Vertical Helicity Analysis on the First Rainstorm of the Rainy Season in Hubei in 2009

The heavy rainfall event occured over Hubei Province from 28 to 30 June 2009 was studied with the NCEP 1.0x1.0 FNL operational global analysis data and automatic rainfall station data by means of vertical helicity analysis. The results indicated that there exists close relationship between vertical helicity and strong precipitation period and heavy rainfall area. The combination of the gradient large value areas of vertical helicity at 700 hPa level and the energy frontal zone of ∑θse(500+700+850) would provide with good indicative significance for the 6 hours heavy rainfall areas. The heavy precipitation was generated where exists the positive vertical helicity center at low-level and negative vertical helicity center at high-level,vertical in the lower level slightly higher than the negative helicity,the center is more conducive to produce heavy rain.