Alert archive / Guam / Flash Flood Warnings in 2021

Flash Flood Warning 9, NWS Guam

October 6, 2021

NWS Guam issued this flash flood warning at Oct 6, 2021, 1:46 AM CDT. 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: Oct 6, 2021, 1:46 AM CDT (06:46 UTC)
Expired: Oct 6, 2021, 4:45 AM CDT
In force: 3 hr
Issued by: NWS Guam
Area: Storm-based polygon
Flood severity: None

The radar

The Andersen AFB radar (PGUA), 7 km from the middle of the area, began a volume at 06:47 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 text

As transmitted.

475 
WGMY50 PGUM 060646
FFWGUM
GUC010-060945-
/O.NEW.PGUM.FF.W.0009.211006T0646Z-211006T0945Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Tiyan GU
446 PM ChST Wed Oct 6 2021

The National Weather Service in Tiyan has issued a

* Flash Flood Warning for...
  Guam Island in the Marianas...

* Until 745 PM ChST.

* At 446 PM ChST, Doppler radar and automated rain gauges indicated 
  heavy rain falling across the warned area. Between 1.5 and 2 
  inches of rain have fallen. Additional rainfall amounts of 1 to 2 
  inches are possible in the warned area. Flash flooding is ongoing 
  or expected to begin shortly.

  HAZARD...Flash flooding caused by heavy rain.

  SOURCE...Radar and automated gauges.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Dededo, Tamuning, Yigo, Mangilao, Chalan Pago-Ordot, Barrigada, 
  Yona, Hagatna Heights, Andersen AFB, Talofofo, 
  Mongmong-Toto-Maite, Sinajana, Inarajan, Asan, Merizo, Piti, Santa 
  Rita and Umatac.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 1346 14462 1359 14483 1365 14486 1360 14490
      1360 14495 1352 14493 1342 14478 1327 14475
      1325 14472 1326 14467 1334 14463 1342 14467
      1344 14463 1346 14469 1346 14464

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

PD

The office that day

Everything else NWS Guam issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 6, 1:12 AM CDT	Areal Flood Advisory	GUM		3 hr
Oct 6, 6:54 PM CDT	Areal Flood Advisory	GUM		3 hr

Nearby

Flash Flood Warnings in Guam, 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; radar from the NEXRAD Level II archive.