Meiyu is the main rainy season in the middle and lower reaches of the Yangtze River basin. However, the mechanism and predictability of atypical Meiyu are not clear. In 2022, an atypical “hot-and-dry” Meiyu occurred in the lower Yangtze River basin (LYRB). By taking the 2022 dry Meiyu as an example, causes of the atypical Meiyu are diagnosed from the perspective of subseasonal evolution, and its predictability is further evaluated with ECMWF and CFSv2 forecast models. The 2022 atypical Meiyu featured an early onset and a three-stage back-and-forth swing through LYRB, with two sudden meridional rainband shifts: a southward withdrawal in early June and a northward leap in late June respectively. Influenced by the active phases of the Boreal Summer Intraseasonal Oscillation (BSISO) and the “Cold Vortex-Heat Dome” (CVHD) pattern in northern East Asia, the Meiyu rainband was suppressed and retreated southward to South China in early June. A northwestward expansion of WPSH and an abrupt northward leap of the rainband terminated Meiyu near early July due to a sudden northward displacement of the East Asian summer westerly jet and the BSISO2-modulated anomalous cyclone in the subtropics. Two eastward-propagating intraseasonal wave trains along the polar front and subtropical westerly jets played crucial roles in triggering the CVHD pattern and forming an enormous upper-tropospheric anomalous anticyclone over western East Asia, responsible for the jet displacement. Both ECMWF and CFSv2 models exhibited lower prediction skills on extratropical ISOs than tropical ISOs. The models well predicted the rainband position in the first and third stages, but overestimated the LYRB rainfall in the second stage, which was caused by poor representation of the two intraseasonal wave trains and the CVHD pattern. These results highlight the cooperative effects of tropical and extratropical intraseasonal variabilities on atypical Meiyu events.梅雨是长江中下游的主要雨季，然而相较于传统梅雨，非典型梅雨的机理和可预测性仍不清楚。本文以2022年长江下游发生的“干热”梅雨为例，分析了其成因并评估了业务模式的预测效果。2022年入梅偏早，雨带呈“先退后进”的三阶段季节内摆动，在长江下游停留短而形成干梅。本文进一步分析了北半球夏季季节内振荡（BSISO）、沿极锋急流和副热带急流的两支东传次季节波列和东亚“冷涡-热穹”（CV-HD）模态等次季节因子在不同阶段及雨带两次跳跃中的作用。ECMWF和CFSv2模式对阶段二的雨带位置预测有较大偏差，因而高估了梅雨量，这主要与模式对中高纬次季节波列和CV-HD模态的预测能力较差有关。以上结果突显了热带和热带外次季节变率对非典型梅雨事件的协同影响作用。