1991 Western Pacific typhoon season
Typhoon Walt 1991
Typhoon Walt developed a notably symmetrical structure over the western Pacific in May 1991. Its eye later expanded during an eyewall replacement cycle before the storm turned northeast and merged with a midlatitude cyclone.
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161 mph
May 12, 1991 during the tropical stage
Full archive record, including non-tropical stages if present
Along the recorded center positions
STORM HISTORY
May development and a symmetrical core
Walt's precursor formed southeast of the Mariana Islands in early May. The system strengthened over the following days and reached typhoon intensity. By 11 May, it displayed an unusually symmetrical ring of thunderstorms around its eye, characteristics associated with an annular cyclone.
The archive records peak one-minute winds of 140 kt and a minimum pressure of 915 hPa on 12 May. Walt's strongest phase remained over water, with no archived center position over land.
A larger eye before the northeastward turn
Late on 13 May and into 14 May, an outer eyewall replaced the inner one in a process lasting about four hours. The new eye was roughly 65 km across. Walt subsequently turned northeast and weakened.
The storm became extratropical on 17 May and merged with another cyclone northeast of Japan. Its archived track continues through 18 May.
Further reading
QUICK ANSWERS
Walt in brief
What was Typhoon Walt's highest wind speed?
161 mph, the highest one-minute sustained wind in its tropical stage, recorded on May 12, 1991, 06:00 AM UTC.
What category was Typhoon Walt?
Category 5 at its peak on the Saffir–Simpson one-minute wind scale, first reaching Category 5 on May 12, 1991, 03:00 AM UTC. Other agencies classify storms differently.
What was Typhoon Walt's lowest pressure?
915 mb, the minimum central pressure recorded during its tropical stage, on May 12, 1991, 06:00 AM UTC.
When did Typhoon Walt occur?
The archived track runs from May 4, 1991, 12:00 AM UTC to May 18, 1991, 06:00 AM UTC, with the tropical stage from May 6, 1991, 12:00 AM UTC to May 17, 1991, 12:00 AM UTC.
Where did Typhoon Walt form?
In the Western Pacific basin, in the 1991 season. Its first archived position is 4.6°N, 151.9°E on May 4, 1991, 12:00 AM UTC.
Did Typhoon Walt make landfall?
No archived position places Typhoon Walt's center over land, but positions are six-hourly and a brief landfall can fall between them.
METHODOLOGY
Data sources and limitations
The map and summary are generated from NOAA's IBTrACS v04r01 archive. Wind and category use US-agency records; minimum pressure is calculated during the tropical stage, with the archive's pressure source retained. Category 5 refers to the Saffir–Simpson one-minute wind scale; local agencies may use different classifications. Coastlines use Natural Earth's 1:10m land data.
Track distance adds great-circle distances between consecutive observations, excluding gaps over 12 hours. This track has no gaps over 12 hours. The line shows the storm's center, not its size, rainfall or flood extent. Converted wind speeds are rounded to the nearest whole unit.
Archive retrieved
NOAA IBTrACS archive and Field documentation
Sources & methodology