Case Description: 22 January 2019

Summary

Two intense systems develop next to each other

Description

Relatively calm background until isolated convective initiation over the site at 19:15 UTC with rapid growth into an intense system. A secondary cell initiates at 20:45 UTC that develops adjacent to the existing system until both systems start to decay by the end of the day. Strong shear is present. CAPE values are in the top third of their ranges (at 20 UTC MUCAPE=3420; MLCAPE=2920 J kg^-1).

Available assets

CSAPR2, CSU C-Band data

Unavailable: GOES rapid scan, G1, RELAMPAGO data

Critical period: 19:15–22:15

15 Initiation over AMF and grows
45 Second system initiates just south of the system
15 Both systems have matured in parallel

Brightness temperature, 2019-01-22 21:45 UTC — Figure 7 GOES16 band 13 brightness temperature at 2019-01-22 at 21:45 UTC. Two intense systems develop next to each other.

Available LES ensemble members

Table 7 Summary of LES cloud behavior for 2019-01-22
Impression	Ensemble Member	Cloud Behavior
Poor	EDA00-Morr	Model initiates 0.5 h early and immediately grows into a forked pattern by 20:30 UTC versus the cohesive system observed, which is also composed of underdeveloped convection.
Dud	GEFS01	Initiates late by 1.5 h and underdevelops.
Poor	GEFS18	Initiates 1 h late and underdevelops. It does get some of the forked pattern by 21:15 UTC. The main issue is the simulated cells are shifted northward.
Marginal	GEFS18-Morr	Initiation timing good and just a tad north. Misses the rapid upscale development from 19:15 to 20:45 UTC, being seriously underdeveloped at 20:15. Model development catches up to observed by 21:30, showing the development of a second cell forming a forked pattern with a slight northward displacement. At 22:30, shows the 3-forked pattern, albeit slightly displaced eastward and with an errant cell just south of the AMF. After that, the simulated systems start moving east while the observed systems mostly stay put.