East Asia and Western Pacific METEOROLOGY AND CLIMATE

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and caused severe flood. Local rainfall rates of lOOnim per 24 hours
were sustained during 8-10 August. Fig.l shows the 24h predicted and
observed accumulated rainfall. Both the area and the intensity of the
precipitation were predicted successfully. The area covered by the
predicted rainfall is nearly coincident with the observations. The
predicted maximum value of 24h rainfall is more than 100mm for the last
two days, although it is still less than the
observation.
Case 2: A southwest
vortex formed in the Sichuan
Basin on 14 June 1986. When
a cold front tied with a
Mongolian cyclone reached the
Changjiang valley on 15th, the
vortex moved eastward out of
the Basin and a coastal
cyclone was initiated at the
Changjiang Estuary on 16th.
The precipitation associated
with the vortex and the front
intensified and moved eastward.
A heavy rain belt with a
maximum rate of about 100 mm
per 24 hours occurred over the
north of the middle and lower
reaches of the Changjiang
River. The rain area located at
Northeast China was associated
with the Mongolian cyclone
moving eastward (Fig.2, right).
The corresponding 24-hour
precipitation forecasts are also
shown in Fig.2 (left). As
mentioned above, when the
southwest vortex stayed in
Sichuan east of the Xizang
Plateau (14-15th), the rain
associated with the vortex was
not well predicted. But the
movement and intensification Fig.2. The 24-hour precipitation
of the precipitation are predicted
quite well (15-16th),
diction, 0--observation, a—OOZ
for casts and observation (F—pre-
even though the predicted 14th~OOZ 15th June 1986, b—OOZ
amount of precipitation is not ISth-OOZ 16th June 1986)
as much as that observed.
2. Statistical Evaluation
Thirty weather stations in the middle and east of China are selected as
a base to verify the forecast skill of the model. Three scores, i.e.,threat
score (T), pass over score (PO) and swing with no hit (NH)