Case Description: 29 November 2018

Summary

Convective initiation with halted upscale growth

Description

Early-day convection clears out of the region by 14 UTC and a line of convective initiations starts to form roughly along the ridgeline by 16 UTC. Two convective initiations occur very close to the AMF but die out shortly after 18 UTC, presenting a case where the upscale growth halts. Both CAPE values are in the lower third of their ranges (at 15 UTC MUCAPE=1470; MLCAPE=632 J kg^-1).

Available assets

CSAPR2, G1 flight, GOES rapid scan, RELAMPAGO mission (30 soundings), CSU C-Band data

Critical period: 17:00–19:00

00 Two convective initiations over and south of site that grow
15 Growth abruptly stops and cells advect away while dissipating
00 Some remnants merge with a cell residing at the south of the D4 domain

Brightness temperature, 2018-11-29 18 UTC — Figure 3 GOES16 band 13 brightness temperature at 2018-11-29 at 18:00 UTC. The system of interest initiates over the AMF site starting at 16 UTC but the upscale growth halts and the system dies out. The system south of the AMF starting at 33°S is not of interest as it is just at the edge of the CASPR2 domain.

Available LES ensemble members

Table 3 Summary of LES cloud behavior for 2018-11-29
Impression	Ensemble Member	Cloud Behavior
Bust	GEFS00	Does not get convective initiation around the AMF, only at the outer southern edge of the domain.
Bust	GEFS03	Essentially no initiation. LES CSI Skill a third of the meso value.
Acceptable	GEFS09	Initiation displaced a bit south, but morphs pretty well. Model lingers too long after the critical period with okay CSI Skill of 0.3. (Does not have the errant northern system that the respective meso run has.)