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Mesoscale Convective Vortex migrates from southern Arizona to southeast California

By Scott Bachmeier •

5-minute GOES-18 daytime True Color RGB and Nighttime Microphysics RGB images, from 0901 UTC on 16 July to 2301 UTC on 18 July [click to play MP4 animation]

5-minute PACUS Sector GOES-18 (GOES-West) daytime True Color RGB and Nighttime Microphysics RGB images created using Geo2Grid (above) revealed the cyclonic circulation of a Mesoscale Convective Vortex (MCV) that migrated west-northwestward across southern Arizona into southeast California (not far south of the California/Nevada border) during the 2-day period from 16 July to 18 July 2025. This MCV emerged from a dissipating cluster of thunderstorms over far southeast Arizona after about 0900 UTC on 16 July — and was moving through an environment of enhanced moisture and instability that was favorable for additional convective development.

This MCV was highlighted in NWS/WPC Mesoscale Precipitation Discussions on 16 July, 17 July and 18 July — since this middle-tropospheric feature was helping to force the development of new thunderstorms, further enhancing flash flooding risks in the vicinity of the MCV.

GOES-18 Shortwave Infrared images visualized using RealEarth (below) included outlines of the numerous Flash Flood Watches/Advisories/Warnings that were issued as the MCV propagated from southern Arizona to southeast California.

5-minute GOES-18 Shortwave Infrared images with overlays of Flash Flood Watch (darker green), Flash Flood Advisory (lighter green) and Flash Flood Warning (red) outlines, from 0601 UTC on 16 July to 2301 UTC on 18 July [click to play MP4 animation]

Categories: Geo2Grid, GOES-18, Heavy rain / flooding, RealEarth, Red-Green-Blue (RGB) images