“The miscellaneous synoptic forcings in the four-day widespread extreme rainfall event over North China in July 2023” by Yin et al.

In the present work, the persistent heavy rainfall event during the period from 29 July to 2 August 2023 (“23·7” event) was examined, focusing on synoptic forcings. Special attention was paid to an inclined vertical distribution on the western boundary was figured out, except for the remnant vortex originating from typhoon Doksuri(2305) and tropical storm Khanun(2306). Although previous studies considered the influence of the western Pacific subtropical high (WPSH) on heavy rainfall over north China, little has been documented on a tilted western boundary of WPSH. Interestingly, warm-dry cap overhead associated with the WPSH explains well the absence of convection and rainfall along the western boundary of WPSH. Overall, this study broadens the horizon of extreme precipitation in North China.

The study is well-designed and clearly organized, making it both interesting and relevant. Prediction of extreme rainfalls is an important field with significant implications for public safety. I would like to recommend publishing this paper in NHESS after addressing the relatively minor comments and clarifications below.

Specific comments:

(1) Although wind bars are given in Fig. 2, it is still hard to get low-level jet(s). It is recommended to draw the contour lines of wind speed or color the wind bars with wind speed for low-level jets.

(2) Lines 240-243: “The shift moments (roughly marked by thick black lines) are near at 0800 UTC 31, 2000 UTC 30, and 1600 UTC 30 July for the MTG, YX, and XT regions, respectively”. Why wind shift occurred at different moments? It is necessary to indicate the difference in the weather system during these two periods.

(3) Line 434: “this precipitation was mainly dominated by warm cloud processes (Fig. 14).” The result is derived from the simulation. Can similar structural features be observed from radar observations?

(4) Since terrain plays an important role in the precipitation, it is recommended to take terrain over 1000 m into account in the three-dimensional diagram (i.e., Fig. 15).

(5) Technical comments: Please consider adjusting your reference list with the manuscript preparation guidelines of NHESS.

In this study, authors examined the convective initiation and subsequent persistent heavy rainfall over North China during the period from 29 July to 2 August 2023 with station observation data and WRF model simulations. From observations, it is found that the rainfall was featured by long duration and widespread coverage but low intensity, like a warm front rainfall. Further analyses based on the WRF model simulations show that this persistent precipitation was caused by a combination of a remnant vortex originating from typhoon Doksuri(2305), the tropical storm Khanun(2306), the west Pacific subtropical high (WPSH) with an unusual westward extension of the northwestern corner, and stable cold dry air from over northern China. These results are important for understanding the reasons of this extreme precipitation event occurring over North China. But there are some flaws in the manuscript which are needed to improve. The comments are as follows:

1.In the title of the manuscript, “miscellaneous synoptic forcings” is not reasonable. Actually authors only analyzed the remnant vortex originating from typhoon Doksuri(2305), the tropical storm Khanun(2306), the west Pacific subtropical high (WPSH) with an unusual westward extension of the northwestern corner, and stable cold dry air from over northern China. These factors are only the synoptic circulation patterns, not “forcings”;

2.Line 67：”such large-scale weather conditions”, what is such large-scale weather conditions? It is not clear;

3.Line 74：“surface rainfall”，surface should be deleted;

4.Line 85：“emerged in this precipitation”，probably there is something wrong in this sentence;

5.Line 101-103：”The spatial distribution of heavy rainfalls is consistent with the orography of the Yanshan Mountains on the north and the Taihang Mountains on the south, suggesting that the heavy rainfall may be associated with the orography.” Generally speaking, the spatial distribution of heavy rainfalls is consistent with the orography, but for this event, there are only three heavy rainfall centers near MTG、YX and XT, they are not distributed with Yanshan and Taihang Mountains;

6.Is Xiangtai (XT) right? It seems Xingtai(XT);

7.How to identify the wind direction in Figure 2?

8.Line 139-142：“One can see that the large-scale flow patterns exhibited a coexistence of a remnant vortex originating from typhoon Doksuri(2305) and tropical storm Khanun(2306). The former weakened significantly into a vortex at this time, while the latter was in the rapid development stage.” It is known from this sentence that tropical storm Khanun(2306) is in the rapid development stage, so the circulation associated with tropical storm Khanun(2306) is not remnant vortex.

9.In the caption of Fig. 6, (a-d) observed and (e-h) simulated daily rainfall are not consistent with that in the text;

10.The caption of Figure 7: How many stations/grid points over the (a, d) MTG, (b,e) YX, and (c,f) XT regions used to draw these figures?

11.Line 240-241：Based on the wind profile and rainfall features, the simulated rainfall is roughly divided into two stages？What is the rationale to divide the precipitation into two stages? For this event, the rainfall belt moved from south to north with the Typhoon Doksuri movement, so it can not be divided into two stages;

12.Line 353-354：”Consequently, the rainfall intensity is increased, compared to those in the first stage (Figs. 7d,e). The weak convections may be attributed to ……”，rainfall intensity increase is inconsistent with the weak convections;

13.The sub-title of Part 4 “Characteristics of the rainfall event” is not reasonable. The contents of this part are only physical quantity diagnoses, not related to the miscellaneous synoptic forcings.