Guam, 2015

Tropical Storm in Guam, May 6 to 13, 2015

May 6 to 13, 2015 · NWS GUM · 1 event in 1 county or zone

A circulation formed over the eastern half of Micronesia the first week of May. This weather system gradually became Typhoon Dolphin.

The toll

Deaths
0
Injuries
0
Property damage
$50,000
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.

A circulation formed over the eastern half of Micronesia the first week of May. This weather system gradually became Typhoon Dolphin. Dolphin brought rain and wind to portions to eastern Micronesia and the Marianas Islands.

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 May 5, 7:33 AM UTC, 6 hours 27 minutes earlier.

Area forecast discussion, May 5, 7:33 AM UTC, 6 hours 27 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
533 PM CHST TUE MAY 5 2015

.SYNOPSIS...
RADAR SHOWS ISOLATED LIGHT SHOWERS ACROSS THE COVERAGE AREA AND
SATELLITE SHOWS PARTLY CLOUDY ACROSS THE LOCAL REGION. TROPICAL
STORM NOUL IS VERY CLOSE TO YAP AND EXPECTED TO MOVE VERY SLOWLY
WESTWARD. ALSO...A CIRCULATION/DISTURBANCE CENTERED JUST SOUTHWEST
OF POHNPEI NEAR 5N156E WILL NEED TO BE WATCHED IN THE COMING DAYS.
VAD GRADIENT WINDS ARE FROM THE EAST AT 15 KT AND IPAN BUOY SHOWS
COMBINED SEAS NEAR 5 FEET.

&&

.DISCUSSION...
NO SIGNIFICANT CHANGES WERE MADE TO THE FORECAST AT THIS TIME...AND
PLEASANT WEATHER WILL CONTINUE OVER THE MARIANAS INTO THIS WEEKEND.
MOST OF THE MODELS STILL INDICATE THE CIRCULATION NEAR POHNPEI WILL
SLOWLY DEVELOP AND START MOVING TOWARD THE NORTHWEST BY SATURDAY OR
SUNDAY. THERE IS STILL UNCERTAINTY IN REGARDS TO THE DEVELOPMENT
AND TRACK OF THIS DISTURBANCE AND LATER FORECASTS MAY NEED
ADJUSTMENTS.

&&

.MARINE...
MODERATE TO FRESH TRADE WINDS WILL CONTINUE. A SMALL SOUTHWEST TO
WEST SWELL WILL ARRIVE DURING THE NEXT COUPLE OF DAYS...AND COMBINED
SEAS WILL BUILD TO 6 TO 9 FEET LATE SATURDAY AND POSSILY HIGHER BY
MONDAY OR TUESDAY. THE CIRCULATION NEAR POHNPEI THIS AFTERNOON WILL
NEED TO BE WATCHED...BUT NO SIGNIFICANT CHANGES WERE MADE TO THE
MARINE GRIDS AT THIS TIME.

&&

.TROPICAL SYSTEMS...
TYPHOON WARNING REMAINS IN EFFECT FOR YAP AND TROPICAL STORM WARNING
REMAINS IN EFFECT FOR ULITHI. TROPICAL STORM NUOL WILL LIKELY BECOME
A TYPHOON TONIGHT AND MOVE ACROSS YAP ISLAND EARLY WEDNESDAY MORNING
AND CONTINUE MOVING SLOWLY WESTWARD. THE WEAK CIRCULATION JUST SW OF
POHNPEI AT 5N156E WILL NEED TO BE MONITORED SINCE MOST OF THE MODELS
INDICATE IT WILL GRADUALLY DEVELOP AND START MOVING TOWARD NORTHWEST
BY SATURDAY OR SUNDAY.

&&

.EASTERN MICRONESIA...
ASCAT ANALYSIS SHOWS A CIRCULATION JUST SW OF POHNPEI AT 5N156E...
WHICH IS JTWC INVEST 93W...AND A WEAK CIRCULATION FARTHER EAST NEAR
2N178E. WEATHER CONDITIONS AT POHNPEI AND CHUUK WILL BE UNSTABLE IN
THE COMING DAYS WHILE INVEST 93W REMAINS NEARBY. INVEST AREA 93W IS
EXPECTED TO START MOVING TOWARD NORTHWEST BY SATURDAY OR SUNDAY AND
WEATHER SHOULD THEN GRADUALLY IMPROVE AT POHNPEI AND CHUUK FOR NEXT
WEEK. RELATIVELY DRY WEATHER PERSISTS AT KOSRAE AND MAJURO FOR THE
NEAR TERM...BUT MODELS INDUCATE A PATTERN OF TRADE-WIND CONVERGENCE
WILL HELP TO TRIGGER A FEW SHOWERS AND POSSIBLE THUNDERSTORMS AT
TIMES THROUGH THIS WEEKEND.

&&

.WESTERN MICRONESIA...
THE CHUUK DISCUSSION IS INCLUDED WITH EASTERN MICRONESIA BECAUSE
OF SIMILAR SYNOPTIC CONDITIONS.

YAP AND KOROR...TROPICAL STORM NUOL WILL LIKELY BECOME A TYPHOON
TONIGHT AND MOVE ACROSS YAP ISLAND EARLY WEDNESDAY MORNING...THEN
CONTINUE MOVING SLOWLY WESTWARD. A TYPHOON WARNING REMAINS IN EFFECT
FOR YAP AND A TROPICAL STORM WARNING REMAINS IN EFFECT FOR ULITHI.
HAZARDOUS SEA AND SURF ADVISORIES WILL CONTINUE AT KOROR WHILE NOUL
MOVES SLOWLY ACROSS YAP STATE. IMPROVING WEATHER IS EXPECTED ACROSS
FAR WESTERN MICRONESIA BY THIS WEEKEND.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...NONE.
MARIANAS WATERS...NONE.
&&

SIMPSON/DEVITA/W. AYDLETT

Event by event

1 tropical storm. Local standard time, as filed.

Tropical Storm, Micronesia

When
May 6, 12:00 AM GST to May 13, 12:00 AM GST
Where
Micronesia forecast zone
Property damage
$50,000
Crop damage
$50,000
Reported by
Official NWS Observations

On the 6th of May a circulation was located about 200 miles south of Pohnpei|near 4N158E. By the following morning the circulation, located 165 miles south-southeast of Pohnpei, gained enough strength to become Tropical Depression 07w. |The depression drifted around to the southwest of Kosrae for a few days eventually|becoming a tropical storm on the morning of the 9th. On the night of the 9th Tropical Storm Dolphin passed 50 miles west of Kosrae. Scatterometer data indicate that much of the stronger winds remained west of Kosrae, however winds did gust to 37 mph on the morning of the 10th. | On the morning of the 10th Tropical Storm Dolphin passed 15 miles west of Pingelap. During the late afternoon of the 10th Dolphin passed within 20 miles of Mokil.

On the morning of the 11th, Dolphin passed about 155 miles east of Pohnpei.|Despite being this far away from the center of the tropical storm, rain bands|passed across the island. From the 9th through the 12th 23.73 inches of rain fell on the island with 15.26 inches of rain falling in one day, the 10th. Gusty winds were also associated with the rainbands with a gust to 55 mph being reported on the afternoon of the 11th.

Dolhpin moved north of Pohnpei and traveled westward. On the morning of the 13th, Dolphin became a typhoon as it was 350 miles east-northeast of Weno Chuuk.

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, May 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 2026-09-24. Each event’s entry at NCEI: 596418.