Alert archive / Hawaii / Flash Flood Warnings in 2021

Flash Flood Warning 40, NWS Honolulu, HI

December 4, 2021Kalawao County, Hawaii

NWS Honolulu, HI issued this flash flood warning at Dec 4, 2021, 1:59 AM HST for Kalawao County, Hawaii. It was in force for 109 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Dec 4, 2021, 1:59 AM HST (11:59 UTC)
Expired: Dec 4, 2021, 3:48 AM HST
In force: 109 min
Issued by: NWS Honolulu, HI
Area: Storm-based polygon
Flood severity: None

County Kalawao County, HI

The radar

The Kamuela/Kohala Apt radar (PHKM), 77 km from the middle of the area, began a volume at 12:01 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

Hilo, (PITO), launched 00:00Z, 12.0 hours before the alert went out and 165 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: 732 J/kg
Mixed-layer CIN: -35 J/kg
Mixed-layer LCL: 902 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 54 m²/s²
0-3 km storm-relative helicity: 125 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.7

Open this sounding in Storm Lab

The text

As transmitted.

631 
WGHW50 PHFO 041159
FFWHFO
HIC009-041400-
/O.NEW.PHFO.FF.W.0040.211204T1159Z-211204T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Honolulu HI
159 AM HST Sat Dec 4 2021

The National Weather Service in Honolulu has issued a

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

* Until 400 AM HST.

* At 159 AM HST, Rain was falling at a rate of 1 to 2 inches per 
  hour. Water levels in streams and rivers have risen quickly, and 
  will likely continue.

  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...
  Kaupo, Kipahulu, Kula, Nahiku, Keokea, Hana, Ulupalakua, Wailea, 
  Makena, Haleakala National Park, Wailua and Hamoa.

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.

A Flood Watch remains in effect until 600 PM HST Tuesday for all 
Hawaiian Islands.

&&

This warning may need to be extended beyond 400 AM HST if flooding 
persists.

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

LAT...LON 2063 15647 2065 15647 2086 15612 2084 15611
      2081 15600 2077 15597 2070 15598 2064 15604
      2061 15614 2062 15619 2057 15630 2057 15642

FLASH FLOOD...RADAR INDICATED

$$

GIBBS

1 follow-up statement

331 
WGHW70 PHFO 041348
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
348 AM HST Sat Dec 4 2021

HIC009-041358-
/O.CAN.PHFO.FF.W.0040.000000T0000Z-211204T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maui HI-
348 AM HST Sat Dec 4 2021

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

Stream are receding and the heavy rain has ended. Flooding is no 
longer expected to pose a threat, however stream will remain 
elevated for a while longer.

A Flood Watch remains in effect until 600 PM HST Tuesday for the 
entire state of Hawaii.

LAT...LON 2063 15647 2065 15647 2086 15612 2084 15611
      2081 15600 2077 15597 2070 15598 2064 15604
      2061 15614 2062 15619 2057 15630 2057 15642

$$

M BALLARD

The office that day

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

Issued	Product	Office	Counties	Lasted
Dec 3, 6:09 PM HST	Areal Flood Advisory	HFO	Hawaii	3 hr
Dec 3, 9:06 PM HST	Areal Flood Advisory	HFO	Hawaii	92 min
Dec 3, 10:59 PM HST	Areal Flood Advisory	HFO	Hawaii	2 hr
Dec 4, 12:13 AM HST	Areal Flood Advisory	HFO	Kalawao	106 min

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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.