The physical quantities and their indices relative to heavy rain occurred in Linxia of Gansu were summarized． Based on surface
and aerological observations and T213 data，the physical quantities at each meteorological station in Linxia were accounted by triangular
interpolation method，and a physical quantity diagnostic integration forecasting model about heavy － rain in Linxia was established．
And the model has the certain forecasting ability to heavy rain in Linxia．

Using the observations of cloud and precipitation from July to September during 1900 － 2009 in Linxia，the statistical character
about the parochial cloud and its relation with rainfall in midsummer in Linxia was analyzed，and the instruction relation about the
parochial cloud at Linxia observation station to territorial rain weather and turning weather process was summarized． Results show that
the primary period in which the yellow steamed bread cloud was observed is from the last ten － day of July to the first ten － day of September，
and occurrence of the yellow steamed bread cloud could indicate it would rain in 24 or 48 hours，the probability of moderate
rain is biggish． The yellow steamed bread cloud occurring at Linxia observation station has well instruction significance to rain weather
and turning weather process in Linxia．

A heavy rain occurred in the eastern edge of Tibetan Plateau during August 25 － 26 of 2007 resulted in serious disaster． The
weather system and vapour transportation was analyzed by using NCEP( 1° × 1°) data，and then the PV theory was used to study the
mechanism of the heavy rain． The results show that the strong vapour transportation in the edge of the subtropical high and vapour convergence
over the rainstorm area was the important reason for the rainstorm occurrence． The strong instability before the rainstorm provided
benefit thermal condition． The northwest cold low trough had not obvious sign on the pressure field in the course of the rainstorm，
which only formed a weak wind shear near the rainstorm area，and it had small effect on this heavy rain． But the 325 K isentropic surface
had obvious indicating meaning for the rainstorm occurrence，when the cold air with higher PV value slided down to the low level
along the steep isentropic surface，the vertical vorticity increased rapidly because of the conservation of PV，as a result，the heavy rain occurred．