Jebi (T1821)

RSMC Tokyo - Typhoon Center
Japan Meteorological Agency

1Outline of Jebi••••Jebi (T1821) formed in the sea north of Micronesia in late August.
It reached its peak intensity with 105 kt and 915 hPa.
Jebi made landfall in western part of Japan, holding intensity of very strong TY.
It was the first time in 25 years since 1993 that a very strong TY landed in Japan.
[Circle]6 hourly position

992[Circle with number]
Position at 00UTC

982

Number: Day[TC grade ]976

TYSTSTSTD or L
Other950
940
935915915 955 990
10001008 hPa

2

Impact of Jebi
• Jebi brought strong wind, storm surgeand heavy rain in western and easternJapan, having left 14 people dead andmore than 900 people injured.
• A significant storm surge caused by Jebiin the Osaka Bay inundated the KansaiInternational Airport. The airport
suspended service for three days.
Wind at 2km
estimated byDopplerradar

https://www9.nhk.or.jp/nw9/digest/2018/09/0905.html

Kansai International Airport and port facilities wereseriously damaged due to storm surge.

Sea level anomaly at OsakaObservation

Storm surge
modelfrom press release of MRI/JMA3

Track and atmospheric conditions•••

Jebi slowly moved westward along the southern edge of the dominant Pacific High.
As the Pacific High gradually weakened, it gradually turned to the north.
It moved northward under the influence of the upper trough that moved eastward
while deepening.
Geopotential height and vorticity field at 500 hPa

Track of Jebi

movingnorthward
movingwestward
Graduallyturning tothe north4

Intensity change and atmosphericand ocean conditions
Maximum
Velocity
Upper-levelDivergence
VerticalWind Shear•
Divergence(*10e-6/s)

Velocity and shear(kt)Landfall••

Weak vertical shear
Clear upper-level divergence
High Sea Surface Temperature(SST)High Tropical Cyclone Heat Potential(TCHP)

SST（℃)

TCHP(KJ/cm2)

SST

TCHP

Jebi continued to develop well overthe sea south of Japan and reached
its peak intensity with violent TY.
It subsequently landed in Japan,
holding intensity of very strong TY
without significantly weakening.
Atmospheric and ocean
environment fields were in goodcondition for the development oftropical cyclones as follows, mainly
during the development period.

•In addition, SST was 28 ℃ or morejust before landing, contributing to
the maintenance of its intensity.
5Track and Intensity forecast• Forecast accuracy for Jebi was higher than the average forecast accuracy of all
named TCs in 2018 in both track and intensity.

Accuracy of track forecast

Accuracy of intensity forecast

6Forecasts on landfall• Forecasts for Jebi were fairly good for both track and intensity, even when itslandfall was focused.
3days before landfall

2days before landfall

85kt945hPa

85kt
945hPaAnalysis just before landfall

1day before landfall

85kt
945hPa85kt
950hPa7

Forecast issued 3 days before landfall
Track forecast
Maximum wind (kt)Intensity forecast
LandfallBest Track
RSMC
TIFS

Date (MM/DD)••Best Track
RSMC
ECMWF
JMA
NCEP
UKMO
EJNU

••

The track forecast by RSMC was slightly east
compared to the Best Track.
This is because that the track prediction results ofthe global NWPs of each organization had slightlydifferent in both course and speed, and manymodels predicted a course from the east to theBest Track.
The intensity forecast by RSMC predicted theintensity and trend of changes close to the BestTrack.
This is because the intensity forecast guidance TIFS
(Typhoon Intensity Forecast scheme based onSHIPS) used as the base of the forecast made agood prediction.
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Forecast issued 2 days before landfall
Track forecast
Maximum wind (kt)Intensity forecast
LandfallBest Track
RSMC
TIFS

Date (MM/DD)Best Track
RSMC
ECMWF
JMANCEPUKMO
EJNU• The variation of the global NWPs of eachorganization had become smaller, and the
RSMC track forecast had approached theBest Track.
• The intensity forecast by RSMC continued
to be as good as because the TIFS
prediction.

9Forecast issued 1 day before landfall
Track forecast
Maximum wind (kt)Intensity forecast
LandfallBest Track
RSMC
TIFS

Date (MM/DD)Best Track
track
RSMC
ECMWF
JMANCEPUKMO
EJNU• The variation of the global NWPs of eachorganization had become much smaller,
and the RSMC track forecast were muchcloser to the best track.
• The intensity forecast by RSMC continued
to be good, making up for the slightlyunderestimated TIFS.

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Summary• Jebi made landfall in western part of Japan, holding
intensity of very strong TY at the first time in 25 years
since 1993.
• It brought strong winds, storm surges, and heavy rainsto the western and eastern part of Japan, causing
serious damage such as inundation of KansaiInternational Airport and damage to buildings, mainlyin the Kansai region.
• Forecasts for Jebi were fairly good for both track andintensity, even when its landfall was focused.

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