Case Description: 19 December 2018


Convective initiation and growth over site within a complicated background field


Convection early during the day persists around the region, potentially complicating model initialization, before the convective initiation over the site at 15 UTC. The system develops until 17:30 UTC after which it decays. CAPE values are in the lower third of their ranges (at 16 UTC MUCAPE=1096; MLCAPE=532 J kg-1).

Available assets

CSAPR2, CSU C-Band data

Unavailable: GOES rapid scan, G1, RELAMPAGO data (RELAMPAGO’s last mission was on 16-Dec)

Critical period: 15:00–19:30

15:00 System initiates over AMF and grows
15:30 Another initiates to the north
16:15 Systems have merged
17:30 Largest size has been attained and dissipation begins
19:30 System has dissipated while advecting out of domain
Brightness temperature, 2018-12-19 17:30 UTC

Figure 6 GOES16 band 13 brightness temperature at 2018-12-19 at 17:30 UTC. System of interest near its peak development.

Available LES ensemble members

Table 6 Summary of LES cloud behavior for 2018-12-19


Ensemble Member

Cloud Behavior



Severe underprediction of convective area. CSK Skill only a fraction of that for the respective meso run.



CSK Skill double that of respective meso run but with convective area that is much broader than observed, over extending to the west and far east of observed area.



Initiates northwest behind the ridge and moves in to initiate cell over the AMF while the transition in the observations is from the southwest. About 16:15, a northern cell has developed in the observations to match that in the simulation that had propagated in.