Based on hourly observations of wind field at Nanyue Mountain station between April and June from 2005 to 2013, conventional
sounding data, rainfall data from automatic weather station and 2.5 °×2.5° global reanalysis data from NCEP/NCAR, we analyze the representativeness
of data collected at the Nanyue station to the atmospheric general circulation field in the lower troposphere and the indicative
function of the evolution characteristics of wind field at the station to heavy rain over Northern Jiangxi in flood season. Main results are as follows.
(1) The most significant correlation (correlation coefficient 0.72-0.78) between daily wind at the Nanyue station and daily 850 hPa wind
field from NCEP, locates around Nanyue Mountain, in which the wind has a good indicative function to the local wind field at 850 hPa. The
average correlation coefficient (0.75) is higher between wind at the station and 850 hPa wind field from NCEP than that (0.68) between wind at
the station and 925 hPa wind field from NCEP, which proves that wind at the station is much closer to local wind field at 850 hPa. (2) The
closer (farther) the distance between a sounding station and the Nanyue station is, the better (worse) the correlation of various meteorological
elements between them is, which further confirms the above conclusions. (3) In flood season, when there is southwest wind at Nanyue station
and corresponding shear index, the probability of heavy rain over Northern Jiangxi within 24 h reaches 89.8%. When the above criteria are
met and after the wind at the Nanyue station changes from other direction (weak southwest wind) to southwest direction (strong southwest
wind) from 20:00 BT of the current day to 08:00 BT next day, we can forecast heavy rain over Northern Jiangxi within 4-18 h (10 hours on average).
After the occurrence of heavy rain over Northern Jiangxi, the severe precipitation area starts to shift southwards and moves eastwards
after 1-3 h when wind at the Nanyue station changes from southwest direction sustained to northerly direction. Then, it shifts southwards or
moves eastwards out of Northern Jiangxi within 6-17 h (10.5 hours on average).