Case Description: 29 January 2019


An intense case like January 22nd that has similar CAPE but less shear


Very calm background until multiple convective initiations form at 17:15 UTC in a line south of the site. They grow and merge into an intense system by 18:30; by then another cell has also developed to the northeast of the site. Both systems grow, but the one closest to the site grows larger and more quickly such that the other starts to wane by 20:45. CAPE values are in the top third of their ranges (at 15 UTC MUCAPE=3226; MLCAPE=2356 J kg-1).

Available assets

CSAPR2, CSU C-Band data, GOES rapid scan

Unavailable: G1, RELAMPAGO data

Critical period: 17:15–22:30

17:15 Two systems initiate south of the AMF
18:00 While they grow and merge, another system has initiated to the northeast of the site
20:00 The large system continues to grow in parallel with the system northeast of the site
22:30 The large system has overtaken the one to the northeast to generate a single, big system
Brightness temperature, 2019-01-29 18:30 UTC

Figure 10 GOES16 band 13 brightness temperature at 2019-01-29 at 18:30 UTC. An intense system has formed over the site from the merging of multiple convective initiations. A system to the northeast has formed that later gives way to the faster growing system nearest the site that becomes an intense, organized system.

Available LES ensemble members

Table 10 Summary of LES cloud behavior for 2019-01-29


Ensemble Member

Cloud Behavior



Convective initiation late by 1 h. Misses northeast cell and underdevelops other big system over the AMF with a weak 2-cell pattern.



Good initiation and initial growth from 17:15 to 18 UTC. After that, the morphology starts to depart from observed with simulations taking on a more elongated shape compared to the more compact/blobular shapes in the observations and the convection over the AMF being errantly connected westward behind the ridge. Convection is about the right place at 19 UTC but lacks a distinct northeast cell. The main cell over the AMF is underdeveloped at 20 UTC. Eventually produces the large MCS by 22 UTC, but with an errant cell to the north. (Simulation is run but not released yet.)



Good timing and location of convective initiation, but it underdevelops and the northeast system is missed entirely.



Initiates 1 h early. By 18:30 UTC, the northeast cell is missing and the main cell over the AMF is very underdeveloped, having a sheared pattern compared to the more circular pattern seen in the obs. The simulation catches up to the observed by 22 UTC, both having large MCSs with excellent overlap, but this is a case of the right answer for the wrong reason.