The synoptic circulation and surface characteristics of 46 convective events occurring over the Huaihe River and Yellow River basins from June to September during 2007-2010 are investigated. The related environmental conditions are classified as dry (10 cases) and moist (36 cases) environments according to whether precipitable water is less than, greater than or equal to 50 mm. The synoptic patterns in dry (moist) environments could be classified into post-trough and rim of subtropical high (pre-trough, post-trough, and rim of subtropical high) patterns. In addition, cases in moist environments are frequently accompanied by warm and moist flow. The pre-trough pattern in moist environments is characterized by various surface systems including a stationary front, inverted trough, cold front, and warm front. The pre-trough pattern occurs frequently in moist environments but does not occur in dry environments among the cases studied here. The convective cases are initialized at the corner of the “S” pattern from the surface to 500 hPa for the rim of subtropical high pattern in both dry and moist environments, but some cases in moist environments occur near the shear lines at low levels. The post-trough pattern occurs frequently in dry environments but rarely in moist environments. The aforementioned analyses show that significant differences exist between dry and moist environmental conditions where severe convective systems occur.