Alert archive / Guam / Flash Flood Warnings in 2018

Flash Flood Warning 7, NWS Guam

August 20, 2018

NWS Guam issued this flash flood warning at Aug 20, 2018, 11:15 PM CDT. It took effect at Aug 20, 2018, 11:25 PM 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 counties it named.

The facts

Issued
Aug 20, 2018, 11:15 PM CDT (04:15 UTC)
In effect from
Aug 20, 2018, 11:25 PM CDT
Expired
Aug 21, 2018, 2:15 AM CDT
In force
3 hr
Issued by
NWS Guam
Area
Storm-based polygon
Flood severity
None

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Guam wrote its last area forecast discussion before this flash flood warning went out at Aug 20, 4:47 PM CDT, 6 hours 28 minutes earlier.

Area forecast discussion, Aug 20, 4:47 PM CDT, 6 hours 28 minutes before
Area Forecast Discussion
National Weather Service Tiyan GU
747 AM ChST Tue Aug 21 2018

.Marianas Synopsis...
Cloudy skies with rain, numerous showers and isolated thunderstorms
are seen across the region this morning. Fresh to strong monsoon
winds are also present across the Marianas. Latest buoy readings show
seas between 9 and 11 feet.

&&

.Discussion...
Conditions are slowly improving across the Marianas. The Tropical
Storm Warning has been cancelled for Tinian and Saipan. A monsoon
tail continues to affect the islands, however, and will continue to
generate showers and thunderstorms through late Wednesday morning.
Showers will begin to decrease this evening with cloud cover thinning
out a bit Wednesday afternoon. A fairly dry pattern will then move in
to the region, with only isolated showers for the remainder of the
week. As of now, the weekend looks to be partly cloudy with isolated
showers.

&&

.Marine...
The affects of Typhoon Cimaron and the monsoon surge will continue to
affect the Marianas coastal waters through Wednesday morning. Seas
between 9 and 12 feet will gradually subside over the next couple of
days. Seas and winds will both fall below small craft advisory levels
early Wednesday morning. this should allow surf to also fall below
hazardous levels at the same time.

&&

.Tropical systems...
Typhoon Cimaron continues to move away from the Marianas. Cimaron is
now to the north of Agrihan as well, and is now moving away from the
northern CNMI. As Cimaron continues northwest, the monsoon affects
will be pulled away with it as well. For more information on Cimaron,
see bulletins issued by the Joint Typhoon Warning Center under WMO
header WTPN31 PGTW and by the National Weather Service under WMO
header WTPQ31 PGUM.

&&

.Eastern Micronesia...
A surface trough continues its trek westward through east Micronesia
this morning. Showers and thunderstorms are clearing out at Majuro
and Kwajalein. Isolated showers and thunderstorms will linger at
Kosrae today but most showers and thunderstorms will keep to the
north. Scattered showers and thunderstorms will arrive at Pohnpei by
midday as the trough approaches. This trough will weaken a bit as it
approaches Chuuk on Wednesday with only isolated showers and
thunderstorms. A couple days of fair weather will follow this trough
through the region. Another surface trough will bring isolated
showers and thunderstorms to Kosrae and Majuro Thursday and Friday.

&&

.Western Micronesia...
Fair weather prevailed much of the night at Yap and Koror with much
of the monsoon moisture keeping just north of Yap. Showers and
thunderstorms have shifted southward over Yap bringing cloudy skies,
scattered showers and thunderstorm for the day. Will have to watch
Koror closely. Much of this weather is expected to keep just north
of Koror, but showers may develop closer to the republic. GFS shows
isolated showers and thunderstorm at Yap tonight and Wednesday and
drier weather at Koror. As distant Typhoon Cimaron continues farther
away, a weak ridge will pass through Yap and Koror. Showers and
thunderstorms from a surface trough to the east will reach Yap and
Koror on Thursday.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...High Rip Current Risk through late tonight for GUZ001>004.

     Flash Flood Watch through this evening for GUZ001>004.

     High Surf Advisory until 6 AM CHST Wednesday for GUZ001>004.

Marianas Waters...Small Craft Advisory until 6 AM CHST Wednesday for
	 PMZ151>154.

&&

Kleeschulte/M. Aydlett

The office that day

Everything else NWS Guam issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 20, 7:32 PM CDTFlash Flood WarningGUM4 hr
Aug 20, 10:35 PM CDTFlash Flood WarningGUM4 hr
Aug 21, 2:03 AM CDTFlash Flood WarningGUM4 hr

Nearby

Flash Flood Warnings in Guam, 2018Every flash flood warning in 2018

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text.