Based on the conventional data of Micaps and Doppler radar data，the rain to heavy snowfall event occurred in Langfang from 31 October to 1 November 2009 has been analyzed．The results show that the major influencing system of this heavy snowfall was the 500 hPa trough，wind shear line at the level of 700 hPa and 850 hPa，the inverse trough at ground level．And this snowstorm weather was a typical backflow over north China process．Vapor transportation from Bohai was the important source of steam for this snowfall．The strong convergence at the lower level resulted in strong ascending motion．The rise of the height of warm advection and echo tops would be one of criterions for snow enhancement．According to the echo characteristics of Doppler radar in Beijing，after 1－2 hours of the height of the 0℃layer bright band decreases quickly，it could be concluded that rainfall weather would change into snowfall weather in Langfang of Hebei Province．

Abstract:Results from the data of meteorological disasters in 2008 in Langfang show that the torrential rain and flood disasters are the
most damageable．From 1949 to 2007，the direct economic losses caused by the torrential rain and flood disasters are 198．673 billion，
which are 82．2%of those caused by all the meteorological disasters．The sustainable development of national and local economic is
significantly affected by the torrential rain and flood disasters．Based on the system theories and principles of natural disasters evaluation，8 indexes are calculated，including topographic index(H)，intensity(C)and frequency(R)index of the torrential rain and lood disasters，onomical disaster bearing capacity index(E)，economic loss index(E')，life vulnerability index(L)，life damage ndex(L')and disaster relief index(K)，respectively．Combined disaster index were obtained for each county after systematically assessed the regional differences in risks of the torrential rain and flood disasters in Langfang，and 4 grades(extremely high，high，medium and low)were used to divide the torrential rain and flood disasters．Studies on the division of the torrential rain and flood disasters an provide us scientific basis for the precaution of the torrential rain and flood disasters and reduction of their economic losses and taking effective measures to these disasters．

According to the date of thunderstorm-day from1968 to 2007 and lightning disaster statistics data from 1998 to 2007 in Langfang, combined with its economic status and population density, vulnerability analysis, evaluation and vulnerability division of lightning disaster aremade. Four indices are selected to evaluate the vulnerability of lightning disaster in Langfang, including annual mean thunderstorm days (M), lightning disaster frequency (R), economic vulnerabilitymodule(D), economic lossmodulu(D), vital vulnerabilitymodule(L) and life and injurymodulus (L’). Based on them, the vulnerability assessmentstructure of thunderstorm disasters in each counties ofLangfang are given. Then, the vulnerability assessment indices of thunderstorm disasters are classified as five gradeswith given values. The comprehensives vulnerability assessment indices of these nine counties are also graded as corresponding five degrees. Finally, vulnerability division of the lighting disaster is obtained based on the vulnerability degree values of the nine counties in Langfang. The result shows thatKaifaqu and Guangyang districtbelong to themaximal damageable area, Xianghe county, Bazhou city, Sanhe city, AncidisrictandGu’an county belong to the high damageable area.The restcounties belong to themedium dam-
ageable area. Scientific basismightbe provided for the planning of regionalprevention and reduction of lightning disaster in Langfang.

Using NCEP 1⁰x 1⁰ reanaLyzed data, a heavy rain process occurred in south seacoast of Zhejiang province caused by the eaStfy  Wave On f}LIgLISt 3-4 In Z}}f  WaS anafyZed, 1nCflldlng 1tS eVOflltlOn and the  CaLISe Of CyCfOn1C  VOrteX enlarged  by the eaStfy  Wave Wlth  Q  VCCtOT  d1VCTgenCe.  MeanWhlfe,  the  pTOCCSS  WaS  Slmllfated  by  MMSVZ  m0(fef.  RCSLIftS  SNOW  that  the  deVefOplng  Of  Center lntenSlty  and  pOSltlOn  Of  Q  VCCtOT  d1VCTgenCe  maXlmlnn  TeffeCted  the  heavy  Taln  arid  the  enlarging  Of  CyCfOn1C  VOTteX,  arid  the fOTCCaStlng 1S  mOTe  aCCLITate than that Of  MMS  m0(fef,  SO  COmhlnlng Q  VCCtOT d1VCTgenCe  arid  MMS  m0(fef  Can Offer the  mOTe  COTTCCt weather forecast in similar to this weather process.