Alert archive / Hawaii / Flash Flood Warnings in 2021

Flash Flood Warning 10, NWS Honolulu, HI

February 27, 2021Kalawao County, Hawaii

NWS Honolulu, HI issued this flash flood warning at Feb 27, 2021, 9:59 AM HST for Kalawao County, Hawaii. It was in force for 86 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: Feb 27, 2021, 9:59 AM HST (19:59 UTC)
Expired: Feb 27, 2021, 11:25 AM HST
In force: 86 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), 78 km from the middle of the area, began a volume at 19:59 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 12:00Z, 8.0 hours before the alert went out and 164 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: 88 J/kg
Mixed-layer CIN: -53 J/kg
Mixed-layer LCL: 531 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: -25 m²/s²
0-3 km storm-relative helicity: 5 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

891 
WGHW50 PHFO 271959
FFWHFO
HIC009-272230-
/O.NEW.PHFO.FF.W.0010.210227T1959Z-210227T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Honolulu HI
959 AM HST Sat Feb 27 2021

The National Weather Service in Honolulu has issued a

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

* Until 1230 PM HST.

* At 959 AM HST, radar indicated heavy rain over persisting over 
  windward portions of Haleakala, affecting the area from Nahkiu to 
  Hana to Kaupo, and stream gages indicate rapidly rising waters.

  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...
  Kipahulu, Kaupo, Nahiku, Hana, Keanae, 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.

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

&&

This warning may need to be extended beyond 1230 PM 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 2064 15624 2070 15622 2078 15622 2083 15621
      2085 15619 2087 15612 2085 15612 2084 15611
      2081 15600 2078 15597 2070 15597 2064 15604
      2061 15613 2062 15619 2060 15624

FLASH FLOOD...RADAR INDICATED

$$

Birchard

1 follow-up statement

031 
WGHW70 PHFO 272125
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
1125 AM HST Sat Feb 27 2021

HIC009-272135-
/O.CAN.PHFO.FF.W.0010.000000T0000Z-210227T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maui HI-
1125 AM HST Sat Feb 27 2021

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

The heavy rain over the slopes of windward Haleakala has eased for 
now, and water levels in streams are gradually receding. Flooding is 
no longer expected to pose a significant threat to life and 
property. A Flash Flood Watch remains in effect, and the potential 
remains for additional heavy showers to develop.

LAT...LON 2064 15624 2070 15622 2078 15622 2083 15621
      2085 15619 2087 15612 2085 15612 2084 15611
      2081 15600 2078 15597 2070 15597 2064 15604
      2061 15613 2062 15619 2060 15624

$$

Birchard

The office that day

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

Issued	Product	Office	Counties	Lasted
Feb 26, 2:29 PM HST	Areal Flood Advisory	HFO	Hawaii	3 hr
Feb 26, 5:59 PM HST	Special Marine Warning	HFO		61 min
Feb 27, 7:19 AM HST	Areal Flood Advisory	HFO	Hawaii	6 hr
Feb 27, 8:51 AM HST	Areal Flood Advisory	HFO	Kalawao	68 min
Feb 27, 10:08 AM HST	Areal Flood Advisory	HFO	Honolulu	3 hr
Feb 27, 1:06 PM HST	Areal Flood Advisory	HFO	Hawaii	12 hr
Feb 27, 1:51 PM HST	Areal Flood Advisory	HFO	Kalawao	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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.