Abstract:
Short-duration heavy rainfall (SDHR) is one of the types of severe convective weather. Located on the coast of East China, Zhejiang Province experiences frequent SDHR events during summer. To improve the forecasting capability for SDHR in Zhejiang, this study utilizes hour rain gauge data from national and regional meteorological stations in Zhejiang Province, ERA5 reanalysis and fine-grid numerical forecast products during June to August from 2010 to 2023. First, the distribution characteristics of environmental parameters prior to the occurrence of SDHR are analyzed. Then, the forecast predictors are optimized using point-biserial correlation analysis. Finally, a potential forecast model for summer short-duration heavy rainfall in Zhejiang Province is established based on the naive Bayesian method, and the model is evaluated under different weather patterns. The results show that: (1) Convective available potential energy (CAPE), precipitable water (PWAT), lower-level relative humidity (RH
700 and RH
850), lower-level specific humidity (q
700 and q
850), and mid-to-lower level vertical wind shear (SHR
03 and SHR
06) are optimal predictors for SDHR in Zhejiang Province. Before the occurrence of SDHR, the median values of CAPE, PWAT, RH
700, RH
850, q
700, q
850, SHR
03 and SHR
06 are 738 J·kg
-1, 56.7 mm, 79.8%, 86.1%, 9.5 g·kg
-1, 14.8 g·kg
-1, 6 m·s
-1 and 7 m·s
-1, respectively. (2) The model was tested and evaluated for short-duration heavy rainfall events in Zhejiang Province from June to August 2023. The
POD at lead times of 3 h, 6 h, and 12 h is 94.9%, 91.6% and 90.5% respectively, and the
TS are 58.4%, 64.0% and 58.2%, indicating that the potential forecast model has reasonable applicability for forecasting SDHR events. (3) For the Meiyu-front-type, subtropical-high-edge-type, and upper-level-trough-type short-duration heavy rainfall events in the summer of 2023, the model achieves a
POD of 95% at all lead times, with a
MAR below 8% for these three types. For the subtropical-high-controlled-type heavy rainfall event, the
POD reaches 80%. These results demonstrate that the model provides useful indications for the potential forecasting of SDHR under different weather patterns and has good application value.