Tropical Storm in Guam, July 5, 2018

Name: Tropical Storm in Guam, July 5, 2018
Start: 2018-07-05T00:00
End: 2018-07-05T20:00
Location: Guam

July 5, 2018 · NWS GUM · 1 event in 1 county or zone

Tropical Storm Maria passed across Guam on the 5th of July bringing gusty winds and minor damage.

The toll

Deaths: 0
Injuries: 0
Property damage: $100,000
Crop damage: $50,000
Events: 1

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS GUM wrote it up.

Tropical Storm Maria passed across Guam on the 5th of July bringing gusty winds and minor damage.

What forecasters said that day

The local office's own words before the first event, 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 the first event at Jul 4, 9:53 AM UTC, 4 hours 7 minutes earlier.

Area forecast discussion, Jul 4, 9:53 AM UTC, 4 hours 7 minutes before

Area Forecast Discussion
National Weather Service Tiyan GU
753 PM ChST Wed Jul 4 2018

.Marianas Synopsis...
Tropical Depression 10W is centered southeast of Guam near
12N146E, it is moving northwest. Frequent showers and isolated
thunderstorms are seen across the Marianas. Combined seas are
between 6 and 9 feet at the buoys.

&&

.Discussion...
The forecast through at least Thursday night will be influenced by
Tropical Depression 10W. Currently, the system is southeast of
Guam and moving northwest. TD 10W is forecast to move across the
Marianas overnight into Thursday morning and gradually
strengthen. Conditions will deteriorate. A flash flood watch has
been issued as heavy rain is anticipated, especially for Guam and
Rota.

&&

.Marine...
Latest buoy observations are between 6 and 9 feet--6 feet at
Saipan and Tinian and 9 feet at Guam and Rota. Seas and winds
will increase overnight into Thursday morning as Tropical
Depression 10W makes its closest point of approach and
strengthens. Tropical storm conditions are expected for the Guam
and Rota coastal waters and possible for Tinian and Saipan. The
best course of action at this point is for boats to remain in
port.

&&

.Tropical systems...
Tropical Depression 10W continues on a course to pass through the
Rota Channel sometime Thursday morning. 10W did strengthen a
little today, now with sustained winds of 35 mph, or just shy of
tropical storm strength. We expect 10W to become a tropical storm
overnight as it passes through the Marianas. Folks on Guam, Rota,
Tinian and Saipan should expect heavy showers and gusty winds this
evening through Thursday afternoon. Tropical storm force winds
are expected across Guam and Rota early Thursday morning and
possibly through much of Thursday. Similar conditions are possible
at Tinian and Saipan on Thursday. Latest guidance shows showers
and strong southerly winds persisting through much of Thursday,
possibly into Friday morning as strong monsoonal flow east and
southeast of 10W gets pulled up over the Marianas. Small changes
in timing and intensities are still possible over the next 12
hours, but forecast uncertainty has decreased considerably as 10W
becomes better organized and is evident on the Doppler radar.

&&

.Eastern Micronesia...
A disturbance is causing widespread showers and thunderstorms
across the Marshall Islands this evening while drier weather is
found at Kosrae and Pohnpei. Wet weather will persist through
tonight at Majuro before gradually subsiding Thursday. Unsettled
conditions could continue into the weekend though. Quiet weather
at Kosrae and Pohnpei will persist through Friday, before a
surface trough brings isolated showers and thunderstorms over the
weekend.

&&

.Western Micronesia...
A low-level ridge brought drier weather to Chuuk today and will
keep fairly dry weather and light winds across the area an
additional couple of days. Winds will shift to the northeast
Thursday. A surface trough will bring increasing clouds and
showers Friday.

Developing west to southwest monsoon flow will bring increasing
showers and thunderstorms to Koror tonight and to Yap on
Thursday. Because TD 10W is expected to be relatively slow moving
to the northwest, the wet monsoon flow will persist into the
weekend. Went ahead and bumped up winds, seas and showers for the
region, for the next couple of days. Hazardous seas and surf are
not expected.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...High Rip Current Risk through late Thursday night for GUZ001>005.

     Flash Flood Watch through Friday morning for GUZ001>004.

     Tropical Storm Warning for GUZ001-002.

 Tropical Storm Watch for GUZ003-004.

Marianas Waters...Tropical Storm Warning for PMZ151-152.

 Tropical Storm Watch for PMZ153-154.

&&

Nierenberg/M. Aydlett/Miller

Event by event

1 tropical storm. Local standard time, as filed.

Tropical Storm, Guam

When: July 5, 12:00 AM GST to 8:00 PM GST
Where: Guam forecast zone
Property damage: $100,000
Crop damage: $50,000
Reported by: Official NWS Observations

On the morning of July 1st a circulation was noted north of Chuuk near 11N152E.

By the morning of the 3rd it strengthened enough to become Tropical Depression 10W.|At this time it was near 10N146E. The depression gathered strength to the southeast of Guam and in the early morning of July 5th it became Tropical Storm Maria. At this time (2 am ), it was only 55 miles southeast of Guam. Maria moved west-northwest and passed over the northern part of Guam around 4 a.m.. While much of the island experienced only tropical storm-force winds, a brief blow-up of meso-vortex associated with severe thunderstorm activity near the center caused a short period of typhoon force wind at Andersen AFB. A wind and damage assessment of structures and vegetation conducted by WFO Guam and the University of Guam assessed at least Typhoon Category 1 winds at the Ritidian Wildlife Refuge a few miles west of Andersen AFB.

At the National Weather Service Office in central Guam, the highest sustained wind reported was a 39-knot wind (45 mph) at 1554UTC (1:54 am lChST) and multiple peak winds at 59 knots (68 mph). Andersen AFB measured a few episodes of sustained winds of 38 knots (44 mph) with a peak wind of 83 knots (96 mph) at 1742UTC (3:42 am ChST). The Rota airport measured a maximum sustained wind of 36 knots (41 mph) with a gust to 45 knots (52 mph).

Damage across most of the island of Guam amounted to downed power lines and trees. The downed power lines caused an island wide power outage. The power was restored by the evening of the 5th. Weather radar was also knocked out. With the higher gusts across Andersen AFB, some damages occurred to several KC-135 tankers on the base.

What these are

Tropical Storm: A tropical cyclone with sustained winds of 34 to 63 knots (39 to 73 mph).

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Guam in 2018 Every state in 2018 This day in weather history Warnings in Guam, July 2018 The 2018 hurricane season

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 788402.