Case Description: 23 January 2019


An intense, organized system is formed from multi-cell interactions


Vigorous convection occurs in less pronounced shear than the prior day. Convective initiation at 14 UTC to the south of the site, while another initiates north of the site at 14:30 that dies out. The southern cell grows and merges at 15:15 with a smaller, trailing cell. A new cell pops up over the site at 16:15 and grows to merge and overtake the growth of the southern system by 17:30. The organized system continues to grow while a smaller cell forms at 17:30 to the northeast of the site and merges with the system by 18:30. Potentially a challenging simulation because of the multi-cell interactions. CAPE values are in the very top third of their ranges (at 15 UTC MUCAPE=3932; MLCAPE=1864 J kg-1).

Available assets

CSAPR2, CSU C-Band data, GOES rapid scan

Unavailable: G1, RELAMPAGO data

Critical period: 14:00–18:00

14:00 System initiates south of the AMF and grows
14:30 System initiates north of the AMF and advects away
16:15 System initiates over the AMF
16:45 The system grows and merges with the now-large southern system
17:15 A system has initiated north of the merged cells
18:00 It has grown and merged with the southern system; a large system advects in from the southwest
Brightness temperature, 2019-01-23 17:30 UTC

Figure 8 GOES16 band 13 brightness temperature at 2019-01-23 at 17:30 UTC. An intense, organized system over the site, which resulted from the merging of two systems. Another cell is developing to the northeast of the site that later merges with the system.

Available LES ensemble members

Table 8 Summary of LES cloud behavior for 2019-01-23


Ensemble Member

Cloud Behavior



Initiation lags 2 h and has poor morphology–overdevelops to some extent.



Unobserved extensive convection to the northeast of the domain with far saller convective cells within the domain than observed. The pre-storm environment in the 6-12 UTC period simulated by D3 gets a giant MCS to the north that is misplaced and sticks around too long, which then disrupts development of the later systems near the AMF that we want to simulate.



No convective initiation south, north, or over the AMF. The southern cell advects in versus being initiated. et a similar pattern of convection at 18:30 UTC, but it is the right answer for the wrong reason.