Alert archive / Hawaii / Flash Flood Warnings in 2021
Flash Flood Warning 49, NWS Honolulu, HI
NWS Honolulu, HI issued this flash flood warning at Dec 30, 2021, 8:29 PM HST for Honolulu County, Hawaii. It was in force for 3 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
- Dec 30, 2021, 8:29 PM HST (06:29 UTC)
- Expired
- Dec 30, 2021, 11:23 PM HST
- In force
- 3 hr
- Issued by
- NWS Honolulu, HI
- Area
- Storm-based polygon
- Flood severity
- None
County Honolulu County, HI
The radar
The Molokai radar (PHMO), 92 km from the middle of the area, began a volume at 06:28 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 00:00Z, 6.5 hours before the alert went out and 152 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.
- Mixed-layer CAPE
- 175 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 542 m above ground
- 0-6 km bulk shear
- 14 kt
- 0-1 km storm-relative helicity
- 35 m²/s²
- 0-3 km storm-relative helicity
- 68 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
877
WGHW50 PHFO 310629
FFWHFO
HIC003-310930-
/O.NEW.PHFO.FF.W.0049.211231T0629Z-211231T0930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Honolulu HI
829 PM HST Thu Dec 30 2021
The National Weather Service in Honolulu has issued a
* Flash Flood Warning for...
The island of Oahu in Honolulu County
* Until 1130 PM HST.
* At 829 PM HST, radar indicated heavy rain over the Koolau range
with the heaviest rain falling over the slopes for Heeia to
Kaaawa. Rain was falling at a rate of 1 to 2 inches per hour. The
Waiahole Stream has risen rapidly in response to the rain, and the
Waihee Stream gage remains elevated. 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...
Waikane, Waiahole, Mililani, Wahiawa, Kahaluu, Pearl City,
Ahuimanu, Aiea, Halawa, Moanalua, Kaneohe, Kalihi, Haleiwa,
Maunawili, Manoa, Kailua, Waimanalo, Kahana Valley State Park,
Whitmore Village and Helemano Housing.
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 1130 PM 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 15811 2170 15801 2135 15773 2134 15788
FLASH FLOOD...RADAR INDICATED
$$
M BALLARD2 follow-up statements
832
WGHW70 PHFO 310752
FFSHFO
Flash Flood Statement
National Weather Service Honolulu HI
952 PM HST Thu Dec 30 2021
HIC003-310930-
/O.CON.PHFO.FF.W.0049.000000T0000Z-211231T0930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Honolulu HI-
952 PM HST Thu Dec 30 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1130 PM HST THIS
EVENING FOR THE ISLAND OF OAHU IN HONOLULU COUNTY...
At 952 PM HST, radar indicated heavy rain up to 2 inches per hour
continuing over the portions of the Koolau mountains. While some of
the rain is beginning to subside, additional rain is possible. Many
area streams such as the Punaluu, Kahana, Waikane, Waiahole, Waihee
and Heeia streams remain elevated.
HAZARD...Flash flooding caused by heavy rain.
SOURCE...Radar.
IMPACT...Flooding in drainages, streams, rivers, roads,
properties, and other low-lying areas. Public road
closures possible in some areas. Landslides are possible
in steep terrain.
Some locations that will experience flash flooding include...
Waikane, Waiahole, Mililani, Wahiawa, Kahaluu, Pearl City,
Ahuimanu, Aiea, Halawa, Moanalua, Kaneohe, Kalihi, Haleiwa,
Maunawili, Manoa, Kailua, Waimanalo, Kahana Valley State Park,
Whitmore Village and Helemano Housing.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Stay away from streams, rivers, drainage ditches, and culverts, even
if they are currently dry.
Do not cross fast flowing or rising water in your vehicle, or on
foot. Turn around, don't drown.
&&
LAT...LON 2160 15811 2170 15801 2135 15773 2134 15788
FLASH FLOOD...RADAR INDICATED
$$
M BALLARD777 WGHW70 PHFO 310923 FFSHFO Flash Flood Statement National Weather Service Honolulu HI 1123 PM HST Thu Dec 30 2021 HIC003-310933- /O.CAN.PHFO.FF.W.0049.000000T0000Z-211231T0930Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ Honolulu HI- 1123 PM HST Thu Dec 30 2021 ...FLASH FLOOD WARNING IS CANCELLED FOR THE ISLAND OF OAHU IN HONOLULU COUNTY... The heavy rain has tapered off. Streams are slowly subsiding but remain elevated. Showers are expected through the night, however flooding is no longer expected to pose a threat. LAT...LON 2160 15811 2170 15801 2135 15773 2134 15788 $$ M BALLARD
The office that day
Everything else NWS Honolulu, HI issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 30, 3:04 PM HST | Areal Flood Advisory | HFO | Kalawao | 3 hr |
| Dec 30, 3:07 PM HST | Winter Weather Advisory | HFO | Hawaii | 19 hr |
| Dec 30, 3:42 PM HST | Areal Flood Advisory | HFO | Hawaii | 3 hr |
| Dec 30, 7:34 PM HST | Areal Flood Advisory | HFO | Honolulu | 55 min |
| Dec 31, 4:52 AM HST | Areal Flood Advisory | HFO | Kauai | 3 hr |
| Dec 31, 6:26 AM HST | Flash Flood Warning | HFO | Kauai | 3 hr |
| Dec 31, 9:11 AM HST | Areal Flood Advisory | HFO | Hawaii | 6 hr |
| Dec 31, 12:18 PM HST | Areal Flood Advisory | HFO | Kalawao | 4 hr |
| Dec 31, 1:28 PM HST | Areal Flood Advisory | HFO | Kalawao | 3 hr |
Nearby
Flash Flood Warnings in Hawaii, 2021Every 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.