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Monsoon moisture and thunderstorms across the Southwest US

By Scott Bachmeier •

GOES-16 Total Precipitable Water product [click to play animation | MP4]

GOES-16 Total Precipitable Water product [click to play animation | MP4]

The GOES-16 Total Precipitable Water product (above) highlighted the northward surge of monsoon moisture across portions of the Southwest US on 25 July 2019. TPW values as high as 2.0-2.1 inches were seen over the California/Arizona border early in the day, and also over far southeastern California and southwestern Arizona later in the day. The TPW value of 1.56 inches as derived from 12 UTC Las Vegas rawinsonde data was a record maximum for 25 July (below), and the TPW value of 1.76 inches at Phoenix was above the 90th percentile of the climatological average for the date.

Plot of Total Precipitable Water climatology for Las Vegas, Nevada [click to enlarge]

Plot of Total Precipitable Water climatology for Las Vegas, Nevada [click to enlarge]

Overlapping GOES-17 (GOES-West) Mesoscale Domain Sectors provided imagery at 30-second intervals from 1445-2100 UTC — and “Red” Visible (0.64 µm) images (below) showed the development of thunderstorms across the region during that period. Many of these storms produced heavy rainfall, prompting the issuance of numerous Flash Flood Warnings in California, Nevada and Arizona (with a Dust Storm Advisory being issued due to thunderstorm outflow in Arizona).

GOES-17

GOES-17 “Red” Visible (0.64 µm) images [click to play MP4 animation]

Categories: GOES-16, GOES-17, Heavy rain / flooding