Alert archive / Hawaii / Flash Flood Warnings in 2021

Flash Flood Warning 3, NWS Honolulu, HI

January 18, 2021Kalawao County, Hawaii

NWS Honolulu, HI issued this flash flood warning at Jan 18, 2021, 2:59 PM HST for Kalawao County, Hawaii. It was in force for 3 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: Jan 18, 2021, 2:59 PM HST (00:59 UTC)
Expired: Jan 18, 2021, 6:00 PM HST
In force: 3 hr
Issued by: NWS Honolulu, HI
Area: Storm-based polygon
Flood severity: None

County Kalawao County, HI

The radar

The Molokai radar (PHMO), 83 km from the middle of the area, began a volume at 00:59 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.

What was reported inside it

Time	Report	Where	Remark
Jan 18, 5:37 PM HST	FLASH FLOOD	Honokohau, HI	WASHING MACHINE SIZE BOULDERS BLOCKING THE ROAD ON HONOAPIILANI HIGHWAY NEAR MILE MARKER 35.
Jan 18, 5:40 PM HST	FLASH FLOOD	1 Ene Makawao, HI	ROAD CLOSED ON MAKAWAO BETWEEN KEE ROAD AND KAILIILI ROAD 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, 1.0 hours before the alert went out and 197 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: 4 J/kg
Mixed-layer CIN: -38 J/kg
Mixed-layer LCL: 884 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 50 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.

293 
WGHW50 PHFO 190059
FFWHFO
HIC009-190400-
/O.NEW.PHFO.FF.W.0003.210119T0059Z-210119T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Honolulu HI
259 PM HST Mon Jan 18 2021

The National Weather Service in Honolulu has issued a

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

* Until 600 PM HST.

* At 259 PM HST, radar indicated heavy rain anchored over and near 
  the West Maui Mountains. Rain was falling at a rate of 1 to 2 
  inches per hour, in areas which have already seen significant 
  rainfall today. 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 could experience flash flooding include...
  Kahului, Kihei, Lahaina, Puunene, Paia, Haliimaile, Wailuku, 
  Waiehu, Pukalani, Maalaea, Makawao, Waikapu, Waihee, Pauwela, 
  Haiku-Pauwela, Kula, Kahakuloa, Huelo, Olowalu and Honokohau.

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 600 PM HST if flooding 
persists.

LAT...LON 2076 15649 2078 15650 2076 15656 2085 15669
      2088 15671 2093 15672 2098 15671 2104 15666
      2106 15660 2100 15651 2092 15647 2097 15633
      2096 15624 2088 15613 2088 15612 2085 15610
      2082 15602 2079 15605

FLASH FLOOD...RADAR INDICATED

$$

R BALLARD

2 follow-up statements

534 
WGHW70 PHFO 190255
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
455 PM HST Mon Jan 18 2021

HIC009-190400-
/O.CON.PHFO.FF.W.0003.000000T0000Z-210119T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maui HI-
455 PM HST Mon Jan 18 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 6 PM HST THIS EVENING 
FOR THE ISLAND OF MAUI IN MAUI COUNTY...

At 455 PM HST, radar showed heavy rain over portions of Maui, mainly 
over the north slope of Haleakala near Haiku, Pukalani, and upslope 
from Huelo and Keanae. Other heavy showers were lingering over the 
west Maui mountains. In the heavier showers, rain was falling at a 
rate of 1 to 2 inches per hour, over areas which have already had 
significant rainfall earlier. Flash flooding is likely in some of 
these areas.

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...
  Kahului, Kihei, Lahaina, Puunene, Paia, Haliimaile, Wailuku, 
  Waiehu, Pukalani, Maalaea, Makawao, Waikapu, Waihee, Pauwela, 
  Haiku-Pauwela, Kula, Kahakuloa, Huelo, Olowalu and Honokohau.

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 600 PM HST if flooding 
persists.

LAT...LON 2076 15649 2078 15650 2076 15656 2085 15669
      2088 15671 2093 15672 2098 15671 2104 15666
      2106 15660 2100 15651 2092 15647 2097 15633
      2096 15624 2088 15613 2088 15612 2085 15610
      2082 15602 2079 15605

FLASH FLOOD...RADAR INDICATED

$$

R BALLARD

625 
WGHW70 PHFO 190358
FFSHFO

Flash Flood Statement
National Weather Service Honolulu HI
558 PM HST Mon Jan 18 2021

HIC009-190408-
/O.EXP.PHFO.FF.W.0003.000000T0000Z-210119T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maui HI-
558 PM HST Mon Jan 18 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 6 PM HST THIS EVENING FOR THE 
ISLAND OF MAUI IN MAUI COUNTY...

Radar indicates the heaviest rainfall has subsided, but locally 
heavy showers continue. Please see the Flood Advisory which is now 
in effect for Maui until 9 pm.

However, conditions remain favorable for additional heavy rain to 
develop later. Thus, a Flash Flood Watch remains in effect until 600 
PM HST Tuesday that includes the island of Maui.

LAT...LON 2076 15649 2078 15650 2076 15656 2085 15669
      2088 15671 2093 15672 2098 15671 2104 15666
      2106 15660 2100 15651 2092 15647 2097 15633
      2096 15624 2088 15613 2088 15612 2085 15610
      2082 15602 2079 15605

$$

R BALLARD

The office that day

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

Issued	Product	Office	Counties	Lasted
Jan 18, 2:25 PM HST	Flash Flood Warning	HFO	Kalawao	9 hr
Jan 18, 3:41 PM HST	Areal Flood Advisory	HFO	Hawaii	3 hr
Jan 18, 5:54 PM HST	Areal Flood Advisory	HFO	Kalawao	5 hr
Jan 19, 5:38 AM HST	Areal Flood Advisory	HFO	Honolulu	3 hr
Jan 19, 10:26 AM HST	Special Marine Warning	HFO		2 hr
Jan 19, 10:55 AM HST	Areal Flood Advisory	HFO	Kauai	2 hr
Jan 19, 12:01 PM HST	Special Marine Warning	HFO		78 min
Jan 19, 1:18 PM HST	Flash Flood Warning	HFO	Kauai	9 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.