Guam, 2015

Tropical Storm in Guam, October 16 to 17, 2015

October 16 to 17, 2015 · NWS GUM · 4 events in 4 counties and zones

Tropical Storm Champi moved across the Marianas during the middle of October.

The toll

Deaths
0
Injuries
0
Property damage
$100,000
Crop damage
None recorded
Events
4

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 Champi moved across the Marianas during the middle of October.

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 Oct 15, 12:32 PM UTC, 1 hour 28 minutes earlier.

Area forecast discussion, Oct 15, 12:32 PM UTC, 1 hour 28 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
1032 PM CHST THU OCT 15 2015

.SYNOPSIS...
TROPICAL STORM CHAMPI WAS NEAR LATITUDE 16.3 NORTH AND LONGITUDE
150.5 EAST AT 7 PM CHST. MOVEMENT IS TOWARD THE WEST-NORTHWEST AT
17 MPH. MAXIMUM SUSTAINED WINDS HAVE BEEN HOVERING NEAR 60 MPH
SINCE THIS MORNING. DENSE CLOUD COVER AND RAIN SHIELD OF CHAMPI
IS SPREADING OVER TINIAN AND SAIPAN.

&&

.DISCUSSION...
A TROPICAL STORM WARNING AND TYPHOON WATCH REMAIN IN EFFECT FOR
THE NORTHERN CNMI. A TROPICAL STORM WARNING REMAINS IN EFFECT FOR
THE ROTA...TINIAN AND SAIPAN ZONES. LATEST WARNING FROM JTWC TAKES
CHAMPI THROUGH THE MARIANAS NEAR ALAMAGAN...SO STRONGEST WINDS AND
HEAVIEST RAINS ASSOCIATED WITH CHAMPI ARE EXPECTED TO AFFECT THE
TINIAN AND SAIPAN ZONES FRIDAY AND FRIDAY NIGHT. CWFMY AND ZFPMY
ARE WORDED ACCORDINGLY. CONDITIONS ARE EXPECTED TO GRADUALLY
IMPROVE OVER THE WEEKEND AND EARLY NEXT WEEK...BUT MONSOONAL
WEATHER PATTERN WILL KEEP UNSETTLED WEATHER IN PLACE THROUGH DAY
7.

&&

.MARINE...
TROPICAL STORM WARNING REMAINS IN EFFECT FOR ROTA...TINIAN AND
SAIPAN ZONES. IF CHAMPI CONTINUES TO MOVE AND EVOLVE AS
EXPECTED...WATCHES AND WARNINGS SHOULD NO LONGER BE NECESSARY BY
SUNDAY EVENING. SMALL CRAFT AND HIGH SURF ADVISORIES REMAIN IN
EFFECT FOR GUAM ZONES. THESE MAY BE REQUIRED FOR SEVERAL DAYS
LONGER...AS MONSOONAL WINDS FROM THE SOUTHWEST COULD PROLONG
ADVERSE MARINE CONDITIONS WELL INTO NEXT WEEK.

&&

.TROPICAL SYSTEMS...
TROPICAL STORM CHAMPI CONTINUES TRACKING TOWARD THE WEST-
NORTHWEST AND IS EXPECTED TO PASS SOMEWHERE NEAR ANATAHAN IN THE
NORTHERN CNMI ON FRIDAY AFTERNOON. DEVELOPMENT OF CHAMPI CONTINUES
TO BE RETARDED BY STRONG VERTICAL WIND SHEAR. TOPS OF CONVECTION
CONTINUE TO BE ADVECTED TOWARD THE SOUTHWEST AWAY FROM THE CENTER.
QPF FORECAST IN THE HLSPQ2 TAKES THIS INTO ACCOUNT VIA HIGHEST
EXPECTED RAINFALL ACCUMULATIONS SOUTH OF THE CENTER NEAR TINIAN
AND SAIPAN. NIGHT SHIFT WILL NEED TO MONITOR RAINFALL
ACCUMULATIONS ON TINIAN AND SAIPAN FOR POSSIBLE FLOOD PRODUCT
ISSUANCE. LATEST WARNINGS FROM JTWC HAVE TRENDED NORTHWARD WITH
THE TRACK OF CHAMPI...SO LATEST WIND FORECASTS FOR GUAM...ROTA...
TINIAN AND SAIPAN ZONES HAVE BEEN TONED DOWN A BIT. CENTER OF
CHAMPI IS EXPECTED TO PASS THROUGH THE MARIANAS ON FRIDAY
AFTERNOON...AFTER THAT...CONDITIONS ARE EXPECTED TO IMPROVE.

&&

.EASTERN MICRONESIA...
TROPICAL STORM CHAMPI IS MOVING AWAY FROM EASTERN MICRONESIA AND
APPROACHING THE MARIANA ISLANDS. ASCAT ANALYSIS SHOWS SOUTHWEST TO
WEST WINDS PERSIST FROM CHUUK ACROSS POHNPEI TO KOSRAE WHERE THEY
TURN NORTHWEST ACROSS THE MARSHALL ISLANDS TOWARD A WEAK
CIRCULATION SOUTHEAST OF MAJURO NEAR 6N176E. THIS CIRCULATION IS
ASSOCIATED WITH JTWC INVEST AREA 93W. THE GFS MODEL INDICATES 93W
WILL MOVE TOWARD NORTHWEST AND SLOWLY DEVELOP DURING THE NEXT FEW
DAYS...MAINLY JUST AFFECTING THE MARSHALL ISLANDS AND KOSRAE
STATE. CHUUK AND POHNPEI SHOULD REMAIN IN A SLIGHTLY DRIER
SOUTHWEST WIND FLOW. IN THE LONGER TERM...A LITTLE DRIER WEATHER
IS EXPECTED FOR MAJURO AND KOSRAE BY EARLY NEXT WEEK AS INVEST
AREA 93W MOVES FARTHER AWAY THIS WEEKEND.

&&

.WESTERN MICRONESIA...
REASONING FOR CHUUK FORECAST IS INCLUDED IN THE EASTERN MICRONESIA
DISCUSSION DUE TO A SIMILAR MONSOON PATTERN.

TROPICAL STORM KOPPU IS CENTERED ALMOST 600 MILES NORTHWEST OF
KOROR AND MOVING TOWARD LUZON. GFS MODEL INDICATES FRESH TO STRONG
SOUTHWEST WINDS WILL CONTINUE ACROSS KOROR AND YAP THE NEXT COUPLE
OF DAYS. HIGH PRESSURE AND DRY WEATHER ARE CENTERED TO THE
SOUTHEAST OF YAP BUT MODELS STILL INDICATE A FEW SHOWERS FOR YAP
STATE DURING THE WEEKEND AS TROPICAL STORM CHAMPI MOVES WEST-
NORTHWEST THROUGH THE MARIANAS. DRIER CONDITIONS WILL RETURN TO
YAP SUNDAY...AND FAIR CONDITIONS AT KOROR ARE EXPECTED TO CONTINUE
INTO NEXT WEEK.

FRESH TO STRONG SOUTHWEST WINDS AND LARGE WAVES WILL CAUSE HAZARDOUS
SEA AND SURF CONDITIONS FOR YAP AND KOROR DURING THE NEXT FEW DAYS.
CONDITIONS SHOULD START IMPROVING BY SUNDAY OR MONDAY.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...HIGH SURF ADVISORY FROM 6 AM FRIDAY TO 6 PM CHST WEDNESDAY FOR
     GUZ001.

     TROPICAL STORM WARNING FOR GUZ002>004.

MARIANAS WATERS...TROPICAL STORM WARNING FOR PMZ152>154.

     SMALL CRAFT ADVISORY UNTIL 3 PM CHST SUNDAY FOR PMZ151.

&&

MCELROY/WILLIAMS/STANKO

Event by event

4 tropical storm. Local standard time, as filed.

Tropical Storm, Guam

When
October 16, 12:00 AM GST to October 17, 2:00 PM GST
Where
Guam forecast zone
Reported by
Official NWS Observations

On the night of October 13, Tropical Depression 25W formed 1080 miles east of Guam. Twenty-four hours later on the night of the 24th, the depression intensified enough to become Tropical Storm Champi.

Tropical Storm Champi moved across the Marianas on the 16th, passing 65 miles north of Saipan during that afternoon. Winds varied across the Mariana Islands as some of the strongest gusts occurred in shower bands south of the tropical storm.

Across Guam, the maximum sustained wind recorded was 30 knots (35mph) at 10:54 local time. Peak wind over Guam occurred later on the morning of the 17th at 3:32 am local time with a gust to 48 knots (55 mph). The lowest SLP was 999.1mb| |Across northern Guam, Andersen AFB observed maximum sustained winds of 36 knots (41 mph) at around 7 pm on the 16th with a peak wind gust of 49 knots (56 mph) at 10:50 am on the 16th. Lowest SLP was 998.3 mb

The inclement weather associated with Champi's passage caused the cancellation |or delay of several airline flights.

Tropical Storm, Saipan

When
October 16, 12:00 AM GST to October 17, 12:00 PM GST
Where
Saipan forecast zone
Property damage
$100,000
Reported by
Official NWS Observations

On the night of October 13, Tropical Depression 25W formed 1080 miles east of Guam. Twenty-four hours later on the night of the 24th, the depression intensified enough to become Tropical Storm Champi.

Tropical Storm Champi moved across the Marianas on the 16th, passing 65 miles north of Saipan during that afternoon.

Winds varied across the Marianas as some of the gusts occurred in shower bands south of the tropical storm. At Saipan, maximum sustained winds were 42 knots (48 mph) at 2 and 3 pm on the 16th with a peak gust to 68 knots (78 mph) at 1:32 pm. Lowest SLP was 991.6 mb

Rainbands associated with Tropical Storm Champi produced heavy rain in some areas. On Saipan at the International AIrport, 10.60 inches of rain fell on the 16th. This rain caused flooding, which damaged portions of Kanat Tabla Road on Saipan.

The inclement weather associated with Champi's passage caused the cancellation |or delay of several airline flights.

Tropical Storm, Rota

When
October 16, 12:00 AM GST to October 17, 12:00 PM GST
Where
Rota forecast zone
Reported by
Official NWS Observations

On the night of October 13, Tropical Depression 25W formed 1080 miles east of Guam. Twenty-four hours later on the night of the 24th, the depression intensified enough to become Tropical Storm Champi.

Tropical Storm Champi moved across the Marianas on the 16th, passing 65 miles north of Saipan during that afternoon.

Winds varied across the Marianas as some of the gusts occurred in shower bands south of the tropical storm.

An automated weather station on Rota recorded maximum sustained winds of 32 knots (37 mph) just after 6 pm on the 16th with a gust to 47 knots (54 mph) at 4:30 pm. Lowest SLP was 996.5 mb.

Rainbands associated with Tropical Storm Champi produced heavy rain in some areas. The automated weather station on Rota recorded 8.01 inches of rain on the |16th.

Tropical Storm, Northern Marianas

When
October 16, 12:00 AM GST to October 17, 12:00 PM GST
Where
Northern Marianas forecast zone
Reported by
Official NWS Observations

On the night of October 13, Tropical Depression 25W formed 1080 miles east of Guam. Twenty-four hours later on the night of the 24th, the depression intensified enough to become Tropical Storm Champi.

Tropical Storm Champi moved across the Marianas on the 16th, passing 65 miles north of Saipan during that afternoon.

Winds varied across the Marianas as some of the gusts occurred in shower bands south of the tropical storm.

An Automated weather station at Tinian recorded maximum sustained winds of 39 knots (45 mph) at 4:30 pm on the 16th with gust to 63 knots (73 mph) at 2 pm. Lowest SLP was 989.2 mb.

Rainbands associated with Tropical Storm Champi produced heavy rain in some areas. The rainfall was the most intense on Tinian with 26.25 inches of rain falling between 6 pm on the 15th and midnight on the 17th (30 hours). The automated weather station on Tinian produces 15-minute rainfall information. On the 16th, very high 15-minute rainfall totals were observed between 1145 am and 1 pm where over an inch of rain fell during five 15-minute periods.

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

More

Every storm in Guam in 2015Every state in 2015This day in weather historyWarnings in Guam, October 2015The 2015 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 2026-09-30. Each event’s entry at NCEI: 608220, 608221, 608222, 608223.