Alert archive / Hawaii / Flash Flood Warnings in 2021

Flash Flood Warning 33, NWS Honolulu, HI

March 15, 2021Honolulu County, Hawaii

NWS Honolulu, HI issued this flash flood warning at Mar 15, 2021, 1:50 PM HST for Honolulu County, Hawaii. It was in force for 3 hr. 1 report 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: Mar 15, 2021, 1:50 PM HST (23:50 UTC)
Expired: Mar 15, 2021, 5:00 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), 93 km from the middle of the area, began a volume at 23:50 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
Mar 15, 2:01 PM HST	FLASH FLOOD	Wahiawa, HI	HEAVY ROAD FLOODING.

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

The nearest sounding before it

Lihue, (PHLI), launched 12:00Z, 11.8 hours before the alert went out and 151 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: 767 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 597 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: -37 m²/s²
0-3 km storm-relative helicity: -46 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

761 
WGHW50 PHFO 152350
FFWHFO
HIC003-160300-
/O.NEW.PHFO.FF.W.0033.210315T2350Z-210316T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Honolulu HI
150 PM HST Mon Mar 15 2021

The National Weather Service in Honolulu has issued a

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

* Until 500 PM HST.

* At 150 PM HST, radar indicated heavy rain over central Oahu. Rain 
  was falling at a rate of 2 to 4 inches per hour. Flash flooding is 
  occurring or expected to begin shortly.

  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...
  Wheeler Field, Mililani, Wahiawa, Schofield Barracks, Kunia, 
  Waikele, Waipahu, Pearl City, Aiea, Ewa Beach, Halawa, Waialua, 
  Iroquois Point, Salt Lake, Haleiwa, Moanalua, Whitmore Village, 
  Helemano Housing, Lualualei and Waimalu.

Since the heaviest rain is near the saddle in central Oahu, runoff 
will flow both north toward Haleiwa and Waialua and south toward 
Waipahu and Pearl City.

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 500 PM HST if flooding 
persists.

LAT...LON 2154 15819 2161 15810 2153 15794 2135 15788
      2131 15793 2131 15794 2130 15794 2131 15801
      2144 15812

FLASH FLOOD...RADAR INDICATED

$$

DONALDSON

The office that day

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

Issued	Product	Office	Counties	Lasted
Mar 14, 2:21 PM HST	Areal Flood Advisory	HFO	Hawaii	114 min
Mar 14, 6:16 PM HST	Areal Flood Advisory	HFO	Hawaii	3 hr
Mar 15, 1:27 PM HST	Areal Flood Advisory	HFO	Honolulu	3 hr
Mar 15, 1:32 PM HST	Areal Flood Advisory	HFO	Kalawao	58 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.