 to 10 inches of rain 
  overnight, and rainfall remains high.

  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...
  the entire island of Maui, especially leeward Maui. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The heavy rains may cause rock and mudslides in steep terrain areas.

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 915 AM HST if flooding 
persists.

LAT...LON 2093 15672 2102 15668 2105 15660 2100 15652
      2091 15647 2096 15633 2095 15624 2087 15612
      2084 15611 2081 15599 2076 15597 2071 15598
      2064 15604 2061 15614 2057 15642 2063 15647
      2077 15648 2076 15654 2080 15663 2088 15670

FLASH FLOOD...RADAR INDICATED

$$

Birchard

508 
WGHW70 PHFO 061721
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
721 AM HST Mon Dec 6 2021

HIC009-061915-
/O.CON.PHFO.FF.W.0044.000000T0000Z-211206T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maui HI-
721 AM HST Mon Dec 6 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 915 AM HST THIS 
MORNING FOR THE ISLAND OF MAUI IN MAUI COUNTY...

At 721 AM HST, radar and rain gages indicated that another band of 
heavy rainfall moved over Maui. Peak rain rates of 1 to 2 inches per 
hour were detected over the Central Valley and over east Maui near 
Oheo Gulch. Stream levels also remain elevated over most areas of 
the island.

HAZARD...Flash flooding caused by heavy rain.

SOURCE...Radar and automated gauges.

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...
  Kahului, Kihei, Lahaina, Kula, Pukalani, Makawao, Keokea, 
  Haliimaile, Paia, Puunene, Haiku-Pauwela, Wailea, Pauwela, 
  Maalaea, Ulupalakua, Huelo, Makena, Waikapu, Wailuku and Waiehu.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The heavy rains may cause rock and mudslides in steep terrain areas.

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.

&&

LAT...LON 2093 15672 2102 15668 2105 15660 2100 15652
      2091 15647 2096 15633 2095 15624 2087 15612
      2084 15611 2081 15599 2076 15597 2071 15598
      2064 15604 2061 15614 2057 15642 2063 15647
      2077 15648 2076 15654 2080 15663 2088 15670

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

KODAMA

414 
WGHW70 PHFO 061821
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
821 AM HST Mon Dec 6 2021

HIC009-061915-
/O.CON.PHFO.FF.W.0044.000000T0000Z-211206T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maui HI-
821 AM HST Mon Dec 6 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 915 AM HST THIS 
MORNING FOR THE ISLAND OF MAUI IN MAUI COUNTY...

At 821 AM HST, rainfall has eased, but the Maui emergency management 
reported that Lower Kula Road has been closed due to flooding. 
Although rainfall has eased, runoff and stream levels will remain 
elevated for a few more hours.

HAZARD...Flash flooding caused by heavy rain.

SOURCE...Emergency management reported.

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...
  Kahului, Kihei, Lahaina, Kula, Pukalani, Makawao, Keokea, 
  Haliimaile, Paia, Puunene, Haiku-Pauwela, Wailea, Pauwela, 
  Maalaea, Ulupalakua, Huelo, Makena, Waikapu, Wailuku and Waiehu.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The heavy rains may cause rock and mudslides in steep terrain areas.

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.

&&

LAT...LON 2093 15672 2102 15668 2105 15660 2100 15652
      2091 15647 2096 15633 2095 15624 2087 15612
      2084 15611 2081 15599 2076 15597 2071 15598
      2064 15604 2061 15614 2057 15642 2063 15647
      2077 15648 2076 15654 2080 15663 2088 15670

FLASH FLOOD...OBSERVED

$$

KODAMA

371 
WGHW70 PHFO 061855
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
855 AM HST Mon Dec 6 2021

HIC009-061905-
/O.CAN.PHFO.FF.W.0044.000000T0000Z-211206T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maui HI-
855 AM HST Mon Dec 6 2021

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

Flood waters have receded. Piilani Highway remains closed at Pahihi 
Gulch due to earlier flood damage.

A Flood Watch remains in effect for Maui County through Tuesday 
afternoon.

LAT...LON 2093 15672 2102 15668 2105 15660 2100 15652
      2091 15647 2096 15633 2095 15624 2087 15612
      2084 15611 2081 15599 2076 15597 2071 15598
      2064 15604 2061 15614 2057 15642 2063 15647
      2077 15648 2076 15654 2080 15663 2088 15670

$$

KODAMA

The office that day

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

Issued	Product	Office	Counties	Lasted
Dec 5, 2:30 PM HST	Areal Flood Advisory	HFO	Hawaii	86 min
Dec 5, 3:18 PM HST	Areal Flood Advisory	HFO	Kalawao	3 hr
Dec 5, 3:35 PM HST	Coastal Flood Statement	HFO	Hawaii, Honolulu, Kauai, Kalawao	42 hr
Dec 5, 3:56 PM HST	Flash Flood Warning	HFO	Hawaii	5 hr
Dec 5, 4:27 PM HST	Flash Flood Warning	HFO	Kalawao	5 hr
Dec 5, 5:33 PM HST	Areal Flood Advisory	HFO	Kalawao	6 hr
Dec 5, 6:22 PM HST	Flash Flood Warning	HFO	Kalawao	3 hr
Dec 5, 8:02 PM HST	Gale Warning	HFO		7 hr
Dec 5, 8:02 PM HST	Small Craft Advisory	HFO		10 days
Dec 5, 9:20 PM HST	Flash Flood Warning	HFO	Kalawao	11 hr
Dec 6, 12:37 AM HST	Areal Flood Advisory	HFO	Hawaii	11 hr
Dec 6, 3:24 AM HST	Winter Weather Advisory	HFO	Hawaii	12 hr
Dec 6, 3:26 AM HST	Gale Warning	HFO		12 hr
Dec 6, 3:37 AM HST	High Surf Advisory	HFO	Hawaii, Honolulu, Kauai, Kalawao	12 hr
Dec 6, 5:54 AM HST	Special Marine Warning	HFO		2 hr
Dec 6, 7:09 AM HST	Special Marine Warning	HFO		51 min
Dec 6, 7:39 AM HST	Special Weather Statement	HFO	Hawaii	51 min
Dec 6, 7:40 AM HST	Areal Flood Advisory	HFO	Honolulu	6 hr
Dec 6, 7:57 AM HST	Areal Flood Advisory	HFO	Kauai	3 hr
Dec 6, 11:30 AM HST	Flash Flood Warning	HFO	Hawaii	2 hr
Dec 6, 12:26 PM HST	Special Marine Warning	HFO		64 min
Dec 6, 1:12 PM HST	Special Weather Statement	HFO	Honolulu	63 min
Dec 6, 1:16 PM HST	Flash Flood Warning	HFO	Honolulu	15 hr
Dec 6, 1:20 PM HST	Special Marine Warning	HFO		55 min
Dec 6, 1:43 PM HST	Areal Flood Advisory	HFO	Hawaii	3 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.