A four-dimensional variational Doppler radar analysis system (VDRAS) has be
rn developed and implemented at a weather forecast office to produce real-t
ime boundary layer wind and temperature analyses using WSR-88D radar data.
This paper describes significant changes made to convert VDRAS from a resea
rch tool to a real-rime analysis system and presents results of low-level w
ind and temperature analysis using operational radar data. In order to prod
uce continuous analyses with time. VDRAS was implemented with a cycling pro
cedure. in which the analysis from the previous cycle is used as a first gu
ess and background for the next cycle. Other enhancements in this real-time
system include direct assimilation of data on constant elevation angle lev
els. addition of mesonet observations. inclusion of an analysis background
term. and continuous updating of lateral boundary conditions.
An observed case of a line of storms and strong outflow is used to examine
the performance of the real-rime analysis system and its sensitivity to var
ious system changes. The quality of the analysis for this case is examined
by comparing the subsequent 90-min forecast with the observed radial veloci
ty. It is shown that the forecast initialized using the VDRAS analysis outp
erforms persistence and a forecast using a mesoscale analysis. The accuracy
of the retrieved wind in six convective cases is also verified against aut
omated weather reports from commercial aircraft data. The verification show
s an average difference of 3.3 m s(-1) over these six cases.